Genes and Social Behavior
By Ryan Chen
Social behavior is exhibited by a wide range of organisms including social bacteria, slime moulds, social insects, social shrimp, naked mole-rats, and humans. It is behavior among two or more organisms, typically from the same species. Usually when people think of social behavior, they picture, communication, organization and dominance. In sociable organisms such as humans and honey bees, the group is centered around the society that they had built up, they count on each other and usually follow a mutualistic relationship. In humans, there are societal norms that everyone grew up with and fundamental, unspoken rules that everyone tries to follow, such as the Golden Rule, “Treat others as you would like them to treat you”. But where do these rules come from? The majority would have been refined through trial and error, where humans evolved and adapted their communication and social behavior strategies to the particular situation, after thousands of years of honing, we now have many different types of government, one crucial aspect of our social behavior. Obviously, not every person is the same nor do they think the same, some of their social behaviors might have been developed through their upbringing, or their environment. But as we dig deeper, the signs all point to our DNA.
Eusociality, the highest level of organization of animal sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. To examine higher insect social order, researchers looked into the potential evolutionary history of a “foraging gene” in honey bees (Apis mellifera) and in order to discover how foraging in bees is genetically encoded, the honey bee genome was searched for genes that may be shared by other species. A molecular basis for feeding behavior has been determined in Drosophila melanogaster, which shares a common insect ancestor with the honey bee. Genes do not specify behavior directly but rather encode molecular products that build and govern the functioning of the brain through which behavior is expressed. The “foraging gene” in D. melanogaster encodes a cGMP mediated protein kinase (PKG). Naturally occurring allelic variation produces behavioral syndromes in D. melanogaster, both “sitters” and “rovers”. The needs of a honey bee colony are communicated between bees by pheromones, chemical signals which trigger behavioral responses. Honey bees have a variant of the same foraging gene that controls the onset of foraging behavior. Elevated expression of this gene correlates with increased foraging activity; precocious foraging was induced in young workers by experimentally introducing PKG.