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Old May 5th, 2005, 06:30 PM
James Brody James Brody is offline
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Default "Endless Forms Most Beautiful": Raff Rules!

Endless Forms Most Beautiful: Raff Rules!
A review of Endless Forms Most Beautiful: The New Science of Evo Devo. Sean Carroll, (2004) NY: Norton, about $26.

Structure

"Endless Forms Most Beautiful" extends Carroll, Grenier, & Weatherbee (2001) which is still the best $0.25 per page that I ever spent. It explained hox genes as the master organizers that organized our bodies and led to our cathedrals for the last 600 million years and that now convince us of the common ancestry of starfish and the oysters they eat and of humans and all that we eat. Hox genes are "way cool" and Carroll (2004) tells about the same story as he did in 2001 but with more detail and greater ambition.

Carroll's Case

He starts with what we know of hox genes and finishes with the unification of evo devo and paleontology! The ride is an entertaining one: hox organizers arrange the materials at a particular site into wings, claws, fingers, or antennas in response to biochemical gradients established by other hox organizers. (Gould, 2002, called this the "hoxology"!) Spots become stripes and segments: the rhombomeres of our brainstem share their architects with crayfish, insects, and Rover. And some of our receptor systems that draw us to Nemo possibly arose in our ancestors of the Devonian period. (And it may be that the navigation tools employed by birds and bikers also first emerged in that same era. As Eiseley,1957, reminds us, a Devonian fish became a character in a straw hat.)

Carroll is also proud of a second idea: 1.5% of our DNA has identifiable purposes and he compares the rest to "dark matter" that functions as switches that turn on/off developmental sequences. I like the idea of switches: they allow the possibility of Lamarckian changes in response to uterine conditions as well as those that are the context for a particular mating. A starving mother might produce several generations of runts, it took two generations for the Japanese to grow tall after they lost the War but won the Corn Flakes.


Carroll once more gives lots of pictures as he progresses through:
1. Adding stalks to tubes (lobopodians) and joints to stalks (arthropods & vertebrates).
2. Reducing the number of identical segments but increasing the specialization of those that remain (Williston's Law). Gills, fins, legs or wings appear while bodies become shorter.
3. Symmetry (left/right) and polarity (head/tail and top/bottom) unfold. Longitude and latitude apply to fate maps drawn on a zygote.
4. Lots of explanations of how tubes, spots, and stripes make flies, spiders, butterflies, and zebras.
5. Melanism in moths, cats, and zebras.
6. A nice recap in Chapter 11.

You do need to memorize some labels.

Carroll is still not an easy read but easier for most of us than his earlier book that had more pictures but fewer jokes. For many of us Carroll gives a familiar landscape at a very different time of day. He also reveals different highlights about Bateson, Spemann, Thomas Huxley, and a busload of others. I also appreciate knowing that Monod, Jacob, and Lwoff not only shared a Nobel Prize in 1965 but were active in the French Resistance. Francois Jacob, for example, was a medic and severely wounded at Normandy.
References are scattered through his notes and a master list is omitted but, all in all, not a major problem and perhaps an asset. All the stuff on a specific point is listed together. The notes are also fun. For example, I learned that Monod never said "chance on the wing": Stu Kauffman did when he misquoted Monod! (There are several bits of nastiness towards Kauffman which might suggest that Carroll actually met Kauffman somewhere. Kauffman seems to be one of those guys who never finds anyone else in the room with him.)

Weiner's "Time, Love, & Memory" is a more vivid introduction to behavior genetics and, indirectly, the worlds shown to us by mice and hox. Jacob(1973) tells a similar story but with fewer details and better writing. Nonetheless, I'm glad that I bought "Endless Forms" and will refer to it often.

Shortcomings

- Carroll opens with one more phrase from Darwin's golden paragraph (so much ink from a patch of mud, water, and weeds) and promises me another new science, one that he pitches to the market that also buys Time Magazine: "new science," however, is no longer the magnet that it was; neither, thankfully, is Time. Most of us know that Haeckel organized our modern ideas of evo devo nearly 150 years ago (Gould, 1977, 2002) on the basis of what he found in embryos: "Ontogeny recapitulates phylogeny" in one version or another and Carroll as well as Gould (1977; 2002) and Austin (2004) argue that evolution depends on compounded, heritable changes in the development of individuals. Hardly a "new science" except to Norton's marketing department.
- Carroll likes the "climate change" explanation for the emergence of human intelligence. Implication: he probably hasn't thought much about emergent networks (e.g., Barabasi, 2002. See below.)

