Sapiens, pages 12-13: Taco Tuesday

I’m reviewing Sapiens: A Brief History of Humankind by Yuval Noah Harari one page at a time, sometimes two.

We are still in Chapter 1, but I’m feeling a little punchy. I’m kind of dying to get to Chapter 8 (p. 133-159). And then I cannot wait for the bombshell on page 196. But those pages are so far away. And… the only way to get there is to get through the pages before. So… 

One foot in front of the other. It’s taco Tuesday and we’re onto cooking. There is a source! “Beliefs” are conveyed instead of 100% fact-sounding fictions! Let’s get fired up.

Page 12

Okay! Cooking enables us, today, to…

1. eat more kinds of food 

2. devote less time to eating, specifically chewing

3. make do with smaller teeth

4. make do with smaller intestines

And as far as thinking about ancestral hominins goes… as in, what cooking would have enabled for them, as far back as Homo erectus times…

The first seems revolutionary. Cooking would have made more kinds of food digestible and therefore available for consumption. Do we know they were cooking hard to digest things? I don’t believe that cooked starches (from potato-like foods) are preserved for very long in teeth and think it’s only like within the last 50,000 years we might have those things. Here we really understand Harari’s perspective on hunting for so much of the last two million years: there was next to none of it. Well, that’s an opinion, and it’s nicely conservative given how little evidence there is, but (but!) there is still evidence that Homo erectus were hunting (and not necessarily only scavenging). 

And here’s the bigger but. Were they even cooking? Here’s some evidence to suggest they were cooking fish around 800,000 years ago.  The record doesn’t really have much more than that, until we get closer to the present. 

The second seems revolutionary too when he says that chimps spend five hours chewing everyday and we spend up to one. I’m not going to fact check that. I’m sorry but I don’t care. I bet I don’t even spend and hour a day chewing and I buy it that chimps spend more time chewing than I do. Australopiths probably did too. Check out the trees in the A. sediba teeth! 

The third? Well, there is actually a way to look at the evidence for this one. Hominin molars do shrink over the last two million years. Why? We cannot know exactly. Like, someone might describe all the genes that contribute to the phenomenon and even then we wouldn’t know why teeth got smaller. They did though.

The fourth? People have tried to estimate gut size from the shape and size of the pelvis, but it’s not as straight forward as estimating brain size from the space inside the cranial bones. And so, it’s really tough to know gut size of fossil hominins. So it’s not easy to know if the hominins who were cooking were having smaller guts as well. And that’s doubly hard to do because we have so little evidence for cooking until very recently. 

Of course when we see evidence of fire we’d love to imagine it was used for cooking but that’s science fiction. Evidence for hominin control of fire is evidence for hominin control of fire. 

Harari doesn’t even get into the question of how hominins could even think to control fire. It’s fascinating to imagine. I think a lot of people fantasize about some genius who strikes two rocks together, notices the spark, and thereby invents the greatest thing since sliced buffalo. But here’s my own favorite fantasy about hominins who, at various times over the eons, definitely lived near hot lava:

A ready source of fire. Just poke it with a stick and go. https://petapixel.com/2013/07/13/photographer-gets-so-close-to-lava-that-his-shoes-and-tripod-catch-on-fire/

Page 13

Oh finally. He’s prefaced some ideas with, “Some scholars believe…” This nuance is overdue by page 12, but at least it’s here. Which scholars? He cites this news piece which contains them:

1. Ann Gibbons, “Food for Thought: Did the First Cooked Meals Help Fuel the Dramatic Evolutionary Expansion of the Human Brain?” Science 316: 5831(2007), 1, 558-60.

Right. 

One idea is that cooking enabled the shortening of the gut, which is expensive tissue, and then with what energy is freed up from growing and using that, our ancestors could evolve to embiggen the expensive tissue in our heads, whose higher costs were met by the cooked food. (The idea is that cooling allows us to get more energy and nutrients from our food, and from food we wouldn’t normally eat without cooking. I do not know the current evidence that goes into these ideas, but they are mainstream and I know this study has contributed to them.) 

The link between cooking, guts, and brains is made in the spirit of the expensive tissue hypothesis, but instead of emphasizing the digestive needs of plants over those of meats, it’s emphasizing the even lower digestive needs of cooked food and the caloric rewards of cooked food. 

And, to digress, I think this line of thinking, about how shrinking one cost enables the ballooning of another, is what inspired the idea that our relatively smaller testicles, compared to chimpanzees, may be how we got larger brains. Why would evolution shrink anyone’s balls, or keep them smaller than chimpanzees’? Well, what chimpanzees are working with sounds expensive, energetically. And so, people who think in terms of evolutionary tradeoffs might imagine that testes are some of the first things to downsize if the opportunity arises. That’s selection-themed thinking. But subtly different, passive evolutionary thinking is just as legit. If size isn’t a matter of life and death, then size can ride the waves, up and down, of genetic drift–a creative evolutionary process that’s always changing everything that can change without killing off the lineage. 

But back to the point. Fire.

The regular control of fire for at least the last 400,000 years has been transformative in so many imaginable and unimaginable ways. Witnessing any of that transformation in what preserves of the past, however, is a major challenge! Still, we have fire. And while fire has a lot going for it, it’s also destructive. Sounds exactly like a certain lineage, doesn’t it? True to form, Harari ends this section by making fire a harbinger of “things to come.”

Page 14 is next. To be continued…

Source: http://ecodevoevo.blogspot.com/2026/04/sapiens-pages-12-13-taco-tuesday.html