As a narrative about how science works, this is pretty strong. I got it as part of my new policy of not reading emotionally intense books right before bed, and while it didn’t produce the post reading anxiety that, say, that book about slavery did, it was pretty exciting and pushed my bedtime back quite a bit.
The actual science, I’m not sure about. He’s doing molecular biology without any background in basic bio, so he says things like “I didn’t know insects were animals.” on his first day as a zoology professor (he’s since realized his error) or “Can we really say they’re the same species just because they fertily interbreed.” in his book, on biology, that people paid him actual money to publish. Yes, we can say that because that is exactly what species means.
I’m also a little confused by how they determined humans and neanderthals interbred. It seems like they’re using the same data to calibrate the technique they’re using to sequence the DNA, the degradation rate of DNA, the contamination rate of the sample, when humans and neanderthals diverged, and when/how much they interbred. He also doesn’t make a good distinction between when he’s talking about junk DNA (which is not subject to selection pressure, so is a pretty good molecular clock) and when he’s talking about genes (which is, and so it’s difficult to distinguish inheritance from the same source, interbreeding, and convergent evolution).
Lots of very smart people with much more information and training in this area than I have seem to be okay with his conclusions, so I assume this is one of those things where he is simplifying, and I know enough to know that he is missing something but not enough to fill in the gaps myself. But if you are not in that uncanncy valley, it’s very well written and entertaining.