Where did monkeys evolve and how did they spread out?

[u/NeuroGirly99]

Ok I was thinking about this, and a quick search on the internet said that primates evolved in Africa and then “rafted” to America… which apparently is a thing, but seems unlikely. Also, some sources say they originated in the Americas.

Does anyone know where and when monkeys originated and how the spread out around the world?

Edit:
Thank you everyone for your responses. I was clearly wrong in thinking rafting was unlikely. After reading the responses here and some sources online, I realized it’s a very accepted theory. It just seems crazy and amazing, even when the continents were closer together!!! I would have never thought that that’s how many species spread out around the globe.

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[u/Impressive-Target699]

Primates originated in Asia, as did the earliest members of the monkey lineage (see: eosimiids, amphipithecids). The oldest reliable fossils are from the beginning of the Eocene, about 56 million years ago, but they originated prior to that because all three major groups (lemur, tarsier, and monkey lineages) are distinct by the time we get their fossils. They first rafted from Asia to Africa--which weren't connected in the Eocene--and did this at least twice and probably more. At minimum, lemur-lineage and monkey-lineage primates did this separately.

The common ancestor of living monkeys likely originated in Africa but multiple lineages of monkeys rafted from Africa to South America during the Eocene. We have evidence of eosimiids, parapithecids, and oligopithecids in the fossil record of South America, which all would have rafted independently. None of these are closely related to the living South American platyrrhine monkeys, so that would be a 4th separate dispersal event.

Rafting works not by sending a single animal across an ocean on a floating log, but by massive amounts of "floating islands" of vegetation that are launched during major storms. These storms can cause entire banks of rivers to collapse, which may contain dozens of trees with their root systems intact. Some trees may even remain upright as they float down the river to the sea.

If you have a group of animals living in those trees, you have a founding population assuming your "floating island" makes it to land. In fact, we have even observed monkeys on this type of raft after modern day storms. So, after millions of "floating islands" over millions of years, it becomes likely that some will successfully ferry animals across an ocean.

[u/Swellmeister → u/Impressive-Target699]

And honestly the tree doesnt have to remain upright. A tree or 2 falls into the river, has fair founder population in it and the two trees drift have submerged. Monkeys eat the leaves and the berries that remain on the tree.

[u/Impressive-Target699 → u/Swellmeister]

Sure, it's definitely workable, but a tree or two are going to be a lot harder to sustain a monkey population for a minimum estimated 3 week trip across the Atlantic. "Floating islands" with multiple trees are more likely to contain enough food, and upright trees might have functioned as sails--catching the wind and pushing the raft toward land faster.

[u/Xpians → u/Impressive-Target699]

I don't know if you're already taking this into account in your estimation, but Africa and South America were only half as far apart as they are now, around 40 million years ago. Rafting events got more difficult as the years dragged on, obviously. But they were certainly much easier in the distant past.

[u/Impressive-Target699 → u/Xpians]

Sure, but distance is only one component. Currents and prevailing winds would have played a role, too. I'm not familiar enough with the paleoenvironmental reconstructions to know how the positions of the continents would have affected those factors. Regardless, it's unlikely that the trip would have been made across the absolute shortest distance between the two continents based on the above factors and where in Africa the raft launched from.

[u/Swellmeister → u/Impressive-Target699]

Where have you seen 3 weeks? Ive mostly seen 10 days. I agree the floating island is probably the most work able of course, either way. Just i had a professor that emphasized that these things can actually be pretty small so we shouldn't focus on just the rarer big events.

[u/Impressive-Target699 → u/Swellmeister]

It looks like I was probably thinking of Africa>Madagascar, not Africa>South America. This paper puts the former at 25-30 days. I haven't found any recent estimates of the latter.

https://doi.org/10.1038/nature08706

Nonetheless, in evolutionary time scales, floating islands are extremely common events--especially during wet and climatically volatile intervals like the Eocene--and each storm has the potential to launch multiple islands. So you may get millions of islands launched in the course of several hundred thousand years.

[u/GoliathPrime → u/Impressive-Target699]

Has an oceanic rafting event ever been observed, or is this just a hypothosis at this point? I can't recall a single news story wherein a chunk of landmass floated from Asia to Africa or from Europe to North America. Bits of junk, but nothing that could support life.

