What is the origin of the human species?

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Overview

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].

Key genetic findings

• 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].

• 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].

• 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].

Conflicting interpretations

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.

Timeline of scientific and public discourse

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

• 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.

• 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.

• 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].

• 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.

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].

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

1. A structured coalescent model reveals deep ancestral structure shared by all modern humans – Nature Genetics (2025 peer-reviewed research article)
2. Current Status: It’s Complicated – Razib Khan’s Unsupervised Learning (2023 newsletter essay / Blog commentary)
3. Pervasive findings of directional selection realize the promise of ancient DNA to elucidate human adaptation – bioRxiv (2024 pre-print; Empirical research)

Question

What is the origin of the human species?