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| Today's article, from Nautilus, is even older than most that grab my attention: first published in, apparently, 2013. That's ancient by internet standards. Well, technically, each species is unique in its own way. But it's unsurprising that humans would be most interested in the uniquity of humans. (I just made that word up, and I like it.) If you dropped a dozen human toddlers on a beautiful Polynesian island with shelter and enough to eat, but no computers, no cell phones, and no metal tools, would they grow up to be like humans we recognize or like other primates? That's a lot of restrictions for one experiment. How about we just drop them off on the island? (Ethics bars the toddler test.) Annoying. Neuroscientists, geneticists, and anthropologists have all given the question of human uniqueness a go, seeking special brain regions, unique genes, and human-specific behaviors, and, instead, finding more evidence for common threads across species. And yet, evidently, there is something that makes humans different from nonhumans. Not necessarily better, mind you. But if there weren't a unique combination of traits that separates a human from a chimpanzee, or a mushroom from a slime mold, we wouldn't put them in different conceptual boxes. Meanwhile, the organization of the human brain turns out to be far more complex than many anticipated; almost anything you might have read about brain organization a couple decades ago turns out to be radically oversimplified. And this is why the date of the article matters: in the twelve years since it came out, I'm pretty confident that even more stuff got learned about the human brain. To add to the challenge, brain regions don’t wear name tags (“Hello, I am Broca”), and instead their nature and boundaries must be deduced based on a host of factors such as physical landmarks (such as the hills and valleys of folded cortical tissue), the shapes of their neurons, and the ways in which they respond to different chemical stains. Even with the most advanced technologies, it’s a tough business, sort of like trying to tell whether you are in Baltimore or Philadelphia by looking out the window of a moving train. Yeah, you need to smell the city to know the difference. Even under a microscope human brain tissue looks an awful lot like primate brain tissue. That's because we are primates. When we look at our genomes, the situation is no different. Back in the early 1970s, Mary-Claire King discovered that if you compared human and chimpanzee DNA, they were so similar that they must have been nearly identical to begin with. Now that our genomes have actually been sequenced, we know that King, who worked without the benefit of modern genomic equipment, was essentially right. "Must have been nearly identical to begin with." Congratulations, you just figured out how evolution proceeds. Why, if our lives are so different, is our biology so similar? The first part of the answer is obvious: human beings and chimpanzees diverged from a common ancestor only 4 to 7 million years ago. Every bit of long evolutionary history before then—150 million previous years or so as mammals, a few billion as single-celled organisms—is shared. Which is one reason I rag on evolutionary psychology all the time. Not the only reason, but one of them. Lots of our traits were developed long before we were "us," and even before we diverged from chimps. If it seems like scientists trying to find the basis of human uniqueness in the brain are looking for a neural needle in a haystack, it’s because they are. Whatever makes us different is built on the bedrock of a billion years of common ancestry. And yet, we are different. I look at it like this: Scotch is primarily water and ethanol. So is rum, gin, vodka, tequila, other whisk(e)ys, etc. But scotch is unique because of the tiny little molecules left after distillation, plus the other tiny little molecules imbued into it by casking and aging. This doesn't make scotch better or superior to other distilled liquors, but it does make it recognizable as such. (I mean, I think it's superior, but I accept that others have different opinions.) I was unable to find, with a quick internet search, the chemical breakdown of any particular scotch, but, just as I'm different from you, a Bunnahabhain is different from a Glenfiddich, and people like me can tell the difference—even though the percentages of these more complicated chemicals are very, very small. Point is, it doesn't take much. But trying to find this "needle in a haystack" (how come no one ever thinks to bring a powerful electromagnet?) might be missing the point. And yes, that pun was absolutely, positively, incontrovertibly intended. Humans will never abandon the quest to prove that they are special. We've fucking sent robots to explore Mars. I say that's proof enough. But again, "special" doesn't mean "superior." Hell, sometimes it means "slow." |
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