Secret Lives of Ants

13. Conflict in the Queendom: Divine Right of the Queen? Or the Will of the Masses?

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 divine right of the queen? or the will of the masses? Conflict in the Queendom 13 When I observe ant colonies, these stiflingly organized societies with every individual faithfully performing its duty often remind me of George Orwell’s classic novel 1984. In human society, such events may largely be fiction, but ant societies have to some extent made them a reality. In ant colonies the life of the individual seems subordinate to the common good. The individual worker must sacrifice her own reproductive capacity so she can devote herself to helping her mother, the queen, handle all of the reproduction. The sacrifice may seem altruistic, but when analyzed genetically this is actually selfish behavior. The Gene’s Point of View Genetically, how similar are we to our mothers? That is, how many genes do we share in common? The answer is that every human being has exactly 50% of the mother’s genes. This is because one of the two sets of chromosomes comes from the egg that the mother provides at conception. The other 50% of a human’s genes come from the father. When our bodies make reproductive cells, sperm or eggs, through the process of meiosis, we impart only half of the chromosomes that are in the somatic cells of the rest of our bodies. Another genetics question: how much genetic similarity is there between brothers and sisters? Brothers and sisters who share the same mother and father have on average 50% of genes in common, that is, a genetic relationship of 50%. Even though two brothers may inherit the exact same genes from their mother, it is possible that one brother will take after . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c o n f l i c t i n t h e q u e e n d o m 111 the mother and the other take after the father. Hence, the average genetic relationship between two brothers is estimated to be 50%. The same is true for sisters. The more distantly two people are related, the lower the genetic relationship is between them. British geneticist J. B. S. Haldane quipped at his favorite pub, “I would be prepared to lay down my life for two brothers or eight cousins.” He was meaningfully referring to the fact that we share one-half of our genes with our brothers and one-eighth with our cousins. With aunts and uncles, we share one-fourth of our genes. However, Hymenopterans such as ants and bees have more unusual genetic relationships between individuals due to their peculiar sex-determination system. Unlike diploid organisms such as we humans, they are haplodiploid organisms; that is, males carry only one set of chromosomes, while females carry two. According to British biologist William Hamilton, who established the theoretical foundation to answer this question in 1964, worker ants and later generations of queens born from the same mother have genetic relationships of 75%—much higher than the 50% relationship found in brothers and sisters of diploid animals. This high genetic relationship occurs because worker ants’ fathers only have one set of chromosomes to pass on through their sperm. Ant males pass all of their chromosomes to their daughters. Although ant males die before they can see their daughters, they give daughters everything they have and thus have a 100% genetic relationship with them. The 75% genetic relationship between worker ants is much higher than the 50% relationship they would have with their own offspring, were they able to have them. For this reason, Hamilton suggests we should consider the situation of worker ants from a genetic viewpoint rather than an individualistic viewpoint. If we look at evolution as the struggle to pass as many of one’s genes as possible on to the next generation, then worker ants are doing a much better job by helping their queen to produce more workers and the next generation of queens. As they share a 75% genetic relationship with their younger sisters, helping to raise them does more to ensure the survival of their own genes than it would for . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . t h e p o l i t i c s o f a n t s o c i e t y 112 them to give birth to and raise their own offspring, with whom they would only have a 50% relationship. Hamilton maintains that this is why worker ants have evolved as altruists, abandoning their own reproduction...