Dear Victor:

The hypothesis you mention is the one that best fits the presently available anthropological evidence. The clearest evidence is genetic.

There is a lot to read. I suppose a good starting place would be the Wikipedia article, then following up on the references:

http://en.wikipedia.org/wiki/Human#Rise_of_Homo_sapiens

Best regards,

David

yes,  both from molecular biology and digging up bones,  there are moocs on this sort of thing....

@David, Arjun, Mark Roberts: thank you so much for all your references, especially one in PNAS suggesting that hunter gatherer genomic diversity suggests African origin of modern humans. I am no specialist in genomic or genetic, but it seems that the title indicates no convincing logic. 

http://www.scirp.org/journal/PaperDownload.aspx?DOI=10.4236/aa.2012.24022

Victor; thank you for the link. I hadn't seen the article "Re-examining the Out-of-Africa theory [...]" by Anatole A. Klyosov and colleagues, which presents Y-chromosome evidence for a possible African, European, Asian, or Middle Eastern origin for anatomically modern humans: "We have no indication of where the common ancestor of the a-haplogroup lived; he could just as easily have been from Europe, Asia, or the Middle East, as from Africa" ("Conclusion," page 207). The authors seem to exaggerate the "incorrectness" of the Out-of-Africa hypothesis, though; at most they present evidence for expanding the hypothetical geographic scope of the earliest modern humans. The arguments for discarding this hypothesis are more rhetorical than scientific.

I find an epistemological problem with the last sentence of the conclusion: "The Out-of-Africa hypothesis has never been proved; our research suggests that it is incorrect with respect to anatomically modern humans." As I see it, science "proves" nothing. What scientific research produces are falsifiable hypotheses that have or have not been refuted. Those that have not been refuted remain on the discussion table as possibilities. The authors suggest that they don't agree with the Out-of-Africa hypothesis, but they have not refuted it.

The article looks, at first glance, like it was published in a legitimate scientific journal, but there are some red flags when one looks under the surface. The journal, Advances in Anthropology, is published by Scientific Research Publishing (SCIRP), which appears on the Beall's List of "Potential, possible, or probable predatory scholarly open-access publishers":

http://scholarlyoa.com/publishers/

This usually indicates that there is a less-than-rigorous peer-review process, and often that authors are simply paying to have their papers published.

This case is a bit different, though, since the primary author, Anatole A. Klyosov, is presently listed as "Editor-in-Chief" of Advances in Anthropology (http://www.scirp.org/Journal/EditorialBoard.aspx?JournalID=737), and at approximately the time the article was published he was on the journal's Editorial Board. At some time, perhaps around 2013, there was a mass resignation of the former Editor-in-Chief, Fatimah Linda Collier Jackson of the University of North Carolina, together with several members of the Editorial Board, who were concerned that the "editorial staff in China" were not permitting the members of the Editorial Board to make decisions about the peer-review process, and were more interested in "making money," using these scholars' names to legitimize the editorial process. See:

http://scholarlyoa.com/2014/10/02/an-editorial-board-mass-resignation-from-an-open-access-journal/#more-4251

A Google search for this article's title shows that it has been widely cited (540 results), mostly in the non-academic media, as "scientific proof" for "debunking" or "disproving" the Out-of-Africa hypothesis, and in fringe blogs, sometimes by people who are eager to distance their own lineages from modern Africans and their descendents; one blogger even claimed, after posting the abstract of this article, that Europeans and Africans belong to two distinct species!

Another search on Google Scholar, which filters out most of the web "noise" and finds web pages with an academic origin, turned up very few citations of this article, which is surprising when considering that the authors claim that the current consensus on a major anthropological topic is incorrect. Most of the 12 results are pages with this same article, or pages uploaded by Klyosov himself. Thus the article's impact was far greater among the general public than it was in the scientific community.

I am probably getting in over my head here, as I am not a specialist in the field of human origins. Hopefully someone who has been working in this area can help us out with a better-informed summary of the relevant evidence.

