Spiderman at the intersection of physics and biology

We’ve all noticed that, in the Spiderman movies, the hero ejaculates tremendous amounts of protein constantly to make those spider threads he’s swinging on and splattering all over the bad guys. Part of that is plausible; spider silk is amazingly strong stuff, and if you could produce it, sure, thin strands would support your weight. The problem is the volume. Mark Lorch calculates how much protein Spiderman would have to consume to make the thread for one scene in the movie.

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Death to Dollo’s Law!

Hint for science journalists: if the hook to get readers to pay attention to your story is to warn them to sit down because a 19th century “law” of evolution has been shown to be wrong, you’re going to irritate scientists, who will then write rude blog posts sneering at your writing. That’s the case with this story titled The Wrists of Birds Reveal Evolution Undoing Itself, which is also subtitled Contrary to earlier claims, a new study shows that evolution may be reversible.

It’s describing a paper on the re-emergence of a wrist bone in birds, and it touts Dollo’s Law.

The 19th-century biologist Louis Dollo taught that evolution is irreversible; once a structure is lost, that pathway is closed forever. It’s a principle now known as Dollo’s law.

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Getting from here to there isn’t necessarily linear

You may recall that sad comment by Scott Aaronson on his blog, Shtetl-Optimized, in which he deplored the way no respect is given to men’s biological imperative to have sex with all the women. Or more recently, Paul Elam’s bizarre appeal to badly interpreted biology and duck rape to justify MRA entitlement. It’s all of a piece, and it’s annoying: it’s reductive nonsense, in which people see a well-established set of scientific principles, and see their own complex situation, and imagine out of whole cloth a clear, simple path from one to the other. And suddenly, they’ve portrayed their messy life as the outcome of a purely determined, clockwork series of inevitable interactions, and they find refuge in the lowest common denominator of possible explanations. “It’s not my fault,” they can say, because of the way electrons interact, because biochemistry and thermodynamics, because genes, because everything follows from astronomical impacts and geology and Chicxlub at the end of the Cretaceous.

As it turns out, that’s what Scott Aaronson (with seemingly little comprehension on his part) was discussing in that notoroious comment section, in part, with someone named Amy. What started as a discussion about a grab-ass professor losing his job evolved into a lot of denial and defensiveness, and of course whenever a lot of nerds try to defend the status quo, they ultimately try to bring up Human Nature and Behavioral Science and This Is How We Evolved. I struggle myself to avoid falling into that trap, and sometimes I do anyway, but a whole gang of male nerds tends to inevitably drift into gross reductionism. Because of thermodynamics, I think, or maybe van der Waals forces.

Anyway, the provocateur behind all that argument, Amy, has now beautiful essay on all the phenomena in the middle that get ignored.

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