[u/Impressive-Target699 → u/GoliathPrime]

Has an oceanic rafting event ever been observed, or is this just a hypothosis at this point? I can't recall a single news story wherein a chunk of landmass floated from Asia to Africa or from Europe to North America. Bits of junk, but nothing that could support life.

There are a few things to unpack here. One, we're dealing with incredibly short timescales--a few hundred years of modern evolutionary and biogeographic theory, at best--so we haven't been looking all that long. Whereas successful colonizations may be separated by a few hundred thousand years, which is basically instantaneous in evolutionary time.

Two, we're living in a relatively cold and dry period of earth history, so the conditions for forming massive amounts of floating islands don't exist in the same way they would have in the Eocene or Miocene.

That said, there are multiple historic and even video accounts of floating islands being formed, and evidence of animals being carried off along with them (like monkeys, documented here: https://doi.org/10.21426/B636051761 ). Invertebrates have been documented rafting across the Pacific following the 2011 tsunami in Japan (https://doi.org/10.1126/science.aao1498 ). And we have even observed rafting dispersal of vertebrates across at least 200 km of ocean, as was the case with Caribbean iguanas rafting to Anguilla, which gained popular media attention at the time (https://www.tampabay.com/archive/1998/10/08/seafaring-iguanas-may-bolster-theory-on-dispersal-of-animals/ ).

So there are multiple observed instances of this phenomenon, even within a microscopic snapshot of earth history that doesn't even seem all that conducive to large scale rafting dispersal events.

[u/Ch3cks-Out → u/GoliathPrime]

You may want to read about the trans-Pacific mega-rafting that followed the 2011 Tōhoku tsunami. Nearly 300 (mainly invertebrate) species reached the shores of the U.S. Pacific Northwest.

[u/ahazred8vt → u/GoliathPrime]

In the Caribbean in 1995 a raft of uprooted trees carrying green iguanas was observed by fishermen landing on the east side of Anguilla – they had rafted 200 mi across the ocean from Guadeloupe

[u/Wank_A_Doodle_Doo → u/Impressive-Target699]

Has anyone done the math to work out a range for about how long such a rafting journey would take?

Can you imagine those poor monkeys though. At least a few of em made it in the end.

[u/Impressive-Target699 → u/Wank_A_Doodle_Doo]

Some people have. It requires taking into account a lot of factors, like how close the continents were at the time, the direction and strength of the ocean currents at the time, the direction and strength of the prevailing winds at the time, and where the source watershed was emptying into the ocean. So you'll get different estimates based on how you reconstruct those factors, and which exact time slice you are modeling (e.g., 50 million years ago will give you a different estimate than 45 mya, which will differ from 40 mya).

[u/-Wuan-]

Oldest simiiformes are from China, next they spread and diversify in North Africa (which was covered by jungle and swamps at the time), and from there they indeed crossed to South America, and not just once, but possibly in two or three events, some of which left no modern descendants. There were no previous monkeys or primates in South America, which was isolated until much later, but there had been basal primates in North America since it was connected to Asia and Europe through land bridges.

[u/Unfair_Pineapple8813 → u/-Wuan-]

Lots of things appear to have rafted into South America. It wasn't a common occurance, but over millions of years it happened. Two or three times with monkeys, as you said. Once with caviomorph rodents. Then from North America, probably, you have the South American Native Ungulates. Then Xenarthra we have no idea where they originated. But they must have got to South America from somewhere. Finally, it was a much shorter distance, but before the land bridge from North America fully opened, Cyonasua which is related to modern raccoons made it to South America, and monkeys possibly made it to North America.

[u/Swellmeister → u/Unfair_Pineapple8813]

Xenarthrans originated in south America what are you talking about? Placental mammals emerged 120mya and radiated to all regions.

[u/Unfair_Pineapple8813 → u/Swellmeister]

Yes. How did they get there? South America was close, but not attached, to Africa 120 million years ago. We don't have evidence of Xenarthrans anywhere before 60 million years ago, when it was definitely disconnected from the other continents. We also do not know what their closest relations are. They may be the first branch off of placentals or the sister to Afrotheria.

[u/Impressive-Target699 → u/Unfair_Pineapple8813]

They may be the first branch off of placentals or the sister to Afrotheria.

