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Reconstruction of early Homo sapiens from Jebel Irhoud, Morocco, c. 315 000 years BP

Early modern human, or anatomically modern human,[1] are terms used to distinguish Homo sapiens (the only extant Hominina species) that are anatomically consistent with the range of phenotypes seen in contemporary humans, from extinct archaic human species. This distinction is useful especially for times and regions where anatomically modern and archaic humans co-existed, for example, in Paleolithic Europe. Among the oldest known remains of Homo sapiens are those found at the Omo-Kibish I archaeological site in south-western Ethiopia, dating to about 233,000[2] to 196,000 years ago,[3] the Florisbad Skull found at the Florisbad archaeological and paleontological site in South Africa, dating to about 259,000 years ago,[citation needed] and the Jebel Irhoud site in Morocco, dated about 315,000 years ago.[4]

Extinct species of the genus Homo include Homo erectus (extant from roughly 2,000,000 to 100,000 years ago) and a number of other species (by some authors considered subspecies of either H. sapiens or H. erectus). The divergence of the lineage leading to H. sapiens out of ancestral H. erectus (or an intermediate species such as Homo antecessor) is estimated to have occurred in Africa roughly 500,000 years ago. The earliest fossil evidence of early modern humans appears in Africa around 300,000 years ago, with the earliest genetic splits among modern people, according to some evidence, dating to around the same time.[5][6][note 1][9] Sustained archaic human admixture with modern humans is known to have taken place both in Africa and (following the recent Out-Of-Africa expansion) in Eurasia, between about 100,000 and 30,000 years ago.[10]

Name and taxonomy

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Further information: Homo and Names for the human species
Main article: Human taxonomy
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The binomial name Homo sapiens was coined by Linnaeus, 1758.[11] The Latin noun homō (genitive hominis) means "human being", while the participle sapiēns means "discerning, wise, sensible", or taken together essentially "intelligent human".[citation needed]

The species was initially thought to have emerged from a predecessor within the genus Homo around 300,000 to 200,000 years ago.[note 2] A problem with the morphological classification of "anatomically modern" was that it would not have included certain extant populations. For this reason, a lineage-based (cladistic) definition of H. sapiens has been suggested, in which H. sapiens would by definition refer to the modern human lineage following the split from the Neanderthal lineage. Such a cladistic definition would extend the age of H. sapiens to over 500,000 years.[note 3]

Estimates for the split between the Homo sapiens line and combined Neanderthal/Denisovan line range from between 503,000 and 565,000 years ago;[16] between 550,000 and 765,000 years ago;[17] and (based on rates of dental evolution) possibly more than 800,000 years ago.[18]

Extant human populations have historically been divided into subspecies, but since around the 1980s, the consensus has been to subsume all extant groups into a single species, H. sapiens, avoiding division into subspecies altogether.[note 4]

Some sources show Neanderthals (H. neanderthalensis) as a subspecies (H. sapiens neanderthalensis).[22][23] Similarly, the discovered specimens of the H. rhodesiensis species have been classified by some as a subspecies (H. sapiens rhodesiensis), although it remains more common to treat these last two as separate species within the genus Homo rather than as subspecies within H. sapiens.[24]

All humans are considered to be a part of the subspecies H. sapiens sapiens,[25] a designation which has been a matter of debate since a species is usually not given a subspecies category unless there is evidence of multiple distinct subspecies.[25]

Age and speciation process

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Further information: Human evolution, Homo, Multiregional origin of modern humans, Timeline of human evolution, and Early human migrations

Derivation from H. erectus

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Further information: Homo ergaster, Homo antecessor, Homo heidelbergensis, Homo rhodesiensis, and Acheulean

The divergence of the lineage that would lead to H. sapiens out of archaic human varieties derived from H. erectus, is estimated as having taken place over 500,000 years ago (marking the split of the H. sapiens lineage from ancestors shared with other known archaic hominins).[9][6] But the oldest split among modern human populations (such as the Khoisan split from other groups) has been recently dated to between 350,000 and 260,000 years ago,[26][27] and the earliest known examples of H. sapiens fossils also date to about that period, including the Jebel Irhoud remains from Morocco (ca. 300,000 or 350–280,000 years ago),[28] the Florisbad Skull from South Africa (ca. 259,000 years ago), and the Omo remains from Ethiopia (ca. 195,000, or, as more recently dated, ca. 233,000 years ago).[29][2]

An mtDNA study in 2019 proposed an origin of modern humans in Botswana (and a Khoisan split) of around 200,000 years.[30] However, this proposal has been widely criticized by scholars,[31][32][33] with the recent evidence overall (genetic, fossil, and archaeological) supporting an origin for H. sapiens approximately 100,000 years earlier and in a broader region of Africa than the study proposes.[33]

In September 2019, scientists proposed that the earliest H. sapiens (and last common human ancestor to modern humans) arose between 350,000 and 260,000 years ago through a merging of populations in East and South Africa.[34][5]

An alternative suggestion defines H. sapiens cladistically as including the lineage of modern humans since the split from the lineage of Neanderthals, roughly 500,000 to 800,000 years ago.

