2019-07-01_Discover

EVERYTHING

WORTH

KNOWING

44 DISCOVERMAGAZINE.COM

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Monkeys

FORGET PLANET OF THE APES. Earth has long been

the planet of the monkeys. With over 330 species,

monkeys are a diverse group of primates, split into two

major lineages: Old World monkeys of Africa and Asia, and

New World monkeys of South and Central America.

Apes — including gorillas, chimpanzees and humans — are

merely an offshoot of the Old World branch. Some 15 million

years ago, apes flourished as a group, but they’ve dwindled to

a handful of species, a near evolutionary dead-end of animals

“barely managing to scrape it together, while the monkeys

clearly have things figured out,” says Duke University primate

evolution expert Matthew Borths.

Size is one way to distinguish between hulking apes and

more diminutive monkeys: Male gorillas can weigh over

400 pounds, but monkeys max out at the 80-pound mandrill.

Monkeys also have tails, which apes lost through evolution.

“I’ve often thought that was the very saddest part of human evo-

lution,” says primatologist Dorothy Fragaszy. “It would be won-

derful to have a tail. You’re so much more three-dimensional in

your movements.” Some New World species evolved prehensile

tails, capable of grasping and dangling from trees.

Tails aside, humans and monkeys share many other

traits, including big brains, color vision and dexterous

hands, suggesting these adaptations were present in our

common ancestor.

Despite our shared roots, people are the greatest threat to

monkeys. According to a 2017 Science Advances paper, nearly

half of monkey species are nearing extinction because of defor-

estation and other unsustainable human activities. “Now seems

to be the worst time ever to be a monkey,” says Borths.

Monkey in the Middle (of a Raft)

Researchers think New World monkeys descended from a

population of Old World animals that accidentally rafted to

South America 36 million to 43 million years ago, trapped on a

mass of vegetation that washed off the African coast. More like floating

islands, vegetation mats as big as baseball infields have occasionally

been spotted by sailors on the high seas.

During this period, the continents were closer, but still separated

by more than 600 miles of ocean. Yet, provided enough plant material

for chow, rain for drinking water and optimal winds, it’s estimated

some unintentional mariner monkeys could have crossed the ancient

Atlantic in a couple of weeks. “You imagine them being a little

stressed about the situation,” says Borths.

Getting into their business.

BY BRIDGET ALEX

Old World

monkeys

Lemurs Lorises

23 million

years ago

34 Ma

56 Ma

Source: National Science Foundation 66 Ma

Source: Alejandro Estrada, et al, "Impending extinction crisis of the world’s

primates: Why primates matter," Science Advances, 2017

Tarsiers

Apes and

humans

New World

monkeys

Old World

monkeys

An ancestor common to monkeys and apes (including humans) split off

from other primates in the Paleocene, more than 56 million years ago.

Monkeys divided into Old and New World lineages around 40 million years

ago. Apes are the most recent offshoot of the primate family tree, and one

of the less diverse.

A pair of howler monkeys

go out on a limb (or two)

in Panama’s Soberania

National Park.

The Primate Family Tree

New World

monkeys