It’s been a while since my last update on the Paleo diet (perhaps a better name for it is ‘Post-Neolithic diet’). Here are the links to previous blogs on this theme:
As long-time readers of my blog remember, I switched to Paleo diet in May of 2012. Within two months I noticed an improvement in my health. After half a year I lost 20 pounds and my health improved dramatically. A number of chronic health problems cleared up. At that point, I made the decision to permanently switch to this diet, and I never looked back.
Over the last year I noticed another incremental and slow, but real, improvement. I feel better than when I was 10 years ago. I became noticeably stronger – I can now easily lift and carry things that used to give me trouble before. More embarrassingly, people comment on how well I look. I am getting a bit tired of explaining the Paleo diet, over and over again.
The gospel of Paleo diet is spreading. My wife has converted to it, then my mother. My secretary. Several friends and colleagues. I am not urging anybody to switch, but the results speak for themselves. On the other hand, none of the people whom I infected with Paleo had experienced as great improvement as me. This can be due to my genetics (I have very few generations of Neolithic ancestors). It could also be due to the fact that I am simply not tempted to stray. When I am home, I stay strictly within the guidelines (no grains, no legumes, no dairy). When I travel I periodically get poisoned because I have no control over the ingredients.
Anyway, the real purpose of this blog is to discuss the book I just finished reading, which is very relevant to the Paleo diet (but I thought that an update on my own experience was due). The book is by a colleague of mine, Richard Wrangham: Catching Fire: How Cooking Made Us Human. It’s a great book, and I recommend that everybody interested in human evolution read it.
What I found most interesting in Richard’s book is his reconstruction of the dietary shifts that enabled the evolution of large human brains (which then made possible culture, living in large groups, language, art, science, and civilization – and who knows what else).
The first step, which took place 5-7 million years ago, was the transition from our chimpanzee-like ancestors, forest apes, to australopithecines that inhabited drier savanna-woodlands. Australopithecine brain size (in anthropologese, “cranial capacity”) was 450 cubic cm, compared to 350-400 cm3 in forest apes.
Incidentally, and as an aside, I find slightly amusing, but mostly exasperating, Richard’s dutiful translation of cubic centimeters into cubic inches. Americans, isn’t it time to grow up? Get used to metric units! Does it really help you to know that the cranial capacity of Australopithecus was 27.5 cubic inches? If I show you an object, will you be able to estimate its volume in cubic inches? End of diatribe.
The food resource that enabled this transition was the underground storage parts of plants, highly concentrated sources of energy-rich starch. Parenthetically, that’s why potatoes, yams, carrots, beets, sweet potatoes, and taro are such great foods for humans – we have been eating them, or equivalents, for millions of years. Australopithecines dug these tubers, rhizomes, and corms (we are now speaking ‘botanese’) with sharpened sticks.
The next step was the transition to ‘habilines’ (such as Homo habilis) more than 2 million years ago: from 450 to 612 cm3. The big dietary change that fueled this increase in brain size was probably meat eating. Or marrow eating – see my blog on this issue.
After that, brain size in early human started growing in a really explosive manner. Early Homo erectus (1.8 million years ago) had brains of 870 cm3. 800 thousand years ago Homo heidelbergensis (which could be simply a subspecies of erectus) had brains of 1200 cm3. That’s awfully close to the modern Homo sapiens, whose cranial capacity is 1400 cm3.
Where did the energy that fueled these oversize brains come from? Wrangham argues that it came from cooking. I find his argument quite convincing. Thermal processing of tubers and meats doubles the ability of our guts to extract calories and nutrients from these food sources.
The use of fire is securely attested at the Gesher Benot Ya’akov site near Jordan River, which is dated to 790,000 years ago. But here we have archaeological evidence of hearths, permanent fires around which human nuclear families would gather around every evening for the most important meal of the day. It is quite likely that hearths were a product of long evolution, with humans using fire for cooking well before the evolution of human family (which as Wrangham argues, was itself a result of cooking food – but you will have to read his book to find out the details of the argument).
Even if you buy Wrangham’s theory (which I do), it raises some questions. When did humans learn how to start fires? Remember The Quest for Fire, where the plot centers on this issue?
OK, it’s getting late, so I’d better end this post. But I can’t resist adding one thing. What makes Richard’s arguments particularly compelling is his ‘experimental’ approach to the questions he discusses. He has tried eating like a gorilla (he failed, we simply don’t have the guts for the gorilla diet). Another experiment he tried with his friends was chewing raw goat meat – with or without adding tough leaves. Sure, adding leaves produced better traction to reduce goat’s thigh muscle. But cooking it worked even better.
So what’s the take-home lesson? Fire up that barbecue grill – we evolved to eat meat cooked over the open fire!