The time of divergence between archaic H. sapiens and ancestors of Neanderthals and Denisovans caused by a genetic bottleneck of the latter was dated at 744,000 years ago, combined with repeated early admixture events and Denisovans diverging from Neanderthals 300 generations after their split from H. sapiens, as calculated by Rogers et al. (2017).[35]

The derivation of a comparatively homogeneous single species of H. sapiens from more diverse varieties of archaic humans (all of which were descended from the early dispersal of H. erectus some 1.8 million years ago) was debated in terms of two competing models during the 1980s: "recent African origin" postulated the emergence of H. sapiens from a single source population in Africa, which expanded and led to the extinction of all other human varieties, while the "multiregional evolution" model postulated the survival of regional forms of archaic humans, gradually converging into the modern human varieties by the mechanism of clinal variation, via genetic drift, gene flow and selection throughout the Pleistocene.[36]

Since the 2000s, the availability of data from archaeogenetics and population genetics has led to the emergence of a much more detailed picture, intermediate between the two competing scenarios outlined above: The recent Out-of-Africa expansion accounts for the predominant part of modern human ancestry, while there were also significant admixture events with regional archaic humans.[37][38]

Since the 1970s, the Omo remains, originally dated to some 195,000 years ago, have often been taken as the conventional cut-off point for the emergence of "anatomically modern humans". Since the 2000s, the discovery of older remains with comparable characteristics, and the discovery of ongoing hybridization between "modern" and "archaic" populations after the time of the Omo remains, have opened up a renewed debate on the age of H. sapiens in journalistic publications.[39][40][41][42][43] H. s. idaltu, dated to 160,000 years ago, has been postulated as an extinct subspecies of H. sapiens in 2003.[44][25] H. neanderthalensis, which became extinct about 40,000 years ago, was also at one point considered to be a subspecies, H. s. neanderthalensis.[25]

H. heidelbergensis, dated 600,000 to 300,000 years ago, has long been thought to be a likely candidate for the last common ancestor of the Neanderthal and modern human lineages. However, genetic evidence from the Sima de los Huesos fossils published in 2016 seems to suggest that H. heidelbergensis in its entirety should be included in the Neanderthal lineage, as "pre-Neanderthal" or "early Neanderthal", while the divergence time between the Neanderthal and modern lineages has been pushed back to before the emergence of H. heidelbergensis, to close to 800,000 years ago, the approximate time of disappearance of H. antecessor.[45][46]

Early Homo sapiens

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Further information: Human subspecies, Middle Paleolithic, Mousterian, Interbreeding between archaic and modern humans, Homo sapiens idaltu, and Skhul and Qafzeh hominins
100 to 80 thousand year old Skhul V from Israel

The term Middle Paleolithic is intended to cover the time between the first emergence of H. sapiens (roughly 300,000 years ago) and the period held by some to mark the emergence of full behavioral modernity (roughly by 50,000 years ago, corresponding to the start of the Upper Paleolithic).

Many of the early modern human finds, like those of Jebel Irhoud, Omo, Herto, Florisbad, Skhul, and Peștera cu Oase exhibit a mix of archaic and modern traits.[47][48][28] Skhul V, for example, has prominent brow ridges and a projecting face. However, the brain case is quite rounded and distinct from that of the Neanderthals and is similar to the brain case of modern humans. It is uncertain whether the robust traits of some of the early modern humans like Skhul V reflects mixed ancestry or retention of older traits.[49][50]

The "gracile" or lightly built skeleton of anatomically modern humans has been connected to a change in behavior, including increased cooperation and "resource transport".[51][52]

There is evidence that the characteristic human brain development, especially the prefrontal cortex, was due to "an exceptional acceleration of metabolome evolution ... paralleled by a drastic reduction in muscle strength. The observed rapid metabolic changes in brain and muscle, together with the unique human cognitive skills and low muscle performance, might reflect parallel mechanisms in human evolution."[53] The Schöningen spears and their correlation of finds are evidence that complex technological skills already existed 300,000 years ago, and are the first obvious proof of an active (big game) hunt. H. heidelbergensis already had intellectual and cognitive skills like anticipatory planning, thinking and acting that so far have only been attributed to modern man.[54][55]

The ongoing admixture events within anatomically modern human populations make it difficult to estimate the age of the matrilinear and patrilinear most recent common ancestors of modern populations (Mitochondrial Eve and Y-chromosomal Adam). Estimates of the age of Y-chromosomal Adam have been pushed back significantly with the discovery of an ancient Y-chromosomal lineage in 2013, to likely beyond 300,000 years ago.[note 5] There have, however, been no reports of the survival of Y-chromosomal or mitochondrial DNA clearly deriving from archaic humans (which would push back the age of the most recent patrilinear or matrilinear ancestor beyond 500,000 years).[57][58][59]

Fossil teeth found at Qesem Cave (Israel) and dated to between 400,000 and 200,000 years ago have been compared to the dental material from the younger (120,000–80,000 years ago) Skhul and Qafzeh hominins.[note 6]

Dispersal and archaic admixture

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Further information: Recent African origin of modern humans, Southern Dispersal, Early human migrations, and List of first human settlements
Further information: Interbreeding between archaic and modern humans

