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| Another thing for me to be skeptical about, this one from Smithsonian. This Is What Our Thumbs Say About Our Brains, in a Pattern That Holds True for Other Primates  Researchers have found a link between long thumbs and big brains, suggesting the two features evolved together Does it really suggest that, though? Or does it only suggest that Smithsonian really wants us to click on the article? Well, I bit. As the sole surviving human species, our big brains and nimble hands have always made us feel special, compared to our extinct relatives. Oh, we're off to a great start, aren't we? Are they "extinct," or did they become assimilated? And if two populations can interbreed to produce fertile offspring, aren't they usually defined as the same species, morphological differences notwithstanding? Because that's what happened with the populations we call Neanderthal and Denisovian, and maybe some others. And that's not getting into the controversy about correlating brain size with what we call intelligence.I'll not argue the "nimble hands" thing, except to say that most primates have "nimble hands." Now, new research has associated bigger brains with longer thumbs across a wide selection of primates—the group of mammals that includes lemurs, lorises, tarsiers, monkeys, apes and humans. I'm also not going to argue with that finding. It may or may not stand up to peer review and reproducibility; I don't know. In a study published Tuesday in the journal Communications Biology, a team of researchers in the United Kingdom investigated nearly 100 primate species spanning extinct and living animals and revealed that the creatures with relatively longer thumbs usually also had larger brains. Okay. I presume one can measure brains and thumbs to some degree of precision, then put the results into a spreadsheet and do a regression analysis or whatever. Again, I'm not going to be overly skeptical about measurement data, except to say that the usual process of science needs to apply. The paper represents the first direct evidence that brain evolution and hand dexterity are associated throughout the primate family tree. And that brings me to a screeching halt while I dodge the apparent conclusion-jumping. Remember, there's argument about how well physical brain size correlates with intelligence. Moreover, while brain size can be determined with some degree of precision, there's also debate over what constitutes intelligence and, therefore, how to measure it. Furthermore, we're not "more evolved" than lorises and lemurs and whatever. We've all been evolving for the same amount of time, reacting to different environmental and genetic pressures. One could even argue that since humans have longer generations, we're less evolved. Or that rats, e.g., are more evolved because they're highly adaptable without having to create special environments for themselves. But I'm not going to get into that mess; all I'm saying is to watch out for the implicit assumption that "more intelligent" is the same thing as "more evolved." The researchers suspect that our ancestors first evolved manual dexterity, which then drove the development of a larger brain. They "suspect." Okay, they're allowed to do that. Now, how about doing some more science to support or falsify that hypothesis? For instance, I "suspect" that hands with opposable thumbs were one way that evolution enabled tree-swinging, and they were only later adapted to making and holding tools, even in descendant species that weren't arboreal (us, and gorillas, e.g.). I have nothing to back that up, and I admit it. So don't take that as ultimate truth, either. And just because that tracks with their suspected timeline doesn't mean either one is right. Even when the team removed humans from their analysis, the trend held true across other primates. They also tested the idea that the evolution of longer thumbs is associated with tool use, but they didn’t find any correlation. That would throw their "suspicion" into, well, suspect territory. Fotios Alexandros Karakostis, a biological anthropologist at the University of Tübingen in Germany who was not involved in the study, tells the Guardian’s Nicola Davis that the research indicates that adaptations to the brain and hand likely evolved together. If they're going to study this further, I "suspect" that they'll need to account for the possibility that, rather than being a causal link, the same genetic influence affects both brain and thumb. In other words, correlation because of some other cause. Oh, and one other thing, but an important one: I can easily see this being spun as "people with longer thumbs are more intelligent." That is not what the article implies, but humans, intelligent or not, like easy answers. And nothing would be easier than to think that one can determine someone's intelligence merely by holding a thumb-measuring contest. Which, again, is not the case. It's bad enough that nearly half of us hold dick-measuring contests on a regular basis. Quibbles aside, I'm not saying this isn't a promising avenue of research. I only have a problem with how it's presented. Maybe they need to find science reporters with longer thumbs? |
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