Comment by thrw045
17 hours ago
But is the diversity really that staggering? I mean most animals including possibly dinosaurs that have ever existed share a lot of internal organs, in the same place. They have eyes, brain (with a lot of the same brain areas, even birds have something like a prefrontal cortex but it's called something different). They all have legs, torso, head. I would say there is a lot more commonality than difference. The differences come from slight variations on a basic template that works, and then the body looks different and so on.
I'm not sure how to think about the diversity that evolution creates and how diverse it actually is. I would say there are _a lot_ of repeating patterns all across history, with variations on those repeating patterns always changing.
You're choice of samples is rather skewed towards ones sharing a relatively recent common ancestor. Octopus and Sea Squirts are also animals, and they don't have legs or torsos or, in the later case, heads or eyes. Octopus brains are also rather different from those of vertebrates, and they have 8 mini-brains for more distributed/localized control of each major limb.
That said, I agree with you that there is a lot of commonality in life. Even in the case of Octopus we share a lot of DNA. I just mostly think that is due to common ancestor and common environmental pressures, not to some fundamental limit in the breadth of evolutionary potential itself. Its probably worthwhile to wonder at how that actually works though. Maybe evolutionary potential could be improved.