Evolutionary biology

News from biology, and its implications for engineering

Thursday, December 23, 2004

The other way around

I remember a scary building, long since demolished, in the sciences complex at the University of Oregon in Eugene. This must have been the late 1970's -- I had a key to most of the science buildings, and would explore the nooks and crannys in my off hours, to clear my head. The scary one had a "danger: radiation" sign on almost every door from the outside all the way through to the bathroom. It was filled with sinks and tables labeled as badly irradiated.

This was a biology laboratory. What on earth was all this unnatural radiation for? What did it have to do with biology? The answer, as it turns out, is "nothing".

These labs were for drosophila research. Generations of fruit flies were bred with different levels of background radiation in order to 1) quantify the genetic damage of different levels of radiation and 2) track the cross-bred journey of mutations over generations.

Although much was learned about the structure of the genetic transmission, the impetus for the research was a theory, which in my mind is now discredited: that genetic variation emerges through radiation-induced genetic mutation. This was, with hindsight, a convenient interpretation of Darwinism in the Age of the Atom. In much the same way, "Social Darwinism", preaching survival of the strong, was a convenient interpretation of Darwin in the age of Robber Barons.

The notion that "hopeful monsters" would provide the necessary variation, flew in the face of this basic observation: living things tend to be quite healthy, but genetic damage tends to kill.

I saw the answer to this problem presented quite clearly, although not generalized, on a NOVA the other day, about dogs. Dogs under selective pressures, for example "friendliness towards humans", undergo changes in metabolic and hormonal pathways, and developmental timing, which radically change their morphology. [From experiments by Dmitri Belyaev]

Morphological evolution is the direct result of selective pressures. It doesn't require a separate "mechanism", such as random mutation introduced by environmental radiation, acted upon by selection. The pressure creates the evolution.

As is often the case, our cognition tends to "separate" aspects of nature before recognizing that ... they are not separate.

Note that much of genetic programming is based on this superceded notion of random mutation. It may need to evolve to the new model, if the goal is to achieve levels of adaptation equivalent to nature's.