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Why do Modern People have so few Children?
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Lesley Newson
Lesley Newson
is a honorary post-doc at University of California, Davis. She studies the cultural evolutionary process known as “modernization” which most human populations are now experiencing.

If you’re reading this article, you probably believe that Darwinian theory can shed light on human behaviour. And you probably think that this article is going to be an account of how the theory can explain yet more of the puzzling choices that humans make.

I’m afraid not. This article is about a mystery that Darwinian theory has no ready answer for – at least not yet. It’s the mystery of our own reproductive choices. Darwinists have had a good deal of success convincing the general public that evolutionary theory can provide a means of gaining an understanding of their own behaviour. But we do this by weaving tissue-paper thin scraps of argument to hide the trunk and tusks of the beast in the room.

Why are we producing so few children?

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At a superficial level, it isn’t puzzling. Each of us can give our own reasons for not producing a large number of children. For one thing, the kind of effort that would be necessary to raise a large family would leave us little effort to spare for learning about Darwinian theory and reading articles like this.

But we Darwinists aren’t satisfied with superficial explanations so it’s time we discussed this. Today’s humans are able to access vastly more resources than our ancestors but we choose to devote them to purposes and activities that don’t enhance our fitness. Let’s face it; over the courser of our lives we invest a relatively small proportion of our time and effort producing and raising offspring or helping our close relatives raise theirs. Our ancestors, or at least most of them, were different; all of them had at least one child that survived to reproduce and many of them succeeded in raising large families in conditions that we can barely imagine surviving. According to one of the basic tenets of Darwin’s theory, we should have inherited the characteristics associated with this reproductive success. So what drove them to put so much effort into producing children and why haven’t we inherited it? Perhaps you have a theory. If so, please share it in the comments.

The desire to mate seems to be an important driver of reproduction in many non-human animals. They aren’t motivated to produce offspring, just to pursue a set of behaviours that resulted in their ancestors’ genes being passed on to them. Human behaviour suggests we also experience desire to mate – but it is unlikely to be a very important driver of reproduction in humans. It doesn’t fit with our reproductive biology or our behaviour.

Raising a human from conception to independence requires an enormous amount of parenting effort, more than can be provided by its mother alone or its mother and father working together (Hrdy 2009). Conceiving a child when support isn’t available would have been very detrimental to fitness. It follows from this that an uncontrollable desire to mate would have been strongly selected against, certainly in females. Every human population that has been studied has rules which establish responsibilities of parents and their supporters. These rules strongly influence who reproduces and when they reproduce. It’s impossible to know the extent to which our ancestors actually obeyed those rules. No doubt reproductive norm compliance varied from population-to-population, from time-to-time and from individual-to-individual but it’s likely that the most successful people were people like us – people who obeyed most of the rules most of the time.

Our own experience of being human tells us that we’re motivated to pursue goals that seem within our reach and worthy of our effort. Except for the last few generations, our ancestors behaved as if they believed that raising children, as many as possible, was a worthy goal, a top priority. Most young adults today don’t believe this. Why not? What has changed?

Well, many things have changed in the last couple of centuries and this has given social scientists scope to propose many possible “solutions” to the mysterious decline in human fertility. Here is a sample of the explanations offered:

  • There was no birth control technology then.
  • Women were oppressed then and were forced to have babies.
  • Religion taught that it was people’s duty to have many children.
  • They needed children to work on the farm and to support them in their old age.
  • They expected many of their children to die in infancy or childhood.

The problem with these explanations is that they’re uninformed by Darwinian theory and by the facts gathered by historians and anthropologists studying how people in high fertility populations really behave and what was really going on in different populations when their fertility began to decline. For more information about this, future articles will explore these topics:

  • How people in high fertility populations behave.
  • The transition to low fertility reproductive behaviour.

Amongst this information must be some clues that will help us to develop testable hypotheses to explain the revolution in human reproductive behaviour that has occurred in the last 200 years.

We need hypotheses that are consistent with Darwinian theory. Those of us who take a Darwinian approach are able to appreciate an important thing about this revolution that most social scientists haven’t recognized: It results in humans starting to make extraordinarily altruistic choices while believing that we’re selfishly following our best interests.

This altruism has had severe fitness costs and differences in the timing of a population’s change of mind about family size have shaped modern history. The new altruism first began to take hold in the people of France toward the end of the 18th century, more than two generations earlier than the rest of Europe (Coale and Watkins 1986). In the middle of the 18th century France’s prospects seemed similar to those of England. Her farms were becoming more efficient and her traders and artisans were finding new ways creating wealth. Her scientists and intellectuals were second to none. And her colonial empire included substantial parts of North America as well as the Caribbean, Africa and South Asia.

By and large, life started to become easier for ordinary Europeans during the 18th century and, in the rest of Europe, people took advantage of this new prosperity. Families boasting of more than eight surviving children were not uncommon. But they were much less common in France. We know this in part because of the research that Jean-Baptiste Moheau (2000) did in his spare time while working as private secretary to the provincial governor in the port city of La Rochelle in South West France. He collected data on births, marriages and deaths and in 1778, when only 30, Moheau published a pamphlet entitled “Recherches et considérations sur la population de la France” (“Empirical Studies on the Population of France and Their Interpretation”). His work revealed that in parts of France fewer children were being born and more dying in infancy. He makes his feelings about this clear in his conclusion. He mostly blames women:

“…rich women, for whom pleasure is the greatest interest and the sole occupation, are not the only ones who regard the propagation of the species as a dupery of olden times; already the fatal secrets unknown to any animal but man have penetrated in the countryside: nature gets cheated even in the villages.”

The “secrets” he refers to are ways of achieving sexual pleasure without the risk of conceiving a child. He also criticises women who don’t breast-feed their babies as his data revealed that infants not fed by their own mothers suffered higher mortality. Moheau predicts that “if these licentious practices, if these homicidal tastes, spread further, they will be no less fatal to the State than the plagues that devastated it in the past.”

To modern ears, Moheau sounds crazy but, in a way, he had a point, a point, which is amply demonstrated by what followed. The practises and tastes that he complained about did spread through France and, while the rest of Europe enjoyed a population boom, population growth in France stagnated. The industrial revolution was transforming people’s lives and throughout the 19th century as young people from the countryside flooded into the areas where they could get work in factories, mines and construction sites. First Britain and then other Northern European countries became manufacturing powerhouses with vast trading empires – but not France, where there were simply not that many people to employ in industry.

The numbers leaving Europe during the 18th, 19th and first half of the 20th century are staggering.

Many Europeans decided to travel further and colonize new territory, displacing and in some cases subjugating the peoples already living there. The numbers leaving Europe during the 18th, 19th and first half of the 20th century are staggering. It’s been estimated that over two million Spanish went to South and Central America. Nearly a million and a half Portuguese settled in Brazil. South America also became the new home of 1.8 million Austro-Hungarians and 3.7 million Italians. North America received 5 million immigrants from Germany, 3.6 from Poland, 2.7 from Scandinavia, 3.2 from the Austro-Hungary, 5 million from Italy and 2.2 million from Russia. Another 10 million Russians colonized Siberia and Central Asia. But the biggest stream of immigrants came from the two large English-speaking islands off the coast of Europe, Great Britain and Ireland. Thirteen and a half million went to North America and another three million went to southern African and Australia. The fertility and dispersal of people on these two islands goes a long way to explaining why English is now the language of business, diplomacy and science.

The French people’s early adoption of the idea that it’s better to have small families meant that France contributed only a trickle to the river of European immigration. Most North Americans of French ancestry are descended from the few thousand French colonists who settled there in the 17th and 18th centuries.

The great European population expansion (sans France) didn’t last long. By the end of the 19th century small families started to become common in other parts of Europe and, by the 1920s, fertility in many parts of Europe had dropped to the same low levels that we see today. And now, less than a hundred years later, the fertility of almost all human populations is as low as that of Europeans or falling rapidly.

