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Daily (intermittent) Open-Ended Puzzle: Skull-brain evolution

While watching our local squirrel digging up the flowerpots on our porch, thinking about how much easier it would be for both of us if the stupid thing would just evolve a bigger brain, I got to thinking about how unpleasant the bigger-brain mutation would be if it didn’t come with a simultaneous bigger-skull mutation. But having both of those mutations occur at the same time seems to multiply the improbability, doesn’t it?

So, how’s it happen? Are the two sizes controlled by the same gene? Do skulls form around brains so brains don’t rattle around in them? Does it really take multiplicative random mutations? Or what?

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3 Responses to “Daily (intermittent) Open-Ended Puzzle: Skull-brain evolution”

  1. With respect to evolution, I have no direct answer. Actually, it would be easier if I didn’t believe in evolution. But, non-evolutionarily (?), in infancy if the head contents enlarge, as in hydrocephaly, the skull enlarges to contain it, at least until the skull “joints” grow together in ossification.

  2. It’s been a while since I read “The Plausibility of Life” but I recall that Kirschner et al describe how the growth signaling of fetal structures are interelated so that yes, a change/mutation in one area (eg, skeletal structure) will trigger appropriate changes in the formation of muscle, vascular structure, skin, etc. My foggy layman’s description – not so much controlled by the same gene, but some systems use (I’ll call it) second-order signaling to conform to the fundamental genetic signals. So no, you don’t necessarily need multiple, coordinated changes in genes to trigger useful mutations.

  3. I don’t know the answer to your evolutionary question. Aside from that I have a hard time getting around the deeply disturbing implications of more intelligent and persistent squirrel kind.

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