I have not made an extensive study of this topic, but it seems to me that I have read many reports which suggest interbreeding with other hominoid species in our past, I think that up to 5% of our DNA is Neanderthal in origin, and that for those from the Far East there is another hominoid species present in their DNA also.  This could be a minor blip in the "out of Africa" argument, but I think that "out of Africa" is the most likely in general.

@David and William: thank you for your answers. May be the actual truth is somewhere in between those two opposites. Best wishes

Victor: what two opposites?

@David: i mean with two opposites are Out of Africa hypothesis, and other one is hypothesis claiming non-africa origin. Am i wrong? Best wishes

I see what you mean, Victor. I think you are correct, then, when you say that maybe "the actual truth is somewhere between those opposites." It looks like most specialists are now somewhere in between, and not at the extremes, since the Out-of-Africa hypothesis is strongly supported by recent evidence, while it is becoming clear that there was interbreeding with local, non-modern varieties of Homo sapiens in several regions, although this was minimal, as William suggests. But the "in-between" is much closer to Out-of-Africa than to the multiregional hypothesis.

It is important to specify your time frame as well, because if you go back far enough, the genus Homo clearly originated in Africa and from there colonized other continents (after 2,000,000 years ago). What we are discussing here is the origin (after 200,000 years ago) and geographic diffusion (after 70,000 years ago) of anatomically modern Homo sapiens.

Thus our anatomically modern ancestors came out of Africa relatively recently and may have mixed a bit with some populations whose ancestors left Africa in more ancient times. At any rate, the answer to your initial question would be "yes."

Meanwhile, here are some links to pages with elementary but up-to-date summaries of the question:

https://genographic.nationalgeographic.com/human-journey/

https://genographic.nationalgeographic.com/migratory-crossings/

http://en.wikipedia.org/wiki/Recent_African_origin_of_modern_humans

http://en.wikipedia.org/wiki/Multiregional_origin_of_modern_humans (see especially the section "'Classic' vs 'weak' multiregionalism)."

http://en.wikipedia.org/wiki/Archaic_human_admixture_with_modern_humans

If you want to take a peek at what these early modern humans were doing in Africa before they expanded into other continents, check out the Blombos Cave archaeological site:

http://en.wikipedia.org/wiki/Blombos_Cave

Following up on the references cited on the pages mentioned above will provide a lot of material for forming a well-informed overall vision of this topic.

@David: thank you for your appreciation, i just follow dialectics, that there could be synthesis between two opposites. Thanks for the references.

Btw, there is more grand view on our ancestors, called the Tree of Life. See a paper by Chris King at DNAdecipher journal, as cited bellow. What do you think? Thanks

http://dnadecipher.com/index.php/ddj/article/view/74

Thank you for the link, Victor. It looks like a useful resource. I think visualizing ourselves as part of the great tree of life gives us a healthy perspective in our conceptual image of ourselves, as a species and as individuals. Biological reality is more powerful, and ultimately more genuine, than ideological factors (religious, nationalist, "racial," etc.), as important as these latter factors may be for constructing identities.

I like to identify myself as a primate; on a good day, Homo sapiens. (;o  )

Best regards,

David

@David: ok thanks and best wishes

Victor, thanks for link to the paper.  The last time I checked the thought was that there was no single universal common ancestor. but I will still look at the paper, maybe something new for me will be there.

Interesting.

I'm afraid there will not be any certainties on this field. The more we advance , the more disturbing opposite evidences arise... The more doubts come to our minds.

Thank you David very much. However I don't need a scientific proof to claim that  all women and men are subjects of moral concern, whatever the geographic origine  could be.

Guido, the science that many people find distasteful or insufficient (please excuse me if I have misinterpreted your words) isn't what is presently being used to expand the frontiers of human knowledge, but a caricature of science, perhaps based on 19th century positivism and popularized by mass media for over a century. I quote from my post of three days ago:

"As I see it, science 'proves' nothing. What scientific research produces are falsifiable hypotheses that have or have not been refuted. Those that have not been refuted remain on the discussion table as possibilities."