Why have humans stopped competing for fitness? It’s hardly scientific to say that we should stop worrying about why it’s happening and just congratulate our species for being sensible and realizing that failing to curb population growth will be our downfall. And besides, congratulations are hardly in order. As our production of offspring has waned, our production and consumption of many other things has rocketed. Over the last century, the populations that produced the fewest children consumed by far the largest chunk of the world’s resources.

Low fertility alone isn’t going to protect the planet from human desecration but our species’ sudden abandonment of competition for fitness has had other effects. Only a hundred years ago, Europeans were sending their young men off to fight and die for the right of their leaders to claim territory for their nation. In demographic terms, it’s a reasonable thing to do. If populations are expanding, new territory is needed. Records show that most Europeans living at the time did see the First World War as reasonable. The population was still rising rapidly. Many couples had decided to limit the size of their family but there were a lot of reproductive age couples producing offspring. After the war, the idea of family limitation continued to spread and the number of reproductive age couples declined.

Meanwhile, another idea began to spread among Europeans: that military might does not give one people the right to claim ownership of territory occupied by another people. They did fight another huge war and have had a few military skirmishes but the idea has now really taken hold. Most of today’s Europeans have trouble believing that their antecedents could have been so immoral. Most of us believe we must share the planet, not only with other humans but with other species too.

Sharing the territory that we think of as “our own” is not so popular. A lot of Westerners are unhappy about people moving to their country from poorer, less secure parts of the world. These immigrants mostly come from places where the human population had boomed in the 20th century. Like Europeans a few generations earlier, the children of that boom are dispersing and attempting to colonize new territory. Luckily for them, Western countries created many unfilled niches for them to occupy. Despite the brief and tiny “baby boom” that some populations experienced in the 1950s and early 60s, Western couples produced so few children that the economies of many countries in Europe and North American grew much faster than the population. As a result, there were potentially many more jobs than native Westerners to fill them. Some of the immigrants have been highly educated or skilled but many weren’t and they eagerly took unskilled jobs that natives were unwilling to do for the wages being offered.

As they enhance the lifestyle of the natives of their new country, immigrants enhance their own fitness, raising families in the West and often setting aside part of their earnings to help support their relatives back home. This fitness boost has only been temporary, however. Most immigrants to the West arrive with, or soon adopt, the belief that it’s prudent to only have a small number of children. And in their countries of origin, fertility is now low or falling rapidly. According to United Nations estimates (http://esa.un.org/wpp/unpp/panel_indicators.htm), fertility in the Philippines is now at less than three children per women, down from over seven in the 1960s. Fertility in Mexico and Bangladesh, which peaked at nearly seven in the late 1970s, has now plummeted to just over two. Only in some parts of Sub-Saharan Africa is fertility remaining high.

Without a doubt, life is more comfortable for people who have smaller families. And once people no longer compete for fitness they can strive for sporting or artistic accolades or higher degrees, good jobs and getting papers into Science or Nature. Or they can just take it easy and watch TV. Women need no longer spend the prime years of their lives being pregnant and lactating. Marriage no longer needs to be a longterm reproductive partnership. It can just be the joining together of two people who get pleasure out of being together. If it stops being pleasurable, divorce is possible. And those who decide to have a couple of kids can afford to make their childhood fun and to educate them to increase their chances of having a comfortable and interesting life too.

A person not trained in Darwinian theory might think that the real mystery is why humans took so long to work out that it’s a good idea to have fewer children – or no children at all if times are tough. For Darwinists it’s no mystery. People in the past did get the idea – after all it’s not a hard idea to get. But for the most part, the people who chose that easier life are not our ancestors. Our ancestors were mostly the ones who kept on reproducing and out-competed the ones who had few or no children.

Something kept our ancestors’ noses to the fitness grindstone and whatever it is either didn’t get passed on to us or is ineffective in today’s environment. Because of this, human life today is very different from that of our ancestors and it is continuing to change rapidly. If evolutionary theory is be of real help in understanding our present behaviour and what our future might hold, we need to get a grip on what it is.

So what is it? Please place your ideas below. Or, if you think the question should continue to be ignored, tell us why.

Literature cited

Coale, A. J. and S. C. Watkins (1986). The Decline of Fertility in Europe. Princeton, N.J., Princeton University Press.

Hrdy, S. B. (2009). Mothers and Others: The evolutionary origins of mutual understanding. Cambridge, MA, Harvard University Press.

Moheau, J.-B. (2000). “Jean-Baptiste Moheau on the moral causes of diminished fertility.” Population and Development Review 26(4): 821-826.

 

61 Comments

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61 Comments

  1. Toe says:

    I think “Predictability” of the modern environment makes the difference. When we bear children, it’s very unlikely that the children would die because of the lack of food, diseases or predations. So for middle class family, bearing children as few as possible, but with all the best qualities parents could provide will ensure genetic legacy. In the families that lack basic needs or face predation problems , the optimal number of children would be as many as possible. The same goes for rich families where best quality cares should be easily and equally available for all children. I predict families in upper and lower-classes would significantly bear more children than those in middle class.

  2. Lesley Newson says:

    Can I suggest both a theoretical and an evidence-based argument in hopes of convincing you that the apparent predictability of the modern environment is not the solution to the mystery. First the theoretical argument: Given that it is very costly to produce a human baby, natural selection would not favour the behaviour of producing many babies during times when the risk of the babies dying is especially high. Those who produced fewer children and invested more parental care would have greater reproductive success. On the other hand, producing offspring rapidly during times when conditions are predictable and risk low is a behaviour that natural selection IS likely to favour. Second, the empirical argument: We know a considerable amount about the conditions that existed when various populations experienced the fertility decline. It has not been found that fertility decline occurs as the conditions for raising children becomes more predictable.

    • Toe says:

      You are right that “predictability” of the environment is not the solution to the mystery. I only mentioned that it makes the differences, and the factor might be one of the solutions. For the theoretical point you made on natural selection, natural selection also operates under r and k selection based on predictability of the environment. To maximize the fitness in a risky environment, it is “better” to reproduce as many and as quickly as possible (r selection). The genetic legacy maintains via a few (not all) of the offsprings. Hence my argument sounds counterintuitive. The fertility rate is declining worldwide. Yet the developing countries worldwide still have higher fertility rates and higher number of childbirths. May be “they” do not have better access to birth controls, compared to more developed nations.
      link to ourworldindata.org
      link to worldfamilymap.org
      Maternal and child mortality rates are high in nations like Africa. However, when we consider natural selection, the context of relative mortality rates must be considered within their environment, not with developed nations.
      May I also get the article or the study on the empirical arguments that you made.

      • Lesley Newson says:

        Toe, The fertility decline began in Europe long several generations before the introduction of new birth control technology. The timing and conditions of decline have been well studied by historical demographers. A good place to start is Coale, A. J., and S. C. Watkins. The Decline of Fertility in Europe. Princeton, N.J.: Princeton University Press, 1986. I am currently writing another piece of TVOL looking at this.

    • Bruce says:

      First, thank-you for such a nicely written statement of the problem, and invitation to contribute.
      And, second, there is a sound, evolutionary mechanism suggesting that greater predictability in the survival of children could, in well-identified circumstances, lead to smaller sibling sets. In two sentences, if a young couple’s aim is a completed family of a certain size and perhaps gender composition — there being a variety of social and economic pre-modern circumstances in which this might be the case — and if the if the risk of childhood mortality is high and unpredictable, then they will over-produce children. As predictability of offspring survival increases say with better sanitation and medical practice, family size will fall, again as a matter of fitness. The necessary assumptions and mathematical details are worked out here [Leslie, P. W., & Winterhalder, B. 2002. Demographic consequences of unpredictability in fertility outcomes. American Journal of Human Biology, 14, 168-183] and here [Winterhalder, B., & Leslie, P. W. 2002. Risk-sensitive fertility: The variance compensation hypothesis. Evolution and Human Behavior, 23, 59-82]. Empirically, it remains an open question how large a role, if any, this particular mechanism had in any particular case, but it does give the issue of predictability raised by Toe some theoretical cover.

