Evolution's selection target depends on your weighting

post by tailcalled · 2024-11-19T18:24:53.117Z · LW · GW · 3 comments

Contents

3 comments

I think it's common on LessWrong to think of evolution's selection target as inclusive genetic fitness - that evolution tries to create organisms which make as many organisms with similar DNA to themselves as possible. But what exactly does this select for? Do humans have high inclusive genetic fitness?

One way to think of it is that all organisms alive today are "winners"/selected-for by that competition, but that seems unreasonable to me, since some individual organisms clearly have genetic disorders or similar which make them unfit according to this criterion.

There's some sort of consensus that we can assign individual organisms to "species", and then we could count it by the number of members of that species. Supposedly, the most numerous species is Pelagibacter communis, with 10^28 individuals, vastly outnumbering humanity. Maybe we could say that this is the selection target of evolution?

Of course as would be expected, pelagibacter is a very minimalist species, being single-celled and having very few genes. This minimalism also makes it hard to notice, to the point where according to Wikipedia, it was first discovered in 1990. (I wonder if there's another species that's smaller, more common, and even harder to notice...) This raises the question of pure numerousity is the correct way of thinking of it.

If we instead weight by biomass, most life is in the form of plants, and I think more specifically trees. This makes perfect sense to me - trees evolve from a direct competition for height, which is one of the traits most directly related to mass. And in a way, biomass is more sensible to weight by than numerousity, since it is less dependent on the way you slice a species into individual organisms.

But trees are pretty static. Maybe the problem is that since mass has inertia, this weighting implicitly discourages more dynamic species, like humans? An alternative is to weight by energy flow, but in that case, algae and grasses end up accounting for most of it. Sensible, because if you go up the trophic levels, you rapidly lose energy. That said, energy flow does have the dissatisfying (to me) element that it is "shared" between organisms that predate upon each other. I wonder if one could use something like entropy production to get a conceptually similar metric that's more attributable to a single organism.

I don't know of any weightings or metrics where humans are the winners, but it seems likely to me that there is one.

3 comments

Comments sorted by top scores.