Turns out that regulation is biological and genetic as well as political. One major functions of genes is to regulate, mostly in the form of on and off signals. It is genes that have the job of activating immune system responses to external microbes—and then to shutting off those responses once the threat is defanged. Hence, over-reactive immune systems are results of the off switch not being pulled, whereas immune system deficiencies occur because the on button does not get pushed. The body, too, can overdo things, can push past limits best left intact.
Immune system responses are obvious cases where genes are activated by environmental triggers. There are other fairly obvious environmental factors—like adequate nutrition. More mysterious is “incomplete penetrance”—i.e. the fact that two organisms can possess the same gene, but it only expresses itself in one of them. Such is the case, for example, for women who carry a gene highly associated with breast cancer. But only highly associated; that gene does not result in 100% of the women who possess it eventually getting breast cancer. More like 60%. (Incomplete penetrance, then, is one way harmful genes do not get eliminated through natural selection.)
Mukherjee sums up what genes do with the three “R”s: regulation, replication, and recombination. To which he then adds a fourth: repair. It’s the replication part that gets most of the press: cloning and all that. But it’s regulation and recombination that makes straight-forward genetic engineering and simple-minded Darwinian fundamentalism equally pipe dreams. There’s just way too much slippage in the process, too large an element of chance along with environmental factors that would be difficult to control even if we understood them completely.
Hemophilia offers a good example of why a simple fitness story doesn’t work. The gene that causes can be carried by the mother, but only expresses itself in male progeny. Therefore, because the gene is recessive in women, natural selection doesn’t get the opportunity to eliminate it. Even though there is no way to link hemophilia to fitness, it persists.
Furthermore, while hemophilia is one of those diseases that can be linked to a specific gene, there are lots of conditions and abilities—smell is one good example—that are the product of multiple genes, often in the dozens, sometimes over one hundred. Natural selection can’t zero in on a defective gene in such cases, plus mucking around in such complex systems often has bad side effects. The complexity of human biology, in other words, works against any simplistic understanding of natural selection. Features of the human organism are just too inter-related to make targeted elimination of specific features possible in many, many (although not all) instances.
In addition, there are the benefits of diversity itself. The trouble with Darwinian fundamentalism is that it takes the ranking approach to human behavior and personality and capabilities—as if it were the AP ranking of college basketball teams. The “fittest”—absolute superlative—is what emerges from evolution. But that’s nonsense. There are multiple possible ways of surviving to the point of reproduction. Evolution, at best, eliminates those that can’t survive until reproduction. It does not optimize; it does not only select the best. The “good enough” survive as well.
And the survival of that diverse range is crucial because a diverse gene pool is the vast reserve army by which a species arms itself against environmental change. An over-specialized species, ill equipped to adapt to change, will not survive in the long run. Far from needing the fittest, evolution needs the diverse, a whole range of types and variants.
To switch the focus to emphasizing how evolution selects a wide range instead of “the fittest” is to understand why evolution is not destiny nor even an indicator of set limits. New environments will call forth new adaptive behaviors—and a rich gene pool will ensure that such adaptions are possible. Not for everyone perhaps, but for some. Not to mention that the complexity of the system lays itself open to new interactive patterns, along with innovative recombinations and the development of regulative responses to new triggers. Of course, translating from a specific genetic make-up to behavioral patterns and capabilities is very difficult. Such a holistic vision of human functioning–arising out of the base of genes–is still far beyond our analytic abilities.
Natural selection, in short, is not the conservative’s dream of a Hobbesian competition of all against all. It is not just that humans, quite obviously given their extra-long immaturity, cannot survive except in mutual aid societies; it is also because the elimination of all diverse others would quickly lead to the extinction of the species. To put it in the bluntest terms: if I only worked to ensure the survival of my genes—and not those of anyone else—I would be murdering the species. A purely selfish gene will not see too many generations.