      • Lesley Newson says:

        Thanks Bruce, you are right of course – but also right about it leaving more to explained. The most important thing to be explained is why a young couple might set themselves a limit on how many children to have. They may limit their own reproductive success it they could maximize their fitness by helping to raise sibs etc. Also, ethnographic evidence suggests that people in natural fertility populations did not have a family size “goal”. They were puzzled when health workers asked how many children they wanted. As the demographers used to say, they perceived it as “outside the realm of conscious choice”.

        • Lesley Newson says:

          I mean that natural fertility populations that have been studied don’t provide evidence that a target family size is common. That doesn’t mean that such societies don’t or can’t exist. John Knodel’s studies with birth and death records of 14 German villages showed that during the 19th century couples began to act like they had adopted a target family size. Women who had lost children due to illness or accident continued to give birth to children into their 40s but women who had not lost children began to stop child-bearing in their 30s.

  3. Jona says:

    You’re over-analysing the situation. Human reproduction has little in common with animals, the latter being driven by instinct and food supply versus by intellect and choice.

    If intelligent and responsible, humans make complex and refined choices, and the reason any person or couple chooses to spawn or not is a matter of personal preference.
    The ignorant humans who recklessly spawn freely don’t make a good choice except to be irresponsible: they dump the problems of their excessive reproduction on the rest of us through social welfare.

    Smart people make informed choices and are responsible; lesser humans don’t, and aren’t: closer to animal behavior. Simple.

    • Tor says:

      I sense some and ignorance & hatred in your comment. You cannot divide humans between lesser and smarter humans. We are part of nature. First “Smart” people are also the ones who have been causing global warming and animal extinctions on a massive level. Secondly, even ” smart” people eat, reproduce and die. Some of the natural forces may undergo under unconscious decisions and mechanisms. And by that I do not mean we should not be responsible.

  4. David says:

    It’s a great question. And a puzzler for sure.

    The first thing that occurs to me in searching for a Darwinian explanation here is that one may not exist. What we may be looking for is an existing Darwinian based behavioral structure to understand an epiphenomenal or emergent property that is, in fact, non-adaptive. It is hard, after all, to argue population decreases as adaptive.

    Obviously, this has happened over too short a period for much consideration to be given to genetic evolution, which, of course, leaves culture. I haven’t given this problem any previous thought, but my hunch is that the explanation involves status. People today don’t want to have large families because it interferes with pursuits they consider to be more important. The main pursuit of most first world people is advancing their status, position, and importance. I have plenty more to say on this, but if it is true, the question then becomes: is there an adaptive purpose to the pursuit of status.

    That answer seems an obvious yes. Only recently has it resulted in lower birthrates. There is also a posible adaptive purpose based on group fitness. Groups without entrenched status systems may not fare as well as those that have one. Group selection would have fed back to individual genetic selection to have created the type of status systems of post agricultural life.

    However, I favor a slightly different explanation that paints modern incarnations of status systems more as a result of a mismatch between the small scale cooperation of the EEA and the large-scale, complex, industrial cooperation we engage today. Again, I have more to say on this, but will spare you for now.

    Whatever the cause, the result is that we are more interested in status (individual advancement) than having lots of kids. This might well prove to be a non-adaptive behavior, but in the short run, it has made for some powerful nations.

    There is also this: Today, kids are an expense. They used to be an asset. There’s a simple Darwinian explanation for an animal able to choose how to maximize their personal resources.

    Thanks for the question. If anyone out there is thinking about status, please give me a shout.

  5. Lesley Newson says:

    David, Are you saying that a Darwinian explanation doesn’t exist or that Darwinists will never be able to agree on one? I believe that a high priority should be given to thinking about and discussing this because if we do find the answer it will be important to understanding the behaviour of people living today. I see our situation as being a bit like that of physicists at the end of the 19th century. Newtonian mechanics was doing a good job of explaining everything except for a few pesky anomalies, like the results of the Michelson–Morley experiment and the things that Röntgen, Becquerel and the Curies were seeing with X-rays. Modern low fertility is a pesky anomaly but it is also important. Understanding it will give us a better understanding of the evolution (genetic and cultural) of human behaviour.
    Your suggestion about status is interesting but it is so hard to define in the complicated modern world. We are all part of several social groups. What it is that “status” attaches to, the group or the individual? Experiments in social psychology suggest that people who identify strongly with a group that is regarded as low status don’t regard it as “low” (although they may pretend to when interviewed by non-group members). Susan Watkins makes an interesting point about the fertility of different social groups in early modern Europe. Diaries and birth records reveal that children of upper class landowners often didn’t marry and have children because they didn’t inherit sufficient capital to give them the income to provide their offspring with an upper class lifestyle. The children of the “lower status” tradesman and artisans therefore enjoyed much greater reproductive success.

    • David says:

      Hi Lesley,

      Thanks again for the question and for your reply.

      When you ask about whether a Darwinian explanation exists, I would answer that, yes, in a broad sense a Darwinian explanation ALWAYS exists. Everything that happens to life on the planet ultimately comes down to a Darwinian explanation, so to speak, since there is no other way that things can occur.

      But this is different than saying it is adaptive. Will populations with lower birth rates somehow ultimately lead that DNA to replicate more successfully than populations with a higher birth rate? Maybe so, maybe not. What I was saying is that lower birth rates may not be adaptive at all.

      But whatever the reason, we can be somewhat confident that it is not something genetic that has changed in these last few hundred years. The assumption is that this low birth rate phenomenon is due to genetics that were established a long, long time before birth rates slowed. So, yes it’s Darwinian in the sense that everything is, but since this phenomenon is not likely something that represents a selection process acting directly on this behavioral trait, we might best look at it as epiphenomenal.

      When I look at anecdotal evidence among the people I know, one thing I see is that people don’t want to make the sacrifices involved in having more kids, or any kids at all. They are busy focusing on themselves. One of the big things the people I know and see are doing is working hard to get ahead. Kids take time and energy and money.

      Why do people work to get ahead? I can argue that the answer generally comes back to social position (status). It can be measured in any way you like, and is in fact calculated in a nearly infinite number of ways. The most common is income, power, and possessions, but it is also computed by athletic achievement, number of countries traveled, amount of philanthropy done, speed of a guitar solo, or how beautiful a cake you can make for your child’s birthday party.

      For this discussion it doesn’t matter how status is sought, but only that it keeps us very busy developing skills. I’m not saying that riding your bike across France can’t be fun. I’m only saying that we are driven to push harder, practice longer, and pedal further by a sense of competition buried deep in our psyches.

      Why is this sense of competition buried deep in us? My guess is that is part adaptive behavior and part a neurotic result due to a mismatch in our primitive genes and the modern world in which we live.

      I think we tend to suffer today from a lack of feeling important and included. We are driven hard by our primitive biology to insure our inclusion in a group. We only know that we have achieved this when we receive continuous direct feedback from the people that we depend on that they similarly depend upon us. This is how we made sure that we were not in danger of being excluded and sent out to fend on our own, or in other words, to die. This was critical to our survival. Those that did have a strong dose of this drive didn’t have descendants. And we all still feel this need.

      But we have, for the most part, dissolved the small groups from which we were designed to obtain this needed feedback in favor of complex cooperation in very large, industrialized populations. Most jobs and lifestyles do not provide anything near the daily feedback we need to confirm our importance, inclusion, and safety. The natural, genetic response is to work harder to insure our inclusion and gain this feedback. But it is simply not very available anymore. THIS is the common source of our general neurosis and a lot of our suffering.

      This drive to work harder to earn inclusion by making ourselves more important is generally mistaken for a drive for status, but it’s actually something different. It is really a more fundamental need to be feel part of a group. For humans, inclusion comes first, since we could not survive without it in the EEA. Position within the group (actual status) logically comes after that. Status is gravy. Inclusion is the real meal.

      So, it may be that we have less kids because we are too busy with what feels to be an even more pressing need. Of course, we know in our minds that we are not actually in danger of being sent into a primitive environment alone. But our minds can not easily overcome this very deep drive. The implications of this mismatch are many, and lower birth rates may be one of then.

      I hope this makes sense and better explains what I meant.

      Thanks again.

