View Full Version : Early Humans Probably Didn't Evolve from a Single Population in Africa

07-21-2019, 01:11 PM
https://www.livescience.com/63058-humans-evolved-different-places-africa.html?fbclid=IwAR0Cn7RuqUG6_vm6xE5aB6AwECHEc fc4i3W3rR2VJfu7O_av4183Sj6laRA

Homo sapiens are incredibly diverse — we live in wildly different societies, follow different rules and love and fear different gods.

Despite that awesome diversity, mounting evidence suggests the first humans were even more different from one another than we are today.

In a new commentary published online on Wednesday (July 11) in the journal Trends in Ecology & Evolution, an interdisciplinary group that includes geneticists, bioanthropologists, and archaeologists argues that we didn't evolve from a single population in a single region of Africa, but rather from separate populations across Africa that fully mixed only much later. [Image Gallery: Our Closest Human Ancestor]

Evidence is showing that "human ancestors were already scattered across Africa," said Eleanor Scerri, a research fellow at Oxford University and lead author of the paper. And "the combination of behavioral and physical and cognitive features that define us today started to slowly emerge within the occasional mixing of these different ancestral groups," she added. (Scerri is also a research associate for the Max Planck Institute for the Science of Human History in Germany.)

07-27-2019, 07:17 AM
If this is indeed the case, I wonder why all of our haplogroups have a common and (relatively) recent origin.

07-27-2019, 10:15 AM
If this is indeed the case, I wonder why all of our haplogroups have a common and (relatively) recent origin.
Good question.
For example, we appear to have Neanderthal and Denisovian admixture, which is more distant than the common origin of the Y and mtDNA haplogroups, but so far we haven't found anyone who lived recently with a Neanderthal or Denisovian haplogroup - and probably won't. The same could end up being true of admixture with other archaic populations. Starting with the current population, as we consider previous generations, the number of ancestry paths grows exponentially, but only two paths per person (the pure male/female lines) transmit haplogroups. Of course many of those paths converge due to inbreeding. But still it seems quite possible that all the haplogroups from an archaic population could have "gone extinct" while some autosomal and X segments from that population survived.

07-27-2019, 10:29 AM
This is the August 2018 paper mention in the Livescience article linked by the OP:

Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter? (https://www.cell.com/trends/ecology-evolution/pdf/S0169-5347(18)30117-4.pdf)

Eleanor M.L. Scerri, Mark G. Thomas, Andrea Manica, Philipp Gunz, Jay T. Stock,
Chris Stringer Matt Grove, Huw S. Groucutt, Axel Timmermann, G. Philip Rightmire,
Francesco d’Errico Christian A. Tryon, Nick A. Drake, Alison S. Brooks
Robin W. Dennell, Richard Durbin, Brenna M. Henn, Julia Lee-Thorp, Peter deMenocal,
Michael D. Petraglia, Jessica C. Thompson, Aylwyn Scally, and Lounès Chikhi

We challenge the view that our species, Homo sapiens, evolved within a single
population and/or region of Africa. The chronology and physical diversity of
Pleistocene human fossils suggest that morphologically varied populations
pertaining to the H. sapiens clade lived throughout Africa. Similarly, the African
archaeological record demonstrates the polycentric origin and persistence of
regionally distinct Pleistocene material culture in a variety of paleoecological
settings. Genetic studies also indicate that present-day population structure
within Africa extends to deep times, paralleling a paleoenvironmental record of
shifting and fractured habitable zones. We argue that these fields support an
emerging view of a highly structured African prehistory that should be considered
in human evolutionary inferences, prompting new interpretations, questions, and
interdisciplinary research directions.

A Different View of African Origins

The lineage of Homo sapiens probably originated in Africa at least 500 thousand years ago (ka) [1], and the earliest observed morphological manifestations of this clade appeared by 300 ka [2]. Early H. sapiens fossils do not demonstrate a simple linear progression towards contemporary human morphology. Instead, putative early H. sapiens remains exhibit remarkable morphological diversity and geographical spread. Together with recent archaeological and genetic lines of evidence, these data are consistent with the view that our species originated and diversified within strongly subdivided (i.e., structured) populations, probably living across Africa, that were connected by sporadic gene flow [1,3–8]. This concept of ‘African multiregionalism’ [1] may also include hybridization between H. sapiens and more divergent hominins (see Glossary) living in different regions [1,9–12]. Crucially, such population subdivisions may have been shaped and sustained by shifts in ecological boundaries [7,13,14], challenging the view that our species was endemic to a single region or habitat, and implying an often underacknowledged complexity to our African origins.

