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The DNA extracted show that the extinct Jamaican monkey was most closely related to modern titi monkeys, which are found across much of South America © LABETTA Andre/Shutterstock

Ancient DNA reveals the origins of the bizarre Jamaican monkey

Driven to extinction by human activity hundreds of years ago, little was known about where the strange Jamaican primate Xenothrix mcgregori came from.

By sequencing the DNA extracted from fossils, researchers have finally been able to place the monkey on the evolutionary tree. 

There used to be five species of primate native to the Greater Antilles, an area which includes most of the larger islands in the Caribbean Sea. All of these primates are now extinct, meaning that there are many outstanding questions about their biology.

One of these extinct primates, the Jamaican monkey Xenothrix mcgregori, is a particular oddball and has long baffled scientists. 

With short, rodent-like legs and a squat body like a slow loris, it is deemed so unlike any living primate today that no one has been able to agree on where it came from or what other species it was most closely related to.

In a new paper published in PNAS, researchers have been able to extract ancient DNA from the fossils of X. mcgregori and finally resolve its evolutionary position.

It is now thought that the Jamaican monkey was most closely related to the South American titi monkeys, which arrived on the island some 11 million years ago.

Prof Ian Barnes, a Research Leader and expert in ancient DNA at the Museum, says, 'Recovering DNA from the bones of extinct animals has become increasingly commonplace in the last few years.

'However, it's still difficult with tropical specimens, where the temperature and humidity destroy DNA very quickly. This has been a focus for our work here at the Natural History Museum, and I'm delighted that we've been able to extract DNA from these samples and resolve the complex history of the primates of the Caribbean.'

Sailing the high seas

Primates have been living in the Americas for roughly 40 million years. After rafting across the Atlantic from Africa on mats of vegetation, the monkeys had remained isolated from all other groups of primates until humans turned up some 15,000 years ago.

These New World monkeys are distinct from their Old World descendants: they have flat noses and are the only monkeys to have evolved a prehensile tail capable of grasping branches.

The skull of a now extinct Jamaican monkey

A partial Xenothrix skull discovered on Jamaica © Woods et al. 2018

This was not the only boating excursion that the New World monkeys made, however. A number of different primates species are known from the islands scattered across the Caribbean Sea - two from Hispaniola, two from Cuba and one from Jamaica.

The Jamaican monkey is thought to have gone extinct in the 1700s due to human activity. Its fragmentary fossils indicate that it was a slow moving, tree-dwelling creature unlike any other primate found in the Americas.

The DNA extracted from these fossils now show that it was most closely related to the titi monkeys, which are relatively small arboreal primates found across much of South America. Their split goes back 11 million years.  

Prof Samuel Turvey, a Senior Research Fellow at the Zoological Society of London, says, 'This new understanding of the evolutionary history of Xenothrix shows that evolution can take unexpected paths when animals colonise islands and are exposed to new environments.

'However, the extinction of Xenothrix, which evolved on an island without any native mammal predators, highlights the great vulnerability of unique island biodiversity in the face of human impacts.'

The timing of the split between titi monkeys and the Jamaican monkey in relation to the age of the other four Caribbean primates also suggests that there was not one but many rafting events from the mainland to the Great Antilles.

This means that small New World primates were discovering new lands long before humans even existed.  

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