Charlie McDonnell is the author of a book called Fun Science: A Guide To Life, The Universe And Why Science Is So Awesome. He made a video on misconceptions about the theory of evolution (see below). Sally Le Page (below left) is an evolutionary biologist working on her Ph.D. at Oxford (UK). She noticed a few problems with the McDonnell video so she made one of her own to correct the misconception in the first video. Now it's my turn to correct the misconception in the video that corrects the first video!
Sally Le Page highlights six misconceptions in the McDonnell video. She points out that none of them are very important—they are "little niggles"—but she still thinks a comment is necessary. (I agree.)
- The animal in the video is not a monkey, it's an ape!
- Evolution is not the same as progress. Trees should not have humans on top. (I could add an additional nitpick—don't use a nineteenth century tree to illustrate evolution.)
- Modern bananas are actually designed! They have been specifically bred by artificial selection to produce a tasty treat.
- Fish don't have better eyes than mammals.
- Evolution is NOT just about survival. It's survival AND reproduction. Modern evolution includes inclusive fitness (her thesis topic). Inclusive fitness is when you help relatives to reproduce.
- Sequence similarity doesn't mean anything, those statistics are meaningless. "Are we including the junk DNA. The DNA that we don't know what it does but we think has a really important purpose but we haven't found out that purpose yet so we just call it 'junk'."
Sally Le Page is studying at Oxford. She's a fan of Bill Hamilton and Richard Dawkins. It's safe to assume she's a confirmed adaptationist. The problem with the first video is that it focused on the "Theory of Evolution" and on natural selection. I would have mentioned evolution by accident and random genetic drift just to make sure my audience didn't equate evolution with natural selection.
If you are going to correct the original video then it seems very strange to pick on inclusive fitness as the key concept that was omitted. By doing that, you are emphasizing natural selection over drift and that just adds to the original misconception. Inclusive fitness is a insignificant factor in evolution in 90% of all species because individuals don't even know who their relative are. (Think bacteria and protozoa.) In the rest, mostly animals, inclusive fitness only accounts for fixation of a small percentage of the alleles that are fixed by natural selection. Furthermore, alleles fixed by selection are only a fraction of those fixed by random genetic drift.
I'm afraid that Sally Le Page has missed the real problem in the original video and only made the misconception worse by bringing up inclusive fitness.
The last point (#6) is complicated. Charlie_McDonnell said in the video that we share 50% of our DNA with bananas. This is clearly incorrect. I don't know what the exact number might be but let's do a back-of-the-envelope calculation. Let's say that bananas and humans have 10,000 orthologous protein-coding genes and let's say the coding regions are 50% identical in amino acid sequences. That would account for less than 0.5% of the genomes. Adding in a bit of other genes and functional sequences won't get us over 1%. The rest is mostly junk DNA and it's unlikely there is any significant sequence similarity. We certainly don't share 50% of our DNA with bananas.
However, Sally Le Page goes too far when she dismisses all such comparisons as meaningless. When we say the genomes of human and chimps are 98% identical in sequence and humans and macaques are 94% identical then that actually means something [How do you explain the differences between chimpanzees. humans, and macaques?]. We can also say that orthologous human and banana genes are 50% similar whereas human and bacterial genes are only 30% similar. That means something.
Like all good adaptationists, Sally Le Page is probably skeptical of junk DNA because the presence of so much unselected DNA goes against her worldview. That's why she says that junk DNA isn't really junk—it's just DNA that has a purpose we haven't yet discovered. (This is the "dark matter" point of view.)
She is entitled to her opinion but she is perpetuating a misconception if she fails to mention the views outside of Oxford. If you are really interested in educating the general public about evolution then you'd better make sure you mention controversial ideas and make sure you aren't promoting your personal opinion as fact. In this case, the correct statement would be that less than 10% of our genome is conserved in other species and the rest may or may not have a function. Many scientists believe it is junk and many believe that it has a mysterious unknown function.
