# Why did our prehistoric ancestors migrate out of Africa? **URL:** \ **Category:** Factual Questions\ **Created:** [August 11, 2010, 4:16pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944 "2010-08-11T16:16:59Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 15, 2010, 6:13pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/61 "2010-08-15T18:13:10Z")
> [@Sven\_of\_the\_Jungle](#): > > What about the Sahara Desert? I read about how the expansion and contraction of the Sahara allowed hominids to migrate out of Africa, but I only have a vague recollection of the timing. Anyone more knowledgeable than I am able to elaborate on this? It’s called the [Sahara Pump](http://en.wikipedia.org/wiki/Sahara_pump_theory) theory. Wiki has a good intro. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [August 15, 2010, 6:35pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/62 "2010-08-15T18:35:41Z")
> [@Wendell\_Wagner](#): > > It was one of the earliest civilizations, in the sense of societies with cities that we can find the remains of. That doesn’t mean it was early in the history of the human race. The human race goes back around 200,000 years ago in Africa and spread out from there. (Undoubtedly now someone is going to post with other estimates than 200,000 years for the beginning of the human race.) Happy to oblige. 🙂 The oldest fossil identified as _H. sapiens_ is 195,000 years old. But you’re right. The generally accepted date is 200,000 years. ---
**Author:** ![Cartooniverse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cartooniverse/32/3084_2.png) [@Cartooniverse](https://boards.straightdope.com/u/Cartooniverse)\ **Post date:** [August 16, 2010, 3:48am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/63 "2010-08-16T03:48:15Z")
> [@MrDibble](#): > > > [@Cartooniverse](#): > > > > a smidgen of Jewish and virtually zero Muslim / Middle Eastern. > > Genetically, there’s not that much difference here - your average Jew has a lot more European ancestry, your Muslim, more African and Turkic, but if you have Jews, then you \*have \*Middle Eastern. So very true. ---
**Author:** ![Sampiro](https://avatars.discourse-cdn.com/v4/letter/s/2acd7d/32.png) [@Sampiro](https://boards.straightdope.com/u/Sampiro)\ **Post date:** [August 16, 2010, 5:29am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/64 "2010-08-16T05:29:03Z")
> [@MrDibble](#): > > > [@Sampiro](#): > > > > Addendum to above: > > > > At the same time people were migrating _out of Africa_ they were also migrating from central Africa into southern Africa. It wasn’t just a northward expansion. > > There were already modern humans right at the Southernmost point of Africa (Blombos Cave etc.) thousands of years before the Out of Africa migration. True, just as there were people in Britain before the Celts, but there were subsequent major migrations into the area. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [August 16, 2010, 6:28am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/65 "2010-08-16T06:28:13Z")
> [@Cartooniverse](#): > > And 6,000 years is nothing. Should we reason that first names existed 25,000 years ago One thing every human society likes to do is gossip. I imagine that in a society of three people, they’d come up with names so they could talk about the third one behind her back. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [August 16, 2010, 12:16pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/66 "2010-08-16T12:16:03Z")
> [@lazybratsche](#): > > In terms of overall migration rates, humans moved thousands of miles over tens of thousands of years. That’s actually pretty slow most estimates of migration rates are in the ballpark of a mile per year. You could imagine that some tribe moves a few tens of miles towards better conditions, once every generation. > [@md2000](#): > > Consider the Americas, which were NOT inhabited by proto-humans. General thought (contested) is that humans arrived about 12000BC, or 14,000 years ago. Even allowing 2,000 years to reach Tierra Del Fuego, about 10,000 miles - that’s 5 miles a year. It’s been estimated (in _Guns, Germs, and Steel_) that humans spread from the Bering Land Bridge to the tip of South America in 1000 years or less. Given that the first multicellular life is believed to have exploded to fill an essentially empty world in certainly less than 5 million years (probably less than 2 million years, and Stephen Jay Gould has argued for much less time than that) it seems to me we probably spread very quickly. The more interesting question may be, what took us so long to get started? Why did we stay in the Rift Valley for so long? ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [August 16, 2010, 1:32pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/67 "2010-08-16T13:32:05Z")
