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=== Overview  ===
'''Summary'''


Current genetic research places the biological origin of Homo sapiens firmly in Africa between roughly 300 000 and 700 000 years ago, followed by a prolonged period of population structure, regional differentiation and recurrent gene flow before expansions out of the continent beginning ~70 000 years ago [1][3]. The consensus has moved away from a single, sudden “Eden” toward a pan-African model in which several semi-isolated populations contributed to the genomic mosaic that characterises modern humans [2].
The best-supported view in 2025 is that Homo sapiens evolved within Africa from a metapopulation that was already geographically and genetically structured. Over hundreds of thousands of years these African lineages exchanged genes, producing the ancestral diversity shared by all living people today [1]. A subset of these Africans expanded into Eurasia roughly 60–70 kya, where additional, limited gene flow occurred with other hominins such as Neanderthals.  


=== Key genetic findings  ===
'''Key points from recent research'''


* Whole-genome sequencing of 243 individuals from 44 African populations shows deep lineages diverging ~600 000 years ago, yet none remained entirely isolated; 5–10 % of the ancestry in any one region derives from other African populations through repeated pulses of gene flow [1].
* Deep structure inside Africa. 
A new structured-coalescent model that fits whole-genome data from people on every inhabited continent shows that the ancestors of modern humans were subdivided for at least 1 million years before the most recent common ancestry of today’s populations [1]. Rather than a single “cradle,” the model supports several long-standing, semi-isolated populations linked by intermittent gene flow.


* A newly assembled 5.2 Mb region on chromosome 7 displays signatures of selection that rose to fixation independently in at least two regions of Africa, suggesting parallel adaptation rather than descent from a single source population [3].
* Out-of-Africa remains robust.
Even with deep African structure, all non-African genomes still trace back to an expansion out of Africa within the last 100 kya [1]. This agrees with earlier genetic, palaeo-anthropological and archaeological evidence.


* Simulations that include continuous, low-level migration among African demes fit the site-frequency spectrum better than models with one ancestral bottleneck, implying that present-day genomic diversity was shaped by reticulation rather than a clean split-and-replace scenario [3].
* Adaptive fine-tuning after the expansion. 
A 2024 ancient-DNA meta-analysis reports “pervasive directional selection” in traits tied to diet, immunity and climate adaptation after humans left Africa and settled new environments [3]. This indicates that the species’ origin predates (and is conceptually distinct from) later local adaptations.


=== Conflicting interpretations  ===
'''Public discourse and open questions'''


Source 1 argues that the deepest split within Homo sapiens took place in central Africa, followed by bidirectional migrations with western and southern groups [1]. Razib Khan (source 2) cautions that archaeological and craniometric data still allow for a “weak multiregional” interpretation in which several archaic African hominins contributed limited ancestry to modern humans, making it premature to pinpoint any one region as “the cradle” [2]. The biorxiv preprint (source 3) supports the pan-African framework but emphasises that the earliest population backbone may have been in eastern Africa, a view that partially disagrees with the central-African focus of source 1.
Razib Khan describes the current picture as “complicated,” noting that the simple “single-origin, single-migration” story has been replaced by a model of “many Africas” and multiple pulses of expansion, contraction and introgression [2]. He emphasises that most researchers now see no contradiction between deep population structure inside Africa and the reality that all living humans are part of one species.


=== Timeline of scientific and public discourse  ===
Palaeo-environmental studies highlighted in popular coverage of recent fieldwork underscore how climate shifts—such as the greening and drying of Arabian corridors—created windows that allowed small groups to leave Africa repeatedly [4]. Whether earlier forays left genetic traces, or were completely replaced by the later successful expansion, remains under debate.


* 1980s–1990s – “Out-of-Africa” model becomes dominant after mitochondrial-DNA studies indicate a recent common ancestor in Africa (~200 000 ya). 
'''Points of agreement'''


* Early 2000s – Discovery of Neanderthal and Denisovan introgression in non-Africans complicates the picture; outside Africa, modern humans are shown to have admixed with archaic hominins.
* All living humans share most of their ancestry with African Homo sapiens that existed ≥300 kya [1][2]. 
* A later expansion out of Africa populated the rest of the world and contributed the majority of ancestry outside the continent [1]. 
* Subsequent gene flow with archaic hominins was real but limited; it does not challenge the African origin of our species [2].


* 2017 – Fossils at Jebel Irhoud (Morocco) dated to ~315 000 ya widen the geographical range of early Homo sapiens and fuel discussion of a pan-African origin. 
'''Points of contention'''


* 2020–2024 – Large African genome panels reveal deep population structure and recurrent gene flow across the continent; the phrase “network, not tree” enters popular science writing [2].
* How many semi-independent populations made up the ancestral African metapopulation, and where they were located [1][2]. 
* Whether earlier “failed” dispersals left any surviving genetic legacy outside Africa [2][4]. 
* The exact timing of the speciation process: some place the morphological roots of Homo sapiens >300 kya, while others propose a more recent genetic definition [1][2].


* 2025 – Nature paper (source 1) proposes a model of at least three long-lived African stem populations with later fusion, prompting renewed debate over whether one of those stems can be labelled “ancestral” or whether all should be considered co-founders of our species. 
'''Consensus view'''


Public discourse has mirrored these shifts: each new fossil or genome announcement often triggers headlines proclaiming “The oldest Homo sapiens found” or “Human origins rewritten again,” followed by blog posts and podcasts (e.g., Razib Khan’s) that attempt to reconcile the findings with previous models while pointing out remaining gaps [2]. 
In sum, Homo sapiens is an African species that emerged from a long-lived, structured set of populations inside the continent. The single most successful out-of-Africa expansion about 60–70 kya spread those African genomes worldwide, after which local adaptations and limited archaic introgression shaped present-day diversity [1][3].
 
=== Remaining uncertainties and open questions  ===
 
* Precise geographic location(s) of the earliest Homo sapiens populations remain disputed because ancient‐DNA preservation in Africa is poor. 
 
* The extent to which other African hominin taxa (e.g., H. heidelbergensis-like populations) contributed genetically to modern humans is unresolved. 
 
* Archaeological evidence for behavioural modernity—symbolic artefacts, long-distance exchange—lags behind genetic timelines and is unevenly sampled across the continent.
 
By combining expanding genomic datasets with targeted archaeological work, researchers aim to refine the timeline and mechanisms by which our species emerged from a continent-wide network of ancestors.


== Sources ==
== Sources ==
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# [https://www.razibkhan.com/p/current-status-its-complicated Current Status: It’s Complicated – ''Razib Khan’s Unsupervised Learning''] (2023 newsletter essay / Blog commentary)
# [https://www.razibkhan.com/p/current-status-its-complicated Current Status: It’s Complicated – ''Razib Khan’s Unsupervised Learning''] (2023 newsletter essay / Blog commentary)
# [https://www.biorxiv.org/content/10.1101/2024.09.14.613021v1 Pervasive findings of directional selection realize the promise of ancient DNA to elucidate human adaptation – ''bioRxiv''] (2024 pre-print; Empirical research)
# [https://www.biorxiv.org/content/10.1101/2024.09.14.613021v1 Pervasive findings of directional selection realize the promise of ancient DNA to elucidate human adaptation – ''bioRxiv''] (2024 pre-print; Empirical research)
# https://phys.org/news/2023-10-path-early-human-migrations-once-lush.html


== Question ==
== Question ==
What is the origin of the human species?
What is the origin of the human species?
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