Okay, I give up. It's everywhere (e.g. here), it's wrong, and I have to waste time arguing about it. Can't these people run after straightforward drivel? Doesn't Britney Spears need someone to criticize her nail polish?
Get out your notebooks. The class will be starting with a refresher on evolution. The definition of it is heritable change through time. Change occurs because there is a range of variation, and only some of that range gets passed on to the next generation. Usually, natural selection decides which characteristics win out, but there can be other factors. For instance, if a volcano erupts and wipes out half a species, the remaining half survived through luck, not because it was adapted to volcanoes.
So far, so good. Random mutations produce variation in the DNA, some of the DNA is lost due to natural selection and other factors, and the result is heritable change through time.
What the media has done with these simple concepts is beyond pathetic, probably because they're applied to humans which causes them to lose their heads completely. The research itself is respectable, even if I do I have technical bones to pick about their assumptions regarding single nucleotide polymorphisms (SNPs) and their implications for the evolution of associated genes. (Having trouble finding the original link. Please leave it in comments if you find it, and I'll include it.)
The media trumpets the fact that human DNA now has more variation than it did in the Paleolithic. Well, duh. Natural selection isn't operating with anywhere near its former ferocity. All kinds of weaklings survive these days, like naturally thin people who would have starved in the first famine. That variation in the genome would have been pruned off pronto in the good old days. Likewise for Leiden's Factor V clotting disorder, achondroplasia, probably color blindness, and so on through hundreds of other variations on the human theme. Of course there's more variation now. And, as the researchers themselves point out, there are a lot more of us, and larger populations contain more variation than smaller ones.
Variation is not the same as evolution. Evolution is what comes after some of the variation has been selected for over time.
It should come as no surprise that evolution in humans is an ongoing process. One of the examples cited is increased resistance to malaria, which is plain old natural selection and has nothing to do with culture. Another example, not cited, is increased lactose tolerance, which really is an example of heritable change over time due to cultural factors. Whether it's happened faster than evolution in the absence of culture is debatable.
There's scant evidence of faster evolution since the invention of culture. But there's plenty of evidence that variation accumulates more quickly because culture provides a sheltered environment that prevents most natural selection from operating.
Which brings me to the second point. The examples cited of how selection has speeded up due to cultural factors have little to do with natural selection. One of the media's favorite points is the increase in blond and blue-eyed Europeans because those features are considered attractive. (Now I wonder what's so great about that example?)
That's not natural selection. When mate choice has a noticeable effect on a species' physical characteristics that's called sexual selection. It's what makes male peacocks carry around unwieldy tails. Because better success in mating means more offspring, those charactersitics can be passed on even when they actually make it harder to survive. In the most famous example, male Irish elks developed such huge antlers that their nutritional requirements grew too high. (It takes a lot of good eating to grow all that bone.) They couldn't survive lean years when the climate changed, and with one sex mostly missing, the species didn't survive either.
So we're getting some changes, but breeding nonfunctional humans based on the preferences of fashion editors hardly deserves the name "evolution." Unintelligent design, perhaps.
Get out your notebooks. The class will be starting with a refresher on evolution. The definition of it is heritable change through time. Change occurs because there is a range of variation, and only some of that range gets passed on to the next generation. Usually, natural selection decides which characteristics win out, but there can be other factors. For instance, if a volcano erupts and wipes out half a species, the remaining half survived through luck, not because it was adapted to volcanoes.
So far, so good. Random mutations produce variation in the DNA, some of the DNA is lost due to natural selection and other factors, and the result is heritable change through time.
What the media has done with these simple concepts is beyond pathetic, probably because they're applied to humans which causes them to lose their heads completely. The research itself is respectable, even if I do I have technical bones to pick about their assumptions regarding single nucleotide polymorphisms (SNPs) and their implications for the evolution of associated genes. (Having trouble finding the original link. Please leave it in comments if you find it, and I'll include it.)
The media trumpets the fact that human DNA now has more variation than it did in the Paleolithic. Well, duh. Natural selection isn't operating with anywhere near its former ferocity. All kinds of weaklings survive these days, like naturally thin people who would have starved in the first famine. That variation in the genome would have been pruned off pronto in the good old days. Likewise for Leiden's Factor V clotting disorder, achondroplasia, probably color blindness, and so on through hundreds of other variations on the human theme. Of course there's more variation now. And, as the researchers themselves point out, there are a lot more of us, and larger populations contain more variation than smaller ones.
Variation is not the same as evolution. Evolution is what comes after some of the variation has been selected for over time.
It should come as no surprise that evolution in humans is an ongoing process. One of the examples cited is increased resistance to malaria, which is plain old natural selection and has nothing to do with culture. Another example, not cited, is increased lactose tolerance, which really is an example of heritable change over time due to cultural factors. Whether it's happened faster than evolution in the absence of culture is debatable.
There's scant evidence of faster evolution since the invention of culture. But there's plenty of evidence that variation accumulates more quickly because culture provides a sheltered environment that prevents most natural selection from operating.
Which brings me to the second point. The examples cited of how selection has speeded up due to cultural factors have little to do with natural selection. One of the media's favorite points is the increase in blond and blue-eyed Europeans because those features are considered attractive. (Now I wonder what's so great about that example?)
That's not natural selection. When mate choice has a noticeable effect on a species' physical characteristics that's called sexual selection. It's what makes male peacocks carry around unwieldy tails. Because better success in mating means more offspring, those charactersitics can be passed on even when they actually make it harder to survive. In the most famous example, male Irish elks developed such huge antlers that their nutritional requirements grew too high. (It takes a lot of good eating to grow all that bone.) They couldn't survive lean years when the climate changed, and with one sex mostly missing, the species didn't survive either.
So we're getting some changes, but breeding nonfunctional humans based on the preferences of fashion editors hardly deserves the name "evolution." Unintelligent design, perhaps.