> [@Sailboat](#): > > > [@lazybratsche](#): > > > > In terms of overall migration rates, humans moved thousands of miles over tens of thousands of years. That’s actually pretty slow most estimates of migration rates are in the ballpark of a mile per year. You could imagine that some tribe moves a few tens of miles towards better conditions, once every generation. > > > [@md2000](#): > > > > Consider the Americas, which were NOT inhabited by proto-humans. General thought (contested) is that humans arrived about 12000BC, or 14,000 years ago. Even allowing 2,000 years to reach Tierra Del Fuego, about 10,000 miles - that’s 5 miles a year. > > It’s been estimated (in _Guns, Germs, and Steel_) that humans spread from the Bering Land Bridge to the tip of South America in 1000 years or less. > > Given that the first multicellular life is believed to have exploded to fill an essentially empty world in certainly less than 5 million years (probably less than 2 million years, and Stephen Jay Gould has argued for much less time than that) it seems to me we probably spread very quickly. The more interesting question may be, what took us so long to get started? Why did we stay in the Rift Valley for so long? “We” didn’t stay in the rift valley. As Mr Dibble already noted, modern humans were in Southern Africa over 100k years ago. As for modern humans taking a long time to leave Africa, one reason might be very low population densities. There is strong evidence that we went through a population bottleneck about 75kk years ago. There might have only been a few thousand of us around. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 16, 2010, 5:53pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/68 "2010-08-16T17:53:02Z")
> [@John\_Mace](#): > > > [@Sailboat](#): > > > > The more interesting question may be, what took us so long to get started? Why did we stay in the Rift Valley for so long? > > “We” didn’t stay in the rift valley. As Mr Dibble already noted, modern humans were in Southern Africa over 100k years ago. [Pre-modern hominids](http://en.wikipedia.org/wiki/Homo_gautengensis) as well. People think of East Africa because that’s where African hominid studies got started, but the Rift Valley was neither the be all nor end all of human evolution in Africa - new discoveries have been coming from Southern Africa ever since [Taung](http://en.wikipedia.org/wiki/Taung_Child), and I think other, equally exciting discoveries are waiting in the rest of Africa, especially the Sahara/Sahel areas. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [August 16, 2010, 7:14pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/69 "2010-08-16T19:14:57Z")
> [@John\_Mace](#): > > “We” didn’t stay in the rift valley. As Mr Dibble already noted, modern humans were in Southern Africa over 100k years ago. After evolving 200,000 years ago, is what I was getting at. But that’s because I’m a a believer in the rapid expansion – I have trouble imagining it took 100,000 years to spread to South Africa if it only took 1,000 to go the length of North and South America, so I was inclined to believe we didn’t start spreading for a while. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [August 16, 2010, 7:28pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/70 "2010-08-16T19:28:21Z")
> [@Sailboat](#): > > > [@John\_Mace](#): > > > > “We” didn’t stay in the rift valley. As Mr Dibble already noted, modern humans were in Southern Africa over 100k years ago. > > After evolving 200,000 years ago, is what I was getting at. But that’s because I’m a a believer in the rapid expansion – I have trouble imagining it took 100,000 years to spread to South Africa if it only took 1,000 to go the length of North and South America, so I was inclined to believe we didn’t start spreading for a while. I didn’t mean to imply that we were in Southern Africa only starting about 100k years ago. In fact, I’m not really familiar with the details of the fossil record there re: modern humans. It’s thought that we developed the lifestyle of “beach combing” in Southern Africa, and that’s what helped us hug the coasts as we spread out of Africa. But it wouldn’t surprise me if the fossil record from 15k years ago in South America is better preserved than that of 150k years ago in Southern Africa. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [April 10, 2018, 4:23am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/71 "2018-04-10T04:23:41Z")
[Ancient fragment of finger bone suggests humans travelled east from Africa earlier than thought](https://www.telegraph.co.uk/news/2018/04/09/ancient-fragment-finger-bone-suggests-humans-travelled-east/) An ancient fragment of human finger bone found in the Saudi Arabian desert suggests that mankind ventured east out of Africa 30,000 years earlier than thought. The scrap of bone, measuring little more than an inch long, had lain undiscovered for up to 90,000 years. Its discovery potentially revolutionises our understanding of early human history, challenging a long-held consensus that humans started to move en masse into Eurasia in a single wave about 60,000 years ago.,… ---
**Author:** ![Grim\_Render](https://avatars.discourse-cdn.com/v4/letter/g/a87d85/32.png) [@Grim\_Render](https://boards.straightdope.com/u/Grim_Render)\ **Post date:** [April 10, 2018, 7:33am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/72 "2018-04-10T07:33:42Z")
Meh, we already had results indicating that the Basal Eurasians split from the rest of the out-of-Africa lot 80 000 years ago, so we kindof knew that. Also, we’ve found fairly anatomically modern remains in Morocco dating back 300 000 years. So I think a lot of the excitement is due to our modern concept of “Africa”. I mean its a straight line along mostly coast in the same climate zone and probably much the same ecology. 220 000 is enough to walk quite a ways. ---