- He affirms the consequent: from what is now, we know what was. Fossils depended on hox genes and will, therefore, show properties that are consistent with what we now understand of those genes. The legs of a spider imply the rest of the spider. Nonetheless, Carroll shares a problem with evolutionary anthropologists, psychologists, and biologists and with most contemporary social scientists: he tells us a story.

- He estimates that his new idea, "switches," accounts for only another 2% of our DNA and I, like the old lady in the BK ad, ask "Where's the beef?" Further, Jacob and Monod already told us about switches with their description of the lac operon mechanism for lactose digestion. And Carroll compares switches to integrators that take many imputs and achieve a restricted number of outputs. John Allman (1999), cited elsewhere by Carroll, made that same comparison when he aligned the behavior of stockbrokers, axons, and columns of ants.

- It is very likely that genes act to achieve emergent networks and power laws. Genes that don't work in that fashion probably won't count for much and may be part of the DNA "junk" that we carry. Carroll's ignoring this possibility leaves him not on the ground but merely one cloud lower than advocates of the new synthesis.
- He also ignores the role that organisms have in making their environment. Wilson (2000) called this the "ultimate adaptation." Carroll omits a very important half of the Game.

The Darwin Wars: The Winner Is...

"Simply put, development is the process that transforms an egg into a growing embryo and eventually an adult form. The evolution of form occurs through changes in development." P. 4.
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Carroll, thus, captures the flag.

Segestrale (2000) tells of the combatants and battle ribbons in the disputes between Ed Wilson, on the side of sociobiology and a disciple of the "new synthesis" between genetics, calculus, and evolutionary theory, and, on the other side, Dick Lewontin and Steve Gould, developmental evolutionists and geneticists who loved genetics but balked at its application to human conduct. (Leon Kamin and Steve Rose, each a mini-me, threw empty beer cans from the bleachers!) Twenty years of behavior genetics research suggest that we follow the preferences of our immediate forebears and do so with mosaics of their strategies. We are alike more when our genes are alike than when our environments are alike. In that sense, Wilson won and so did Robert Plomin, Lindon Eaves, Nick Martin, Thomas Bouchard, and perhaps a hundred others. The plot, however, twists and weaves.

Evo devo now does what was impossible in 1980: a universal set of transcription factors, the hox genes, lay out our body plan and other transcription factors, Pax-6, distal-less, and tinman, add eyes, legs, antennae, fins, fingers, claws, wings, and hearts to hox's tube. Move Pax-6 from a mouse to a fly and get a fly eye, not a round, brown one, but one that grows on a wing if that's where you plant it. These breakthroughs are possible because we monitor our fingers and follow our tools more so than our theories. Kerry Mullis, perhaps as much as Gould (1977), Raff (1996) or Gerhart & Kirschner (1997) sustained evo-devo when he discovered polymerase chain reactions.

Carroll (2004) can now tie one line to evo devo and throw its other end back through Gould to Chuck and Thom. Wilson, Dawkins, and Hamilton, however, are either ignored or are represented by Ernst Mayr who takes something of a beating (pp. 71-72). Carroll beckons the fossil collectors to join him but the sergeants and corporals of the New Synthesis in the aging generation of evolutionary anthropologists and psychologists, disappear without grave markers. As both Max Planck and Imo noted: things change in both science and in potato-washing when one generation dies and differently behaving scientists and potato-washers take its place. Nonetheless, it seems unfair that the best thoughts of so many turn into stained bones and dried fur while I'm still alive.

E. O. Wilson remarked (August, 2000, at the Annual Meeting of the Association for Politics and the Life Sciences) that in regard to numbers of students and their productivity, he had won the great debates with Gould and Lewontin. Sorry, Ed. We won the gene-thing in regard to genes and human conduct but the toys and troops are mostly on the other side in regard to how we got here.