      • David says:

        Oops I made a typo. In the 9th paragraph, the sentence should have read:
        Those that DIDN’T have a strong dose of this drive didn’t have descendants.

      • Lesley Newson says:

        You and I see the problem in similar ways but I am more optimistic – thinking that we might be able to find out why humans used to strive for fitness and now don’t. I agree that it isn’t adaptive to produce few or no children. But I think that some mechanism that used to operate to make us strive for fitness is failing to operate nowadays and I believe that it is worth thinking about it because working out what happened to this mechanism will help us to understand how people learn to direct their efforts.
        I love your idea that “This drive to work harder to earn inclusion by making ourselves more important is generally mistaken for a drive for status, but it’s actually something different. It is really a more fundamental need to be feel part of a group.” I agree completely. Have you read Archaeology of the Mind by Jak Panksepp? (link to amazon.co.uk). He argues for the existence of an emotion he calls “seeking” which all mammals experience. I would see this being behind what you call the evolved drive to strive for something. Animals learn what to strive for by discovering what relieves discomfort (i.e. drinking relieves thirst so if you feel thirst you strive to get water).
        As it always the case with humans, social learning plays an important role. We learn from others what is good to drink and eat to satisfy our physiological cravings.
        But social animals like humans also feel psychological discomfort at being alone and unsupported. Young humans must learn how to fit in so as to relieve the uncomfortable feelings associated with being alone and unsupported. They need to be part of a group but face the problem that nowadays there are many different conflicting groups they can be part of. Inevitably fitting in is a complicated problem.
        I am probably simplifying Panksepp far too much in saying that he sees depression in part as insufficient seeking emotion but this makes sense to me. When we don’t know how to relieve our discomfort we can’t direct our efforts. Perhaps in these cases it’s best to just down-regulate the “seeking” emotion. Natural variation might make some people less driven and so more likely to give up.

      • David Trombka says:

        I think the greatest difficulty with this conversation is the marriage of the problem to the premise that evolution MUST be strictly Darwinian. If anything, Lamarckian evolution is making a strong comeback, showing that not all life patterns or lifestyles need be explained by Darwinain explanations. Epigentics, CRISPR technology and more are chiefly Lamarckian and, especially regarding epigenetics, MUST be incorporated into this discussion. Beyond that, though, for those that still insist on a stricly Darwinian perspective, the quality of the environment must also be discussed. The industrial revolution brought without a general lowering of reproductive fitness which continues throughout our day – witness the continuing downward trend of sperm quality and quanitity in men of the industrial world.

  6. Kay says:

    What about the classic quantity vs. quality life history strategy? In unpredictable environments (e.g. high predation rates, stochastic resource environment, etc.) where offspring survival is unpredictable, the strategy is to produce more but lower quality offspring. In more predictable environments, he more favorable strategy is to produce fewer and higher quality offspring. Also, in environments where resources required for producing high quality offspring are expensive, a smaller brood size is favorable. In the modern world, human offspring survival is more predictable, but ensuring high quality offspring, I.e offspring that can live high quality lives and more likely add to the lineage, is expensive. In the modern world, food (which is abundant in the western world) is not the resource that determines quality, but other resources such as good healthcare, high quality education, exposure to different experiences that enrich the mind, etc. which are expensive are predictors of higher fitness. So it appears to make Darwinian sense that in a modernized world, families choose to have smaller brood sizes, whereas in less fortunate countries where resources and healthcare are unpredictable and expensive, families chooses larger brood sizes. That’s my evolutionary understanding of it.
    And I do think human behavior can be understood by understanding evolution. I don’t accept that Darwinina theory cannot explain it. It’s just that for some behaviors we still have not figured out the puzzle; it does not mean that the puzzle cannot be solved.

    • Lesley Newson says:

      Kay, I am saying the same thing as you, I believe that there is an explanation that is compatible with Darwinian theory. I just don’t think the the quality/quantity trade off does it. If we define quality biologically in terms of reproductive success, rather than some culturally-defined sign of success (e.g. a nice house or a well-paid job) then higher quality, especially in females is associated with earlier reproduction and less education. If we say that humans evolved to track cultural signs of success rather than reproductive success, then we have the problem of explaining why culture has changed (and continues to change) so dramatically and so rapidly over the last few generations.

  7. Edward Korber says:

    What role do you believe r and k theories of selection might play in providing reasoned accounts of modern observation of decline in some communities and continued growth in others throughout the world?

    • Lesley Newson says:

      Edward, Look further up in the comments and you will find discussion on that. I used to think that was the case but when I looked into it the evidence and did some research myself I found that not one had been able to shoe that smaller numbers of children lead to more grandchildren.

      • Frank Price says:

        Lesley, you say you have found no one who has been able to show smaller numbers of children lead to more grandchildren. Do you know of any published articles testing the hypothesis?

        • Lesley Newson says:

          Goodman, Anna, Ilona Koupil, and David W. Lawson. “Low Fertility Increases Descendant Socioeconomic Position but Reduces Long-Term Fitness in a Modern Post-Industrial Society.” Proceedings of the Royal Society B 29 August 2012 (2012).
          Kaplan, Hillard, Jane B. Lancaster, J. Bock, and S. Johnson. “Does Observed Fertility Maximize Fitness among New Mexico Men? A Test of an Optimality Model and a New Theory of Parental Investment in the Embodied Capital of Offspring.” Human Nature 6 (1995): 325-60.

  8. John Strate says:

    It’s a puzzle for sure. Perhaps EP has an answer. Sexual reproduction exists as an adaptation to parasites. In the ancestral environment as today, some children were naturally healthy, others not so healthy. In the ancestral environment, many of the not so healthy died. That’s not as true today. I’ve not a clue, but perhaps women’s fertility norms are locally based (acquired from their sisters, friends). They are looking at their own cohort reference group and comparing their number of healthy children to the average for the reference group. It’s a bit like the Red Queen. I’ll just try to do as well or a little bit better than those in my reference group. Whatever fertility might be in Kenya, Gaza, or other places is not part of their consciousness or their fertility decisions.

    • Lesley Newson says:

      Edward, Look further up in the comments and you will find discussion on that. I used to think that was the case but when I looked into it the evidence and did some research myself I found that not one had been able to shoe that smaller numbers of children lead to more grandchildren.

    • Lesley Newson says:

      John, I think that the low fertility of people all around her plays a role in explaining why women continue to have low fertility. The question is, how did it begin? Why does the change form high fertility to low fertility happen? This change is going on right now in many parts of the world.

  9. John Pearse says:

    Excellent article and discussion. My wife and I are both biologists and we interpret the world in Darwinian terms. But we had only one child (now 41 and an evolutionary biologist). My wife was simply enthralled with our son from the first day of his birth and had no desire for another. I wanted only one because of concern about overpopulation; it seemed irresponsible to have more (which I still think). But in terms of evolutionary fitness that “should” not be. Great question. I wonder if the answer isn’t embedded in inclusive fitness and an extended kin selection. With the rapid rise in the human population, we are all very closely related, most of our genes are being perpetuated— or is that too close to species selection?

    • Lesley Newson says:

      John, A couple of people have done research trying to test this idea but not found any support. Most recently: Goodman, Anna, Ilona Koupil, and David W. Lawson. “Low Fertility Increases Descendant Socioeconomic Position but Reduces Long-Term Fitness in a Modern Post-Industrial Society.” Proceedings of the Royal Society B 29 August 2012 (2012).

  10. Lesley Newson says:

    Kay, I am saying the same thing as you, I believe that there is an explanation that is compatible with Darwinian theory. I just don’t think the the quality/quantity trade off does it. If we define quality biologically in terms of reproductive success, rather than some culturally-defined sign of success (e.g. a nice house or a well-paid job) then higher quality, especially in females is associated with earlier reproduction and less education. If we say that humans evolved to track cultural signs of success rather than reproductive success, then we have the problem of explaining why culture has changed (and continues to change) so dramatically and so rapidly over the last few generations.

  11. Juan Alfonso says:

    Leslie, congrats for your article.

    Of course there is a darwinian explanation for this phenomenon. The struggle for status plays an important role on this but if we want to find a complete explanation we have to think in terms of cultural evolution.

