The author of a new book on behavioral evolution explains how primal urges overrun their original purpose
Put a mirror on the side of a beta fighting fish's aquarium and the gaudy iridescent male will beat himself against the glass, attacking a perceived intruder. A hen lays eggs day after day as a farmer removes them for human breakfasts -- 3,000 in a lifetime without one chick hatching, but she never gives up trying. The healthiest, largest male chickadees have the highest crests on their heads and they are sought after as mates. When researchers outfit runt males with little pointed caps, much like the human dunce cap, females line up to mate with them, forsaking the naturally fitter, hatless males.
These animal behaviors look funny to us . . . or sad. The reflexive instincts of dumb animals. But then there's a jolt of recognition: just how different are our endless wars, our modern health woes, our melodramatic romantic and sexual lives?
In my new book, linkurl:__Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose__,;http://www.amazon.com/Supernormal-Stimuli-Overran-Evolutionary-Purpose/dp/039306848X I describe how human instincts -- for food, sex, or territorial protection -- developed for life on the savannah 10,000 years ago, not today's world of densely populated cities, technological innovations, and pollution. Evolution, quite simply, has been unable to keep pace with the rapid changes of modern life. We now have access to a glut of larger-than-life temptations, from candy to pornography to atomic bombs, which cater to outmoded but persistent instinctive drives with dangerous results.
In the 1930s Dutch Nobel laureate Niko Tinbergen found that birds that lay small, pale blue eggs speckled with grey preferred to sit on giant, bright blue plaster dummies with black polka dots. A male silver washed fritillary butterfly was more sexually aroused by a butterfly-sized rotating cylinder with horizontal brown stripes than it is by a real, live female of its own kind. Mother birds preferred to try feeding a fake baby bird beak held on a stick by Tinbergen's students if the dummy beak was wider and redder than a real chick's. Male stickleback fish ignored a real male to fight a dummy if its underside was brighter red than any natural fish. Tinbergen coined the term "supernormal stimuli" to describe these imitations, which appeal to primitive instincts and, oddly, exert a stronger attraction than real things.
Animals encounter supernormal stimuli mostly when experimenters build them. We humans can produce our own: super sugary drinks, French fries, huge-eyed stuffed animals, diatribes about menacing enemies. Instincts arose to draw our attention to rare necessities but now they lead us to harmful behaviors that compromise our health, safety, and sanity.
Though sociobiologists and evolutionary psychologists have incorporated many of Tinbergen's ideas and those of other animal ethologsts such as Konrad Lorenz, they have not used the concept of supernormal stimuli. I believe that this is the single most valuable contribution of ethology for helping us understand many issues of modern civilization. Supernormal stimuli are driving forces in many of today's most pressing problems, including obesity, our addiction to television and video games, and the past century's extraordinarily violent wars. Manmade imitations have wreaked havoc on how we nurture our children, what food we put into our bodies, how we make love and war, and even our understanding of ourselves.
If we become aware of supernormal stimuli, this does more than simply alert us to danger. There's a clear alternative once we recognize how these behavioral triggers operate. Humans have one stupendous advantage over Tinbergen's birds -- a giant brain. This gives us the unique ability to exercise self-control, override instincts that lead us astray, and extricate ourselves from civilization's gaudy traps.
linkurl:__Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose,__;http://books.wwnorton.com/books/978-0-393-06848-1/ by Deirdre Barrett, W.W. Norton, NY, NY. 2009, 224 pp, IBSN 978-0393068481 US $24.95.
__linkurl:Deirdre Barrett;http://www.mentalhelp.net/poc/view_doc.php?type=doc&id=28732&w=9&cn=219 is an evolutionary psychologist at Harvard Medical School's Behavioral Medicine Program. She is the author of several books, including __Waistland__, __The Committee of Sleep__, and __Trauma and Dreams__. She lives in Cambridge, Massachusetts.__
Correction (February 21): The original version of this article incorrectly estimated that a chicken lays 30,000 eggs in its lifetime. The actual figure is 3,000. The Scientist regrets the error.
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