Talmudic Question #26

 

Given that hardly anything in biology is more central yet more elusive than the concept of species, can you con­ceive of a way to portray evolutionary history that is not based on the species concept?

 
 

 
 

Comments

[John S. Wilkins]

Elio: the myth here is that there is a unit of biology, "species". But it's not a myth that actual species exist as objects. M. musculus exists; it simply doesn't happen to fill a prior box of biological categories.

This allows me to add to the giant literature, I trust. Others, such as Jody Hey, have denied the reality of any species as well as the species category, but I do not go so far. I'm no conventionalist, I'm a phenomenalist, and of course a phenomenon requires some set of assays to individuate. So if you have a number of such techniques that tend to coincide, it's a species.

John: Mayr is simply historically wrong about essentialism. I'm sorry, and I can't back it up here, but essentialism is another myth (two myths. Amongst our mythology... I'll come in again). There never was any such conception of species, at any time. Instead I would argue that the default view of species was:

generative power + similarity of form

Mayr makes it identity of form and ignores, in some cases in his 1982 by simply snipping the rest of a passage, the generational aspect of species. I call this a Generative Conception of Species, and it was in play from Epicurus right up until the arrival of genetics.

I believe that there is a Conceptual Delicatessen, which biologists use to assemble the "species concept" that suits their group of organisms, and then they can debate over the best club sandwich for their purposes. This is why, for example, the "species concept" of microbiologists differs radically from the "species concept" of vertebrate zoologists. The one won't do duty for the other. This indicates to me that "species" is an evolved way of being a lineage, just like cell walls, endosymbiosis events, tetrapodality, and so on. We pick the club sandwich that best suits the way these critters have evolved to cluster together. Awful metaphor, I know, but there it is.