    Our western economic system is an evolved group of entities that compete for their own form of fitness: consumption. Life on earth struggle to maximize solar radiation utilization. Analogously our economic system tries to maximize consumption by exploiting resources. It has evolved to increase our status-seeking instincts and take advantage of them. Darwinian evolution is short-sighted so it doesnt care if in the process of increasing economic activity it decreases birth rates. This is exactly what happened when women were incorporated into the labor market: consumption, production and tax payment doubled in less than one generation… but birth rates plummeted. The most relevant prices (i.e houses) adjusted (doubled) in this period, so we didnt achieve that much after all.

    On the other hand birth rates vary along the social spectrum. We tend to think that poor uneducated people have more children than rich educated people. That may be right but it doesnt capture all the subtleties of natural selection. Natural selection is based on differential success, and we can find this differential success not only between different social classes but also INSIDE these same social classes. What I am trying to say is that this is not a case of group selection; This is a case of individual selection. Differential success is fractal in the sense that we are able to find differential reproductive success inside every social class and inside every social group.

    We humans compete for social status but we do not compete with all the population. We compete with our peers: we want to keep up with the Joneses. It is not crazy to state that inside every group of western people, the ones who fare better economically tend to raise more children than the ones that arent capable of achieve relative economic success. There you have the reproductive differential success that constitute the spinal cord of the darwinian processes and natural selection. Could it be posible that differential economic success be linked to reproductive success this way?…

    To summarize, we have only a few children because we live in at least two separate darwinian realms: biological and cultural. Economic cultural evolution is short-sighted and favors short term benefits (increases in consumption and production) even if it decreases birth rates what in turn compromises long term economic development. Despite this, differential reproductive success might be intact and even correlate with economic differential success.

    • Lesley Newson says:

      Juan,
      I am interested in what you think of the argument about he considers to be the real nature of status seeking given by David in the comments above.
      Also, what do you think has driven cultural evolution in the same (low fertility) direction in almost all populations over the last 200 years?

      • Juan Alfonso says:

        All populations? I think you mean all industrialised populations… And there you have your answer: industrialization is what happened 200 years ago. But the process started much earlier, in the Neolithic.

        In my opinion David gets it right. Status-seeking is critical for most animals since it increases the appeal towards the opposite sex and, at the same price, the ability to intimidate the rivals of your own sex when competing for food, territories or mates. Thus, status is directly linked to fitness. According to the costly signalling theory, to prove you are worthy of your status you need to get involved in costly behaviors. The point is: what costly behaviors? Humans are different from other animals in that we can choose our ways of signal our status… or those ways can choose us to be signalled!

        But in any case I think here we are failing to aknowledge the distinction between ultimate causation and proximate causation. Humans have never competed over fitness in terms of number offspring in a conscious way; Indeed that is the ultimate goal of our genes, but what our genes really do is promote neural wirings (proximate mechanisms) for preferences and behaviors that correlate with the ultimate goal: in other words, sex precedes births so a drive for sex is what the gene needs if it wants to replicate successfully. Therefore the proximate causation mechanisms need to be the drive for having sex and also the drive for seeking status (which in turn increases the probabilities of having sex with quality mates).

        In our ancestors times we had a lot of ways to advertise our status: helping people (conspicuous filanthropy), fighting enemies, punishing free-riders and social deviants, hunting big game, etc. That worked well for small bands but badly for larger populations. Step by step Veblen´s conspicuous consumption became the best way to advertise status. Why? Because the consumption signal was plain for everyone to see and because it enabled an “arms races” dynamics with no end at sight.

        This kind of “arms races” dynamics produce what economists call “positional externalities” (see “Darwin Economy” by Robert Frank) which consist of the inefficient allocation of resources resulting in overexploitation and/or inequality. Some of these positional externalities could be the loss of leisure time and indirectly the decrease of birth rates. This can happen because having a lot of children has seldom been the signal of status per se. Instead, accumulating a lot of wealth has become the most relevant signal.

        I blame cultural evolution for this. Having children is still the ultimate goal and the proximate goal is still the status-seeking and having sex. However cultural evolution has helped to dissociate proximal goals from ultimate goals in the form of contraceptives and wrong ideas about personal success and self-realization. Cultural evolution was only interested in increasing the economic productivity in the short-term and the best way seems to have been something like this list of comandments: “Produce a lot. Earn as much as you can. Occupy all the time spending, either for pleasure or for exhibiting status. Invest a lot in the few children you have and teach them to keep the cycle going on”.

        May be fitness is doomed simply because sex is free.

        • Lesley Newson says:

          I don’t mean “all industrial populations”. I mean virtually all human populations. Have a look at recent statistics from the United Nations: link to esa.un.org
          If you read David’s further comments above you’ll see that he doesn’t see status seeking as a way of out doing fellow humans in order to get mates etc. He sees it as in fact a desire to fit in – to be seen as an exemplary member of one’s chosen social group. An awful lot of research in social psychology suggests that this is an important driver of behaviour – albeit most of this research has been done on Westerners. The upshot of this is that a woman doesn’t have an expensive pair of high heeled shoes to match every one of her outfits in order to attract mates or to outdo women prefer comfortable shoes. It’s because the kind of woman she sees herself doesn’t feel comfortable unless she go to this sort of trouble to “look right”.
          The problem I have with your “conspicuous consumption” idea is that almost all of us are all having fewer children, the women who wear high heels, the women who write scientific papers and even the women who see themselves as primarily striving to be good mothers. The “good mothers” believe that they cannot be “good” unless they limit their family size.
          I agree with you that cultural evolution is involved. I am interested in the mechanism. I find your suggested a status seeking via conspicuous consumption mechanism unconvincing.

          • Juan Alfonso says:

            Again, Leslie, what you say is related to the fractal and multilevel nature of Natural Selection. The “need” to belong to a social group is related but different from status-seeking. Humans tend to what Jonathan Haidt terms “Groupishness”, that is, the need to form coalitions with unrelated individuals and become part of something bigger than the individual members of the coalition.

            But this doesn´t mean that every member of the coalition is going to reap the same benefits from belonging to the group (even though, belonging to ANY group is ALWAYS better than not belonging to a group at all). Some of the members of a coalition are fitter than the others and produce more for the entire group. A hierarchical status consolidate itself so that individual fitness keeps being differential even INSIDE the coalition.

            By the way, coalitions tend to form precisely to outcompete other coalitions for differential success in fitness, so here we can probably find the struggle for status again; Only it consists of group status now: palaces and cathedrals are the group symbols of status.

            You say “The upshot of this is that a woman doesn’t have an expensive pair of high heeled shoes to match every one of her outfits in order to attract mates or to outdo women prefer comfortable shoes. It’s because the kind of woman she sees herself doesn’t feel comfortable unless she go to this sort of trouble to “look right”.

            May be women don´t buy shoes to outcompete all other women. However they might prefer NOT to have less shoes than their close friends and co-workers. Besides, women have a strong built-in preference for beautiful things and men and women alike have a preference for high status symbols. All industries take advantage of these easily manipulated preferences… and therefore conspicuous consumption follows. Aditionally what you say seems to me like failing to make the distinction between ultimate and proximate explanations. Both explanations are right. What I say (struggle for status through conspicuous consumption) is more “ultimate” and what you say is more “proximate”.

            The important thing is checking if differential success in fitness is still going on in the different geographical and social human niches. If this is the case we shouldn´t be that worried about the decrease of birth rates… at least regarding to the well functioning of Natural Selection. On the other hand, if we see that differential success in fitness is decreased across all domains we should be worried because, as it is said in Jurassic park, Nature always finds its way to keep going.

