What is the nature of instincts and inborn behaviour? The cover article of this week’s issue of Current Biology is an article by Kim et al. on how the central nervous system produces inborn behaviour. The researchers found that the innate behavior is initiated by a “command” hormone that orchestrates activities in discrete groups of peptide neurons in the brain (peptide neurons are brain cells that release small proteins to communicate with other brain cells and the body). The action of the hormonal influence, however, was not an all-at-once phenomenon. The ecdysis-triggering hormone or ETH, activated discrete groups of brain peptide neurons in a stepwise manner, making the fruit fly perform a well-defined sequence of behaviors.
Says Michael Adams, the research team leader:
Our results apply not only to insects; they also may provide insights into how, in general, the mammalian brain programs behavior, and how it and the body schedule events. By understanding how innate behavior is wired in the brain, it becomes possible to manipulate behavior — change its order, delay it or even eliminate it altogether — all of which opens up ethical questions as to whether scientists should, or would want to, engineer behavior in this way in the future”
An instinct is an inborn disposition for a specific kind of behaviour. Although we often regard instinctual behaviours to be in the domain of non-human animals, humans also have well-known instincts, the most known are found in infants. However, many researchers suggest that other behaviours — such as altruism, disgust, face perception, and language acquisitions are also instinctual, at least in part so.
Would the present result mean that behaviour — let’s start with instinctual behaviours — could be edited? Adams seems to think so, and in the Drosophila it certainly seems to be the case. Since the steps leading to the well-orchestrated instinctual behaviour were identified, and the neurochemical properties of these circuits are — or are soon — known, it should be a trivial thing to alter the behaviour at any stage during the process. What about human behaviour, then? In principle, the same idea should apply.
Complaints will certainly arise that “human behaviour is so much more complex than instincts”. Indeed it is. But recall studies of voluntary action, of subliminal perception and of automaticity (e.g. riding a bike). These behaviours resemble instinctual behaviour a lot. They are not under conscious control, or are at least not initiated by such. In this sense, it might be that even human behaviour can be edited in much the same way as the Drosophila.
Admitted, this study only focuses on the ecdysis sequence behaviour in an insect. So we need more advanced (still instinctual) behaviours to believe the story. Replications & variations as always… But hey, maybe this will end up as the next cure for odontophobia…?