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But now it's turning out that at least for some social insects, you are not only what you eat, you are also the way you were born. In honeybees, different nutrients interact with the genome to switch some developmental pathways on and off, for a much more complex picture than had originally been supposed. In some ant species and at least one kind of termite, females bearing one version of a gene are more likely to be queens, while females with another version end up being workers. A particularly odd version of this genetic influence on caste occurs in harvester ants, in which two genetic lines coexist; queens belong to one line or the other, but workers are a cross between them. If a queen's eggs are fertilized by a male sharing her pedigree, the larvae become queens, but if the father is from the other line, the daughters become workers (recall that sons are produced only from unfertilized eggs, so they don't enter into the calculation). The difference between queens and workers can also be due not to a gene or genes being present or absent but to the regulation of those genes. A recent study of honeybees found at least two thousand genes that were present in both workers and queens were expressed differently in the brains of the two kinds of individuals, further supporting the idea that it's not just what you have but what you do with it—or what it does to you—that counts.

Queens may also specialize, with multiple reproductive females starting a nest together and then divvying up the duties like housemates, so that one goes out and collects food and the other stays home caring for the offspring. Alternatively, in the fire ant common to the southern United States and named for its painful sting, some colonies have one queen and others have two or more. The fatter queens go solo, whereas the burden is shared, literally and figuratively, in the nests ruled by multiple, lighter queens. Queen physiology, and the way the queens are treated by the workers, are both controlled by genes.

The role taken on by a worker had also been thought to be, if not diet related, at least environmentally determined, with all older worker bees, for example, doing more foraging and younger ones staying behind as "nurses." Now, however, the picture seems both more complex and more genetically determined. The age-related changes in tasks occur, to be sure, but altering the genes can change the workers' behavior, making them go out to forage at a younger age than they normally would. At the same time, foraging is influenced by social cues such as the age of other colony members and the type of pheromones given off in the hive, which in turn can feed back to the worker and change the hormones secreted inside the worker's body, further altering behavior. As in the queen-worker distinction, gene expression differs depending on the task the workers do. Hives with differences in genetic makeup also show different patterns of work. Most interesting, when a queen had mated with multiple males, the resulting blended family of workers was more efficient at making honeycomb, rearing the young, and flying off to collect pollen and nectar than were colonies started by a queen that had mated only once.

A group of scientists at the University of Sydney performed a clever experiment to examine the genetic regulation of reproduction in honeybees. Like humans, bees are affected by carbon dioxide gas, but unlike humans, queen honeybees respond to CO2 by increasing their ovary development, as if they had just mated and were getting ready to start a colony. In contrast, if a queen is removed from a hive, something the workers can detect immediately, the workers respond to the gas by suppressing their ovary development, just as if the queen were present and producing all the eggs (worker bees are able to lay eggs, although their sisters often prevent them from doing so).

The researchers, led by Graham Thompson, placed virgin queens and queenless workers in a chamber with CO2 for 10 minutes and then compared the gene expression in the bees' brains as well