In these terms, if there is a way that your claim could be refuted, at least in principle, then it could be put to the test by confronting it with relevant evidence. I don't know if this is the case, because I'm not sure what you mean by people being "subjects of moral concern." If your claim is falsifiable and it stands up to the process of confrontation with the evidence, then it would be scientifically sound, in a tentatiive way, like all scientific knowledge. If your claim is not falsifiable, then it would not be scientifically sound, but it would be a socially relevant (and perfectly respectable) manifestation of your personal values and beliefs.

I hope these words are sufficient to communicate what I have in mind.

Warm regards,

David

William, the "tree of life" metaphor has indeed been criticized as overly simplistic:

http://web.archive.org/web/20060907081933/http://shiva.msu.montana.edu/courses/mb437_537_2004_fall/docs/uprooting.pdf

Like human evolution, these are not so much opposing viewpoints, rather the assimilation of new evidence into an evolving model that continues to be a useful conceptual tool. For example, the Tree of Life Web Project acknowledges horizontal gene transfers and more complex "roots" than was previously claimed:

http://www.tolweb.org/Life_on_Earth/1

These considerations are included in the article that Victor provided.

So the "tree" has complex roots and branches that grow into each other.

Another problem is the definition of "life," its origins, and the status of viruses.

Again, I am venturing out of my "comfort zone." Still, I think anyone should make at least a minimal effort to keep up with the state of the art regarding our context (cosmic, biological, social, etc.) in order to understand ourselves and the place of our specialized studies within the big picture.

@David, Maria, William: while i am no specialist in genetics or genomic, i think i can accept the idea that there is one common ancestor of all human being, be it from africa or elsewhere. But frankly speaking, i cannot swallow the idea of single last universal common ancestor (LUCA). 

http://www.sciencedaily.com/releases/2014/08/140812121731.htm

My tiny contribution is that I have never read any well supported study -whether book or paper- that supports the contrary to the African origin. (I do apologize: and I do read a lot!). Without being a specialist one cannot find opposite evidence. Then...

Dear Carlos: i appreciate that you read a lot of books, perhaps you would like to find a copy of an old book written by Mary Lefkowitz, Not out of Africa, BasicBooks, 1996. Of course i do not mean that all her arguments, but who knows? May be this book will add some new perspectives. Best wishes

Thank you very much Victor. I already knew this book. It is always refreshing going back to Lefkowitz. Kind regards

try

https://www.coursera.org/course/humanevolution

I am still baffled about the out of Africa hypothesis.  It was Darwin who suggested this because the great apes seem to evolve in Africa.  I have not yet read Mary Lefkowiz's  book but I understand that has some interesting hypothesises   

Read 'Henn, BM et al. (2011) Hunter-gatherer genomic diversity suggests a southern African origin for modern humans. PNAS, 108;5154-5162' and you will have your answer.

Thank you Ian

by co-incidence this weeks origins lectures are on this topic,  see cousera:

https://class.coursera.org/origins-001/wiki/courseinfo

@Carlos, Ian, Eulinda, Mark: thank you for all your answers. And happy new year for all contributors. Yours,

Victor

Dear Victor, I wish you all the best in this new year! Cheers!

@Carlos: thank you, and best wishes for you too. Yours

I believe that we should look into this issue by researching it from scratch. For example, did the aboriginals in Australia descended from Africa? What do DNA analyses indicate? And of course, the issue of relationship between Homo Sapiens and Neanderthals should further be investicated under recent/new DNA data.

Andreas,

I think you are correct.  Much of the way we investigate should not be jaded by past work that was jaded by belief not fact.  This is not to say that the conclusion would not be the same just to say that we need to get there honestly or else we will never really know the truth.

In science we should be driven by the truth not the truth as seen by dogma.

the experts keep changing their mind,  at one time it was one out of africa event across to aden,  now it has gone back up to two...  and they always seem certain about what they say,  like many others... 

