Age brings knowledge: but domesticated animals, such as humans, don't seem to recognize this.
Anne Innis Dagg
Johns Hopkins University Press
225 pages, hardcover
"MOST BEHAVIORAL RESEARCH ON WILD animals does not mention older individuals," notes University of Waterloo researcher Anne Innis Dagg, and indeed there is not a single reference to aging in my copy of The Oxford Companion to Animal Behavior. Dagg suggests possible reasons for this omission. Behaviourists are more concerned with reproduction and evolution, she says, and do not consider that post-reproductive animals have much to tell us about either of these subjects; older animals are rarer than young animals or animals in their prime, consisting of only about 10 percent of a population; and, at least in the past, some naturalists assumed that senescence simply did not exist in the wild. "No wild animal dies of old age;' Ernest Thompson Seton wrote in Wild Animals I Have Known, the kind of dubious statement that prompted John Burroughs, in reviewing Seton's book, to comment that Seton might better have called it "Wild Animals Only I Have Known."
If there is a paucity of scientific research, however, there is a wealth of anecdotal evidence that older animals play significant social roles in their various populations. Dagg draws on this vast resource, citing everything from casual references by scientists studying some other aspect of animal behaviour, or even other animals--Jane Goodall taking a break from chimpanzees to write about hyenas, for example--to Timothy Findley's report, in Inside Memory, that his aging dog bowed to the rising sun each morning. Some of Dagg's findings will not surprise those who, like me, are post-reproductive: older rats tend to "have decreased motor activity compared to younger rats" and, "in humans, older men are far less violent." But there is also much that is new and intriguing, and that ought to change the way we view and value the aging process in many species, including our own.
If older animals are unimportant to evolution because they no longer contribute their genes to the special pool, Dagg asks, then why do animals live to be old? Why does a species tolerate members whose consumption of scarce resources is greater than their contribution? It must be that older animals do contribute, often considerably. Older animals are survivors, and so are often the bearers of good genes; they stick around to care for their offspring and grand-offspring, thereby ensuring that good genes remain in the pool. Japanese monkeys, for example, are altruistic nepotists: they defend their own young, but not the troop as a whole. Pilot whales stop having young at around 40 years of age, but females continue producing milk until they are 60 and can babysit their grandchildren while the mothers dive for food. Older animals are also cultural providers, carrying experience and knowledge that benefit the entire population: where the best feeding sites are, which foods are poisonous. Sperm whales can live into their eighties, and elders actually teach the young the vocal dialects of nearby pods so they can more easily find mates outside the family and thus avoid the dangers of inbreeding.
The more social a species is, the more important its elders are. Among African elephants, elder females remain dominant long after they stop reproducing. This is partly because their growth is indeterminate--the older they are, the bigger they get--but also because of their long memories: being able to find water during a drought can be the difference between survival and extirpation. Elephant herds with the oldest matriarch often have the most reproductive success. Older males, too, exert a moderating influence on younger members: when older males are eliminated from a herd (by poachers, because older elephants have larger tusks), the orphans suffer from an elephantine version of post-traumatic stress disorder, displaying "abnormal startle response, depression, unpredictable asocial behavior and hyperaggression." These traits may be familiar to readers of Barbara Gowdy's novel The White Bone.
In patriarchies, such as in mountain gorilla troops, males gain leadership by fighting and competition: gorilla leaders are not elders but alphas, and their constant defence of territory and harems can actually render them unfit for breeding. Among pronghorn antelopes, fighting males so often die in their prime that subordinates live longer and have more offspring, which means that it is not necessarily the best genes that get passed on. In matriarchies, on the other hand, females become leaders by dint of their experience and superior abilities, and remain leaders long after they pass the peak of their physical strength. In vervet monkeys, subordinate females can acquire leadership simply by living long enough to have more offspring, not only because such females have a small army of defenders, but also because it seems to be understood among vervets that a mother who has a large number of surviving young must be doing something right.
In human populations, where our post-reproductive lives can make up as much as 40 percent of our entire lifespans, one would think that elders are highly prized. In some societies they are: among the !Kung in Botswana, "elders are vital in five important areas," Dagg writes, they are the water stewards, they are teachers and caretakers of children, they are healers and they perform religious ceremonies. The same is true for Chipewyans, where the "grandmother hypothesis" holds that older women are both efficient food gatherers and effective cultural repositories. But in most western human societies, with their high reliance on technology, elders are often shunted aside. Even among relatively isolated people, such as the Micronesians inhabiting Etal Island, "with increased Westernization, older people no longer have much self-esteem." Westernization, which usually means technological advancement, has rendered us less social and more like a domesticated species than like wild or even semi-confined animals.
Dagg's book should be a corrective to us all; species that lose or ignore the contributions of their older members do so at their peril. I, for one, am sending a copy of this book to my grandchildren.
Wayne Grady is a science and nature writer whose most recent book is The Great Lakes: The Natural History of a Changing Region (Greystone Books, 2007).
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|Title Annotation:||GETTING OLDER; The Social Behavior of Older Animals|
|Publication:||Literary Review of Canada|
|Article Type:||Book review|
|Date:||May 1, 2009|
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