HOW CULTURE DROVE HUMAN EVOLUTION | Edge.org - 0 views
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anthropology evolution culture tools cooperation religion neuroscience
shared by David McGavock on 07 May 14
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how culture drove human evolution
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cultural brain hypothesis—this is the idea that the real driver in the expansion of human brains was this growing cumulative body of cultural information, so that what our brains increasingly got good at was the ability to acquire information, store, process and retransmit this non genetic body of information.
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but tools and artifacts (the kinds of things that one finds useful to throw or finds useful to manipulate) are themselves products of cultural evolution.
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or a long time was that status in humans was just a kind of human version of this dominant status
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Chimps, other primates, have dominant status.
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social status
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second kind of status. We call this status prestige.
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from being particularly knowledgeable or skilled in an area,
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From this we've argued that humans have two separate kinds of status, dominance and prestige
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give them deference in exchange for knowledge that you get back
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you want to isolate the members of your group who are most likely to have a lot of this resources, meaning a lot of the knowledge or information that could be useful to you in the future
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some of the big questions are, exactly when did this body of cumulative cultural evolution get started?
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may have started early
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another possibility is that it emerged about 800,000 years ago.
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here's theoretical models that show that culture, our ability to learn from others, is an adaptation to fluctuating environments.
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Another signature of cultural learning is regional differentiation and material culture, and you see that by about 400,000 years ago
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400,000 years ago
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there's another possibility that it was a different kind of ape that we don't have in the modern world: a communal breeding ape that lives in family units rather than the kind of fission fusion you might see in chimpanzees
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In the Pliocene, we see lots of different kinds of apes in terms of different species of Australopithecus.
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we now have evidence to suggest that humans were communal breeders, so that we lived in family groups maybe somewhat similar to the way gorillas live in family groups, and that this is a much better environment for the evolution of capacities for culture than typical in the chimpanzee model
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for cultural learning to really take off, you need more than one model.
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trying out different technique
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take advantage of the variation
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the question is, how did we become such long distance runners?
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only humans have it
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humans who don't know how to track animals, can't run them down
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idea being that the religions of modern societies are quite different than the religions we see in hunter gatherers and small scale societies
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Most recently I've been also thinking about the evolution of societal complexity.
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when societies begin to get big and complex
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large-scale cooperation
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What are the causal processes that bring these things about?
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There's an interaction between genes and culture. First you have to get the culturally transmitted knowledge about animal behavior and tracking and spore knowledge and the ability to identify individuals, which is something you need to practice, and only after that can you begin to take advantage of long distance running techniques
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I've worked in a couple of different areas on this, and one is religion.
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there was an intense period that continues today of intergroup competition, which favors groups who have social norms and institutions that can more effectively expand the group while maintaining internal harmony
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they've been shaped in ways that galvanize cooperation in larger groups
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In small-scale hunter-gatherer religions, the gods are typically whimsical. They're amoral.
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but as we begin to move to the religions in more complex societies, we find that the gods are increasingly moralizing.
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if you remind believers of their god, believers cheat less, and they're more pro social or fair in exchange tasks,
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more pro social in are the ones with anonymous others, or strangers. These are the kinds of things you need to make a market run to have a successful division of labor
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ritual plays a role in this
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rituals seem to be sets of practices engineered by cultural evolution to be effective at transmitting belief and transmitting faith
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elevate the degree of belief in the high-moralizing gods
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high-moralizing gods will often require rituals of this kind
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Speaking in unison, large congregations saying the same thing, this all taps our capacity for conformist transmission;
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People also engage in what we call credibility-enhancing displays [during rituals]. These are costly things. It might be an animal sacrifice or the giving of a large sum of money or some kind of painful initiation rite
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We think religions are just one element, one way in which culture has figured out ways to expand the sphere of cooperation and allow markets to form and people to exchange and to maintain the substantial division of labor.
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There's a lot of risk in developing specialization because you have to be confident that there's a market there that you can engage with. Whereas if you're a generalist and you do a little bit of farming, a little bit of manufacturing, then you're much less reliant on the market. Markets require a great deal of trust
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In the intellectual tradition that I'm building on, culture is information stored in people's heads that gets there by some kind of social learning
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We tend to think of cultural transmission, or at least many people think of cultural transmission as relying on language
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, it's quite clear that there is a ton of cultural transmission that is just strictly by observational learning.
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what we don't see amongst other animals is cumulative cultural evolution.
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you can learn one thing from one generation, and that begins to accumulate in subsequent generations.
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One possible exception to that is bird song.
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One of the interesting lines of research that's come out of this recognition is the importance of population size and the interconnectedness for technology.
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looking at a case study in Tasmania.
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You start out with two genetically well-intermixed peoples. Tasmania's actually connected to mainland Australia so it's just a peninsula. Then about 10,000 years ago, the environment changes, it gets warmer and the Bass Strait floods, so this cuts off Tasmania from the rest of Australia, and it's at that point that they begin to have this technological downturn
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You can show that this is the kind of thing you'd expect if societies are like brains in the sense that they store information as a group and that when someone learns, they're learning from the most successful member
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study by Rob Boyd and Michelle Kline
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larger islands had much bigger and more complex fishing technologies, and you can even show an effective contact. Some of the islands were in more or less contact with each other,
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more in contact, you have fancier tools, and that seems to hold up.
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rates of innovation should continue to increase, especially with the emergence of communication technologies
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As an individual inventor or company, you're best off if everybody else shares their ideas but you don't share your ideas because then you get to keep your good ideas, and nobody else gets exposed to them, and you get to use their good ideas, so you get to do more recombination.
