And who even knows how many different times high level intelligence has evolved. I think octopi, birds, and mammals are all good examples of separate intelligence tracks with similar results.
I believe Darwin envisioned that, and the Tree of Evolution was just an introductory notion (I never read his book) before going into subtler reasons for new traits.
Flight is so useful, it evolved 4 times independently. With very similar solutions. https://en.wikipedia.org/wiki/Flying_and_gliding_animals
And crustaceans keep evolving into crabs. https://www.popsci.com/story/animals/why-everything-becomes-...
And who even knows how many different times high level intelligence has evolved. I think octopi, birds, and mammals are all good examples of separate intelligence tracks with similar results.