Steven Crane Compiled Section Handouts. Human Behavioral Biology 2012

Gradualist ("creeps", as opposed to PE "jerks") say the fossil record is incomplete and maybe it's gradualist if we had more data.

Gradualists also say that "sudden" change for PE folks is plenty of time for sociobiologists to examine evolution of behavior in what they'd call a gradual manner.

Gradualists also say that PE folks are only looking at morphology or the way things are shaped. You get very different behaviors based on neurons and brains, and you can't directly examine those with paleontological evidence.

Gradualists in the old days also demanded to see molecular mechanisms for these changes. See below for response.

What's the molecular mechanism of PE changes?

1. Mutations in the regulatory regions of genes. We call these mutations

macroevolutionary.

1. These include: promoters, repressors, TFs, splicesomes, and transposases. Transposon action itself (even when not mutated) can change entire if-then sequences.

1. And multiple genes can be regulated by one TF or one promoter

2. And any given single gene probably responds to multiple TFs and promoters.

• So we have networks of genes and when you disrupt the controllers of those networks, their regulators, you can produce radically new if-then clauses. So a new environmental situation can trigger an existing pattern, OR the same environmental situation can trigger a new pattern if you have just small mutations in any of these regulatory sequences.

What about the mechanisms for the stasis part in PE?

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  The price of complexity of everything we've seen means that these small changes that have big amplfied effects are often going to have very deleterious effects, and will not be selected for. So we'll see a lot of stability in these systems.
  
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  We'll see the saltations at periods where there's an evolutionary bottleneck, like there was with cheetahs.
  

How can you get multiple proteins from one gene?

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