James May, one of the presenters on Top Gear, is trying his hand at providing a little science education. I want to say…please stop. Here he is trying to answer the question, “Are humans still evolving?” In the end he says the right answer — yes they are! — but the path he takes to get there is terrible.
It’s little things that make me wonder if anyone is actually editing his copy. For instance, he helpfully explains that you, the viewer, were produced by your parents having sex. Then he says:
That’s how evolution is driven: by reproduction. But is that still true?
Uh, yes? We haven’t stopped reproducing, so we should be able to stop right there then.
But no, he continues on. He tries to explain evolution, and does manage to verbally describe natural selection correctly as differential survival and reproduction, but it’s illustrated with a pair of goats with telescoping necks. That doesn’t help. He’s describing Darwinian selection and showing it as Lamarckian — it’s a very mixed signal. And as we’ll see, he still seems to be thinking like will and experience drive evolutionary changes.
And do I need to mention that he doesn’t seem aware of processes other than selection in evolution? You need to realize the importance of drift to answer the question of whether evolution is continuing in humans, especially when you’re prone to say glib nonsense like “humans have turned the process of natural selection on its head,” whatever that means.
He also claims along the way that Darwin “tracing this evolutionary process backwards proved that all life came from a common source.” No, he didn’t. A hypothesis is not proof. He found morphological evidence for the relatedness of some groups, but the evidence for common ancestry of all forms wouldn’t really become overwhelming until the molecular evidence linked animals and plants and mushrooms and bacteria together.
By the time he gets around to talking the details of human evolution, we’re mired in a hopeless mess. Apparently, one reason we’re still evolving is that “certain characteristics will improve your chances of breeding” but then he helpfully explains that “its not as if ugly and stupid people don’t get to have children”. So which is it? Is natural selection selecting away for chiseled abs, or whatever he regards as a significant advantage, or isn’t it? And if people he judges as unattractive are having children, that driving force of evolution, then isn’t that undermining his understanding of the process?
And please, if you can’t even get selection straight in your head, please don’t try to explain population structure. He has a weird discursion in which he explains that “the genetic mutations that drive evolution can be most commonly found in a small gene pool” and then somehow tries to argue that we’re “too cosmopolitan,” that the fact that people from all over the world can now intermarry somehow “cuts down on those mutations.” I have no idea what he’s talking about. I suspect he doesn’t either.
Then, as evidence that we have been evolving, he points to big screen TVs as proof that we’re smarter than Stone Age people. Great — we now have a new IQ test. Just measure the dimensions of the individual’s TV. It’ll probably work about as well as regular IQ tests.
He tries to get to specific traits: lack of wisdom teeth is evidence of human evolution, apparently. Never mind that the changes are recent and mixed, and that it’s more likely a plastic response to changes in our diet than a trait that’s been selected for specifically. It’s a very bad example, unless he’s going to argue for selection for people with fewer teeth in their jaws. Do you typically count your date’s molars?
His ultimate proof that humans are evolving is the appearance of lactose tolerance in adults. That is pretty good evidence, I’ll agree…but he messes it up completely.
10,000 years ago, before anybody had had the bright idea of milking a cow, no human could digest the lactose in milk beyond childhood. But now, after a hundred years of drinking cream and milk and squeezy cheese in a can, 99% of people can.
He doesn’t even get the numbers right. The haplotype granting lactose tolerance to North Europeans has a frequency of about 90%; in South Europeans it is about 30%, and less than 10% in people of Southeast Asian descent. This is not a largely lactose tolerant world.
And of course, his explanation is screaming nonsense. We are not lactose tolerant because we’ve been drinking milk; we’ve been drinking milk because we’re lactose tolerant. It is not a trait that appeared in the last century.
Why is this guy babbling badly about evolution? Did he have any informed, educated scientists to consult who could tell him not to make such a ghastly botch of it all?