          • Lesley Newson says:

            Juan, It frustrates me that you say things like “Besides, women have a strong built-in preference for beautiful things and men and women alike have a preference for high status symbols. All industries take advantage of these easily manipulated preferences… and therefore conspicuous consumption follows.” What is the evidence for this? What do you mean “built in”? What do you mean by “beautiful”? And how does something qualify as a “status symbol”. Does the fact that I really don’t want a Porsche mean that my genes are different from those of other people?
            I guess you are saying that if I shared your unsupported opinions, I would see that there is something “ultimate” going on and not worry about “proximate” stuff.
            But consider this: there is a considerable amount of evidence that matriarch or patriarch of a large healthy family was a high status position in many cultures, even in the West until (in evolutionary terms) very recently. Henry the eighth was king for heaven’s sake and what he really wanted was a bunch of sons. Beliefs and desires like these encourage people to strive for fitness. My question is … why did this change?

          • Juan Alfonso says:

            I am afraid I have made myself misunderstood (I blame the idiomatic barrier and the limited length of the answers). That is what has probably made you focus on the least relevant things I said. Sorry if I have offended you or frustrated you in any manner. In any case it is important to leave aside any kind of “politically correct” view of things here (this is ETVOL!). I don´t need to address differences between men and women because in my opinion they are not relevant here at all. Status-seeking is pervasive and extremely important for both sexes whether we like it or not.

            Both men and women are involved in a multilevel competition: those pressures can select for traits as groupishness, love, sharing, friendship, reciprocity, generosity, etc. But also for a drive to show-off because prestige and reputation are really important things when it comes to fitness. One way of signalling status and/or group membership is to exhibit costly markers of various kinds. We humans have flexibility when it comes to “choose” our status symbols. Peacocks have their tails but we can use whatever is at our reach: animal skins, shells, rare bird feathers, costly body paintings and tatoos, risky behaviors, building tools, you name it…

            We are born with some preferences (for things we address as beautiful) and other preferences can be learned and/or modelled. So there are genes and culture (or social learning) involved, not only genes. High heel shoes mean nothing to a Yanomamo girl but they can mean a lot for a young western woman because she has learnt they are associated with a certain status or group memership. Given enough time in a western society even a yanomamo girl could end up appreciating high heel shoes and wishing to wear them. An iPhone-6 means nothing to a yanomamo hunter but it can mean a lot to a young western man. As symbols of status a Yanomamo woman might prefer to have a lot of male sons and a Yanomamo man might prefer to have as many wives (some of them captured) as he can and a reputation for being a brave warrior, what would entitle him to show certain distinctive body markers.

            That is what I am saying: westerners are disproportionately channelling our prestige signals through material stuff. We have abandoned universal symbols of status, as having a lot of children, in favour of conspicuous consumption. One of my unsupported opinions is that cultural evolution is responsible for this. Another unsupported opinion is that low birth rates are a positional externality of this conspicuous consumption .

            I am not an academic and this is a blog so I am expressing my opinions either supported or unsupported. I thought you were looking for a hypothesis here. Hypothesis are unsupported by definition. The only thing that matters is if they are consistent and make sense or they don´t. If they make sense we should find a way to falsate them and so goes the scientific method. Anyway, if you are interested, I am basing my opinions on the works of Amotz Zahavi (“The Handicap Principle”), Geoffrey Miller (“The Mating Mind”), Robert Frank (“The Darwin Economy”), Boyd and Richerson (“Not by genes alone”), Marvin Harris (“Cows, Pigs,…”) and Jonathan Haidt (“The Righteous Mind”).

            Again, sorry if my comments have offended you in anyway.

          • Juan Alfonso says:

            And as for proximate and ultimate causes they are both legitimate and important; Proximate causation always tends to be connected to Ultimate causation. For example: the desire for sex is connected with births. My point is that cultural evolution seems to have dissociated proximate from ultimate. It is an unsupported opinion, all right, but does it make any sense? Shouldn´t it be falsified before ruling it out altogether?…

            Contraceptive methods (and attitudes) have dissociated sex from births. Don´t you agree? Why has this happened? In my opinion it is because companies competed with other companies to increase their benefits faster and faster (one of the conditions for the development of positional externalities)… and eventually faster than demographic growth alone would allow. Governments would collect more taxes so they agreed when it came to encourage women to join the labor market. Don´t you think that contraceptive methods and attitudes facilitated this?

            As a consequence companies and governments almost doubled their revenues in much less than one generation but birth rates plummeted. This is, economic dynamics favoured short-term benefits over long-tern sustainability. Since Darwinian evolution is rather short-sighted this shouldn´t surprise us.

            In any case I think a cultural-biological coevolution perspective could be useful to find answers.

  12. didier says:

    If my life would be harsh and very difficult i would prefer more children to help me, to feel conforted by more other humans. The size of the army has to depend on the might ofvthe enemy. So easy lives = no need to make many children because whe have more enjoyable things to do, such as socialising.

    • Lesley Newson says:

      Darwinian theory predicts that we must be descended from people who had more children when times were good not fewer. I guess you don’t think that Darwinian theory is useful as a means of understanding human behaviour.

      • didier says:

        I’m not an expert in darwinian theory. My guess is the only answer i could come up with.

      • didier says:

        Being rich you don’t have a lot of existensial worries. Poor you’re afraid and looking for help. I’m not an expert in theory but have as much emotions as everyone else. Maybe your theory is wrong.

        • Lesley Newson says:

          I agree with you in as much as I think that the version of evolutionary theory which many scholars are currently applying to human behaviour is too simplistic.

  13. David says:

    Thanks for the link, Lesley. I don’t know that book, but it looks great. The idea that we structure some, if not a lot, of our efforts around relieving discomfort rings true to me. There is obviously a seeking toward pleasure as well, but I’d almost expect an argument that there is no real difference since they are so often two sides of the same coin.

    Thanks for the kind words. I liked that idea about inclusion over status too. I had been thinking of the problem in teams of explanations for status run amok due to the larger populations and massive payoffs in modern society, but as I kept thinking about it, this occurred to me and made more sense.

    I am interested in what you mean when you say we used to strive for fitness and now don’t. I assume you mean adaptive fitness. How would you apply this to your current topic? Would you like to see birth rates rise? And if so, why? Or are more generally interested in how humans can “overcome” deep genetic drives?

    It’s even a more interesting question the more I think about it. The idea of a creature of any kind ever considering whether they “want” offspring strikes me as quite new to the world. I think I may have heard of some instances of animals self-regulting populations, but I am unfamiliar with that. To now find ourselves questioning the fundamental practice that is at the center of all natural selection since the dawn of life is pretty fascinating.

    Since NS has no ability to predict the future, and the process is perfectly happy with any behavior that increases population, it can stumble upon some paths that have more or less future promise. Whatever the previously beneficial suite of mechanisms that has lead some people to have no kids at all, it is possible that, at least in some cases, from a Darwinian POV, it has reached an ironic dead end.

    Personally, in judging human activity and behavior, I put no weight on whether or not it’s adaptive. First of all, we often can’t fully know. But more importantly, my interest is in the quality of our lives. Natural Selection is nothing but a description of the mindless circumstance by which biology happens. It doesn’t care about us, and I feel no obligation at all to adhere to behaviors that seem to conform to maximizing my gene replication.

    Understanding selection is important because it helps us understand what behaviors may be rewarding and which may not. It’s not the only way to inform our understanding about how to live, set policy, and construct social institutions, but it’s often the best. But as soon as it begins to veer from what feels to me like a better path, I think we need to leave it behind.

    With this in mind, my question would become are lower birth rates a good thing or bad? I know I am relieved to hear that the population isn’t growing as fast. I see a lot of our biggest problems due to there being too many people. On a personal level, I suppose I might question whether people I know would be happier with some or more kids. But I find that an impossible question to answer and so I leave it too them. I don’t have any noticeable sense that my friends and family would be be better off with more kids. I might feel a person would be better off if they stopped drinking or worked less, and certainly have hoped for them to find partners, but have never really applied this to the size of their family. So, I can find no reason to want higher birth rates.

    How do you feel about it?

