Friday, 8 May 2009

Protomammal Fallacy

A lively discussion is taking place in the comments at Art Evolved in the new Permian Synapsid Gallery. Are terms like proto-mammal or stem-mammal appropriate? I tend to think they confuse more than help. I understand evolution by natural selection is a sequence, but by defining an extinct creature by its descendants, I think we run the risk of promoting the facile and erroneous amoeba-->fish-->lizard-->mouse-->monkey-->ape-->human progression diagram. That is why for the Synapsid Gallery, I wanted to show a dicynodont with human arms erupting from its own shoulders (and a gorgonopsid with human legs threatening it in the background). To echo Dawkins, Permian synapsids were not half-evolved, not "on their way" to becoming us. They were successful animals living in their own niche.

Successfully made my point? Well, perhaps as an illustration to this blog post.

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Sean Craven said...

The term I'm most familiar with is 'mammal-like reptile,' which seems to connote something along the lines you're suggesting -- it seems to be a description of a working animal, not a link in a developmental chain.

Although I read somewhere that describing them as reptile-like mammals might be more accurate...

Glendon Mellow said...

Yeah, I'd have to agree I like that term better.

I'm willing to admit context helps: if someone was discussing a particular feature shared by Permian synapsids and later mammals, I can sort of see its use. The continuity is there.

Otherwise, I find a term like protomammal makes them sound like half-formed seeds of mammals.

violetlight said...

So the little guy in front, when we those be in pet shops.... I want one :)

Glendon Mellow said...

Oh, sorry Violetlight, yeah, they sold out a few hundred million years ago.

Daniel said...

I disagree. I think it's perfectly fine to name an animal in terms of its best known descendants. Take the protoceratops as an example. Even the word "dinosaur" makes reference to (some of) its descendants.

A term like protomammal is perfectly appropriate to denote the group consisting of the earliest mammals and their immediate relatives. I think that constructions like 'mammal-like reptile' and 'reptile-like mammal' are worse because they suggest a sharp division where there is none.

Glendon Mellow said...

Interesting thoughts, Daniel. I do see the utility in what you are saying, but I wonder how much of that is simply because we are used to speaking that way? It's unlikely to be reversed at this point in our language.

Good point about the word dinosaur, too Daniel. Thanks!

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