@Andreas, George, Mark: thank you for your answers. I agree in particular with Andreas and George, that one should remain as objective as possible while evaluating alternatives, and not preoccupied with one assumption. Today i just found some links on evidence against out of africa hypothesis, see link below. 

http://boards.ancestry.com/topics.ethnic.melungeon.melungeon/1914/mb.ashx

I would also add the following:

http://wakeup-world.com/2013/12/16/dna-evidence-debunks-the-out-of-africa-theory-of-human-evolution/

I do not subscribe to this view considering the recent evidences with dates that have come from India and elsewhere.

@Andreas: thanks.

@Simadri: which view do you support? And would you specify what evidence from India? Do you have a paper on this issue? I recall that i found an interesting book many years ago with title: Forbidden Archaeology, although i do not mean that i support the authors' Vedic view. Best wishes

No. There is absolutely no evidence for that, and more important, the Out of Africa hypothesis itself is not either.

I respectfully suggest that the quality of this discussion would improve if scientific studies, rather than fringe blogs and popular media, were to be cited.

Where does H. erectus fit into all this, and the early H. erectus from Dmanisi in particular? They could have evolved in Eurasia before they went i n t o Africa, which challenges the hypothesis that all of H. erectus evolved in Africa, before leaving. If it is established that they are indeed older than any African H. erectus specimen, instead of perhaps, this would demand a rethink of our ancestry, wouldn't it?

One quick way to spot articles or blogs written by people who don't know much about paleoanthropology (or biology in general) is when a specific (species) name is written with the first letter in upper case, for example "Homo Erectus." In secondary school we all were supposed to learn that the generic (genus) name begins with an upper case letter, the specific name a lower case letter, with both in italics: Homo erectus. If an author does not follow this norm, I generally discard the text and look elsewhere. (I hope I'm not being too pedantic here, but it is important to separate the wheat from the chaff when looking into any academic topic.)

@David: thank you for your tips, that surely will help. Best wishes

Thank you, you've  hit the nail on the head

Are there evidences that all humans descended from a single population of ancestors in Africa?

Yes, our ancestors apparently left Africa at least 3 times (and therefore also re-entered Africa at least 2 times): early-hominoids early- or mid-Miocene (probably), early H.erectus or close relatives Plio- or perhaps early-Pleistocene (retroviral data), and the non-African part of H.sapiens (Out of Africa s.s.).

1) When the Afro-Arabian plate hit the Eurasian plate (20 or 18 Ma?), most or all early hominoids (today's apes+humans) left Africa-Arabia, and probably followed the Tethys coastal forests: no doubt hylobatids (gibbons & siamang now live in SE.Asia) & pongids (orangutans idem), but possibly also the hominids (s.l., now Gorilla-Homo-Pan). In any case, when the hominids split into Gorilla & Homo-Pan (c 8 Ma?) they probably lived in Africa, and when Homo & Pan split (c 5 Ma?) also: Pan stayed in Africa, but our direct ancestors (belonging to Homo), according to retroviral data, seem to be absent from Africa at least between 4 & 3 Ma (orangs & humans lack African retroviral elements on our DNA, see Yohn cs 2005 PLoS).

2) H.erectus-like fossils are found far outside Africa at least since c 1.8 Ma (e.g. Dmanisi in Georgia & probably Mojokerto on Java). Whether our direct ancestors were part of these non-African Homo populations, is unknown, but not unlikely. If so, some of them re-entered Africa at some time during the Pleistocene.

3) In any case, when H.sapiens first split into KhoiSan & the other sapiens (c 0.2 Ma?), this happened very likely somewhere in Africa (Chad? Rift? cf. linguistic families in Africa). Much later, part of these "other sapiens" left Africa = Out of Africa s.s. (c 0.07 Ma?); some of them lived along the Red Sea (African or Arabian side) or might have re-entered Africa.

Yes. Look at the works of the Leakey family in kenya and Olduvai gorge in Tanzania.