    • Lesley Newson says:

      Panksepp agrees with you on the seeking pleasure thing. I was over simplifying. He sees some emotions as pleasurable (e.g. play, care) and some as uncomfortable (e.g. fear, rage, even lust). And there are also physical states that are uncomfortable (hunger, thirst, cold) and some that are pleasurable (satiety, warming up, being cuddled). You must read his book. It is a revelation to see “play” as a pleasant emotion. He points to evidence that the most sophisticated dog trainers now reward their animals by playing with them rather than giving them a food reward. For humans “play” is of course complicated but think of the pleasure of “playing with ideas” in meetings with like-minded friends and colleagues.
      I don’t want to see birth rates rise but I do think that Westerners need to understand that the problem is no longer too many babies being born. Many countries have the problem that the population of old people is beginning to be too large for the young people to support. This will get much worse in the future.
      One valuable cultural change would be for all people (parents and non-parents) to see the care and raising of children as an important social responsibility. We imagine that our society sees children as important – look at the way we go after paedophiles! But children are seen to be the responsibility of their parents. Darwinian theory might suggest this is “natural” – it is, after all, their reproductive success, not ours. But given the (probably) long history of cooperative childrearing in the hominin line, it really does take a village to raise a child. Our current arrangements in industrialized societies place a terrible burden on parents. They get all kinds of “advice” on how to be “good parents”, advice that untested and often impossible to follow. The children themselves are also often given impossible burdens.
      The idea of judging behaviour based on its “adaptiveness” is not useful. I do think, however, that when we try to analyse or pick apart a set of behaviours it is helpful to remember that the thing that is behaving is an animal with a long evolutionary history. Each human is a product of genetic evolution, cultural evolution and his or her own unique development. The evolutionary story is made more complicated by selection having occurred at more than one level. The incredible cultural changes that humans have experienced in the last 200 years, including the near universal abandonment of striving for fitness, is very important and very interesting. We need to understand it better if our goal as societies is to provide members with better lives.

      • Juan Alfonso says:

        It is important to note that fitness is not equal to number of viable offspring. That is an oversimplification. Natural Selection doesn´t have a criterium as to what is the ideal number of offspring per generation. Natural selection is only “concerned” about differential success. It can work perfectly with as little as generational renewal…

        To say that humans are not striving for fitness anymore might be a hasty conclusion. First we need to prove that differential success due to relevant heritable phenotypic traits has decreased; that the statistical distribution of individual fitness outcomes has a diminished standard deviation, for example. In other words, we would need to prove that everyone tend to have the same number of offspring, being that number 7 or 1.2. My bet is that we will not find such a thing. My bet is that Natural Selection is still at work even though birth rates are relatively low.

        As I said in previous answers competition for fitness could be fractal, this is, present at every level and in every human group. If differential success occurs at this levels then the struggle for fitness is unhampered. The problem to me is that material wealth is not a relevant heritable phenotypic trait and it is conditioning the number of offspring.

        • David says:

          Hi Juan,

          Thanks for the thoughts. I’m not sure I followed it all, but I think you are saying that it is hard to understand how wealth could have come to no longer be proportionally correlated with higher reproductive rates. That seems like the question behind this. I imagine that wealth has generally always been a determinant of birth rates since civilization began. So why is it not any more?

          I appreciate your comment that what matters is differential success. Even if overall populations are shrinking, in fact, especially then, natural selection is operating. The actual rate isn’t the key figure; it’s the relative rate.

          Wealth actually operates in a similar way. It’s not only absolute material wealth that matters to a person’s experience, but relative wealth. A person might feel bad about himself because his yacht is only 100 feet, when the others in the harbor stretch over 200. With this in mind, perhaps what we measure to be wealthy is not experienced this way. Maybe the low reproduction rates are due to the fact that the parents do not feel themselves to be high enough status. Maybe they feel that there is still too much to do before their position is secure. In a giant society with an exceptional communication infrastructure, there may well be an abundance of people bearing absolute wealth that feel insignificant and low on the ladder, and thus have low birth rates.

          Just a thought.

          • Juan Alfonso says:

            That is one way of seeing it. Yes.
            As a meter of fact I think that a lot of psychologic disorders have their roots in this. Think of nervous anorexia: teen girls are constantly exposed to images of extra-beautiful women and also extra-thin. Our self-image is relative to the image of others so may be some girls think they are uglier and fatter tan they really are.

  14. David says:

    I’m not sure Darwinian logic would even say parents are solely responsible for their own kids. Perhaps at first glance, in a similar way that a first glance can not understand the logic of a genuine altruistic emotion toward strangers. Our genes are perfectly happy with any method that gets them replicated. So, I agree; it’s hard to imagine a EEA that does not involve raising kids (and doing most everything else) as a group.

    I think this idea is a critical insight into a Darwinian adaptation to connect and cooperate that runs deep enough to inhibit and override the natural bent toward selfishness that has been the prevailing model in most organisms since life began. While the selfish gene can never be any less “selfish” (if you’ll forgive the anthropomorphic view of chemistry), but simply goes about it business by creating cooperative individuals. We now have a cognitive understanding this, thanks to the students of natural selection. But we have lost our collective felt understanding of this, thanks to the productive efficiency of modern, industrial collaboration.

    It is my belief that in this concept is our salvation. We’re troubled because we are not receiving the feedback we need that assures us that we are securely connected. We are actually still very connected and as dependent upon one another now as ever. We’d still never make it truly on our own. It’s just that now we cooperate in ways that FEEL disconnected. We feel isolated and alienated too often. Our typical social interactions are tainted with too much discomfort and competition, AND NOT NEARLY ENOUGH INTERDEPENDENCE. We need to be needed. The lack of that kind of relating leaves us neurotic and unhappy. We get distressed and cranky when our basic needs are not being met, whether it’s hunger or connection.

    So, yes, I agree. We need a village. And we need to understand who and what we are, and what drives us. If we can satisfy our basic drives, we’ll be a lot happier. And satisfied people don’t need to wake up early and figure out new ways to exploit people and resources more profitably.

    I know I’m pipe dreaming, but I can’t help it. I believe in the power of public opinion. When we celebrate and lust for money and power, we get a society like the one we have. When we value connection, community, and mutually respectful cooperation, we’ll get something else. I for one would like to see what what kind of world that might be.

    When you speak of people not pursuing “fitness,” I’m still a bit confused about what you mean. Darwinian fitness might well have us fighting and competing with each other. But it might also have us stepping past the constant competition and individualization and toward a new, large-scale egalitarian social structure before we use up all the fuel and start blowing each other up. I don’t know which way demonstrates Darwinian fitness (though I have not hid my opinion). What I do know is I’d prefer some shifts in culture that would help us satisfy our drives more fully and easily and have a whole bunch more fun in the process whether we are migrant farmers or Fortune 500 CEOs. That feels like fitness to me.

    Sorry to veer off.

  15. Joanna Bryson says:

    I wrote a very simple model showing adaptive advantage in some contexts to limiting reproduction to when you have sufficient resources, and that the consequence of this strategy in a dynamic environment was periods of sub-replacement-rate levels of reproduction. I haven’t had time to write this up, but you can see me describe & demo the model here: minutes 29-35.5 link to youtube.com
    The basic intuition is that of course as we approach carrying capacity for the planet you expect the average number of viable offspring per woman to be two, but if you want to ensure yours are actually the offspring that survive you may want to postpone reproduction until your adequately resourced. If you do that, then you expose yourself in times of hardship to the possibility of never reproducing, but provided your strategy works better on average your strategy can still outcompete that of those who produce less well-equipped offspring.

  16. Lesley Newson says:

    Hi Joanna, Your model is useful and your explanation of it gets to the nub of the problem. When living organisms reproduce, the offspring often disperse so as not to compete with their parents and siblings. If dispersal is impossible then competition is fierce. What is interesting about humans at the moment is that they aren’t really competing for fitness. Most 19th century Europeans were competing for fitness. They had a technological advantage over other cultures and they were producing offspring rapidly. Many offspring dispersed and young males were willing to fight and die to increase their people’s access to resources. Hence the two world wars. But in the process, we have experienced cultural change and many of us now see “our people” as all humans – humans who are sharing a single limited environment. Europeans may be investing a lot in order to produce offspring that are “competitive” but these offspring are not competitive in the arena of fitness and nor do we want them to be. this seems an astonishing cultural change to me and we need to understand it better.

