SHAKES FAMILY TREE FOR NEW MONKEYS
By Laurie Goering
It's hard to walk around Marc van Roosmalen's suburban back yard without a new species of monkey trying to climb up your arm or stick its face in your glass of peach juice.
There's Cucu, the odd brown spider monkey with the strangely shaped face. Lurking shyly near a nest box in the shadows is a unique orange-bearded titi. A new type of saki monkey clings to a branch high in the trees, and a handful of strange-looking marmosets and tamarins chase each other around, screeching excitedly. Van Roosmalen, one of the Amazon's most active tropical primatologists, has officially documented just one new species of monkey, a tiny 5-inch marmoset called Callithrix humilis, revealed to science last April. Altogether, seven new Brazilian monkeys have been discovered since 1990, five of them small marmosets.
The lanky Dutchman, however, is sitting on what may be a revolution in primatology. In jungle regions inland from the well-traveled rivers of the central Amazon, van Roosmalen believes he has found 14 new species of monkeys. One monkey, his already documented marmoset, may even turn out to be a representative of a new genus, the first discovered among primates since 1904.
The explosion of new primate species, he says, is evidence of just how little understood and documented the world's largest rainforest remains, even as more of it vanishes each year to logging and fires. "We don't know anything about the Amazon," said van Roosmalen, who has spent 20 years tromping through it in rubber flip-flops, peering at monkeys and writing guidebooks of plants. "If we don't know about these primates, what don't we know about the insects and birds?"
Primates, our closest cousins who share much of our DNA, were supposed to be well-studied by now, but an explosion of new species and new knowledge is shaking what we thought we knew about the family tree.
In Africa, longtime researchers such as Jane Goodall have found strong evidence of learned culture--from tool-making to changing fashions in social behavior--among chimpanzees.
In Madagascar, scientists expect to document perhaps 10 new species of tiny dwarf and mouse lemurs in the next four or five years, said Russell Mittermeier, a leading lemur researcher and president of Washington-based Conservation International. The Amazon, Mittermeier agrees, should see at least another five to 10 monkey species officially documented in coming years, and the number of species in Asia and Africa may rise as well.
"It's amazing. These aren't museum determinations, where you find a new species by studying old museum skins. These are actually new," he said. "The more we study the more we realize how much we don't know."
Officially the world has about 625 species and sub-species of documented monkeys, from hulking mountain gorillas to tiny dwarf marmosets and lemurs weighing just a few ounces.
Most--particularly the larger species--were scientifically documented in the 1800s, when naturalists with notebooks and rifles set off to explore little-known regions of the world and bag samples of the fauna for museums back home.
Since the start of this century, the discovery of new mammal species, including monkeys, has slowly tapered off. Scientists until recently were fairly sure they had found most of what was out there.
Now that view is changing, as a result of new fieldwork, new DNA analysis techniques that make distinguishing genetic differences easier, and what some scientists say has been a relaxation in the standards needed to declare a new species.
Paul Garber, a longtime primatologist and tamarin expert at the University of Illinois at Urbana-Champaign, believes that for conservation purposes, many animals formerly lumped together as a single species are being split into separate species.
"It's always nicer to say you have a new species when you're looking for money to protect them," he said. "If that's the goal, it's not a bad thing to do." By scientific convention, different species should have genetic or behavioral differences that prevent them from interbreeding. Size and color are not enough to determine a separate species. Consider just domestic dogs, which range from Pomeranians to Great Danes, all within the same species.
Breeding incompatibility, however, can be tough to judge in places like the Amazon, where troops of similar animals may live hundreds of miles apart, separated by impassable rivers.
One way to test for species differentiation is to put the two together and see if romance blossoms. Just because two animals breed successfully in captivity, however, doesn't exclude them from being separate species. The true test is whether they will by choice interbreed in the wild. Such complexities are one reason scientists like Garber remain suspicious of the new species explosion.
I'm not trying to suggest people are dishonest, and I wouldn't be surprised if there are some new species we aren't aware of," he said. "But the criterion we use are very flexible. There's no hard and fast rule to say this is one species and this is another." Van Roosmalen, Mittermeier and other primatologists are convinced that what they have are genuinely new species, and they're seeking DNA and behavioral evidence to back it up.
Van Roosmalen, for instance, believes the baby Callithrix humilis brought crying inside a milk can to his door a few years ago by a river trader is clearly not just a new species but a new genus.
"I saw this little thing, screaming like mad and this big," he said, holding his fingers 2 inches apart. "I knew it was new." The monkeys, which van Roosmalen tracked to the lower Aripuana River, grow to about 5 inches, the size of a small marmoset, but have a single baby instead of the usual marmoset twins. Hair tufts grow out of a different part of their ears.
Their nails have evolved into claws, like the marmosets that also suck sap from trees, and their teeth resemble those of marmosets. But while marmosets are viciously territorial, the new monkeys are not. In the new species various females have infants at any one time, while in marmosets one dominant female is the only member of the troop to breed.
"Even without the DNA we can say it's an anomaly in the monkey world," van Roosmalen said. "I think the DNA will show it's at the start of the (marmoset) radiation, a survivor relic. It may be the missing link to understanding that radiation."
Most of the other new species van Roosmalen is investigating come from he region of the Madeira River, one of Amazonia's swiftest central rivers. In one inland region set back from the river--he'd prefer not to say just where publicly--he has found five new species of monkeys. From talks with local inhabitants he believes he may also be able to document a new species of tapir, several birds and even a new black jaguar. The area, interestingly enough, is listed as "low priority" on international biodiversity hot-spot lists. "I think scientists just don't want to admit they've never been there," he said.
About the only thing van Roosmalen hasn't seen yet deep in the rainforest, is the mapinguari, the Amazon's own rumored version of Bigfoot. The massive animal, described by some remote Indians, is thought--if it actually exists--to be a remnant giant sloth that somehow escaped the long-age extinction of the rest of South America's megafauna.
Van Roosmalen says he does know of a village on the upper Purus River that changed location to the other side of the water after allegedly finding tracks of the Mapinguari near their homes.
Does the monster really exist? "I'm not going to say it's not possible," he said. "Who am I to say that?"
© Chicago Tribune 7/11/99
Source credit:Bob Stansberry
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