Dispersal of early H. sapiens begins soon after its emergence, as evidenced by the North African Jebel Irhoud finds (dated to around 315,000 years ago).[28][61] There is indirect evidence for H. sapiens presence in West Asia around 270,000 years ago.[62]

The Florisbad Skull from Florisbad, South Africa, dated to about 259,000 years ago, has also been classified as representing early H. sapiens.[63][64]Scerri (2018), pp. 582–594[5]

In September 2019, scientists proposed that the earliest H. sapiens (and last common human ancestor to modern humans) arose between 350,000 and 260,000 years ago through a merging of populations in East and South Africa.[34][5]

Among extant populations, the Khoi-San (or "Capoid") hunters-gatherers of Southern Africa may represent the human population with the earliest possible divergence within the group Homo sapiens sapiens. Their separation time has been estimated in a 2017 study to be between 350 and 260,000 years ago, compatible with the estimated age of early H. sapiens. The study states that the deep split-time estimation of 350 to 260 thousand years ago is consistent with the archaeological estimate for the onset of the Middle Stone Age across sub-Saharan Africa and coincides with archaic H. sapiens in southern Africa represented by, for example, the Florisbad skull dating to 259 (± 35) thousand years ago.[7]

H. s. idaltu, found at Middle Awash in Ethiopia, lived about 160,000 years ago,[65] and H. sapiens lived at Omo Kibish in Ethiopia about 233,000-195,000 years ago.[66][2] Two fossils from Guomde, Kenya, dated to at least (and likely more than) 180,000 years ago[63] and (more precisely) to 300–270,000 years ago,[5] have been tentatively assigned to H. sapiens and similarities have been noted between them and the Omo Kibbish remains.[63] Fossil evidence for modern human presence in West Asia is ascertained for 177,000 years ago,[67] and disputed fossil evidence suggests expansion as far as East Asia by 120,000 years ago.[68][69]

In July 2019, anthropologists reported the discovery of 210,000 year old remains of a H. sapiens and 170,000 year old remains of a H. neanderthalensis in Apidima Cave, Peloponnese, Greece, more than 150,000 years older than previous H. sapiens finds in Europe.[70][71][72]

A significant dispersal event, within Africa and to West Asia, is associated with the African megadroughts during MIS 5, beginning 130,000 years ago.[73] A 2011 study located the origin of basal population of contemporary human populations at 130,000 years ago, with the Khoi-San representing an "ancestral population cluster" located in southwestern Africa (near the coastal border of Namibia and Angola).[74]

Layer sequence at Ksar Akil in the Levantine corridor, and discovery of two fossils of Homo sapiens, dated to 40,800 to 39,200 years BP for "Egbert",[75] and 42,400–41,700 BP for "Ethelruda".[75]

While early modern human expansion in Sub-Saharan Africa before 130 kya persisted, early expansion to North Africa and Asia appears to have mostly disappeared by the end of MIS5 (75,000 years ago), and is known only from fossil evidence and from archaic admixture. Eurasia was re-populated by early modern humans in the so-called "recent out-of-Africa migration" post-dating MIS5, beginning around 70,000–50,000 years ago.[76] In this expansion, bearers of mt-DNA haplogroup L3 left East Africa, likely reaching Arabia via the Bab-el-Mandeb, and in the Great Coastal Migration spread to South Asia, Maritime South Asia and Oceania between 65,000 and 50,000 years ago,[77][78][79][80] while Europe, East and North Asia were reached by about 45,000 years ago. Some evidence suggests that an early wave of humans may have reached the Americas by about 40,000–25,000 years ago.[citation needed]

Evidence for the overwhelming contribution of this "recent" (L3-derived) expansion to all non-African populations was established based on mitochondrial DNA, combined with evidence based on physical anthropology of archaic specimens, during the 1990s and 2000s,[note 7][82] and has also been supported by Y DNA and autosomal DNA.[83] The assumption of complete replacement has been revised in the 2010s with the discovery of admixture events (introgression) of populations of H. sapiens with populations of archaic humans over the period of between roughly 100,000 and 30,000 years ago, both in Eurasia and in Sub-Saharan Africa. Neanderthal admixture, in the range of 1–4%, is found in all modern populations outside of Africa, including in Europeans, Asians, Papua New Guineans, Australian Aboriginals, Native Americans, and other non-Africans.[84][37] This suggests that interbreeding between Neanderthals and anatomically modern humans took place after the recent "out of Africa" migration, likely between 60,000 and 40,000 years ago.[85][86][87] Recent admixture analyses have added to the complexity, finding that Eastern Neanderthals derive up to 2% of their ancestry from anatomically modern humans who left Africa some 100 kya.[88] The extent of Neanderthal admixture (and introgression of genes acquired by admixture) varies significantly between contemporary racial groups, being absent in Africans, intermediate in Europeans and highest in East Asians. Certain genes related to UV-light adaptation introgressed from Neanderthals have been found to have been selected for in East Asians specifically from 45,000 years ago until around 5,000 years ago.[89] The extent of archaic admixture is of the order of about 1% to 4% in Europeans and East Asians, and highest among Melanesians (the last also having Denisova hominin admixture at 4% to 6% in addition to neanderthal admixture).[37][49] Cumulatively, about 20% of the Neanderthal genome is estimated to remain present spread in contemporary populations.[90]

