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Thursday, Oct. 9, 2003
UNETHICAL FOR SOME
Behavior, genes in bed together
By ROWAN HOOPER
The job of undertaker is not one that is restricted to human society. In honeybee colonies, too, some individuals have the task of removing the cadavers of their dead fellows.
Researchers have previously demonstrated that bees are genetically inclined to perform the specialist job of undertaker, though they only take on that role when they reach middle age. (As often seems to be the case with human undertakers.)
When they are young adults, honeybees are typically "nurses" who assist with brood care. Nurse bees feed larvae with royal jelly, and later with honey and pollen. When the nurses become older, most become foraging bees, searching for food outside the hive.
All this was well established. What scientists have now found is that a certain set of genes are active in nurses and another set active in foragers. Moreover, forager bees showed increased expression of a gene similar to one that enhances spatial learning and memory in mammals.
What the study, published this week in Science, means, is that the relationship between genes and behavior may be more robust than has been commonly believed. The research was conducted by Charles Whitfield and colleagues at the department of entomology at the University of Illinois, Urbana-Champaign.
The study of genes and how they influence behavior has a controversial history and is not well understood by the public, nor by many scientists. Behavioral genetics seeks to identify genetic influences on human characteristics, such as criminality, intelligence and addiction. Many people find the prospect of such a connection abhorrent, and the controversy is stoked by books such as "The Bell Curve," which sought to explain the difference in average IQ scores between the white European population of the United States and the African-American population as a genetic one.
Neither has the historical antecedent to behavioral genetics -- eugenics -- received good press.
In 1908, Francis Dalton, Darwin's cousin, published "Memories of My Life," his autobiography. In it, Dalton wrote of the influence his cousin's work had upon him and on society in general: "The publication in 1859 of 'The Origin of Species' by Charles Darwin made a marked epoch in my own mental development, as it did in that of human thought generally. Its effect was to demolish a multitude of dogmatic barriers by a single stroke, and to arouse a spirit of rebellion against all ancient authorities whose positive and unauthenticated statements were contradicted by modern science."
Fine sentiments, but then Dalton went on to lament the failure of many members of the public to accept Darwin's work: "I doubt, however, whether any instance has occurred in which the perversity of the educated classes in misunderstanding what they attempted to discuss was more painfully conspicuous."
Dalton's complaint is ironic, as he was to suffer a reaction against his work even more pervasive than that against Darwin's. Galton was a polymath, contributing to many fields (such as geography, statistics and heredity), but is now principally known for establishing the field of eugenics. "Its first object is to check the birth-rate of the Unfit," he said.
Eugenics, of course, was used by the Nazis to justify atrocities during World War II, and was the basis of the Australian government's "White Australia Policy," implemented, in different forms, throughout much of the 20th century.
Behavioral genetics is the scientific descendant of eugenics, but is barely better respected. The subject concerns individual variations in human behavior, and seeks to measure the genetic and environmental influences upon them (which is what Galton, in his attempts to systematically study heredity and human behavior, was the first to do). Whitfield and colleagues' honeybee study might start to change that.
The researchers used a DNA chip to test around 5,500 honeybee genes. The DNA chip measured the activity of messenger RNA, which indicates whether a gene is active. In almost 40 percent of the genes tested, the abundance of messenger RNA changed as the honeybees changed their jobs from nursing to foraging.
The result shows that the adult honeybee brain is far more flexible, genetically, than was previously thought. It shows that genes influence behavior and that behavior influences the activity of genes. In other words, as the British biologist and science writer Matt Ridley says, "Genes are the agents of nurture as well as nature."
"Behavior is a product of genotype and environment and is unique for each individual," Whitfield and colleagues write. "Despite the individuality of behavior, distinct classes of behavior [both normal and pathological] can be recognized in humans and animals. Genes that predict behavior in this way might provide new insights into neural mechanisms in the brain that underlie behavioral plasticity."
As Ridley says in his latest book, "Nature via Nurture,": "Genes are both cause and consequence of our actions. Somehow the adherents of the 'nurture' side of the argument have scared themselves silly at the power and inevitability of genes and missed the greatest lesson of all: The genes are on their side."
Rowan Hooper is a researcher at Trinity College, Dublin. He welcomes comments at firstname.lastname@example.org