Evo-Devo & EP

I find gold in surprising places and it's easier when I cross discipline boundaries.

My reasons:

1) The hox sequence and the phenomena from gene transplants (especially pax-6, called the "evo-devo poster child" by StevenJ) provide another sturdy post under my argument that evolution is a fact. The assertion that human sociality follows evolutionary payoffs, whether statistical, biochemical , or biomechanical becomes easier to sell. (Eldridge comments that his pictures of skulls usually silence doubting fundamentalists: when we manipulate hox phenomena, we push the bones aside.)

2) Raff's discussion of the development of the hox sequence (duplication, divergence, changes in timing, and cooption) also describes the sometimes cooperative, sometimes competitive relationships between species. We find that same structure behind cultural changes: cloning of an established entity, constraint and amplification between the daughter organizations, partial inhibition of established tradition, modification of the onset and duration of influence, and cooption: the exploitation of new opportunities, made possible by the refinements.
Imo, one of your rhesus cousins, is dead but she also lives. She discovered how to wash sand from potato slices and to separate oats from sand. She taught her siblings, aunts, and peers and the practice continues across generations. The old males, however, never picked up the techniques. We face a similar problem in the acceptance of evolution and EP: the kids accept and love the concepts, the senior clerics and school administrators hate them. Sometimes we must out with the old before we in with the new. (I think Haldane commented along these lines, the first test for a mutant is to kill off its parents!). We find these same processes in Raff's model.

3) I sometimes use Raff's sequence when writing essays: start in the middle, then invest in the head but less in the tail, fill in the gaps between them. (My coming paper on ADHD is mostly about emergent network metaphors but anchors them on evo-devo.) Again, duplicate an idea or model, fiddle with the clock, vary the duplicate, apply it to new contexts, and enjoy the new things that it does. (Skinner would have called it "serendipity" and "successive approximations," Thorndike "positive reinforcement," Gerhart & Kirschner "exploratory systems," and many more of us "selection.")

4) Raff speculates that inhibited DNA sequences can remain functional although silenced for up to 5 million years. Curious about Homo erectus? Reverse a methylation the right gene so the original sequences are expressed. Want your kids to be short, thick, and hairy? Zap another gene. (The cooperative interactions during ontogeny will preclude centaurs and other half-and-half outcomes. Disappointed?)

5) Evo-devo gives Steinbeck's Of Mice and Men a literal rather than a literary truth: our small cousins are a useful partner not only in genetics but also in medical research. There is now less surprise that rat psychology differs less than a whisker from that of humans. (Take that, Todd Stark, you damned humanist! :))

Some of the differences between you and me reflect cognitive differences that often appear between men who, in utero, escaped estrogen baths and women who avoided those of testosterone. My mind arranges events in networks and when I build, I sculpt and I construct 3-dimensional things. Likewise when I write. I find linearity tedious and dislike new underwear that is a size too small. I feel this way despite too many years of public schooling when you women and some old men forced my thinking and writing into straight lines. (Thank Fred's God that the effects of shared environment are only temporary.) My mind may be just a developmental quirk, one more male thing that results not only in Nobel prizes but also in more pathology. Nonetheless, I'll take my chances: I like my side of the fence better even though your side has the final say.

JB

PS: You know that crickets, courting humans, and pendulums move in phase. Kuramoto proved that any number of similar oscillators, weakly linked, will eventually come into synchrony! Evo-devo has its own platform...

Copyright, 2004, James Brody, all rights reserved.

Replies:

Hox Genes & Mall Chicks, by James Brody, 06/03/04

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