**Author:** ![Banksiaman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/banksiaman/32/3334_2.png) [@Banksiaman](https://boards.straightdope.com/u/Banksiaman)\ **Post date:** [April 10, 2018, 7:38am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/73 "2018-04-10T07:38:43Z")
This thread did its thing in 2010. Quite apart from Leo Bloom’s waggling finger pointing out how much we dont know, its instructive to see just how much that was considered to be the orthodoxy in human evolution has had to be updated, particularly by more comprehensive genomic studies in less than a decade. That makes me nervous when so many people still seem to fixate on what they were taught at school (or think they remember) and assume it remains the state of play about human evolution, our genetic diviersity, the validity of races etc etc twenty, thirty or more years on. If there is one area of science where things change rapidly and in ways that affect the big picture of our knowledge, its in the study of human evolution. ---
**Author:** ![Grim\_Render](https://avatars.discourse-cdn.com/v4/letter/g/a87d85/32.png) [@Grim\_Render](https://boards.straightdope.com/u/Grim_Render)\ **Post date:** [April 10, 2018, 9:36am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/74 "2018-04-10T09:36:37Z")
> [@Banksiaman](#): > > This thread did its thing in 2010. Quite apart from Leo Bloom’s waggling finger pointing out how much we dont know, its instructive to see just how much that was considered to be the orthodoxy in human evolution has had to be updated, particularly by more comprehensive genomic studies in less than a decade. > > That makes me nervous when so many people still seem to fixate on what they were taught at school (or think they remember) and assume it remains the state of play about human evolution, our genetic diviersity, the validity of races etc etc twenty, thirty or more years on. If there is one area of science where things change rapidly and in ways that affect the big picture of our knowledge, its in the study of human evolution. I think pretty much everyone agrees that race is still a stupid concept applied to todays populations. Might have more validity when speaking of ancient hominids. Otherwise… stuff that was orthodox 3 moths ago might be outdated:) It is an exciting time if you are interested in these things. ---
**Author:** ![Cartooniverse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cartooniverse/32/3084_2.png) [@Cartooniverse](https://boards.straightdope.com/u/Cartooniverse)\ **Post date:** [April 10, 2018, 11:28am UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/75 "2018-04-10T11:28:23Z")
> [@Grim\_Render](#): > > I think pretty much everyone agrees that race is still a stupid concept applied to todays populations. Might have more validity when speaking of ancient hominids. Otherwise… stuff that was orthodox 3 moths ago might be outdated:) It is an exciting time if you are interested in these things. As is the case in many disciplines of science, the concept of Orthodoxy has become quite unorthodox. Sent from my SM-N910V using Tapatalk ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [April 10, 2018, 12:16pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/76 "2018-04-10T12:16:00Z")
> [@John\_Mace](#): > > The oldest fossil identified as _H. sapiens_ is 195,000 years old. And now it’s 195,008 years old 😉 ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [April 10, 2018, 2:05pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/77 "2018-04-10T14:05:34Z")
> [@Banksiaman](#): > > …That makes me nervous when so many people still seem to fixate on what they were taught at school (or think they remember) and assume it remains the state of play about human evolution, our genetic diviersity, the validity of races etc etc twenty, thirty or more years on. If there is one area of science where things change rapidly and in ways that affect the big picture of our knowledge, its in the study of human evolution. I taught science for many, many years, and had a sign posted in the front of the room that said, “…As far as we know.” We had many interesting discussions about that and I used to hope that kids developed the notion (somewhat unsettling as it is for them) that what we “know” is only so up to this point in the history of the universe. In some ways, I hoped that they would then be motivated go out in the world set upon finding new truths. ---
**Author:** ![Cartooniverse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cartooniverse/32/3084_2.png) [@Cartooniverse](https://boards.straightdope.com/u/Cartooniverse)\ **Post date:** [April 10, 2018, 2:09pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/78 "2018-04-10T14:09:56Z")
I love that. It encourages students to know more than their teachers know. Sent from my SM-N910V using Tapatalk ---
**Author:** ![dba\_Fred](https://avatars.discourse-cdn.com/v4/letter/d/c37758/32.png) [@dba\_Fred](https://boards.straightdope.com/u/dba_Fred)\ **Post date:** [April 10, 2018, 2:44pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/79 "2018-04-10T14:44:22Z")
it began with the advent of **2 Hominids & a Truck**. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [April 10, 2018, 3:45pm UTC](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944/80 "2018-04-10T15:45:18Z")
The real question is not “Why?” but rather “When?”. I ask this about a year ago: [When did modern humans leave Africa?](https://boards.straightdope.com/sdmb/showthread.php?t=820726), and the best answer was about 88,000 years ago based on genetics. [Previous page](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944.md?page=3) [Next page](https://boards.straightdope.com/t/why-did-our-prehistoric-ancestors-migrate-out-of-africa/549944.md?page=5)