By: why Evolution is true
I’ve just noticed that this is post #12,002 since we began nearly six years ago. That’s a lot of posts!
“It’s okay to be smart” and PBS are producing a series of short videos, “Twelve days of evolution.” I’ll put up one a day, which should ultimately take us close to the end of Coynezaa.
This first one explains what evolution is. There are a few problems, though: it conflates evolution with natural selection (you can have common ancestry without natural selection), it equates natural selection with differential survival (actually, the differential reproduction of genes, whose vehicles are organisms, is the key), it doesn’t define “allele”, and there’s a long blurb for Dropbox at the end.
To me, the modern theory of evolution is as follows, and this is what I’d prefer to have seen in the video:
- Evolution occurs, and by that we mean genetic change in populations.
- That change is usually gradual, i.e., substantial change requires lots of time: more than just a generation or two. What evolves are populations of organisms, not an individual itself.
- A lineage can not only change, but split, producing new species and new lineages.
- (Flip side of the previous): If you take any two species or individuals, you can go back in time to find their common ancestor. The more recently in time that that ancestor existed, the more closely related the species. All living species descend from a single form of life that lived between three and four billion years ago.
- The only process that can produce the appearance of design that so amazes and delights us is natural selection: the differential ability of genes to get themselves copied into the next generation. But there are also processes beyond natural selection that cause evolution, including genetic drift. Those processes, however, don’t cause adaptation.