I’ve been trying to collate all the current evolutionary ideas out there into something that makes sense to me, and where I always come short is how “native” tribes/people happened. I mean, I understand how if humans started in Africa they then migrated north and so occupied all the adjoining land-masses, but how did the Americas and Australia end up populated? There’s no way they could’ve clung to logs or anything for the distances involved, so how and when did they get there?
Is this known??
Don’t forget that in the timescales involved the landmasses were in different places and sometimes connected via ‘land bridges’
Why not?
In fact this is exactly how they are hypothesized as getting to many of these places - Only in this case they are believed to have used ropes too lash said logs into objects we like to refer to as “rafts” :).
Australia, the Indonesian archipeligo, Madagascar, Polynesia, Micronesia, etc., appear to have been settled in just such fashion. If you look at it as a matter of island-hopping the distances are mostly not that extreme ( places like Hawai’i being the farthest out ).
For the Americas there have long been two competeing hypotheses:
The Bering Land Bridge Hypothesis - Long dominant, the idea here is that during the last big glacial period sea-level dropped to the point that a land connection was exposed between Siberia and Alaska and folks simply walked across.
The Kon-Tiki Hypothesis ( and variants thereofm but I like the name ) - Another rafting scenario. Long the junior hypothesis, it ( or variants thereof ) has had a recent resurgence in popularity due to questions about the dating of remains and synching them with the last glaciation.
The Kon-Tiki hypothesis is the other way round. Thor Heyerdahl had the idea that Polynesia was populated from South America rather than from Asia and to prove this (at least he showed that it was possible) he sailed a raft from Peru to Raroia in the Tuamotu Islands. The general assessment, however, based on linguistics and archaeology is that he was wrong.
That’s the original Kon-Tiki hyppthesis. Tamerlane is referring to the idea that North America was colonized over water, rather than via the Bering Land Bridge. This hypothesis is named after Heyerdahl’s original one, concerning colonization of Polynesia from South America (much later).
Aha. Why not call it the reversed Kon-Tiki hypothsis to avoid confusion. 
The Ikit-Nok hypothesis?
Coupled with the (remote) possibility that neolithic humans might have crossed the Atlantic from Europe on the ice age pack ice, there are many ways to get from one land mass to another.
the whole issue is shrouded in billions of years and millions of theories
i go for the God made us easy option
there’s a book about it
it does not contain 1st and 2nd imaginations
Don’t forget that what you’re talking about (how humans ended up distributed across the earth) is a tiny part of what you called it (evolution). Way way under 1% time wise. Life has been around this place for 3.75 billion years, and man has only been around just over 1 million years (and that’s homo erectus, perhaps not even “man” depending on your definition)
BTW, one theory is that monkeys rafted over to South America from Africa. Sounds kinda strange, and I don’t know how far apart they were when this happened, but it was probably a couple hundred miles.
Also, rats rafted over to one of the Caribbean islands about 120,000 years ago. With no predators on the island, those suckers ended up getting up to 300 pounds!.
So, the moral: If monkeys and rats can do it, it should have been a cake-walk for our ancestors.
Well, I would agree that it is an easy option.
Really!? While I am not exactly sure what “1st and 2nd imaginations” are, I was not aware that that particular book addressed any of the current questions in modern human dispersement. Perhaps we should notify some of the scholars currently working on this that the all of the oustanding issues have been resolved.
Australia.
When? About 60, 000 ya. The figure varies from extremes of 120, 000 to the most conservative 40, 000. General consensus seems to be 60, 000. That’s well before humans (H. sapiens) had found there way into most of Europe.
How? By boat. The fact that at all times in human history there have been ocean channels of at least 50 kilometres in places between Indonesia and new Guinea is taken as evidence of fairly advanced human intelligence and language. The journey was taken on faith since the land masses were presumably not visible to each other. Presumably some form of steering and navigation mechanism was available. It also seems likely that the colonisation was the result of deliberate migration. It seems unlikely that such a colonisation event was achieved by a few people simultaneously washing up in the same place at the same time.
Americas.
When. Figures vary from 5, 000 to 20, 000 ya. Popular consensus is that the migration of the American Indian/Mongoloid people occurred about 12, 000 ya but there seems to have been other colonisations prior to this. Whenever it was it seems to be fairly recent, and well after evidence of potentially ocean-going boats exists in other parts of the world.
How? This is open to immense speculation.
The Mongoloid people that dominated all of North Am and most of South Am until recently almost certainly walked via ice or land bridge from Siberia to North Am.
However there is evidence of several earlier waves.
