What’s the current thinking on how new world monkeys got to the new world?
Thanks.
According to this…
“Some scientists theorize that these monkeys’ ancestors migrated from Africa by crossing the Atlantic on a vegetation raft or crossing a temporary land bridge that later submerged and isolated them. Once in the Americas, they kept evolving separately from the lineage that produced today’s Old World monkeys and apes.”
I like the idea of them rafting over but it sounds a little far fecthed to me…
The Wikipedia article is C&Pd from there I think because it’s the same verbiage. Regardless it seemed a bit far fetched to me too that’s why I posed the question here.
We don’t know completely how humans travelled, though the Bering bridge theory dominates. By the time humans came over some 14,000 years ago, monkeys would have been present much longer.
Much=thousands of times.
Follow up questions if it was a “raft” - how long would it take to drift across naturally? Would the winds carry a raft the right direction? And finally, how big would a breeding population need to be on this raft to sustain the survival of the species?
The general consensus today is that they crossed on a vegetation raft. Even today enormous rafts of vegetation are ejected by the Amazon and other tropical rivers.
There’s no evidence whatsoever for a land bridge at the time primates colonized South America.
Primates weren’t the only group that colonized South America around that time. A group called the hystricomorph rodents colonized about the same time. They include the porcupines, capybaras, agoutis, guinea pigs, chinchillas and other South American endemics.
At the time Africa and South America were much closer together, not having separated so far due to plate tectonics. Equatorial currents and winds today and almost certainly in the past would move a raft westward from Africa to South America. Today equatorial currents move at up to 1 m per second, or around 3.6 km per hour. The shortest distance between Africa and South America today is about 3000 km. Assuming the distance at the time of colonization was half that, it would take about 17 days to make the journey. Considering that the species colonizing would have been small and could have found insects on the raft, that seems possible.
The minimum population size would be one pregnant female. While inbreeding in a small initial population could be a problem, it’s not an insurmountable one.
There are lots of counterintuitive examples of animals coming to the new world in surprising ways.
One of the very smallest animals—the bacterium that causes tuberculosis—likely got to the new world by infecting seals in South Africa that then carried it to South America:
https://www.nature.com/news/seals-brought-tb-to-americas-1.15748
What about animals like trees and grass, then?
That’s an interesting nit to pick. Would you rather I specify “animals and prokaryotes?”
17 days without fresh water For a primate seems like a long time. But then I know nothing about monkey hydration.
Thanks for your insights.
And here I always I thought they escaped from the ark when a dinosaur left the door open.
They probably got water from fruit and leaves.
Remember that most (well, a lot anyway) of your water needs are met through the food you eat. So eating insects and vegetation (and potentially fruit, depending on what the raft consists of) would carry them for quite a while.
Couldn’t small monkeys be carried across the ocean by African Swallows?
This is the answer, with the addition that they would not have had to cross the narrower proto-Atlantic in one go, either. There would have been at least one chain of islands connecting the two continents, now evident as seamount chains.
Also, I think people might be picturing entirely the wrong thing when they hear “rafts”. It’s not a couple animals clinging to one lone tree-trunk we’re talking about. Rafts hundreds of metres square, that persist for a thousand mile journey, are what we’re talking about.
And even if events like that are rare, it only needs to happen once.
EdelweissPirate, calling bacteria “animals” is actually a really big and significant nit to pick. We’re much more closely related to plants than to bacteria.
I’ll guess that if they were lucky, enough rain could have fallen on the raft, and collected in puddles, to supplement the liquid in whatever they found to eat.
The unlucky ones, for whatever reason of being unlucky, died and didn’t get there. These rafts wouldn’t have been something that only happened once.
I just read that old world monkey are more closely related to apes, then they are to new world monkeys.
Which brings all sorts of oddities, such as if this is indeed so then apes are a type of monkey and humans being apes would be included.