  17. Lesley Newson says:

    David,
    The site isn’t letting me reply to specific comments any more but this is in response to your latest.
    Public opinion is a hugely important force. It reflects the shared culture of a population but also drives its evolution. If Americans hear that most Americans are in favour of gay marriage they are more likely to begin to question their opposition to it. I think it is important to understand why the pubic changes its opinion. Those of us alive today are experiencing very rapid cultural evolution. Prevailing wisdom suggests that it is sort of driven by technological and economic change but I’m not happy with this. The rapid widespread adoption of the idea that it is prudent to limit family size is one of the surprising changes that seems to have affected or is currently affecting almost all human populations. No one can explain how technological or economic change has caused it. People can tell stories that make sense but they don’t fit the evidence. I am currently writing another article for TVOL about this.
    I guess we can define fitness any way we want but most evolutionary biologists today see it as a technical term related to number of copies of an individual’s genes that are reproduced in subsequent generations (link to en.wikipedia.org).

  18. Scott Storm Carter says:

    Clearly modern society is much more complex than it used to be. True birth rate declined in France prior to birth control, but birth control still is having an effect. Are we searching for the explanation of France or the modern world? Or one that includes both?

    What about such concepts such as “The Disappearing Male” link to vimeo.com

    As far as the discussion on status, there may be something to it. Why do some of us see a Hummer as a status symbol and others of us see a Smart Car as one?

    I suspect you are right Darwin was not completely right, humans are much more complex than most animals.

    What about the affect that many humans are somewhat disconnected from their instincts and others are not?

    What about something as simple as the emotional affect of so many people everywhere? That is clearly changing our behaviors.

  19. Lesley Newson says:

    Whew, thank you, Juan, for clarifying your thoughts. I agree with you whole-heartedly on some things but not on others. Let me just start with one and I would like your opinion on this. I admit to being a little tetchy at your bringing up of the old “proximate/ultimate” distinction. That this distinction continues to be unquestioningly promulgated annoys me given the force of the arguments suggesting that we question it (see Laland, Kevin N., Kim Sterelny, John Odling-Smee, William Hoppitt, and Tobias Uller. “Cause and effect in biology revisited: is Mayr’s proximate-ultimate dichotomy still useful?.” science 334, no. 6062 (2011): 1512-1516.)

    If we agree that two (or perhaps more) interacting evolutionary processes have shaped and continue to shape human behaviour – the evolution of genes and the evolution of culture, then what do with see as the “ultimate” (i.e. evolutionary explanation). You may suggest that some sort of genetically evolved thing is behind it all, but with humans you will end up explaining most human behaviour by talking about the genetically evolved tendency to need to be in groups and rely on social learning to such an extent that groups have an evolving shared culture. This isn’t very useful, I will be back soon to comment on other things you said.

  20. Lesley Newson says:

    Scott,
    Thank you for your comments. Sorry to take so long to respond.
    It wasn’t just the French that began to limit their family size before rubber condoms became available. Most of Europe had low or declining fertility by the 1930s and so did much of the USA, Australia and Canada.
    On your suggestion about the “Disappearing Male”, components of the modern environment may well have affected our ability to conceive children but the main reason for the change is that people simply started wanting to reduce the number of children they conceived.
    It is hard to make a judgment on the degree to which we are connected to our instincts. There is a great deal of debate among scientists about what instincts are exactly. Much of what many people think of as “instinctive” may be learned. It’s quite possible that many of the things that seem “natural” to us may just seem natural because it is what almost everyone around us thinks or does.
    I am not arguing with Darwin, just with the way many people are interpreting Darwin’s insights. His insights were based on what was known about biology during his lifetime. We have learned a great deal more. This new knowledge has entirely supported Darwin’s theory but it has also led to extensions of the theory. The question is over whether these extensions are entirely correct.
    I agree that the modern social environment – the way we are constantly surrounded by strangers and get information by various media rather than through face-to-face interactions is evolutionarily novel. I think that this is very important.
    Thanks again for your interest.
    Lesley

  21. David says:

    Hi Lesley,

    I too am fascinated by the spread of cultural ideas. The overall trend in evolution seems to be toward faster and faster behavioral adaptation, with culture being the fastest transferable mechanism yet available. But since it doesn’t follow the usual path of needing to passed on genetically, it’s a bit of a free agent, which is what makes it so fascinating.

    The role of culture in group selection seems most obvious. But there needs to be selective pressure for any effects to be easily seen. Since we don’t have much of this in the first world, it is possible that non-adaptive behavioral memes–such as smaller families–can propagate based on other benefits they seem to carry. All this continues to return me to my original thoughts that people who are having less children are indeed finding the cost of having them too great. And that cost is the amount of time and energy and money that must come out of our already full schedules and tapped budgets. So the question again is what are we doing that is so important to us that it beats having kids.

    Or, another way to ask the question is what is so great about having kids anyway?

    We did not used to question the idea of having kids. Similarly, we did not consider divorce. Now we do both. This not only allows us the “liberty” of considering these behaviors ourselves, but also creates a new question which we will then typicaly ask ourselves. In this case, do we really want more, or any, kids?

    Just the fact that this question can exist is new. That we can answer it with a no is new as well. Presumably, other animals do not copulate with an idea of the result in mind. This was surely true for humans too, at least to a point. After that point, the reasons to have kids may have been clear. More kids equals a bigger, more defensible tribe, or more hands in the field, or some other tangible advantage. But in a highly specialized cooperative environment, what is the advantage now? Some extra attention when carrying a cute baby? Someone to look after us when we’re old? When could-be parents consider having kids, what images come to their minds as they weigh the pros and cons? Kids do not typically add to the effort of staying alive anymore. While I have personally grown emotionally and intellectually from the experience, is this the reason for having them in the first place, or was it a bonus I didn’t expect?

    My guess is we have as many kids as we do because the social meme still dictates that we do so. Since kids a liability, when measure at the level of the individual agent who makes this decision, I would expect individuals, now faced with the choice, to continue to opt out in greater numbers. Our genes may have “miscalculated” when handing the decision over to us.

    Thanks again for the topic. This is fun.

  22. Holly says:

    Defining offspring quality as that which succeeds negates the concept of the trade-off between quality and quantity. In life-history theory, quality means that more energy is invested in producing/raising the offspring to independence. This is not itself a solution, but it is a description that may help point in a direction. People are placing different kinds of bets on the future now. One idea to pursue might be the reproductive potential of high status males versus females in human cultures.

  23. Jeffrey says:

    I think in B.Russell’s book, “The conquest of Happiness”,he pointed out that during the early part of 20 century, among the upper-class society of UK, great many of them tended to have very few children as compared to middle or lower classes . I think this might be the thing you’re looking for . It certainly made an impression on me , because the rest of the book is about general happiness and this was mentioned as an aside , part of another topic. I personally worry about this topic, because , if the demographics in the Third World continue to decline,the richer countries won’t be able to rely on immigration to prop up there nations. Maybe higher technology will help , but who knows.

  24. Rain says:

    Maybe it’s because the world is over populated and there are not enough natural resources to go around. Perhaps people are finally becoming responsible for their actions.

  25. Pitiklinov says:

    I am with Juan Alfonso,Leslie. The stronger explanation is the disconnection between proximate and ultimate goals causes by culture. To begin with is not true that humans used to strive for fitness and now don’t. They were pursuing proximate goals.
    The pursue of status is a kind of supernatural stimulus (Tinbergen). This used to be associated to reproductive success but is not anymore
    Thank you Leslie for your question an thank you Juan Alfonso for your answer.
    Anyway, we need more investigation here

  26. Donald says:

    The most plausible reason for people having fewer children is simple: advanced birth control means they can do so and still enjoy sex. It is very doubtful that in the past many women wanted to bear all those children. Trying to force a Darwinian explanation when there is a better explanation is a flawed academic exercise.

  27. Robert says:

    The fast improvement of productivity fools the humans to think that we need always less and less workers.

  28. Luseph says:

    After reading this entire mess I realized that a shitpost is a shitpost no matter how many words.

  29. Kevin Pfeiffer says:

    An interesting topic, but your article first needs to be proofread and edited.