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An important thing to remember is that there's always an incentive to hide your information.
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Embedded in this whole information-sharing thing is a constant cooperative dilemma in which individuals have to be willing to share for the good of the group.
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a norm of information sharing is a really good norm to have
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I've done a lot of work on marriage systems with the evolution of monogamy.
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Eighty-five percent of human societies have allowed men to have more than one wife
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pushes us towards polygyny
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But in the modern world, of course, monogamy is normative, and people who have too many wives are thought poorly of by the larger society. The question is, how did this ever get in place?
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European Marriage Pattern,
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Athens legislates the first rules about monogamous marriage
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people are ready to moralize it,
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it does seem to have societal level benefits. It reduces male-male competition. We think there's evidence to say it reduces crime, reduces substance abuse, and it also engages males in ways that cause them to discount the future less and engage in productive activities rather than taking a lot of risks
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If I talk about normative monogamy as being successful, I mean that it spread,
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especially if you have a society with widely varying amounts of wealth, especially among males. Then you're going to have a situation that would normally promote high levels of polygyny
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to get into the mating and marriage market you would have to have a high level of wealth if we were to let nature take it's course
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Part of my program of research is to convince people that they should stop distinguishing cultural and biological evolution as separate in that way. We want to think of it all as biological evolution.
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Culture is part of our biology.
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We now have the neuroscience to say that culture's in our brain, so if you compare people from different societies, they have different brains.
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Cognition and our ability to think are all interwoven,
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A good example of this is the placebos. Placebos are something that depend on your cultural beliefs. If you believe that something will work, then when you take it, like you take an aspirin or you take a placebo for an aspirin, it initiates the same pathways as the chemically active substance. Placebos are chemically inert but biologically active, and it's completely dependent on your cultural beliefs.
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One of the large research projects that I run in an effort to understand human sociality is called The Root of Human Sociality Project.
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at the time to something called the Ultimatum Game, and the Ultimatum Game seemed to provide evidence that humans were innately inclined to punish unfairness.
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behavioral economists find that students give about half, sometimes a little bit less than half, and people are inclined to reject offers below about 30 percent
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The older you get, even if you have more wealth and more income, you're especially inclined to only offer half, and you'll reject offers below 40 percent.
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I was thinking that the Machiguenga would be a good test of this
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I did it in 1995 and 1996 there, and what I found amongst the Machiguenga was that they were completely unwilling to reject, and they thought it was silly. Why would anyone ever reject?
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they made low offers, the modal offer was 15 percent instead of 50, and the mean comes out to be about 25 percent.
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over the next two summers these field anthropologists went to the field and conducted the ultimatum game as well as a few other games
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we found is that societies vary dramatically, from societies that would never reject, to societies that would even reject offers above 50 percent, and we found that mean offers ranged across societies from about 25 percent to even over 50 percent. We had some of what we called hyper fair societies. The highest was 57 percent in Lamalera, Indonesia.
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able to explain a lot of the variation in these offers with two variables. One was the degree of market integration.
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there seemed to be other institutions, institutions of cooperative hunting seemed to influence offers.
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measured market integration much more carefully
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subsequent project
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large number of other variables, including wealth, income, education, community size, and also religion.
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did the Ultimatum Game along with two other experiments. The two other experiments were the Dictator Game (the Dictator Game is like the Ultimatum Game except the second player doesn't have the option to reject) and the Third Party Punishment Game.
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Third Party Punishment Game, there are three players and the first two players play a Dictator Game.
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This gives us two different measures of willingness to punish strangers
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one is rejection in the Ultimatum Game
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three measures of fairness
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size of the community predicts willingness to punish
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suggesting that if you have small communities, you don't need punishment.
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It could be some kind of reputational mechanism
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There's a number of different ways to create norm systems that operate like that.
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In a big society punishment can be most effective because reputational mechanisms can be weak. If you're in a big society and you encounter somebody, you probably don't have friends in common through which you could pass reputational information for which punishment could be generated. You might want to punish them right on the spot or someone who observes the interaction might want to punish them right on the spot or call the authorities or whatever, which is also costly.
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This creates a puzzle because typically people think of small-scale kinds of societies, where you study hunter-gatherers and horticultural scattered across the globe (ranging from New Guinea to Siberia to Africa) as being very pro social and cooperative.
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but the thing is those are based on local norms for cooperation with kin and local interactions in certain kinds of circumstances
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these norms don't extend beyond food sharing. They certainly don't extend to ephemeral or strangers
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large-scale society run you have to shift from investing in your local kin groups and your enduring relationships to being willing to pay to be fair to a stranger.
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if you're going to be fair to a stranger, then you're taking money away from your family.
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A commitment to something like anti-nepotism norms is something that runs against our evolutionary inclinations and our inclinations to help kin
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In this sense, the norms of modern societies that make modern societies run now are at odds with at least some of our evolved instincts.
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Lately we've been focused on the effects of religion
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adherence to a world religion matters
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People from world religions were willing to give more to the other person in the experiment, the anonymous stranger
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Part of this is your willingness to acquire a norm of impartial roles; that we have a set of rules that governs this system.
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political scientists call it the rule of law
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those rules apply independently of the identities
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If you want the rule of law to spread or to be maintained, you need conditions in which you're managing risk.
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[JOSEPH HENRICH:] The main questions I've been asking myself over the last couple years are broadly about how culture drove human evolution. Think back to when humans first got the capacity for cumulative cultural evolution-and by this I mean the ability for ideas to accumulate over generations, to get an increasingly complex tool starting from something simple. One generation adds a few things to it, the next generation adds a few more things, and the next generation, until it's so complex that no one in the first generation could have invented it.
