Thursday, March 28, 2013

Stranger Things, Horatio

There is a kind of fish called a sheepshead that comes in varieties so diverse that one wonders why they are considered a single kind of fish.  For example, one sort gives you psychedelic hallucinations.  A non-hallucinogenic kind has almost-human teeth:
No canine teeth, for what I suppose would be the obvious reason.  And there are molars all over the inside of the mouth, the telos for which is evidently the eating of shellfish, which tend to come with shells. 

But here is the Asian sheepshead, and you cannot make this stuff up. 

That is one ugly fish, unlikely to show up on your menu.  Like its human-toothed conspecific, it does not give you hallucinations.  It is an hallucination.  Sheesh.  

Undoubtedly, someone can come up with a Darwinian adaptationist just-so story that neatly accounts for this fish's head.  My theory is: a) mutations happen, b) this mutation neither killed the fish nor impeded reproduction, and so c) here it is.  Since the fish uses its head in some manner or other, one can point to this usage and claim that this was the telos for which it was naturally selected; but it is surely just as plausible that the telos was the fish's drive-to-survive. 

Why it's called a sheepshead is a mystery. 


  1. You might enjoy Walter ReMine's The Biotic Message, wherein he proposes the theory that God has intentionally arranged the creation of kinds in such a way that no theory of evolution can actually explain them.

  2. Regarding your theory on the Asian sheepshead, I submit that natural selection is not about what is advantageous, but about what is not disadvantageous; traits are not selected for, but they are selected against. And so, you are probably correct. It has that ugly noggin for no better reason than the reason male mammals have nipples: the possession of such is not disadvantageous.

    1. Blythe, who originated the theory of natural selection, thought it was a force for maintenance of type, because it weeded out divergent forms. IOW, an argument against evolutionary change. Darwin used his theory but claimed an opposite effect.

    2. Technically, Darwin claimed both effects, depending on the environment. In a (relatively) stable environment, change is weeded out. In a changing environment, some changes are become preferred.