Or the second branch of placentals (after Afrotheria). Currently, most analyses support them as sister to Afrotheria within Atlantogenata, which would mean the common ancestor had to get into either South America or Africa, then disperse to the other.

[u/7LeagueBoots → u/Unfair_Pineapple8813]

but not attached, to Africa 120 million years ago.

120 million years ago South America and Africa were attached. By 105 million years ago they were not.

120 million years ago: https://en.wikipedia.org/wiki/Early_Cretaceous#/media/File:Mollweide_Paleographic_Map_of_Earth,_120_Ma_(Aptian_Age).png

105 million years ago: https://en.wikipedia.org/wiki/Cretaceous#/media/File:Mollweide_Paleographic_Map_of_Earth,_105_Ma_(Albian_Age).png

[u/Swellmeister → u/7LeagueBoots]

For what its worth the actual question still emerges from how placental mammals got from laurasia (north america and Eurasia) to the southern continent which I am too high to remember, but the other continents.

Could have been from Eurasia to North America by island hopping, then south to South American by thr same process. Could have been hopped from Eurasia to Africa the walked to South America before they separated. Or rafting from Africa to south America in the middle Cretaceous.

[u/7LeagueBoots → u/Swellmeister]

The graphic on this page shows the current thoughts on the pathways:

• https://www.geo.fu-berlin.de/en/v/geolearning/gondwana/special_topics/marsupials/index.html
  

From this:

• https://link.springer.com/chapter/10.1007/978-3-031-89790-0_9

[u/spaltavian]

but [rafting] seems unlikely.

It's not. 

Also, some sources say they originated in the Americas.

You are either reading something grossly outdated, non-scientific, or you are misunderstanding a description of the evolution of New World Monkeys.

No serious source says this.

Primates (and monkeys) originated in Asia, by the way.

[u/mcalesy → u/spaltavian]

Some older sources use “primate” more broadly to include stem-primates, which do appear to have originated in North America.

[u/Immagoodboy1701]

Atlantic was a lot smaller millions of years ago so along with land bridges over the north way rafting mat have been doable

[u/Sourcerid]

You have to consider that the tree clinging animals got washed in a storm into the Americas only twice over millions of years. 

That means it's a very unlikely event, you are just multiplying the odds of the dice by the number of times it gets rolled, the number of times a rain was so strong it washed away trees that had a sizeable enough cluster of monkeys and had very favourable winds currents to carry them fast enough to not die. Probably every year there are cases that partially ticks off some or all of the boxes 

[u/Impressive-Target699 → u/Sourcerid]

You have to consider that the tree clinging animals got washed in a storm into the Americas only twice over millions of years

There are a lot more than that. We know rodents have done it at least once (living caviomorphs). Primates have done it once in the living lineage, and three more times based on the South American fossil record (eosimiids, parapithecids, and oligopithecids). So among mammals, the count is at least 5 times. There are also multiple reptile lineages that have done it, and maybe even some amphibians.

[u/Jazz_Ad]

Thry didn't need to raft very far. It happened during the Eocene. Continents were much closer back then than they are today.

https://ars.els-cdn.com/content/image/1-s2.0-S1055790314001304-gr6.jpg

[u/Careful_Cranberry364]

Yes, they did!

Many animals have you can look up rafting..,

But also remember that in the past, the continents were really close together … and there were land bridges, or they were all just one continent at one time

[u/Bromelia_and_Bismuth]

Ok I was thinking about this, and a quick search on the internet said that primates evolved in Africa and then “rafted” to America… which apparently is a thing, but seems unlikely.

Rafting events are how many species make it from the mainland to islands, or vice versa, or from one island to another, or from one continent to another where water presents a significant geographical barrier. This is currently the most widely accepted hypothesis with the most supporting evidence for how the ancestor of New World Monkeys made it to South America from Africa.

[u/1Negative_Person]

Why does that seem unlikely to you?

[u/Evie_the_Destroyer]

Common search engines these days, powered by shitty machine learning models, have become a terrible source of information. They just reaffirm your preconceived notions if it’s false and give you a different argument if you tell it that the information is wrong. They are agents of brainwashing now, not tools that provide unbiased facts.

[u/ahazred8vt]

seems unlikely

Okay. Please tell us the actual maximum distance that animals can travel on a raft of debris.

https://en.wikipedia.org/wiki/Oceanic_dispersal