Analysis of an ancient DNA of a mysterious extinct monkey named Xenothrix, which displays bizarre body characteristics very different from any known living monkey has revealed that it was, in fact, closest to South America’s titi monkeys. Having made their way over water to Jamaica, probably on the floating vegetation, their bones reveal that they subsequently underwent remarkable evolutionary changes.
The research reveals that monkeys must have colonized the Caribbean islands more than once and the study reports an incredible discovery of how the unusual ecology of islands can dramatically influence animal evolution.
Unlike any other monkey in the world, Xenothrix was a slow-moving tree-dweller with relatively few teeth, and leg bones somewhat like a rodent’s. Its unusual appearance made it difficult for scientists to work out what it was related to and how it evolved. However, the scientific team successfully extracted the first ever ancient DNA from an extinct Caribbean primate uncovered from bones excavated in a Jamaican cave and providing important new evolutionary insights.
This new understanding of the evolutionary history of Xenothrix shows that evolution might take unexpected paths when animals colonize islands and are exposed to new environments. However, the extinction of Xenothrix, which evolved on an island without any known native mammal predators, highlights the vulnerability of unique island biodiversity in the face of human impacts.
Recovering DNA from the bones of extinct animals became increasingly commonplace in the last few years. However, it is still challenging with tropical specimens, where the temperature and humidity destroy DNA very quickly. I’m glad that we’ve been able to extract DNA from these samples and resolve the complex history of the primates of the Caribbean.
It is likely that Xenothrix’s ancestors colonized Jamaica from South America approximately 11 million years ago, probably after being stranded on natural rafts of vegetation that were washed out of the mouths of large South American rivers. Many other animals, such as big rodents called hutias that still survive on some Caribbean islands today, probably colonized the region in a similar way.
Ancient DNA indicates that the Jamaican monkey is actually just a titi monkey with some unusual morphological features, not a wholly distinct branch of New World monkey. Evolution could act in unexpected ways in island environments, producing miniature elephants, gigantic birds, and sloth-like primates. Such examples have put a very different spin on the old cliché that anatomy is the destiny.
What Xenothrix might have looked like has been greatly debated, with suggestions that it looked like a kinkajou or a night monkey. Living titi monkeys are tiny tree-dwelling monkeys found across tropical South America, with long soft red, brown, grey or black fur. They are most active during the day, extremely territorial and vocal, and live up to 12 years in the wild, with the father often caring for the young.
Though the Galapagos Islands are famous after having inspired Charles Darwin’s theory of evolution, the islands of the Caribbean have also been home to some of the most unusual and mysterious species to have ever evolved. But, the Caribbean has also experienced the world’s highest rate of mammal extinction since the end of the last ice age glaciation, likely caused due to hunting by humans.