Domesticating humans by artificial selection

Did the dawn of agriculture lead to a form of human artificial selection resulting in more passive, less suspicious individuals? Isn’t this a bit like domesticating animals?

When I first read of the influential archaeologist Ian Hodder’s ideas about the ‘domestication of the mind’, I couldn’t help thinking “eh?”

What Prof. Hodder was trying to do was to explain an apparent paradox at the dawn of farming. This is that for the average Palaeolithic individual, the disadvantages of hard work and lowered nutrition resulting from farming seem to outweigh its advantages. So why would they ever have taken up farming at all?

Ian Hodder essentially argued that farming was only possible because humans had been ‘trained’ to accept it. This was not the training of a Machiavelli-figure but a kind of group training. Once people were on-side about the concept of “that is wild and dangerous” and “this is tame and homely” it was easy to make them take up farming. This seemed like so much mumbo jumbo to me.

So I forgot about Prof. Hodder and his ideas. I wanted a better reason than that for why people took up farming. I came up, for better or worse, with trade. Of course, this turns out to be as unproveable as domestication of the mind.

Yet something recently has caused me to go back to Ian Hodder’s idea and look at it again. I have a feeling that ‘domestication of the mind’ and trade are not incompatible.

Meet the ancestors

It’s difficult to know what the normal habits of a Palaeolithic forager were. The clues – paintings and carvings of animals, as well as rather odd shaped, generally faceless women – don’t help much.

Some of these foragers were clearly great artists. Whatever, I still don’t think that I would have enjoyed an encounter with most of them. Generally they were probably distrustful of strangers to the point of extreme violence and killing. I suspect that our first meeting might have been nasty, brutish and short, at least for me.

Of course, at the time there may have been evolutionary advantages to this suspicious and agressive behaviour. A new foraging group in your territory would be competitors for the animals and plants that you saw as your own. Killing or scaring them away would seem the best option.

Our modern tendency to cooperate with most strangers, both at work and on the street, would have been incomprehensible to our Palaeolithic ancestors. Books such as ‘The Company of Strangers’ have long made the case that what humans have become in the twenty first century is a long way from where we started.

Love thine enemy

Yet this cannot have been the whole story. Genetic health requires that Palaeolithic clan groups must have brought in women (or men) from other groups to produce healthy and viable offspring.

Also the style of art known as Gravettian managed to spread across a large area of Europe about 25,000 years ago. If there had been excessive hostility between groups then it would have been impossible to generate and spread this pan-European art style. In fact, it would have been impossible to spread any of the innovations made by humans during the Palaeolithic.

So I’d guess that, yes, humans were more suspicious than they are now. However, there must have been groups or individuals that were less suspicious and, conversely, groups or individuals that were more so.

Neolithic trade and gambling

As Matt Ridley would no doubt tell you, the growth in trade over the last ten or so millennia has been pretty much exponential. Yes, there have been downturns, but overall the pattern is one way.

Trade has always been a gamble, but it’s much less risky than it used to be. For example, shipping crates of bananas from Surinam to Holland, you can be fairly sure that nothing’s going to sink your ship and that the bananas won’t go rotten during the journey.

Compare this with the gamble for any Palaeolithic individual wishing to make contact with another group just to swap stones. Her thoughts would probably be “What are the odds that I’m going to get through this with my life?” I could imagine it would’ve made her a bit jumpy.

The growth of Earth’s population, like trade, has also grown exponentially. But the population that has enjoyed this growth probably didn’t include the suspicious, highly violent end of the Palaeolithic human spectrum.

For when people first started to trade with others there would be an understandable desire to lower the risk and trade with the less dangerous groups or individuals. The suspicious and aggressive groups would have been shunned as just too risky to trade with.

Additionally, the advent of farming meant that it was possible to have more than one clan group living in the same area. This meant that there was no evolutionary advantage in being that suspicious.

Domesticating animals and humans

It seems reasonable to compare the situation above with the domestication of animals.

Archaeologists have long wanted to understand the way in which animals were first domesticated. However, twentieth century Soviet experiments with wild silver foxes showed how it is possible to get rapid results with artificial selection.

Animals in these experiments were selected or rejected according to their aggression levels. Aggressive animals would be culled when young. The small percentage of passive animals would live to reproduce. After 30 or so generations the experiments had managed to produce tame silver foxes.

When people were first domesticatng animals there was an evolutionary advantage to having herds with genetic diversity, but that also didn’t fight each other. Therefore the same selection methods as for silver foxes were probably used.

For humans, it is possible that the first traders and farmers followed a similar, though not identical strategy. By avoiding contact with suspicious and agressive groups they would control their own breeding patterns. By expanding their populations through farming they could outcompete the rest. As time went on, the farming population, relatively passive and accommodating, would outgrow the non-farming population.

Discussion

There are many factors that haven’t been taken into account above. I have not discussed the physical factors driving continued evolution, such as the role of disease in densely packed populations. Also, I would never dream of arguing for an entirely passive and money grabbing population created by trade and farming. There’s plenty of evidence to contradict that.

But I think that ignoring the role of artificial selection on the thinking of early farming communities is to miss something important. I think it also opens up the possibility that early farming populations were ripe for exploitation by cunning and aggressive nomad or forager populations once the technological conditions were right.

Either way, I think that Ian Hodder was on to something. Humans have been domesticated. However, this is probably not by training, as Hodder suggested, but by the only method that’s been shown to work, artificial selection.

References

Hodder, I. 1990 The Domestication of Europe, Oxford/Blackwell, pp331.

Ridley, M. 2010 The Rational Optimist: How Prosperity Evolves, Fourth Estate, pp448.

Seabright, P. 2005 The Company of Strangers: A Natural History of Economic Life, Princeton, pp320.

Trut, L.N. 1999 Early Canid Domestication: The Farm-Fox Experiment, American Scientist 87, p160-169.

Unknown author 2011 Modern Makeover, New Scientist 2804, p36-39 (http://www.newscientist.com)