#geneadaptation

For animals to survive and thrive in this undependable planet, they must develop a cornucopia of techniques for adjusting their responses to current conditions. In the very long term of up to millions of years, the adaptation of their genes by random mutations is the most successful strategy. On a much smaller scale of time, a variety of chemical adaptations may guide the bodies of individuals towards the fulfillment of their survival and reproductive needs. Endocrine organs, including thyroid, adrenal or reproductive cells, store agents for release onto other organs. These hormones affect the function of recipient cells according to circumstance on a time scale from a few years down to a few seconds. Exocrine hormones are embedded in specialized tissue including the intestines, the heart or the kidney and regulate them locally to allow for their short-term needs. The existence and degree of sociality is a prime target for the operation of chemical messengers, which provides the emotional signals to the animal, specific to its needs. It is in this class that we seek candidates that may promote sociality. I will not attempt to identify a particular class of agent directly in this blog, but I will discuss the qualities that it needs to display to respond to circumstances. Hormones that direct animals towards certain rewards include those that alleviate hunger, promote sexual function, and support offspring. We may identify sociality as a reward for being close to other animals of the same species. It is not necessary for its action to be any more elaborate than a proximity reward, which adequately accounts for the pleasure that animals experience from the presence of other animals nearby.  This reward must be adaptable to different circumstances and to the degree of reciprocation of potential partners. It has been well-studied under strict scientific controls, but its effect may also be seen readily in meadow and in ranch where sheep, horses, or cows cluster in a limited area of the pasture. A clever experiment by St-Pierre and associates illustrates the point that adaptability is a major factor in sociality.1 They trained pairs of zebra finches in adjacent cages to distinguish cooperative responses from competitive ones through rewards of seeds either selfishly to themselves or by sharing its reward with their partner. They found that, if the birds were strangers, they invariably chose the seeds selfishly, while, if they had lived together for a short time, all birds chose to share the reward with their partners at a cost to themselves. Sociality usually increases with familiarity and is likely to be the principal cause for related adults to associate and support each other. Adaptability is also a prominent feature of human interactions that trend towards strengthening on each further contact. We may ask why and how the proximity reward overcomes the strictures of Hamilton and Dawkins. The explanation is very simple: a new property of a gene has developed that may overcome selfishness. If cooperation improves the chances for survival of the individual and species, then it will be amplified until it becomes the salient feature of the species. Sociality is widespread among mammals and birds, but it is not tied to particular families or orders; the lion is the only truly social cat. It is very likely that the acquisition of sociality is easily attained by small changes in genes, but only survives if the congregation of the animals is desirable for that species. 1St-Pierre, A., Larose, K., & Dubois, F. (2009). Long-term social bonds promote cooperation in the iterated Prisoner’s Dilemma. Proc. Royal Soc. B: Biological Sciences, 276, 4223-4228. Read the full article