I think the book is clear that this simplification is forced by the data & knowledge we have now - frex he mentions bees as convergent examples but exploring that would be an extra book. This one gives the skeleton of the idea; the fleshed-out version would presumably have the "correct" bushy shape.
But ultimately any study of the evolution of a specific trait along a single lineage in which that trait happened to evolve in a consistent direction is going to look like "great chain of being" and there's only so much you can do to get around that without losing focus.
But this is not evolution of a trait along a lineage; it's using extant species as examples of higher or lower degrees of evolution of a trait. That's literally how the great chain of being was framed. And agency studies are rife with this kind of thinking.
It's not really though. The "intentional agent" stage for example doesn't portray an extant species to my knowledge. The imagery is less obvious for other stages but by the same token it's not obviously extant species either - what species is "lizard" or "nonhuman ape"?
As I mentioned before, he recognises this and goes to some lengths to justify the selection of exemplar species as the best stand-ins we have for ancestral species
But a propos the title: https://www.sciencedirect.com/science/article/pii/S0960982219306803
"The bias can be revealed with a Google Scholar search; "conserved from" AND "to humans" appear over 27,000 times, yet the reverse, “conserved from humans to” is found fewer than 800 times"
Sure. But in this particular instance, Tomasello makes an explicit and acknowledged choice of what to look at and what lens to take and defends it from the outset, without committing to any larger implications
I see, but I think that the title kind of reinforces a wrong way of thinking about the evolution in general (and many people will see the title and not read the book!)
Comments
Hopefully the text overall takes more care in dispelling misconceptions.
"The bias can be revealed with a Google Scholar search; "conserved from" AND "to humans" appear over 27,000 times, yet the reverse, “conserved from humans to” is found fewer than 800 times"
This feedback moves this book from the wish list to the reading pipeline.