Recently a friend of mine called me out for casually referring to the evolution of the human brain as if it were a proven thing. This friend is an advocate of the idea of intelligent design, and questions whether something as amazingly complex as a human (or our brain, or our DNA) could ever arise without some kind of intelligent guiding force.
Unlike most believers in evolution (of which I am one) I actually do believe there is something of an unproven “missing link” in the whole theory of evolution: namely, abiogenesis. That is, no one really knows how organic chemicals really started forming in the “primordial soup.” There is no fossil record of this time period, so it is all pretty much speculation.
However, once we get past that first hump of chemicals that can reproduce themselves, we get into the realm of natural selection. The theory of natural selection is that if data can somehow be encoded in chemical form (i.e., DNA), then random changes in that data will survive if the changes make survival and, especially, reproduction more likely.
So how much data is there in the human genome? About 1.5 GB (from about 6 billion base pairs). Scientists estimate that life has existed on earth for about 3 billion years. So if we drew a straight line from day 0 to now, we could say that on average natural selection got us about 2 base pairs closer to humanity every year. Of course, the road was probably a lot more bumpy than that, but it doesn’t seem too outlandish, does it?
Just for comparison, if you just took 6 billion base pairs and started to change things randomly every six months without natural selection, then it would take roughly infinity years to get a human. Just kidding, but really, the number of years (something on the order of 2⁶⁰⁰⁰⁰⁰⁰⁰⁰⁰) is way, way beyond any estimate of the life of the universe (aside from infinity). It is way, way more than the number of atoms in the universe. It’s hard to even describe how big that number is. Like if you kept saying googolplex times googolplex times googolplex for the rest of your life you wouldn’t even get close. Big exponents will do that to you. (By the way, stop saying that things are increasing exponentially when they really aren’t!)
Anyway, such is the power of natural selection that it can take something (namely, intelligent life) which is impossibly unlikely and make it so that it’s just really, really rare (at least we haven’t seen it on any other planets) and takes billions of years.
But, surprise! This post isn’t really about physical human evolution. What I really want to talk about is the impact of natural selection on culture.
One of the examples in the book The Secret of Our Success talks about how certain South American tribes engage in this really complicated treatment for manioc (to remove cyanide). It’s really complicated and they almost certainly don’t understand why it works, but they keep doing it because, well, that’s what they have always done.
But how did this evolve? Well, the theory of natural selection gives us an idea. Culture is like DNA. It can encode really complicated behaviors. If a group culture is beneficial, the ideas are passed on because people observe what others around them are doing and blindly repeat the same thing. Changing things in this way takes a long time. If some group starts treating manioc just a tiny bit differently than a neighboring tribe, it might take thousands of years before their technique gives them a sufficient advantage to dominate the other tribe.
But like the evolution of humans without natural selection, developing these manioc treatment methods without the blind repetition would never happen (well, at least not until the development of modern science). Also, interestingly, the adaptation of methodology has to be really, really slow for the natural selection to work. If you change something too often you will never really see the effects of the change and you will move on to something worse before your tribe has to dominate.
So the cultural selection story is nice because at least it makes complex manioc processing methods possible. And it explains why humans are so resistant to change. But on some level, it doesn’t really jive with our experience because at least nowadays, humans aren’t really change-resistant enough to let cultural selection happen over the course of several thousand years. These days we have memes that last for a matter of days before we move onto the next thing.
Of course, memes are subject to their own form of natural selection, but they don’t last long enough to give one tribe a significant advantage over another.
My theory about this is that modern culture actually teaches us to be much more tolerant of change, but that it took a long time for this cultural change to take place.
Basically, it used to be that technological change happened very rarely. But at a certain point technology started getting more advanced at a faster and faster rate, and tribes (e.g., nations) that were better at adopting culture to take advantage of technology started out-surviving those tribes that didn’t (mostly, by killing the other tribes with better weapons).
This leads to an interesting question. Was our previous resistance to cultural change a cultural thing or a DNA thing? Well, if it has changed, it kind of has to be a cultural thing, right? But then how did our DNA anticipate the need for us to change not only culture, but the rate of change of culture?
In other words, it seems plausible that we need to preserve culture with a very high fidelity in order for it to evolve, but then any kind of intellectual openness becomes a huge liability and would be selected against with brutal efficiency. Why would nature ever let us try to understand things if it just gets in the way of cultural evolution?
I really don’t know the answer, so if you don’t like random idea mutations (i.e., speculation) you can skip the rest of the this post. Anyway, here goes. Nature provided us with a way to have our cake and eat it too (i.e., to keep certain parts of our our culture that need keeping and to change parts that need changing!).
One way that nature might do this is to create a division of labor between genders. For example, there is a pretty well established correlation between gender and neuroticism. Perhaps one function of neuroticism is to help preserve culture exactly as it is observed.
Furthermore, maybe hunter-gatherer cultures had a division of labor between men and women, where men were more likely to engage in tasks that reward experimentation (e.g., fighting and hunting) and women were more likely to engage in tasks that rewarded strict observance of inherited wisdom (e.g., gathering and child care).
The funny thing about this is that in the long run, the tasks that reward strict observance are actually the more complex ones. That is, if something is so complex that we have no hope of understanding it rationally, the only way to develop a solution is by very slow random mutation combined with strict observance and actual physical natural selection.
The other day Mercedes and I were talking about some of my ideas and, as is often the case, she was having a visceral reaction against it. She commented that sometimes it’s better if I just don’t try and convince her. She was willing to trust me and try things, she explained, and if it works then she will accept it.
In a way, belief in cultural evolution is humbling. Our greatest accomplishments as human beings aren’t really the result of some triumph of reason. In fact, quite the opposite. Our greatest achievements come after thousands of incremental changes in the face of evolutionary pressures. We believe ourselves god-like creatures capable of intelligent design, but really one of our greatest powers is the ability to be skeptical of anything that hasn’t already been proven by trial-and-error.
In a sense, this idea should give us all a reason to be a bit conservative in our approach to culture. Thinking that we can design new cultural institutions, or pretty much anything other than very focused engineering projects without vast unintended consequences is hubris.
We all understand (don’t we?) that one of the great failures of communism is that a command economy doesn’t work on a large scale. The human mind is simply not capable of comprehending the vast amounts of information that determine the organization of human activity in a market economy. One of the reasons we trust markets is that we think that they work without the need to understand them. Instead, it relies on a version of natural selection. And truly, if there is an accomplishment greater than the global economy I don’t know what it is. It’s scale it beyond comprehension. Even the smallest things are produced using the labor and cooperation of millions.
So what does this mean? I am certainly not going to stop trying to come up with new ways of doing things! It’s who I am. But perhaps I can carry on with a bit less condescension toward those who prefer things to be tried and tested, and even toward those who prefer to accept the beliefs of their parents (or the culture of their nation) without the need to question everything. The human race still has need for both adaptation and faithful transmission of culture.