In September 2019, scientists reported the computerized determination, based on 260 CT scans, of a virtual skull shape of the last common human ancestor to modern humans/H. sapiens, representative of the earliest modern humans, and suggested that modern humans arose between 350,000 and 260,000 years ago through a merging of populations in East and South Africa while North-African fossils may represent a population which introgressed into Neandertals during the LMP.[34][5]

According to a study published in 2020, there are indications that 2% to 19% (or about ≃6.6 and ≃7.0%) of the DNA of four West African populations may have come from an unknown archaic hominin which split from the ancestor of humans and Neanderthals between 360 kya to 1.02 mya.[91]

Anatomy

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See also: Human anatomy, Human physical appearance, and Anthropometry
Known archaeological remains of anatomically modern humans in Europe and Africa, directly dated, calibrated carbon dates as of 2013.[75]

Generally, modern humans are more lightly built (or more "gracile") than the more "robust" archaic humans. Nevertheless, contemporary humans exhibit high variability in many physiological traits, and may exhibit remarkable "robustness". There are still a number of physiological details which can be taken as reliably differentiating the physiology of Neanderthals vs. anatomically modern humans.

Anatomical modernity

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The term "anatomically modern humans" is used with varying scope depending on context, to distinguish "anatomically modern" Homo sapiens from archaic humans such as Neanderthals and Middle and Lower Paleolithic hominins with transitional features intermediate between H. erectus, Neanderthals and early anatomically modern humans called archaic Homo sapiens.[92] In a convention popular in the 1990s, Neanderthals were classified as a subspecies of H. sapiens, as H. s. neanderthalensis, while anatomically modern humans (or European early modern humans), was taken to refer to "Cro-Magnon" or H. s. sapiens. Under this nomenclature (Neanderthals considered H. sapiens), the term "anatomically modern Homo sapiens" has also been used to refer to European early modern humans ("Cro-Magnons").[93] It has since become more common to designate Neanderthals as a separate species, H. neanderthalensis, so that anatomically modern human in the European context refers to H. sapiens, but the question is by no means resolved.[note 8]

In this more narrow definition of H. sapiens, the subspecies Homo sapiens idaltu, discovered in 2003, also falls under the umbrella of "anatomically modern".[95] The recognition of H. sapiens idaltu as a valid subspecies of the anatomically modern human lineage would justify the description of contemporary humans with the subspecies name Homo sapiens sapiens.[96] However, biological anthropologist Chris Stringer does not consider idaltu distinct enough within H. sapiens to warrant its own subspecies designation.[97][63]

A further division of anatomically modern human into "early" or "robust" vs. "post-glacial" or "gracile" subtypes has since been used for convenience. The emergence of "gracile anatomically modern human" is taken to reflect a process towards a smaller and more fine-boned skeleton beginning around 50,000–30,000 years ago.[98]

Braincase anatomy

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Further information: Brain size
Anatomical comparison of skulls of H. sapiens (left) and H. neanderthalensis (right)
(in Cleveland Museum of Natural History)
Features compared are the braincase shape, forehead, browridge, nasal bone projection, cheek bone angulation, chin and occipital contour

The cranium lacks a pronounced occipital bun in the neck, a bulge that anchored considerable neck muscles in Neanderthals. Modern humans, even the earlier ones, generally have a larger fore-brain than the archaic people, so that the brain sits above rather than behind the eyes. This will usually (though not always) give a higher forehead, and reduced brow ridge. Early modern people and some living people do however have quite pronounced brow ridges, but they differ from those of archaic forms by having both a supraorbital foramen or notch, forming a groove through the ridge above each eye.[99] This splits the ridge into a central part and two distal parts. In current humans, often only the central section of the ridge is preserved (if it is preserved at all). This contrasts with archaic humans, where the brow ridge is pronounced and unbroken.[100]

Modern humans commonly have a steep, even vertical forehead whereas their predecessors had foreheads that sloped strongly backwards.[101] According to Desmond Morris, the vertical forehead in humans plays an important role in human communication through eyebrow movements and forehead skin wrinkling.[102]

Brain size in both Neanderthals and anatomically modern humans is significantly larger on average (but overlapping in range) than brain size in H. erectus. Neanderthal and anatomically modern human brain sizes are in the same range, but there are differences in the relative sizes of individual brain areas, with significantly larger visual systems in Neanderthals than in anatomically modern humans.[103][note 9]

Jaw anatomy

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Compared to archaic people, anatomically modern humans have smaller, differently shaped teeth.[106][107] This results in a smaller, more receded dentary, making the rest of the jaw-line stand out, giving an often quite prominent chin. The central part of the mandible forming the chin carries a triangularly shaped area forming the apex of the chin called the mental Trigon, not found in archaic humans.[108] Particularly in living populations, the use of fire and tools requires fewer jaw muscles, giving slender, more gracile jaws. Compared to archaic people, modern humans have smaller, lower faces.

