Children have an evolved fascination with fire

From The Secret of Our Success by Joseph Henrich. Page 68.

The impact of this culturally transmitted know-how about fire and cooking has had such an impact on our species’ genetic evolution that we are now, essentially, addicted to cooked food. Wrangham reviewed the literature on the ability of humans to survive by eating only raw foods. His review includes historical cases in which people had to survive without cooking, as well as studies of modern fads, such as the raw foods movement. The long and short of all this is that it’s very difficult to survive for months without cooking. Raw-foodists are thin and often feel hungry. Their body fat drops so low that women often stop menstruating or menstruate only irregularly. This occurs despite the supermarket availability of a vast range of raw foods, the use of powerful processing technologies like blenders, and the consumption of some preprocessed foods. The upshot is that human foraging populations could never survive without cooking; meanwhile, apes do just fine without cooking, though they do love cooked foods.

Our species’ increasing dependence on fire and cooking over our evolutionary history may have also shaped our cultural learning psychology in ways that facilitated the acquisition of know-how about fire making. This is a kind of content bias in our cultural learning. The UCLA anthropologist, Dan Fessler, argues that during middle childhood (ages six to nine), humans go through a phase in which we are strongly attracted to learning about fire, by both observing others and manipulating it ourselves. In small-scale societies, where children are free to engage this curiosity, adolescents have both mastered fire and lost any further attraction to it. Interestingly, Fessler also argues that modern societies are unusual because so many children never get to satisfy their curiosity, so their fascination with fire stretches into the teen years and early adulthood.

The influence of socially learned food-processing techniques on our genetic evolution probably occurred very gradually, perhaps beginning with the the earliest stone tools. Such tools had likely begun to emerge by at least 3 million years ago (see chapter 15) and were probably used for processing meat—pounding, chopping, slicing, and dicing.14 Drying meat or soaking plant foods may have emerged at any time, and probably repeatedly. By the emergence of the genus Homo, it’s plausible that cooking began to be used sporadically but with increasing frequency, especially where large fibrous tubers or meat were relatively abundant.

Our repertoire of food-processing methods altered the genetic selection pressures on our digestive system by gradually supplanting some of its functions with cultural substitutes. Techniques such as cooking actually increase the energy available from foods and make them easier to digest and detoxify. This effect allowed natural selection to save substantial amounts of energy by reducing our gut tissue, the second most expensive tissue in our bodies (next to brain tissue), and our susceptibility to various diseases associated with gut tissue. The energy savings from the externalization of digestive functions by cultural evolution became one component in a suite of adjustments that permitted our species to build and run bigger and bigger brains.

As an Assistant Scout Master, I can testify to the enduring fascination with fire, at least among young boys.