Planet of the Apes…and Monkeys and Humans

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There are a lot of perks that come with being  a primate. You get to be smart. You get to be social. You get to have opposable thumbs — which are very handy things to have. Most of all, you get to keep living even during hard times. If the history of humans indicates anything, it’s that we’re survivors, and a new study is showing just why we — and our primate kin — have been so much more resilient than other species and orders, and what this says about biodiversity in an environmentally stressed world.

In the November 30 issue of the American Naturalist, biologist Bill Morris of Duke University reports on a study he led to track survival patterns among seven species of primates compared to a sample group of two dozen species of birds, reptiles and nonprimate mammals. The study was a painstaking one, relying on 25 years worth of records compiled by the National Evolutionary Synthesis Center (NESCent) in Durham, NC.

Each year, the NESCent researchers tracked birth and death rates for wild populations of South and Central American muriqui monkeys and capuchin monkeys; African blue monkeys, yellow baboons, chimpanzees and gorillas; and Madagascar lemurs. Similar tracking was done of the two dozen  control species.

Morris and his co-researchers collated all of that data and cross-indexed it against variations in rainfall, food supply and other environmental variables across the same habitats and the same 25 years. Then they looked at which species fared the best and the worst throughout  all of the environmental ups and downs. Repeatedly, they found, the primates did significantly better than all of the other animals, and the strategies they used to survive explained a lot.

For one thing, the scientists concluded, primates are social. They may forage or hunt separately, but they recongregate repeatedly throughout the day, and this allows any one primate that finds something interesting — a water source, say — to communicate the information to the others. The fact that they can communicate at all — never mind in comparatively complex ways — is significant too. The more scientists study primates in captivity, the more they’re learning that at least some species are good at  understanding not just objects and actions, but concepts and even motivations. In the wild, this can only enhance survival.

What’s more, primates are omnivores. If all you eat is fruit and all the fruit is gone due to drought, you die. Ditto if you’re a carnivore and all the prey is either eaten already or dying from thirst or hunger itself. “Primates will eat leaves, grasses, fruits, flowers, bark and seeds. They’re gneralists,” said Susan Alberts, a co-author of the paper as well as a Duke University biologist and the associate director of NESCent.

Human beings have all of the other primates’ attributes in spades, and while we may have long ago left the state of nature, the environmental challenges we faced when we were still in the wild is not all that dissimilar from what our primate kin face now — and helps explain why they’re outperforming other species. “Modern humans also arose during a period when Africa’s climate was changing,” said Morris. “So the same traits that allow nonhuman primates to deal with unpredictable environments today may have contributed to the early success of humans as well.”

But primates are hardly indestructible, and one thing primitive humans didn’t have to face that today’s primates do is modern humans. Industrialization, habitat destruction and rapid climate change brought on by greenhouse gas emissions — as opposed to the slow-mo climate change of nature — is causing primate populations to plunge worldwide, especially among the great apes. Monkeys, chimps and others may eventually be among the last complex species standing in an environmentally wasted world, but they too would ultimately succumb. Things are hardly that bad yet, of course, but they could be if we’re not careful. It wouldn’t be much fun being the very highest primate if we also wind up as the loneliest.