For the past three-ish years I’ve off-and-on attended the IGERT (Integrated) Program in Evolutionary Mapping (IPEM) seminars to sort of get a taste for what science is like outside the world of physics, and also because human evolution is just something I find incredibly fascinating, and also because Thursday afternoon is a great time to not be doing work. Over the years, there were many interesting talks, from asking what happens if you just assume neutral theory accounts for genetic differences (answer within Indonesia: you don’t get any real contradictions, but then the methodology is not very good at differentiating the neutral vs. non-neutral outcomes) to what happens if you use cladistics for cultural evolution (answer within rug-making skills: you do see signs that tell you there is a lot of borrowing that isn’t tree-like). It was a good time, but now it seems the seminar series is, sadly, coming to an end. With that, I thought I would pay tribute by sketching out something that a lot of the speakers in the last couple of terms of the seminar were concerned with.
Namely, why does inequality exist? The question is actually not totally stupid. Our hunter-gatherer ancestors lived (if modern hunter-gatherers are anything to go by) a much more egalitarian life than we do. At some point, societies which were the progenitors of ours decided that, to hell with equality, we’ll just have an upper class that gets to inherit all the best stuff. As a snap decision, this is obviously bad for more people than it is good for. So why did it happen? Here is a rough timeline of how it could have occurred. Note that while there are some field studies and computer models backing up some of the claims, they are not all equally trustworthy, and so I present this to you not as a scientific fact, but as a just-so story that you can think about and try to think of ways to test and poke holes in. I’ve linked to the researchers for the individual claims, so that you can see what they have to say on the matter and what evidence they’ve (hunter-)gathered.
1. Our ancestors were not as egalitarian as we think. Eric Alden Smith and co-workers claim that, in studying traditional hunter-gatherer societies, there was a lot of inherited inequality in terms of social status, objects and knowledge etc. happening. While ostensible equality was very strongly defended within hunter-gatherer societies, it still was the case that for parents in the top 10% of the group for some version of “success”, their children were three times as likely to be found in that same top 10% bracket as were other children.
2. Agriculture brought the pre-existent inequality into the material world. Steve Shennan makes the argument that with the advent of agriculture and correspondingly less nomadic lifestyle, land inheritance became a possibility. In order to enhance the survival chances of their progeny several generations down, it actually made more sense for people to spend resources defending their land rather than having more kids, and so resources were shunted from child-bearing to protecting property rights (with sticks and stones and stuff, but also with making rules).
3. When agriculture developed, to be a hunter-gatherer on the agricultural-hunter-gatherer boundary would just be kind of stupid, and so agriculture quickly spread. The evidence (though not unequivocally) suggests that the move to agriculture led to people leading shorter, sicker, more hungry lives. So why would you choose to do that? Arthur Robson looked at the evidence, and came up with a model that showed, basically, that this is a sensible thing to do anyway because there were way more of these sickly agriculture people than there were of the happy hunter-gatherers. The Repugnant Conclusion wins again…
4. Inherited inequality is not a one-way street, and in fact was imposed and de-imposed many times. Shennan is again the source of this claim, which is based on the archaeological record, but is not, it seems, very strongly supported.
5. Intra-group inequality is in many cases beneficial in inter-group conflict. Peter Turchin cites Price Equation-based models to show that inequality could spread through inter-group warfare, if there was regional variability in inequality (likely) and inequality is beneficial in warfare (hierarchical structure seems to be pretty important).
I find this stuff really fun to think about. Hopefully, you do too.