Body skeleton structure

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The body skeletons of even the earliest and most robustly built modern humans were less robust than those of Neanderthals (and - from what little we know - from Denisovans), having essentially modern proportions. Particularly regarding the long bones of the limbs, the distal bones (the radius/ulna and tibia/fibula) are nearly the same size or slightly shorter than the proximal bones (the humerus and femur). In ancient people, particularly Neanderthals, the distal bones were shorter, usually thought to be an adaptation to cold climate.[109] The same adaptation is found in some modern people living in the polar regions.[110]

Height ranges overlap between Neanderthals and anatomically modern humans, with Neanderthal averages cited as 164 to 168 cm (65 to 66 in) and 152 to 156 cm (60 to 61 in) for males and females, respectively, which is largely identical to pre-industrial average heights for anatomically modern humans.[note 10] Contemporary national averages range between 158 to 184 cm (62 to 72 in) in males and 147 to 172 cm (58 to 68 in) in females. Neanderthal ranges approximate the contemporary height distribution measured among Malay people, for one.[note 11]

Recent evolution

[edit]
Main article: Recent human evolution
Further information: Human genetic variation, Race and genetics, and Sexual selection in humans
Reconstruction of a modern man from southwestern Europe c. 30 000 years BP, London Natural History Museum.

Following the peopling of Africa some 130,000 years ago, and the recent Out-of-Africa expansion some 70,000 to 50,000 years ago, some sub-populations of H. sapiens had been essentially isolated for tens of thousands of years prior to the early modern Age of Discovery. Combined with archaic admixture this has resulted in significant genetic variation, which in some instances has been shown to be the result of directional selection taking place over the past 15,000 years, i.e., significantly later than possible archaic admixture events.[113]

Some climatic adaptations, such as high-altitude adaptation in humans, are thought to have been acquired by archaic admixture. Introgression of genetic variants acquired by Neanderthal admixture have different distributions in European and East Asians, reflecting differences in recent selective pressures. A 2014 study reported that Neanderthal-derived variants found in East Asian populations showed clustering in functional groups related to immune and haematopoietic pathways, while European populations showed clustering in functional groups related to the lipid catabolic process.[note 12] A 2017 study found correlation of Neanderthal admixture in phenotypic traits in modern European populations.[115]

Physiological or phenotypical changes have been traced to Upper Paleolithic mutations, such as the East Asian variant of the EDAR gene, dated to c. 35,000 years ago.[note 13]

Recent divergence of Eurasian lineages was sped up significantly during the Last Glacial Maximum, the Mesolithic and the Neolithic, due to increased selection pressures and due to founder effects associated with migration.[118] Alleles predictive of light skin have been found in Neanderthals,[119] but the alleles for light skin in Europeans and East Asians, associated with KITLG and ASIP, are (as of 2012) thought to have not been acquired by archaic admixture but recent mutations since the Last Glacial Maximum.[118] Phenotypes associated with the "white" or "Caucasian" populations of Western Eurasian stock emerge during the Last Glacial Maximum, from about 19,000 years ago. Average cranial capacity in modern human populations varies in the range of 1,200 to 1,450 cm3 for adult males. Larger cranial volume is associated with climatic region, the largest averages being found in populations of Siberia and the Arctic.[note 14][121] Both Neanderthal and European early modern humans had somewhat larger cranial volumes on average than modern Europeans, suggesting the relaxation of selection pressures for larger brain volume after the end of the Last Glacial Maximum.[120]

Examples for still later adaptations related to agriculture and animal domestication including East Asian types of ADH1B associated with rice domestication,[122] or lactase persistence,[123][124] are due to recent selection pressures.

An even more recent adaptation has been proposed for the Austronesian Sama-Bajau, developed under selection pressures associated with subsisting on freediving over the past thousand years or so.[125][126]

Behavioral modernity

[edit]
Main article: Behavioral modernity
Lithic Industries of early Homo sapiens at Blombos Cave (M3 phase, MIS 5), Southern Cape, South Africa (c. 105,000 – 90,000 years old)

Behavioral modernity, involving the development of language, figurative art and early forms of religion (etc.) is taken to have arisen before 40,000 years ago, marking the beginning of the Upper Paleolithic (in African contexts also known as the Later Stone Age).[127]

There is considerable debate regarding whether the earliest anatomically modern humans behaved similarly to recent or existing humans. Behavioral modernity is taken to include fully developed language (requiring the capacity for abstract thought), artistic expression, early forms of religious behavior,[128] increased cooperation and the formation of early settlements, and the production of articulated tools from lithic cores, bone or antler. The term Upper Paleolithic is intended to cover the period since the rapid expansion of modern humans throughout Eurasia, which coincides with the first appearance of Paleolithic art such as cave paintings and the development of technological innovation such as the spear-thrower. The Upper Paleolithic begins around 50,000 to 40,000 years ago, and also coincides with the disappearance of archaic humans such as the Neanderthals.

