All in all it's a rather bizarre story, and not everyone agrees with it. Some have proposed that maybe our dates for continental drift are wrong, or perhaps we simply haven't found the extent of the fossil record yet. The rafting theory is sometimes derided for being a catch-all for when we can't explain an animal's migration.
Perhaps more bizarrely, though, is that we can't better the raft theory. And monkeys are not the only life for which it has been proposed. Going back as far as Charles Darwin in the 19th Century, it’s been used to explain why we find lizards, rats, plants, and more spread across seemingly unconnected locations. Monkeys are some of the larger animals thought to have been involved in a raft crossing.
“Rafting in general is something that comes up quite a lot,” Antonelli said. “When people started to use DNA, they noticed that many [dispersal] events had been long after the continents had separated.”
Primates have one of the most detailed fossil records, so we can paint a pretty good picture of where they’ve been. The fact they sprung up in the Americas, with seemingly no land bridge to get there, suggests that this rafting idea really is true, no matter how odd.
“Monkeys are the weirdest thing,” said Bloch. “Somehow they managed to get from Africa to South America across the Atlantic. Then they dispersed throughout South America, going to the very highest latitudes, all the way down to the southernmost tip of Argentina. Then they somehow became the only mammal to cross the Central American Seaway.”
There’s just one more final twist in the tale. Remember at the start of this article, when we told you about primates originating in Asia and making their way to Africa? Well, the thing is, they may have also relied upon an ocean crossing to do that, across the Tethys Sea about 45 million years ago.
That means that the dawn of humanity itself may very well be dependent on a fluke of nature, when our distant primate ancestors were ripped from their homeland and thrown across the ocean. A monkey raft could be the reason you are sitting here right now, reading this.
“If that’s true, then all monkeys and apes are the result of that earlier ocean crossing, and that includes humans,” said de Queiroz. “Our existence was directly dependent on one of these rafting voyages. All humans are dependent on that event.”