After being found in the jungles of Africa, researchers in South America have now discovered links that connect … [+]
Millions of years before the first man set sail, the first daring expedition into unforgiving waters had already been made. With no maps, no ship – and, to be fair, no choice – a group of monkeys made an impossible journey across the Atlantic Ocean.
Fossil evidence unearthed in South America reveals the incredible story of these ancient primates, who clung to life on rafts of vegetation and survived a seemingly impossible journey – not once, but at least three times.
The journey of a thousand miles began with a natural raft
Approximately 30 to 40 million years ago, South America was an isolated landmass, separated from Africa by an expanse of ocean that stretched 900 to 1,300 miles (1,800 km), depending on fluctuating sea levels. The Atlantic Ocean was no less formidable than it is today, and yet ancient primates from Africa found their way through its vast waters to the distant shores of South America.
Their incredible journey was neither intentional nor voluntary. Storms, floods, or other natural disasters likely engulfed these early primates in large rafts of uprooted trees and vegetation. Carried by ocean currents and favorable winds, these floating ecosystems transported the primates across the Atlantic on a journey that could have taken weeks or even months.
Natural boats like those carried by apes have played a key role in the history of the spread of life across the planet. These haphazard ships, filled with vegetation and debris, carried more than just their cargo – they transported species to whole new worlds.
In 1995, hurricanes in the Caribbean released masses of vegetation into the sea, creating natural rafts that sent green iguanas to previously uninhabited islands.
Even more dramatically, the 2011 tsunami in Japan sent waves of debris drifting across the Pacific. Entire ecosystems were uprooted, with marine species traveling thousands of miles to the shores of North America. Here’s a video about it:
How the story of the rafting monkeys gave a tooth
Evidence for this unlikely journey comes from fossilized teeth discovered in South America. These fossils, representing at least three distinct migrations, belong to species that include Perupithecus ucayaliensis, Ucayalipithecus perdita and recently, Ashaninkacebus simpsoni.
The first fossils of Perupithecus ucayaliensis—dated to approximately 36 million years ago—were discovered in Peru in 2015. The teeth bore a striking resemblance to those of North African primates, suggesting a direct evolutionary link.
Later, in 2020, the fossils of Ucayalipithecus perdita were found in the same region, pointing to another migration about 32 million years ago. Finally, in 2023, the discovery of Ashaninkacebus simpsoni in Brazil we further expanded our understanding of these ancient journeys, discovering a group of primates that were small, fruit-eating and highly adaptable.
The fossil record of New World monkeys has long hinted at an African origin, but recent discoveries provide the clearest evidence yet. The molars of Perupithecus, Ucayalipitecus AND Ashaninkacebus have striking similarities to those of African primates, confirming a common evolutionary ancestry.
These teeth reveal distinctive cusp patterns that are virtually identical to those of parapithecids and eosimiids, families of African primates that lived over 30 million years ago.
What makes these findings even more compelling is their geographic context. Fossil sites in South America, such as the Río Yurua region in Peru, have yielded remarkably well-preserved teeth for their age. These discoveries have bridged the gap between Africa’s primate ancestors and the diverse group of New World monkeys that thrive today, including capuchins, howler monkeys and tamarins.
Regardless of their African connections, however, the apes that rafted across the Atlantic likely represent different evolutionary experiments. The discovery of Ucayalipithecus perditafor example, it suggests that these primates were part of the parapithecid family, a group previously known only from Africa. Their teeth were almost identical to his tarsan African primate from the Eocene epoch, highlighting the evolutionary links between these ancient populations.
These monkeys are not the only explorers in natural history
The natural world is full of examples of animals undertaking extraordinary journeys across oceans, driven by geological forces and chance events. Madagascar’s rich biodiversity, for example, owes much to similar rafting events.
The ancestors of lemurs, tenrecs and other terrestrial vertebrates are believed to have made their way to the island from mainland Africa millions of years ago on rafts of vegetation, according to a May 2023 study published in Biological Reviews.
Similarly, penguins – usually associated with Antarctica and its frigid environs – have been found in Australia, Africa and parts of South America. Fossil evidence suggests that ancient penguins migrated to these warmer regions millions of years ago, possibly aided by shifting ocean currents and favorable climatic conditions.
Even insects such as painted lady butterflies demonstrate amazing feats of migration. These delicate creatures have been observed traveling thousands of miles, moving from Europe to Africa in a multi-generational journey.
The transatlantic journeys of African primates coincided with a time of significant environmental change. During the late Eocene epoch and early Oligocene epoch, sea levels fell as glaciers formed in Antarctica, narrowing the oceanic gap between the continents. This period also saw stronger ocean currents and storm systems, which may have facilitated the creation of large floating rafts capable of transporting animals over great distances.
While the odds of surviving such a journey were slim, those who made it found a land ripe with opportunity. Free from many predators and competitors, South America provided fertile ground for adaptation and evolution. Over time, these early pioneers helped shape the ecosystems we see today.
The story of the monkeys that sailed across the Atlantic is a testament to the resilience of life in the natural world. Do stories like these inspire you to learn more about the world around you? Take a 2-minute test to see where you stand Relation to the scale of nature.
