The only way behavior changes in science is that certain people die and differently behaving people take their places.
Lynn Margulis 1938-2011. “Gaia Is A Tough Bitch”
From The Third Culture: Beyond the Scientific Revolution (1995). Paperback: Amazon | B&N; Edge Online Edition
From many experiments, it is known that if mutagens like X rays or certain chemicals are presented to fruit flies, sick and dead flies result. No new species of fly appears — that is the real rub. Everyone agrees that such mutagens produce inherited variation. Everyone agrees that natural selection acts on this variation. The question is, From where comes the useful variation upon which selection acts? This problem has not yet been solved. But I claim that most significant inherited variation comes from mergers — from what the Russians, especially Konstantin S. Mereschkovsky, called symbiogenesis and the American Ivan Emanuel Wallin called symbionticism. Wallin meant by the term the incorporation of microbial genetic systems into progenitors of animal or plant cells. The new genetic system — a merger between microbe and animal cell or microbe and plant cell — is really different from the ancestral cell that lacks the microbe. Analogous to improvements in computer technology, instead of starting from scratch to make all new modules again, the symbiosis idea is an interfacing of preexisting modules. Mergers result in the emergence of new and more complex beings. I doubt new species form just from random mutation.
Symbiosis has nothing to do with cost or benefit. The benefit/cost people have perverted the science with invidious economic analogies. The contention is not over modern symbioses, simply the living together of unlike organisms, but over whether “symbiogenesis” — long-term symbioses that lead to new forms of life — has occurred and is still occurring. The importance of symbiogenesis as a major source of evolutionary change is what is debated. I contend that symbiogenesis is the result of long-term living together — staying together, especially involving microbes- -and that it’s the major evolutionary innovator in all lineages of larger nonbacterial organisms.