Bifacial silcrete point of early Homo sapiens, from M1 phase (71,000 BCE) layer of Blombos Cave, South Africa

The term "behavioral modernity" is somewhat disputed. It is most often used for the set of characteristics marking the Upper Paleolithic, but some scholars use "behavioral modernity" for the emergence of H. sapiens around 200,000 years ago,[129] while others use the term for the rapid developments occurring around 50,000 years ago.[130][131][132] It has been proposed that the emergence of behavioral modernity was a gradual process.[133][134][135][136][137]

Examples of behavioral modernity

[edit]
Claimed "oldest known drawing by human hands", discovered in Blombos Cave in South Africa. Estimated to be a 73,000-year-old work of a Homo sapiens.[138]

The equivalent of the Eurasian Upper Paleolithic in African archaeology is known as the Later Stone Age, also beginning roughly 40,000 years ago. While most clear evidence for behavioral modernity uncovered from the later 19th century was from Europe, such as the Venus figurines and other artefacts from the Aurignacian, more recent archaeological research has shown that all essential elements of the kind of material culture typical of contemporary San hunter-gatherers in Southern Africa was also present by at least 40,000 years ago, including digging sticks of similar materials used today, ostrich egg shell beads, bone arrow heads with individual maker's marks etched and embedded with red ochre, and poison applicators.[139] There is also a suggestion that "pressure flaking best explains the morphology of lithic artifacts recovered from the c. 75-ka Middle Stone Age levels at Blombos Cave, South Africa. The technique was used during the final shaping of Still Bay bifacial points made on heat‐treated silcrete."[140] Both pressure flaking and heat treatment of materials were previously thought to have occurred much later in prehistory, and both indicate a behaviourally modern sophistication in the use of natural materials. Further reports of research on cave sites along the southern African coast indicate that "the debate as to when cultural and cognitive characteristics typical of modern humans first appeared" may be coming to an end, as "advanced technologies with elaborate chains of production" which "often demand high-fidelity transmission and thus language" have been found at the South African Pinnacle Point Site 5–6. These have been dated to approximately 71,000 years ago. The researchers suggest that their research "shows that microlithic technology originated early in South Africa by 71 kya, evolved over a vast time span (c. 11,000 years), and was typically coupled to complex heat treatment that persisted for nearly 100,000 years. Advanced technologies in Africa were early and enduring; a small sample of excavated sites in Africa is the best explanation for any perceived 'flickering' pattern."[141] Increases in behavioral complexity have been speculated to have been linked to an earlier climatic change to much drier conditions between 135,000 and 75,000 years ago.[142] This might have led to human groups who were seeking refuge from the inland droughts, expanded along the coastal marshes rich in shellfish and other resources. Since sea levels were low due to so much water tied up in glaciers, such marshlands would have occurred all along the southern coasts of Eurasia. The use of rafts and boats may well have facilitated exploration of offshore islands and travel along the coast, and eventually permitted expansion to New Guinea and then to Australia.[143]

In addition, a variety of other evidence of abstract imagery, widened subsistence strategies, and other "modern" behaviors has been discovered in Africa, especially South, North, and East Africa, predating 50,000 years ago (with some predating 100,000 years ago). The Blombos Cave site in South Africa, for example, is famous for rectangular slabs of ochre engraved with geometric designs. Using multiple dating techniques, the site was confirmed to be around 77,000 and 100,000–75,000 years old.[144][145] Ostrich egg shell containers engraved with geometric designs dating to 60,000 years ago were found at Diepkloof, South Africa.[146] Beads and other personal ornamentation have been found from Morocco which might be as much as 130,000 years old; as well, the Cave of Hearths in South Africa has yielded a number of beads dating from significantly prior to 50,000 years ago,[147] and shell beads dating to about 75,000 years ago have been found at Blombos Cave, South Africa.[148][149][150] Specialized projectile weapons as well have been found at various sites in Middle Stone Age Africa, including bone and stone arrowheads at South African sites such as Sibudu Cave (along with an early bone needle also found at Sibudu) dating approximately 72,000–60,000 years ago[151][152][153][154][155] some of which may have been tipped with poisons,[156] and bone harpoons at the Central African site of Katanda dating ca. 90,000 years ago.[157] Evidence also exists for the systematic heat treating of silcrete stone to increase its flake-ability for the purpose of toolmaking, beginning approximately 164,000 years ago at the South African site of Pinnacle Point and becoming common there for the creation of microlithic tools at about 72,000 years ago.[158][141]

In 2008, an ochre processing workshop likely for the production of paints was uncovered dating to ca. 100,000 years ago at Blombos Cave, South Africa. Analysis shows that a liquefied pigment-rich mixture was produced and stored in the two abalone shells, and that ochre, bone, charcoal, grindstones and hammer-stones also formed a composite part of the toolkits. Evidence for the complexity of the task includes procuring and combining raw materials from various sources (implying they had a mental template of the process they would follow), possibly using pyrotechnology to facilitate fat extraction from bone, using a probable recipe to produce the compound, and the use of shell containers for mixing and storage for later use.[159][160][161] Modern behaviors, such as the making of shell beads, bone tools and arrows, and the use of ochre pigment, are evident at a Kenyan site by 78,000-67,000 years ago.[162] Evidence of early stone-tipped projectile weapons (a characteristic tool of Homo sapiens), the stone tips of javelins or throwing spears, were discovered in 2013 at the Ethiopian site of Gademotta, and date to around 279,000 years ago.[163]

