Friday, February 4, 2011

On Lamarck (Get Set, Go)

It is the nature of an hypothesis, when once a man has conceived it, that it assimilates everything to itself as proper nourishment; and, from the first moment of your begetting it, it generally grows the stronger by every thing you see, hear, read, or understand.
               - Laurence Sterne, "The Life and Opinions of Tristram Shandy, Gent."

It appears that, in a recent post to this blog, I dealt with the great biologist Jean-Baptiste Lamarck, if not unfairly then perhaps with a levity unbecoming in me and undeserved by him. Yet even his few devotees (among whom I humbly number myself) admit that he was "largely ignored or attacked during his lifetime [and] never won the acceptance and esteem of his colleagues . . . . Today, the name of Lamarck is associated merely with a discredited theory of heredity, the 'inheritance of acquired traits.'" (My admiration for Lamarck is an intellectual variant of what the Bike Snob calls "salmoning," i.e., riding against the prevailing current of traffic, opinion, etc.)

Lamarck believed that organisms did not originally occur in their present configuration, but were slowly altered over time by adventitious environmental forces; these changes devolved genetically to their offspring and thus became part of the catalog of physical characteristics of any species. Lamarckianism is caricatured in popular stories recounting how animals came to acquire certain marks - there is, for example, a 19th-century poem in American Southern dialect explaining that one of the passengers on the ark, out of utter boredom, shaved the possum's tail to string the first banjo. Pure malarky, of course, but instructive as an impure version of Lamarck.

Lamarck had been long discredited, until now. An interested reader has unearthed recent evidence, buttressed by genetic theory, that Lamarck was not entirely. . . well . . . off the mark. On the contrary, he was on to something - call it 'genetic memory' or more properly, epigenetics. Researchers at the University of Bristol (UK) and the University of Umea (Sweden) used 19th-century records of harvests and food prices to identify times of famine and plenty in an isolated rural community in Sweden. The researchers tabulated three generations of 300 families and found that the health and lifespan of the grandchildren was linked to their grandfathers' access to food while in early adolescence. 

University of Bristol Genetic Research Team

Children tended to live longer if their grandfather endured food scarcity during this time of life. The team concluded that these genetic effects are a short-term genetic modification that allows a forebear's experiences to be 'captured' in his sperm, enabling subsequent generations to respond to periods of scarcity and famine like those experienced by parents or grandparents. Hence, genetic features are not entirely inherent in the genetic material. They can be altered in a generation or two by external factors to answer recurring environmental fluctuations - just what Lamarck originally proposed.

Lamarckian sperm (before 'capture')

This research has vindicated my lifelong admiration for the genius of Lamarck and my own proclivity to find a connection between a person's appearance and their propensity (for example) to write fiction or live a life of voluntary simplicity. And while I concede that his vindication required a more sophisticated understanding of genetics than Lamarck himself possessed, nonetheless I knew he was right from the start. That is the beauty of a spanking good theory, that it assimilates every appearance to its own rule and, try as a man may, he will ride him like a hobbyhorse to destruction or enlightenment, whichever comes first. I might have been badly thrown. I count myself lucky this time.

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