The debate over gene selection versus group or multi-level selection continues unabated in biological circles, and no end appears in sight. Despite a resurgence of interest in group selection, the gene-only theorists refuse to concede an inch of ground, but I fear the high tide of gene selection is on the ebb and will never dominate again.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
For there are two basic flaws in gene selection, flaws so obvious it’s astonishing that the theory ever floated at all.
The first flaw is that evolution, natural selection and biological fitness are inextricably linked to reproduction, yet genes do not reproduce. The entity that reproduces is a group of genes, an organism, and what this group produces is another group of genes.
The second, more significant flaw is linked to the first. When natural selection occurs it is not a gene that is selected, it is a group of genes. Furthermore, it is the combination of characteristics of the group that is selected. Natural selection favours the total, net, end product of these genes, each of which is performing different functions, some beneficial to the organism, some perhaps neutral, some perhaps of doubtful benefit.
This means that a useful characteristic, for example speed in a predator, will not be selected if the organism has a significant impairment in another area that affects its ability to catch prey. And if the individual has characteristics that make it offensive to potential mates, it might survive remarkably well but never get to pass on its favourable characteristics. Clearly the total package is the unit of selection.
But we must keep in mind that the individual is still no more than a group. Natural selection favours those groups of genes whose combined characteristics give them biological fitness. Logically therefore, natural selection is group selection.
Interestingly, Wilson and Wilson in their paper of a few months back titled “Rethinking the Theoretical Foundation of Sociobiology”, came within a whisker of arriving at this redefinition of natural selection. They recognised that individuals are groups and that the selection of an individual is the selection of a group, but they failed to take the tiny final step that would demolish gene selection.
They put a novel twist into their concluding paragraph by including a quote from a rabbi who was famously asked to summarise the Torah while standing on one foot. He did so in a single sentence, making the final point “All else is commentary.” To honour the rabbi the Wilsons summarised their paper as follows: “Selfishness beats altruism within groups. Altruistic groups beat selfish groups. All else is commentary.”
It was a neat ending, but they were clearly outdone by the good rabbi, who was able to summarise the entire Torah in a single sentence! They missed a golden opportunity for this more succinct summary, one that really would lay a new foundation for sociobiology: “All selection is group selection, everything else is mere commentary.”