The Emergence People Race Ahead

The physics people, as noted by Watts (2003), sometimes pick up stray data and explain it with a few squiggles (Ball, 1999, 2002, 2004; Strogatz, 2003). Barabasi (2002) explained how thousands of participants (biochemicals, scientists, termites, dolphins, ecosystems, power grids, and even grammar self-organize: one or two large players manage many thousands of smaller ones in such a way that most participants are often within three steps of any other. The network can, therefore, have lots of clusters and retain a short path length (Watts & Strogatz, 1998). We find the same organization when we move from neighborhood streets to boulevards and freeways. Advantage? The organization rarely "jams" whatever demands are made (Toroczkai & Bassler, 2004)!

Further, networks that recruit resources develop self-interest (Kauffman, 2000; Camazine et al, 2001)! Implication: We can expect segments of the brain to compete as semi-independent organisms with other parts of the brain and with the animal's body. In an important sense, climate didn't make our cerebral cortex and neither did our social networks: we grew a cortex that was marginally better at finding work for itself and that suppressed the behavior of other actors in the CNS. Psychic conflict began when our hypothalamus and cortex each found the other to be a competitive annoyance!

Finally, raise-the-stakes is a powerful amplifier for success: if your gambit is productive, double it! This ignored strategy not only parallels what we observe of dopamine activity and neural firing but also routinely defeats granny's tit-for-tat (Roberts & Sherratt, 1998). And I have argued elsewhere (Brody, 2004) that these principles are a more salient part of our EEA than cats's teeth or glaciers. The evo devo fans should take the network people VERY seriously or join last year's evolutionists!

References

Allman, J. (1999) Evolving Brains. NY: Scientific American.
Austin, W. (2004) Biased Embryos and Evolution. NY: Cambridge University Press.
Ball, P. (1999) Transitions still to be made. Nature, 402, 73-76.
Ball, P. (2002) The Physics of society. Nature, 415: 371.
Ball, P. (2004) Critical Mass: How One Thing Leads to Another. NY: Farrar, Straus, & Giroux.
Barabasi, A-L (2002) Linked: The New Science of Networks. NY: Perseus.
Brody, J. (2004) Bipolar disorder: self-interested networks, cycling, and their management. In M. Brown (Ed.) Progress in Bipolar Disorder Research. Hauppage, NY: Nova Science Biomedical Series, pp. 33-64.
Camazine, S., Deneubourg, J-L., Franks, N., Sneyd, J., Theraulaz, G., & Bonabeau, E. (2001) Self-Organization in Biological Systems. Princeton, NJ: Princeton Univ. Press.
Carroll, Sean, Grenier, J., & Weatherbee, S. (2001) From DNA to Diversity: Molecular Genetics and the Evolution of Animal Design. Malden, MA: Blackwell.
Eiseley, L. (1957) The Immense Journey. NY: Vintage.
Gerhart, John & Kirschner, Marc (1997) Cells, Embryos, and Evolution. Malden, MA: Blackwell.
Gould, S. (1977) Ontogeny and Phylogeny. Cambridge, MA: Harvard Belknap.
Gould, S. (2002) The Structure of Evolutionary Theory. Cambridge, MA: Harvard Belknap.
Jacob, F. (1973) The Logic of Life: A History of Heredity. NY: Pantheon.
Kauffman, S. (2000) Investigations. NY: Oxford.
Raff, Rudolf (1996) The Shape of Life. Chicago, IL: University of Chicago Press.
Roberts, G. & Sherratt, T. (1998) Development of cooperative relationships through increasing investment. Nature, 394, 175-179.
Segestrale, U. (2000) Defenders of the Truth: The Battle for Science in the Sociobiology Debate and Beyond.NY: Oxford.
Strogatz, S. (2003) Sync: The Emerging Science of Spontaneous Order. NY: Hyperion.
Toroczkai, Z., & Bassler, K. (2004) Network dynamics: jamming is limited in scale-free systems. Nature. 428: 716.
Watts, D. (2003) Six Degrees: The Science of a Connected Age. NY: Norton.
Watts, D. & Strogatz, S. (1998) Collective dynamics of 'small-world' networks. Nature. 393: 440-442.
Weiner, J. (1999) Time, Love, Memory: A Great Biologist and His Quest for the Origins of Behavior. NY: Knopf
Wilson, E. O. (1975/2000) Sociobiology: The New Synthesis. Cambridge, MA: Belknap, Harvard University Press.
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Copyright, James Brody, 2005, all rights reserved.
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