Study suggests that humans killed off the Jamaican monkey

Extinction mystery solved? Study of 1,500-year-old Jamaican monkey bone fragments suggests that HUMANS killed off the species

Previous theories suggested humans drove the Jamaican monkey to extinction

But no evidence existed that the two species lived in Jamaica at the same time

Scientists carbon dated monkey leg bone fragments found in the 1990s

They show the monkeys lived alongside humans around 1,200 years ago

The monkey may be the world's most recent primate species to become extinct

Published: 05:01 EST, 10 August 2017 | Updated: 05:04 EST, 10 August 2017

A new study of Jamaican monkey bone fragments suggests that humans killed off the species after they settled on the creature's island home.

The research suggests that the Jamaican monkey may be the most recent primate species anywhere in the world to become extinct.

While scientists had previously suggested humans drove the Jamaican monkey to extinction, no evidence existed that the two lived in Jamaica at the same time.

Through carbon dating of monkey leg bone fragments, the new study shows that the monkeys lived alongside humans around 1,200 years ago.

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A new study of Jamaican monkey bone fragments suggests that humans killed off the mysterious species after they settled on its island home. Pictured is a fossilised piece of the lower jaw of the Jamaican monkey

JAMAICAN MONKEY

According to fossil evidence, small primates - a group of mammals that includes humans and our closest monkey relatives - first arrived in Jamaica during the Miocene period between 23 million and 25 million years ago.

They probably got there on mats of vegetation that can form during major weather events, like hurricanes, that could have carried them from the American mainland.

Once on the island, they began adapting to its habitat, which would have been free of major predators and competition for resources, since rodents were the only other mammals on the island.

They probably grew in size over time, becoming stouter than South American mainland monkeys but remaining under about 11 pounds (5 kilograms) in weight.

According to previously studied fossilised teeth and other bones first found in island caves in 1920, the monkeys likely survived on fruit and nuts, had long tails, and lived in trees, hanging from the branches like sloths.

The researchers, from Johns Hopkins University in Baltimore, Maryland, say their study is the strongest evidence yet that the Jamaican monkey - Xenothrix mcgregori - overlapped with the country's first human settlers as they arrived from South America.

'We already knew that these monkeys lived in the same area as the humans because remains of both have been found in the same caves,' Dr Siobhán Cooke, lead author of the study.

'What we couldn't be sure of is whether they overlapped in time, but the new study suggests they did.

'At this time, we can't say how much of a role humans played in the extinction of X. mcgregorion Jamaica, but the timing is too coincidental for there to be no role.'

The team argue that although their finding is indirect, it is consistent with previous theories that humans sped up the species' extinction.

A combination of human predation, competition for resources, habitat destruction and the introduction of invasive species likely killed off the monkey.

'Understanding how this extinction happened and what role humans may have played could help us understand how extinctions are progressing today and what we can do to prevent them,' said Dr Cooke.

Dr Cooke said the evidence supports the idea that the monkeys survived longer than monkey species on other Caribbean islands - long enough to have overlapped with the arrival of native people from South America around 800 AD.

They probably got there on mats of vegetation that can form during major weather events, like hurricanes, that could have carried them from the American mainland.

The research suggests that the Jamaican monkey may be the one of the most recent primate species anywhere in the world to become extinct. Pictured is the roof of the mouth of a Jamaican monkey skull

WHAT KILLED OFF THE JAMAICAN MONKEY?

The Jamaican monkey probably survived long enough to overlap on the island with non-European humans.

Archaeological remains suggest these humans had already arrived from the American continent around 1,200 years ago, or between 687 and 929 A.D.

Other archaeological and fossil evidence suggests the earliest human populations in Jamaica were foragers who lived off of available local resources, together with some cultivation of native island and mainland plants.

There is no direct evidence of humans hunting the monkeys for food, such as cut marks on monkey bones or monkey.

But in addition to hunting, the clearing of land for farming and the introduction of invasive species can all put a deadly strain on native island populations.

This is because they are adapted to a very specific environment and have nowhere else to go.

Once on the island, they began adapting to its habitat, which would have been free of major predators and competition for resources, since rodents were the only other mammals on the island.

They probably grew in size over time, becoming stouter than South American mainland monkeys but remaining under about 11 pounds (5 kilograms) in weight.

Clues to the animals' extinction emerged during the 1990s, when experts found a new set of bones in a cave on the southern coast of Jamaica.

The remains included cranial specimens and a leg bone, which scientists used in the new study.

Experts used radiocarbon dating on a fragment of the leg bone to estimate that the monkey died around 1,470 years ago - likely somewhere between 505 and 573 AD.

An artist's sketch of the monkey Callicebus donacophilus, a living species closely related to the Jamaican monkey, also known as Xenothrix mcgregori

The team then put that date in the context of all other radiocarbon dates from Jamaica.

'These new radiocarbon data make X. mcgregori the longest-surviving Caribbean primate, at least as far as we know,' said Dr Cooke.

'And its extinction was one of the most recent for any primate worldwide.'

In addition, Dr Cooke said that the Jamaican monkey probably survived long enough to overlap on the island with non-European humans.

Archaeological remains suggest these humans had already arrived from the American continent around 1,200 years ago, or between 687 and 929 A.D.

There is no direct evidence of humans hunting the monkeys for food, such as cut marks on monkey bones or monkey.

But Dr Cooke said that in addition to hunting, the clearing of land for farming and the introduction of invasive species can all put a deadly strain on native island populations.

This is because they are adapted to a very specific environment and have nowhere else to go.