Some evidence suggests colonisation of South Am by Australoid/Negroid/Polynesian people, presumably by boat via the pacific. This has been dated at 15, 000 years plus.
There is fairly strong evidence of colonisation of (presumably Caucasoid) people from western Europe going back over 16, 000 years. (http://www.bbc.co.uk/science/horizon/2002/columbus.shtml )
Australia.
When? About 60, 000 ya. The figure varies from extremes of 120, 000 to the most conservative 40, 000. General consensus seems to be 60, 000. That’s well before humans (H. sapiens) had found there way into most of Europe.
How? By boat. The fact that at all times in human history there have been ocean channels of at least 50 kilometres in places between Indonesia and new Guinea is taken as evidence of fairly advanced human intelligence and language. The journey was taken on faith since the land masses were presumably not visible to each other. Presumably some form of steering and navigation mechanism was available. It also seems likely that the colonisation was the result of deliberate migration. It seems unlikely that such a colonisation event was achieved by a few people simultaneously washing up in the same place at the same time.
Americas.
When. Figures vary from 5, 000 to 20, 000 ya. Popular consensus is that the migration of the American Indian/Mongoloid people occurred about 12, 000 ya but there seems to have been other colonisations prior to this. Whenever it was it seems to be fairly recent, and well after evidence of potentially ocean-going boats exists in other parts of the world.
How? This is open to immense speculation.
The Mongoloid people that dominated all of North Am and most of South Am until recently almost certainly walked via ice or land bridge from Siberia to North Am.
However there is evidence of several earlier waves.
Some evidence suggests colonisation of South Am by Australoid/Negroid/Polynesian people, presumably by boat via the pacific. This has been dated at 15, 000 years plus.
There is fairly strong evidence of colonisation of (presumably Caucasoid) people from western Europe going back over 16, 000 years. (http://www.bbc.co.uk/science/horizon/2002/columbus.shtml )
Any cites for either of those? Monkeys evolved when Africa and S.A. were one landmass. If there was any floating involved, it happened when there wasn’t much water between them. Genetic comparisons of new vs old world monkeys confirms the split happened long before Africa and S.A. assumed their current geological positions.
I call BS on the rat theory. Evolving from about 1 pound to 300 in 120k yrs? I don’t think so.
Africa and South Am were last one landmass about 150 MYA give or take 50 MY.
The earliest known monkey fossil only dates to about 30 MYA.
The earliest primate fossils in South Am date from about 25 MYA.
Monkeys rafting to South Am from Africa is the hypothesis that best fits the genetc and fossil evidence, even though it seems improbable.
Blake:
Any other mammals that got to S.A. that way from Africa? I thought monkeys were believed to have first arisen about 45M yrs ago, based on genetic data. As I look at the continetal drift data, it looks like the “one land mass” claim I made is incorrect, as you pointed out. My mistake.
I still call BS on the rat theory, until we get a cite from Tucker.
John: the “giant rats” to which our snake-hipped friend refers is most likely Amblyrhiza inundata, a large heptaxodontid rodent. Fossils dating to about 125,000 years ago were found on the islands of the Anguilla Bank. This beast was close to the size of a black bear. See here. And here.
You’re almost certainly correct. Earliest fossil =/= earliest occurence. Given their size and lifestyle it’s quite probable for monkeys to have existed for 10 MY before any fossil we’ve yet found.
Of course as you note 45MYA still doesn’t equate to a time when Africa and South Am were connected, although the Atlantic may have been a lot smaller.
AFAIK the monkeys are the only group where we need to invoke rafting to explain current distributions. That doesn’t mean they are the only one that did so. It’s just that they’re the only group found in South Am and Europe/Africa that never existed in North Am. Maybe South America’s rats or ungulates arrived the same way, but Ockhams razor dictates we explain those groups by saying they travelled the shorter route from North Am.
Thanks for the answers all. I’m still not sure I buy the rafting idea. Rats and other animals that spread by drifting didn’t really do so on purpose and also lacked inherent fear that our ancestors would’ve felt - for example, they would’ve had no idea where the water (ocean) went, if anywhere, what was on the other side, what kind of supplies to take with, how much could they really take, would they be able to return etc… I dunno
my bad - by evolution I meant human evolution. What I’m trying to figure out is how advanced man was when he distributed. From the answers so far, it seems fairly advanced? so it wasn’t a matter of an early homo (whichever one it was) distributing and then developing, but rather a developed homo that just settled?
Homo Sapiens developed in Africa and has spread from there, but our species is not the first one that has done so. The so called Java man belonged to Homo Erectus (as did, IIRC, the Peking man).