Animal taxonomy is actually much weirder than you would think at first glance. The classic definition of species is the group of organisms which are capable of producing fertile offspring. However, there are also ring species, where you have populations A,B,C where B can interbreed with either A or C, but A cannot interbreed with C. Or in an alternate phrasing, members of B are members of both species A and species C. This obviously becomes intractable beyond a very few interbreeding populations.

So really, even nature favors composition over inheritance.

This is really interesting.

I've been turning this idea over in my head every now then as a mental exercise (bus ride material). One, it validates my reasoning that rigid single-inheritance trees are a bad representation.

What my mind kept turning to was the possibility of Neanderthals and early humans interbreeding yet being different species that had a common ancestor. It isn't really a tree in that case.

Two, this comment gives my past time more food for thought!

Biological taxonomy is just not a good analogy. Object behavior hierarchies aren't analogous to any real world thing, IME. They are what they are.

in fact the tree of life can't be traced back to a single root because us Eukaryote organisms are the result of a train crash between Eubacteria and Archaea maybe 2 billion years ago.

How do Cobb's Normal Forms fit in here? They are all about relations. I suppose a single inheritance pattern cannot get more complex than first normal form, but I don't really remember this from a long time ago.

"Codd's"