Wednesday, 11 February 2015

New Evidence To Support The African Origin Of South American Primates

The simian family is divided into two camps. The Old World Monkeys (OWMs) are the primates which live in Africa and Eurasia. Humans are included in this category as we originated in Africa. The New World Monkeys (NWMs) inhabit the Americas; fossil and genetic records show that the OWMs evolved first. The NWMs are descended from the OWMs, but the debate is not where they came from biologically, but geographically.

One scenario states that the ancestors of the NWMs lived in Asia and crossed into the Americas by the Bering Straits. Tens of millions of years ago sea levels were lower and a subcontinent-sized bridge known as Beringia connected two landmasses, rather than the incomplete chain of islands which exist today. There is strong fossil evidence to support this and geographically it makes sense.
An artist's impression of what this new species of 36 million year
old South American New World Monkey looked like

The other scenario is little more out there. It states that the ancestors of the NWMs lived in Africa and were transported across the Atlantic on chunks of mangrove swamps broken off from the African or European coasts by powerful storms. Such events have been recorded and the species of animals, mainly invertebrates, survived for weeks.

In theory the right conditions could allow for a mangrove raft, containing enough food to support a small population of simians, to cross the Atlantic in a few weeks. Recent evidence leans towards Asian origins, but new fossil evidence swings back in favour of African origins.

In 2010 Dr Ken Campbell from the Natural History Museum of Los Angeles, uncovered a series of teeth from the Peruvian portion of the Amazonian Basin. 'Fossils are scarce and limited to only a few exposed banks along rivers during the dry seasons,' said Campbell. 'For much of the year high water levels make palaeontological exploration impossible'.

Analysis of the teeth, showed that they came from a species of NWM. Mammalian teeth can provide a wealth of information regarding the owner's diet, identity and evolutionary ancestry. The Peruvian teeth displayed clear links to species of OWM from Africa.

In addition to the this, the fossils dated to 36 million years old, 10 million years older than the previous oldest known NWM fossils. There needs to be an increased focus on research in the Amazonian Basin to make these origins clearer still, despite the practical difficulties involved. It is likely that there is a great deal more to discover. Considering that the fossils came from Peru, on the opposite side of South America to the Atlantic, the origin of the NWMs could be several million years older.