Expanding subsistence strategies beyond big-game hunting and the consequential diversity in tool types have been noted as signs of behavioral modernity. A number of South African sites have shown an early reliance on aquatic resources from fish to shellfish. Pinnacle Point, in particular, shows exploitation of marine resources as early as 120,000 years ago, perhaps in response to more arid conditions inland.[164] Establishing a reliance on predictable shellfish deposits, for example, could reduce mobility and facilitate complex social systems and symbolic behavior. Blombos Cave and Site 440 in Sudan both show evidence of fishing as well. Taphonomic change in fish skeletons from Blombos Cave have been interpreted as capture of live fish, clearly an intentional human behavior.[147]

Humans in North Africa (Nazlet Sabaha, Egypt) are known to have dabbled in chert mining, as early as ≈100,000 years ago, for the construction of stone tools.[165][166]

Evidence was found in 2018, dating to about 320,000 years ago at the site of Olorgesailie in Kenya, of the early emergence of modern behaviors including: the trade and long-distance transportation of resources (such as obsidian), the use of pigments, and the possible making of projectile points. The authors of three 2018 studies on the site observe that the evidence of these behaviors is roughly contemporary with the earliest known Homo sapiens fossil remains from Africa (such as at Jebel Irhoud and Florisbad), and they suggest that complex and modern behaviors began in Africa around the time of the emergence of Homo sapiens.[167][168][169]

In 2019, further evidence of Middle Stone Age complex projectile weapons in Africa was found at Aduma, Ethiopia, dated 100,000–80,000 years ago, in the form of points considered likely to belong to darts delivered by spear throwers.[170]

Pace of progress during Homo sapiens history

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See also: Sapient paradox and The 10,000 Year Explosion

Homo sapiens technological and cultural progress appears to have been very much faster in recent millennia than in Homo sapiens early periods. The pace of development may indeed have accelerated, due to massively larger population (so more humans extant to think of innovations), more communication and sharing of ideas among human populations, and the accumulation of thinking tools. However it may also be that the pace of advancements always looks relatively faster to humans in the time they live, because previous advances are unrecognised.[171]

Notes

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References

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Further reading

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Early modern human

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Early modern humans, also known as anatomically modern , represent the earliest members of our characterized by a suite of modern skeletal features, including a high-vaulted and rounded cranium, vertically oriented , reduced supraorbital tori (brow ridges), a prominent , retracted profile, and a lightly built, gracile postcranial with thinner cortical and more slender limb proportions compared to archaic hominins. These traits distinguish them from earlier and mark the emergence of the morphological pattern seen in all living humans. The origins of early modern humans trace back to Africa during the Middle Pleistocene, with the oldest known fossils discovered at Jebel Irhoud in Morocco, dated to approximately 315,000 years ago through thermoluminescence dating of associated heat-treated flint artifacts and electron spin resonance on a tooth. These remains include skull fragments, a jawbone, and long bones showing a mix of modern facial features and more archaic braincase morphology, suggesting a mosaic evolution toward full modernity. Additional early African fossils, such as those from Florisbad in South Africa (~259,000 years ago) and Omo Kibish in Ethiopia (dated to about 233,000 years ago via uranium-thorium dating of a hippopotamus tusk in overlying sediment), further support an African origin around 300,000 years ago, with genetic evidence indicating divergence from other hominin lineages between 400,000 and 700,000 years ago. The Herto skulls from Ethiopia, dated to 154,000–160,000 years ago, exhibit fully modern cranial traits like a globular braincase and are classified as Homo sapiens idaltu, an archaic form of modern humans. Early modern humans initially dispersed within , adapting to diverse environments from savannas to coastal regions, as evidenced by archaeological sites with Levallois technology and evidence of large game. The earliest evidence of their movement comes from the Misliya Cave in , where a partial dated to 177,000–194,000 years ago via uranium-series dating confirms anatomically modern morphology, including modern dental features and associated Levallois tools, hearths, and faunal remains indicating sophisticated behaviors like use and . These dispersals were likely episodic and limited, influenced by fluctuations during Marine Isotope Stage 6, with more permanent migrations occurring around 60,000–70,000 years ago, leading to the peopling of , , and eventually the . Genetic studies reveal that early modern humans interbred with archaic populations, such as s and s, incorporating 1–2% Neanderthal DNA into non-African genomes and Denisovan DNA in some Asian and Oceanian populations, which influenced traits like and skin pigmentation. This highlights a complex evolutionary history rather than strict isolation, with modern arising from African population subdivisions and subsequent migrations. By around 45,000 years ago, early modern humans in developed advanced symbolic behaviors, including art, complex tools, and long-distance trade, marking the transition to behaviorally modern humans while retaining anatomical modernity.

