Wednesday, August 5, 2009

Evolution Revealed in Excess Butterfly Sperm

In the best example of creationism-inconsistent evolution since the stab-raping bisexual bedbug:

The sperm of male butterflies has a strange property. About 90% of it is non-fertile -- essentially filler for the females' sperm storage organs that tricks females into thinking they have all the sperm they need to fertilize their eggs. The males' ploy reduces the likelihood that their mates will take another suitor, thereby ensuring their own paternity.

It's tough to imagine the creator god saying "gee, I think I'll design this butterfly so that the female won't be satisfied until she's full, so I'll give the male 10 times as much sperm as he needs, and 90% worthless sperm at that." Still, as good scientists we must always be ready to challenge our assumptions, and this is no exception. The science does have a bit more research left to solidify the case:

...the interpretation of Wedell's results requires some assumptions about the costs and benefits of non-fertile sperm production and storage that have not yet been confirmed, cautioned evolutionary biologist Darryl Gwynne of the University of Toronto, who was not involved in the work. The nutritious gifts that females receive upon mating are likely to be a high incentive for them to mate many times, but there are often costs associated with mating as well. It is therefore unclear how often females should mate to maximize their fitness.

"This paper addresses a really neat potential conflict situation in these butterflies," Gwynne said, "[but you] need to show [that] by filling her sperm storage organs with these non-fertile sperm and increasing her refractory period, you're actually impacting her fitness." In other words, demonstrating that this is a case of sexual conflict requires showing that females incur a cost by storing non-fertile sperm.


Notice however that there is no promise of salvation for the creationists in these criticisms. They only address the issue of whether the cause of the excess sperm is sexual conflict, not whether the excess sperm exists, or that it is nonfertile. It doesn't matter what the natural explanation turns out to be, or whether this one is correct, "god wanted it that way" will never fly as a viable alternative.

2 comments:

foodandotherrequirements said...

Very nice example of scientific exploration at work. Every time I have this discussion with anyone re: creation vs. evolution, I have to remind whomever I'm talking to that science does not pretend to have all the answers--that the whole point of science is to explore and discover the truth--not make up crap in the absence of evidence.

ScienceAvenger said...

That's the great irony in many of these debates. It's the anti-science folks pretending that science must have all the answers to be valid, and the scientists reminding them that we still have much to learn. It's a subtle logical fallacy the deniers use: to know I'm wrong you must know everything. Therefore (they posit), if you can't explain the eye/bombardier beetle/bacterial flagellum, then my theory is just as good as yours. It's binary thinking applied in the worst possible arena.