Nature and Nurture
How honey bees are resolving an age-old debate.
The activity in the hive in Gene Robinson's office looks like mass chaos, but the honey bees crawling in all directions are actually doing specific jobs crucial to the colony.
The nurse bees are feeding the larvae. Scouts are searching out the best food sources. Foragers are collecting food from flowers, and other bees turn the nectar into honey.
The janitors clean the cells of the honeycomb for the queen to lay eggs. Undertakers remove the corpses of dead bees. And the bouncers guard the entrance to the hive, keeping out other insects that might try to steal the colony's food.
How they do their jobs is both a product of their DNA and the needs of the colony. Robinson, the G. William Arends Professor of integrative biology in the LAS Department of Entomology and director of the U. of I.'s Neuroscience Program, is studying how a bee's genes affect its brain function and give rise to certain behaviors. His insights into the social behaviors and organization of honey bees may help us understand the roots of human social behavior and how it is influenced by both heredity and environment—and resolve the nature versus nurture dilemma.
That vexing question is one that has spawned extremist views on both sides, Robinson noted in an op–ed piece in The New York Times in December 2004. People may be comfortable linking traits such as athletic prowess to genes, he says, but not such things as personality or intelligence.
"They're troubled by the ethical implications of genetic determination; it is as if giving a nod toward the genes automatically diminishes the role of the environment and free will," he wrote.
Robinson hopes his research will suggest a less polarizing approach. Heredity and the environment both act on genes and influence how genes are "expressed," or whether they are more or less active in a certain individual, he says.
"Biologists are totally comfortable there are both of these influences," Robinson says. "If that's the case for biology, why is it a polarized subject in the general public?"
It may have to do with the way the subject is phrased—genes versus environment. "It doesn't lend itself to a good understanding of the situation," Robinson says. "It sounds like genes are from Venus and the environment is from Mars."
Robinson was the first to focus on gene activity as a way of determining the roots of behavior—a new approach to the nature versus nurture question.
Honey bees are an ideal species to study, Robinson says, because they have a complex social organization and their society—the hive—is easy to manipulate in order to study it. The bee may have a tiny brain, but it is capable of amazing feats of social behavior—division of labor, symbolic language, organizing a defense. Bees also are ideal because scientists know more about their natural behavior than any other animal. People have been keeping bees for thousands of years.
It Started With Beekeeping
Robinson's own experience with bees goes back more than 30 years. He was smitten by honey bees at age 18 when he was assigned beekeeping duties while volunteering on a kibbutz in Israel.
"There were hundreds of thousands of bees flying around," he recalls. "It did look like chaos, but peering a little more closely, there was organization. That organization in chaos—a society—captivated me."
He worked his way through college as a state bee inspector and by teaching beekeeping courses, then spent a year in Colombia, teaching beekeeping to rural farmers.
"I found that I loved that, but what I was more interested in were the questions about bees that kept coming up," he says.
He began to study bee behavior in graduate school at Cornell University, at one of only a handful of bee labs around the country. His work evolved from behavioral research to an integrative approach, first looking at hormones and how they affect behavior, and later at neurobiology, molecular biology, and genomics (the study of the complete set of genetic information of an organism).
He's moved the research in his field in a new direction, showing that inherited differences and environmental factors interact to affect gene expression, and ultimately behavior.
When he began his research, the prevailing notion was that differences in bee behavior were due primarily to environmental influences. Robinson first showed genetic differences in behavior due to inherited factors. He determined the paternity of honey bees serving as undertakers in a colony, and found those with a particular father were more likely to do that job, meaning the behavior was due to inherited factors.
"His contributions are hugely significant," says Professor Marla Sokolowski of the University of Toronto, one of the world's foremost behavioral geneticists studying fruit flies, who has collaborated on research with Robinson.
"We no longer think genes contribute something and the environment contributes something, and you add it together in the end and get the behavior that you're studying," Sokolowski says. "For these complex behaviors, the two things interact together…and the effect can happen at the level of gene expression."
At the U. of I., Robinson has about 100 bee colonies in 10 different locations around campus. At the height of the summer, the colonies have up to 50,000 bees each—about 5 million bees total.
Honey bees become foragers, collecting pollen for the hive, at a certain age. However, Robinson found, if there is a shortage of foragers, some bees start searching for food earlier in their life cycle than they otherwise would. Their environment in the hive affects the timing of when they begin to gather food.
Robinson also found the gene activity leading to foraging affected the brain's optic lobe and made bees more attracted to light—another stimulus for them to leave the hive to begin searching for food.
Scientists didn't have the tools to study the genetic basis for honey bees' behavior when Robinson first began studying bees, so he developed them—also a major contribution, Sokolowski says.
His biggest accomplishment in advancing the technology of studying honey bee genetics was leading the effort to sequence the honey bee genome, which they recently completed.
Robinson also adapted an approach that had been used to study development, to study behavior. He found a gene known to affect a particular behavior in another species, then looked for a similar gene, and similar effect on behavior, in honey bees.
And he developed a way of looking at the expression of thousands of genes from the honey bee brain at once, to determine the degree to which they were active in relation to certain behaviors.
"It's a phenomenal technique," says May Berenbaum, head of the U. of I.'s Department of Entomology. "You can take the brain of a bee and figure out at every developmental stage which genes are being turned on and which are being turned off."
When he compared the genetic activity of forager bees with that of nurse bees, he found differences in the brain for almost half the genes in the bee brain.
This suggests that many genes are associated with particular behaviors. Robinson says they work together to form molecular pathways, build the brain, and orchestrate complex behavior. In other words, he says, there is no single gene for foraging or any other trait.
"It challenges us to think more broadly in terms of gene networks instead of individual genes," Robinson says. "There is no smart gene or dumb gene, or fast gene or slow gene."
Berenbaum said Robinson's research is already of interest to the business community looking to structure groups so they work together more efficiently, and it also has implications for collaborative decision–making for large–scale disaster relief.
Robinson hopes his research shows how our behavioral differences are influenced in a dynamic, flexible way by both our heredity and our environment—nature and nurture.
By Jodi Heckel