Lamarck Still Walks

"On the surface, this makes sense - a learned behavior in a social, cognitive group is passed down. This learned behavior has advantages, which can be improved upon with certain genetic combinations. The learned behavior and the genes that improve it are now passed down through the generations. More changes in genetic variations occur, some which could lead to reproductive isolation. Now we are on the cusp of speciation, and the trigger was not genes, but a learned behavior."

I have a lot of regard for the spirited instigator who wrote those sentences (meaning that I expect she will kick my rear for this!) and a lot of regard for our shared urge that "learning" has to be adaptive because learning is expensive and that acquired successful traits, including habits, ought somehow to be passed more easily to our offspring. The feedback link, however, from novel, shaped cerebellar routines to gametic juice is elusive.

There are several papers in Belew and Mitchell, "Adaptive Individuals in Evolving Populations" that elaborate on this theme but not always very convincingly. Waddington, Baldwin, and possibly Will James imaginatively constructed scenes in which learned behavioral shifts in behavior allowed a species to survive in a newly hostile environment long enough for natural selection to act and instantiate genetically more efficient systems that replace the learned ones. It's more plausible to me when I've had a little chianti after a long day. (Still, it could have happened, sometime ... maybe?)

I once culled remarks on speciation from a listserve. Agreement was strong that species are usually not defined by genetic reproductive isolation but by isolation of reproductive habits. Differences in behavior sequences eliminate partners from consideration, partners that would be reproductively fertile if the gametes could meet.

The problem arises as to whether we consider these behavior changes as "learned" or as a reordering of response hierarchies, each of them already available to every member of the species but displayed in different frequencies across members. (Remember the detail in Teplica's observations about human characteristics.)

If the latter, then habit changes may reflect genetic drift, a drift that is usually corrected so long as there is not a separation in habitat -- that critters that are a little weird still find mates and their offspring are more "normal" due to the mix of contributions from their partner. (Personal example, my kid appears normal; his mother's physical characteristics and even temperament mask almost perfectly the messy things I contributed and that are blatant in me.) Split the habitats and behavior drift occurs along with other changes that cause hominids to classify the carriers as different species.

Again, "culture" does some wonderful things but it is spun from the biological seeds of our ancestors. A Velasquez Christ or a Russian icon pluck very old strings that may originally have been gifts to us from lizards.

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