The Secret of Our Success

How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter

[Amazon Link]

Yet another Interlibrary Loan book, this one from Tufts. I believe I put it into my to-be-read list when I came across the author, Joseph Henrich, while reading Matt Ridley's The Evolution of Everything.

It's a fine "big idea" book, as you can tell from the subtitle. What unlikely process, asks Henrich, has brought the human species to dominate more terrestrial environments than any other land mammal? We aren't very strong, not very fast, and not that good at tree-climbing. Why weren't our ancestors all Tiger Chow millions of years ago?

Well, we're smart, you say. But Henrich argues convincingly that we aren't that smart either. His thought experiment: dump fifty humans and fifty capuchin monkeys into a central African jungle. ("To be kind we would allow the humans—but not the monkeys—to wear clothes.") Come back two years later and it's a safe bet that there will be a lot fewer surviving humans than monkeys. There are a couple of tragic real-world examples presented: groups of "civilized" humans accidentally finding themselves in an environment in which they rapidly die off, even in the midst of native populations that are doing just fine.

Instead, Henrich argues, we're uniquely well-suited to cultural evolution, the process by which knowledge and skills are transmitted from one generation to the next. In addition, good old genetic evolution co-evolves with the culture, to the extent that our species' hardware/firmware is optimized to handle cooked food, written language, throwing small, heavy objects with deadly accuracy (Craig Kimbrel excluded), run long distances, and the like.

It's a wide-ranging tale, and Henrich runs through his argument with clarity and occasional understated humor. As is typical with these sorts of books, a variety of research is cited from anthropology, psychology, economics, and related fields. Some of these results I'd heard before, most not.

As with most results of "dumb luck" evolution, the beneficiaries often don't understand "the secret of their success". I was able to impress my nutritionist wife with the mystery of why South American natives put wood ash (or burned seashells) into their corn dishes before serving. Why? The alkalinity of the ask makes the niacin in the corn available to the human digestive system.

When corn was introduced into "civilized" countries, this technique was discarded, since nobody knew why it was useful. The result: pellagra, caused by niacin deficiency. And (tragically) the cause of pellagra remained a mystery until the mid-20th century.

Also very mind-bending was Henrich's discussion of the brain's "firmware" for recognizing written language. We English-readers can look at (for example) "READ" and "read" and know within milliseconds: that's the same word, even though the letters don't look anything alike. Multiply that feat over myriad font shapes and sizes. How could that skill, developed only a few thousand years ago, be a result of sluggish Darwinian processes? Cultural evolution, baby!

And there's a lot more. As always: there are controversies, and Henrich is only giving his side. So maybe not the last word on this topic. Nevertheless, a fun and fascinating read.