In this paper we examine and synthesize fossil, archaeological, genetic, and paleoenvironmental data to refine our understanding of the time-depth, character, and maintenance of Pleistocene population structure. In doing so, we attempt to separate data from inference to stress that using models of p

08-04-2019, 02:55 AM
Posted 7/11 2018:


Researchers say it is time to drop the idea that modern humans originated from a single population in a single location

The origins of our species have long been traced to east Africa, where the world’s oldest undisputed Homo sapiens fossils were discovered. About 300,000 years ago, the story went, a group of primitive humans there underwent a series of genetic and cultural shifts that set them on a unique evolutionary path that resulted in everyone alive today. However, a team of prominent scientists is now calling for a rewriting of this traditional narrative, based on a comprehensive survey of fossil, archaeological and genetic evidence. Instead, the international team argue, the distinctive features that make us human emerged mosaic-like across different populations spanning the entire African continent. Only after tens or hundreds of thousands of years of interbreeding and cultural exchange between these semi-isolated groups, did the fully fledged modern human come into being.

Dr Eleanor Scerri, an archaeologist at Oxford University, who led the international research, said: “This single origin, single population view has stuck in people’s mind … but the way we’ve been thinking about it is too simplistic.” This continental-wide view would help reconcile contradictory interpretations of early Homo sapiens fossils varying greatly in shape, scattered from South Africa (Florisbad) to Ethiopia (Omo Kibish) to Morocco (Jebel Irhoud). The telltale characteristics of a modern human – globular brain case, a chin, a more delicate brow and a small face – seem to first appear in different places at different times. Previously, this has either been explained as evidence of a single, large population trekking around the continent en masse or by dismissing certain fossils as side-branches of the modern human lineage that just happened to have developed certain anatomical similarities.

The trend towards more sophisticated stone tools, jewellery and cooking implements also supports the theory, according to the paper in the journal Trends in Ecology & Evolution.
Scerri assembled a multidisciplinary group to examine the archaeological, fossil, genetic and climate data together, with the aim of eliminating biases and assumptions. Previously, she said, scientific objectivity had been clouded by fierce competition between research groups each wanting their own discoveries to be given a prominent place on a linear evolutionary ladder leading to the present day. Disputes between rival teams working in South Africa and east Africa had become entrenched, she said.

The latest analysis suggests that this patchwork emergence of human traits can be explained by the existence of multiple populations that were periodically separated for millennia by rivers, deserts, forests and mountains before coming into contact again due to shifts in the climate. “These barriers created migration and contact opportunities for groups that may previously have been separated, and later fluctuation might have meant populations that mixed for a short while became isolated again,” said Scerri. The analysis also paints a picture of humans as a far more diverse collection of species and sub-populations than exists today. Between 200,000 and 400,000 years ago, our own ancestors lived alongside a primitive human species called Homo naledi, found in southern Africa, a larger brained species called Homo heidelbergensis in central Africa and perhaps myriad other humans yet to be discovered.


08-04-2019, 03:06 AM
https://www.livescience.com/63058-humans-evolved-different-places-africa.html?fbclid=IwAR0Cn7RuqUG6_vm6xE5aB6AwECHEc fc4i3W3rR2VJfu7O_av4183Sj6laRA

The article you linked to is one year old.

09-06-2019, 11:11 PM
If this is indeed the case, I wonder why all of our haplogroups have a common and (relatively) recent origin.

Bottleneck events can be responsible for that.

10-01-2019, 11:47 PM
It's not even clear if all non-Africans are descended from the same group. For example, according to this study, many present-day Oceanians would be descended from a wave that left Africa earlier than the ancestors of Eurasians and Native Americans. https://www.nature.com/articles/s41598-018-35426-z

For the moment, most genetic studies suggest they do, but then we have several >100,000 year old fossils scattered across Eurasia. A few months ago they discovered a >200,000 year old skull in Greece that resembled modern humans more than Neanderthals.

10-02-2019, 09:29 PM
It seems that early human history was more vibrant and dynamic than I previously thought.

11-12-2019, 05:38 AM
in the news here last week 'udo' from the allgäu danuvius guggenmosi

devs. for the upright walk earlier than thought
https://www.nature.com/articles/s41586-019-1731-0.epdf?referrer_access_token=ztv-rDX4MtoTBExAQDDX9NRgN0jAjWel9jnR3ZoTv0MpMJV7uq1pC2 z9TlFLcopWAwsUutKmnIQkQ9UatmGBhFbbK0TqgHY6DOdEwLF7 zxg9jcVJzhHgeUec4SXds2t2K54ZcgXJyXyUChehzfQs_nuIO6 zLpD5p57osl9HmfIS4CCPmGYQlMcB75-PqvezwQ90kw_MMZRjrQzwrHBa8hnOcD0L_Njvf54nYUsK-bkdjTKWc4h-mATX12JgYT5wc2zi6ilBWlhvlnwAYfJH9PixPHxO9HA-QGaaQTP0tKmMgm4MHxVMpNfvPtP5HHS1W&tracking_referrer=www.smithsonianmag.com
supp https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-019-1731-0/MediaObjects/41586_2019_1731_MOESM1_ESM.pdf