There are differences across human populations, yes. For instance. Southeast Asians commonly have a mutation that causes them to be intolerant of alcohol. About 1 in 27 Jews are carriers for Tay-Sachs disease.

My point is that race as most people conceptualize it is not based in fact. I’ve recently watched a TED talk that pointed out that a Nigerian and a Kenyan are more genetically distinct than a Nigerian and a European (can’t recall the exact country in Europe). Our racial divides in society are primarily a product of biased psychological processes that automatically categorize a light-skinned and dark-skinned person as more different than they are. After all, the dark skin of African natives is a product of a single gene involved with melanin production, which is an adaptation to the intense climate and sunlight of Africa.

My point about genetic differences isn’t so much that species are more different than we think. My point is more that our brains are programmed to be keenly aware of differences, even small ones. A 0.3% difference between humans and Neanderthals would certainly be enough for our biased brains to lock onto minute differences and produce erroneous stereotypes and prejudices that would lead to conflict, especially since this happens with a 0.15% difference between human populations.

You’ve picked up on something that’s really interesting. People often categorize everything non-human as “natural” and everything human as “artificial.” Our processed foods or computers or highways aren’t “natural” because they didn’t “form on their own.”

But when you realize that humans are a part of and a product of nature just like everything else, doesn’t that make our “artificial” creations natural as well?

I don’t have a source per se, but as a psychology a major, I can say a major focus of certain courses is on neuroplasticity. There are many sources I’m sure, as I am confident this is an important area of research. Neuroplasticity is simply the brain’s ability to form and break connections. But what is surprising is the extent to which it can do it. For instance, one study has shown 27 minutes of meditation per day for eight weeks produced significant reductions in the density of gray matter in the amygdala, the fear center of the brain (source below). I chose the word “update” because it reflects that our brains change their connections in real-time in response to the environment. Structures in our brains don’t become new structures in our lifetimes, but they do change–and they change physically.

I agree that adaptability is only effective to an extent. Our genes are still basically prehistoric. My main point is that Dunn may be exaggerating the need for us to surround ourselves with things from our natural pasts. We can adjust, but only so far.

http://www.sciencedaily.com/releases/2011/01/110121144007.htm

Regarding trade and spread of ideas in the Americas, I believe later in his book Diamond goes over the fact that if you look at the contents of North and South America, they’re connected via a tiny (relatively speaking) stretch of land, whereas Europe and Asia have vast swaths of land that connect the two. Also, the big things in his theory are lines of latitude being crucial to successful trade. Europe and Asia share lines of latitude, North and South America do not, they share lines of longitude.

The civilizations in the Americas (Inca, Maya, Aztec, etc) certainly were advanced and powerful, but when compared to the Europeans they fell short. The best thing we have in terms of ways to measure the two against one another is what happened when they clashed, and the Europeans dominated that affair. Granted it’s an extremely imperfect comparison, as the Spaniards (and future Europeans) had a biological advantage of using a small group to spread massive epidemics to an enemy continent, but it’s the only one we have.

Great post, technical but not dense.

Regarding the plasticity of the brain, I’m curious where you’re getting that information, do you have a source? When you say the brain updates itself, how do you mean? The brain can certainly grow new neurons and the wiring (for lack of a better term) differs from person to person, but as an organ it is essentially the same across human beings. If you’re talking about learning and storing experiences as memories wouldn’t that fall under the argument you later pose of the blank slate?

Speaking of the blank slate, essentially you’re discussing nature vs. nurture. The nurture might allow people today to adapt to their environment (by the way great point about adaptability), but do you think that would be able to cover all circumstances? For instance, we can build technology to clean air pollution, but at a certain point (Beijing, Shanghai, etc) we can’t keep up with the environment no matter how adaptable we are.

A couple of things with your comment:

Good call on the competition. I meant that where previous theories dealt with a type of warfare that may have extinguished Neanderthals, the truth is that warfare may have only played a (minor) role. Also, regarding racial divides, there are indeed such divides, they’re not illusions. Now don’t get me wrong, I absolutely do not believe the divisions are worth noting or have the slightest bearing on what people are capable of or are worth or anything like that. But biologically speaking there are certainly differences between the races of man. If you’d like we can discuss this at length in person on Tuesday, but I don’t want to have a potential internet discussion that might lead to misunderstandings and accidental racism.

Regarding the differences of DNA, be careful with your numbers. A lot of people don’t understand how much we have in common with almost every living thing, certainly every animal. So the 60% doesn’t really mean much. And yes I agree that out groups lead to conflict, and I’m certainly not discounting conflict as a reason for Neanderthal extinction. However, in anthropology the theories regarding Neanderthal extinction used to run primarily along the lines of warfare between them and Homo sapiens, and today with the new DNA evidence of interbreeding the idea of simply breeding themselves out has become much more accepted.

Great comments though!

I agree with Diamond’s theories as far as they deal with the prerequisite conditions for a developing civilization to arise. Part of his broader theory addresses why European powers gained dominance over the rest of the world, instead of say the Chinese or the Indians. That is where a number of the valid criticisms seem to come in. Europe was not the most advanced area throughout all of history, and the technological revolutions that gave Europe the power to dominate the globe could have happened in other areas. I’d argue that the domesticated animals and plants heavily influenced where developed civilizations would spawn, but past that point other factors began to take over.

Great post. Two things I’ll respond to…

You mention that Neanderthals may have bred themselves out of existence, and that their extinction was not a result of competition. I’d be careful there.

I’d speculate that competition most certainly played a role, though not an exclusive one. Humans, particularly along (illusory) racial divides, have been very competitive historically, and mass genocide of populations is one thing we’re best known for (e.g., Nazi Germany, Native American genocide, etc.). This competition occurs without precluding our obvious willingness to interbreed.

I’ve just read that human and Neanderthal genomes different by about 0.3% — double the difference found between some human populations. Doesn’t sound like much, but when you consider that humans share 60% of their DNA with bananas, this suggests that a 0.3% difference would probably be enough to seriously exacerbate psychological processes that would lead to conflict. We are programmed to recognize and categorize differences, and to project our negative emotions onto out-groups. Neanderthals were probably more likely to be categorized as out-groups than other groups of Homo sapiens and therefore more likely to be a target of competition than cooperation.

Nice post. You make some good points.

I will say that I don’t think Diamond’s proposal is that diversity of vegetation + diversity of animals = developed civilization. Instead, it seems to propose these are INITIALIZING factors, meaning without the ability to supplement our diets with protein, to store crops for long periods of time, and to feed a large population, civilizations like those in Europe and the U.S. are highly unlikely to BEGIN to develop. Once these variables are in place, an amalgam of other factors contribute, some of which it looks like you point out.

Animal power, in the form of horses and cattle, may not have been a part of South American development, but I think Diamond would make the point that crops that can be stored and high protein diets are more important. Hypothetically speaking, I’d guess it’s more important to have a well-nourished population that uses manpower to farm than an under-nourished population that uses animal power.