Cultural Evolution

Right at the end of his On the Origin of Species, the book published in 1859 in which he announced his theory of evolution through natural selection, Charles Darwin wrote:

“In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.”

In leaving things to this final point and in saying so little, Darwin was being neither cowardly nor casual. He knew that as soon as he published the question of human evolution would be on everyone’s mind. He wanted therefore first to get the full theory on the table, as it were. At the same time, he did not want to duck the human question but to show that he knew fully what his theory implied.  In fact, from early manhood, Darwin had always been stone-cold certain that humans are part of the natural order, and while we are clever animals we are animals nevertheless. A major factor driving him this way was his experience of the natives of Tierra del Fuego at the bottom of South America. They convinced him that we are but fancy apes. 

Interestingly, when in 1838 Darwin discovered his mechanism of natural selection, the very first jottings that we have where he refers explicitly to the idea are about humans, and about human intelligence at that.  Some 12 years after the Origin, in 1871, Darwin turned full time to humans, and discussed our origins at length in his Descent of Man. The only real innovation was that now he gave a major role to the secondary mechanism of sexual selection, involving competition for mates within a species. He did this to explain such things as racial differences, which he did not think were of direct adaptive advantage in life’s struggles.

Darwin was right to think that it would be Homo sapiens foremost on people’s minds.  If you study the famous debate in 1860 between Darwin’s “bulldog” Thomas Henry Huxley and the Anglican High-Church champion, Bishop Samuel Wilberforce, you find that it was not evolution as such that divided them, but the status of our own species. This obsession with the status of humankind continues down to this day. The just-published attack on Darwinian evolutionary theory, What Darwin Got Wrong, by philosopher Jerry Fodor and cognitive scientist Massimo Piattelli-Palmarini, makes it clear that what really worries them is that such a mindless process as natural selection might be responsible for all we hold dear. These two writers are atheists, but the Christians if anything are even more concerned to show that nothing in Darwin threatens our species’ status.  Without even bothering to turn to the naysayers about evolution, the Creationists and their cotravelers the Intelligent Design Theorists, look for example at Life’s Solution: Inevitable Humans in a Lonely Universe, the work of the Anglican paleontologist Simon Conway Morris.

If, like me, you are with Darwin, seeing humans as unambiguously natural and wanting to locate us and our origins firmly within orthodox evolutionary theory, you still have got to recognize that we are rather special animals. Without denying that there are traces of it in other species, and certainly without denying that we have it because overall it is (or was) of adaptive advantage, our culture does set us apart. How then are you to deal with it in an evolutionary context?

One approach, started by Richard Dawkins in his Selfish Gene, and more recently championed by philosopher Daniel Dennett in Breaking the Spell, is to separate biology and culture somewhat.  You think of the units of culture, what Dawkins calls “memes,” as akin to units of biology, “genes,” and treat the evolution of culture somewhat independently of what is going on with our physical bodies. Culture may have had adaptive origins, but let us not kid ourselves that adaptation necessarily has much to do with anything today. Thus the spread of religion, to take an obsession of both Dawkins and Dennett, is treated as something with a kind of existence unto itself, a virus that hops from person to person. The virus terminology gives a good indication of how Dawkins and Dennett regard the worth of religion today. However, a major reason why this approach has not attracted more support is that — apart from internal difficulties such as defining a unit of culture (Are the opening bars of Beethoven’s Fifth a meme, or the whole of the first movement, or the symphony itself?) — it leads to no new and exciting predictions. It seems to be merely redescribing what we know in fancy language.

Another approach does take very seriously the action of natural selection on our physical bodies, our brains in particular. The so-called evolutionary psychologists argue that the ways in which we think and behave are often a function of our ancestors’ successes in the struggle for existence. A famous study was done by two Canadian researchers, Martin Daly and Margo Wilson. They studied patterns of homicide, trying to find Darwinian reasons. One significant finding was that stepfathers are far more likely to show murderous acts towards their partners’ children than are biological fathers. Daly and Wilson argued that this pattern fits a general pattern in the animal world. Males want to invest in offspring that carry their own genes rather than in offspring to which they are not related.  Hence, although the violence may not be moral, it is biologically understandable. The real conundrum they argued is why so many males (by far the majority) do not show violence to their non-biological social children.

It is hard to overestimate the hostility that the philosophical community has shown toward evolutionary psychology. With very few exceptions — although I am skeptical about much I am prepared to take it seriously — it is hated and despised, often, it seems to me, on less than convincing grounds. (Misreading statistics and so forth.) But even if the objections are well taken, this does not explain the visceral hostility.  My strong suspicion is that the philosophers are using their clever critiques to mask the same fear as that of Bishop Wilberforce. The nonbelievers stand side by side with the believers in wanting humans on a unique, higher-than-anyone-else pinnacle.

The fact is, however, that we are animals and we were produced by natural selection, so even if you reject evolutionary psychology you had better get over your worries and start looking for a convincing and profitable approach. A number of people have been trying to do this, showing how culture is connected to our biology and how this connection has been shaped by selection. Leaders in this direction are Californian researchers Peter Richerson and Robert Boyd. In their Not by Genes Alone: How Culture Transformed Human Evolution, they argue that culture is influenced and spread because humans have certain biases or tendencies — biases or tendencies rooted in selection — that direct the success of some ideas or practices over others.  One bias is general to go with the crowd. By and large the proven and true is the best strategy — “all other things being equal, imitating the most common behavior in the population is better than imitating at random.”  Another bias is to imitate the successful in the group. “Determining who is a success is much easier than to determine how to be a success.”

The New York Times science section this last week reported on a new study that seems to be in the same mold. Culture and biology interact and it is not a question of natural selection working only on one part of the equation and then the other part being dragged along as a kind of epiphenomenon, but of selection working on both in tandem as it were. A favorite example is of lactose tolerance. Most humans cannot tolerate milk after early childhood. Some obviously can. People living in the USA are (by and large) an example. Why is this? The hypothesis is that as humans moved to agriculture, some 10,000 years or so ago, cattle and other such animals (like goats), opened up a huge new energy resource. There was therefore strong selective pressure on herders for lactose tolerance — for genes that stop the shutting down (after childhood) of the gene that permits lactose tolerance. This then has a feedback into culture allowing the herders to increase in number and to spread as successfully as they (and their descendents) obviously have today.

It is fiendishly difficult to discover if something like this is a one-off or part of a common pattern. But with the human genome now so much better known, the search is going full time for more examples of this or related instances of culture and biology interacting. There have been so many false starts and failed hypotheses since Darwin dropped his famous paragraph into the Origin that one hesitates to say that now we are on the right path. But these are exciting times in the understanding of humankind and its biology and culture. For all that some of the greatest philosophers have also been great scientists — Descartes comes to mind — today’s philosophers are notoriously conservative when it comes to scientific advances. My hope is that perhaps instead of showing why things cannot be done, some at least will join in the quest of showing how things can be done.