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Dear Science

How Does Instinct Work?

by Jonathan Golob

Dear Science,

A termite mound is not a simple thing. In order to thermoregulate their colonies, many species orient them along north-south axes, and the actual architecture fulfills not only the regulation of temperature, but of course, defense against predators, and in some cases, actual agriculture. A single termite queen flies to some location, loses her wings, and then begins pumping out eggs. This is not a case of teaching offspring how to build a mound. This is instinct. So my question is, how the hell is this information encoded in DNA? It seems straightforward to me how proteins are encoded in DNA, and I'm aware that some genes encode instructions for turning other genes on and off, but how do you transmit blueprints for a termite mound?

Programmed To Write This

Robert Provine, professor at the Universityof Maryland, would turn your question back on you, asking you to prove the conscious mind plays a significant role in even complex adult human behavior. The dominant assumption is that the conscious mind, wielding language, is responsible for much of our actions. Forget about the termites: What if most human actions are all a combination of reflexes—preprogrammed (instinct) and learned?

When you're going about your day, try to figure this out for yourself. When you're walking down the street, can you break down your decisions and actions into clear triggers followed by preprogrammed actions? Much of the muscle control involved in walking is contained within reflex arcs that never go much beyond the spinal cord root; the connections between the motor and sensory neurons, stretch and tension sensors and muscle fibers are programmed in the stretches of DNA used in development.

I'll raise your termites with the life of the malaria parasite. This single-celled organism jumps from mosquito to human. Upon entering the body of a human host, it floats around in the blood until it finds the liver. How? By smelling the characteristic proteins made by the liver that are leaching into the blood. A small cue, detectible by a protein, allows a complex behavior—finding the liver among all the organs of the body—to happen.

Science has barely begun to unravel all of the small cues used by various life-forms enacting complex and coordinated behaviors—from trees losing their leaves in the fall and regaining them in the spring to honeybees' collaborative hunt for nectar. This is, in part, why human-caused changes in the environment—like climate change—are so worrisome. We're changing the timing and nature of an incalculable number of cues in rapid order, increasing the risk of breaking down the sorts of coordination that allow a biosphere as complex as the one we enjoy to function.

Automatically Yours,

Science

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