Taxonomy and nomenclature

Classification and naming

The term "early modern human" refers to anatomically modern members of the species Homo sapiens who lived from approximately 300,000 years ago until the end of the Pleistocene epoch around 11,700 years ago. These individuals are distinguished by skeletal morphology closely resembling that of contemporary humans, including a high forehead, rounded skull, and reduced facial robusticity. Historically, early modern humans in were referred to as "" after the French where key fossils were discovered in 1868, but this term has largely been abandoned in favor of "early modern human" to eliminate Eurocentric connotations and emphasize the global, African origins of the . The shift reflects a broader move away from site-specific naming toward inclusive terminology that encompasses populations worldwide. Under , formalized by in his 1758 , humans were classified as Homo sapiens ("wise man"), placing the species within the genus , family , and order . Post-1758 refinements, driven by discoveries since the , have solidified this placement while incorporating evidence of anatomical variation; early modern humans are consensus H. sapiens, though debates persist on whether certain archaic forms (e.g., Neanderthals) warrant subspecies status as H. s. neanderthalensis versus full species separation, contrasting with the fully modern H. s. sapiens. These discussions highlight ongoing tensions between morphological, genetic, and phylogenetic criteria in hominin classification.

Relation to archaic hominins

Early modern humans, or Homo sapiens, occupy a distinct branch on the hominin , descending from a lineage of earlier Homo species that originated in and radiated across continents. This positioning reflects a cladistic framework where H. sapiens represents the sole surviving of the genus Homo, emerging from a shared ancestry with other archaic hominins following divergences driven by geographic isolation and environmental pressures. Fossil and genetic evidence places the root of this tree within the broader hominin clade, which split from the chimpanzee lineage approximately 6–7 million years ago, with subsequent branching among Homo species occurring over the past 2 million years. Key archaic relatives include Homo erectus, an early widespread ancestor that persisted until around 100,000 years ago and served as a basal form from which later Homo lineages evolved; Homo heidelbergensis, a Middle Pleistocene species emerging around 700,000 years ago in Africa and Europe, often regarded as the last common ancestor to H. sapiens and Neanderthals due to its intermediate morphology and tool-using behaviors; Neanderthals (H. neanderthalensis), a sister group to H. sapiens adapted to Eurasian cold climates from about 250,000 years ago; and Denisovans, an enigmatic sister taxon to Neanderthals known primarily from genetic data, diverging within the same archaic lineage. These relatives highlight a mosaic of evolutionary relationships, with H. heidelbergensis bridging earlier forms like H. erectus—from which early modern humans ultimately derive—and the more derived Neanderthal and Denisovan clades. Cladistic analyses of cranial and postcranial fossils support this structure, showing H. sapiens clustering separately from Neanderthals while sharing derived traits like increased brain size with H. heidelbergensis. Evidence from and reinforces a recent common ancestor for H. sapiens and archaic Eurasian hominins around 500,000–800,000 years ago. Phylogenetic reconstructions using morphology, such as mandibular and dental traits, indicate a divergence of the -Denisovan lineage from the H. sapiens lineage approximately 752,000 years ago, calibrated via genomic mutation rates from high-coverage . analyses, which estimate divergence times based on neutral genetic mutations accumulated since , align with this timeline, drawing from complete genomes that reveal a in the archaic lineage shortly after the split. evidence from sites like Sima de los Huesos in further supports H. heidelbergensis as this ancestral form, with specimens dated to 430,000 years ago exhibiting mosaic features transitional to both and modern humans. Debates on the evolutionary origins of H. sapiens have centered on the multiregional evolution model, which posits continuous gene flow and parallel development across archaic populations in Africa, Europe, and Asia, versus the recent African origin (or "Out-of-Africa") model, which emphasizes the origin of modern humans in Africa around 200,000–300,000 years ago, followed by a major dispersal out of Africa around 60,000–70,000 years ago, with limited archaic contributions. Genetic evidence, including mitochondrial DNA phylogenies showing the deepest human lineages in Africa and a recent common maternal ancestor approximately 150,000–200,000 years ago, has established the dominance of the recent African origin model, undermining multiregional continuity by demonstrating low genetic diversity outside Africa consistent with a population bottleneck during expansion. Fossil records corroborating modern traits first in African specimens, such as those from Omo Kibish dated to approximately 233,000 years ago, further bolster this view, though some hybridization with archaic groups is acknowledged as a minor assimilation rather than a primary driver of modern human emergence.

Origins and speciation

Derivation from Homo erectus

The evolutionary derivation of early modern humans (Homo sapiens) from Homo erectus is thought to have involved a speciation event in Africa approximately 600,000 to 300,000 years ago, mediated by the intermediate species Homo heidelbergensis. This transition reflects a gradual morphological and genetic shift within African hominin populations, where H. heidelbergensis populations diverged from earlier H. erectus lineages, eventually giving rise to H. sapiens while a separate branch led to Neanderthals in Eurasia. The process occurred amid increasing encephalization and adaptations to variable environments, marking the Middle Pleistocene as a pivotal period for hominin diversification. Key evidence comes from transitional fossils that exhibit a mosaic of H. erectus-like archaic traits and emerging H. sapiens features. The Bodo cranium from , dated to about 600,000 years ago, displays a low and thick braincase (up to 13 mm thick), prominent supraorbital torus, and midline frontal keel reminiscent of H. erectus, yet it also shows derived characteristics such as a cranial capacity of around 1,300 cm³, broader midvault with parietal bossing, and a more vertical nasal aperture border—indicating a shift toward modern human morphology. Similarly, the () skull from , approximately 300,000 years old, retains H. erectus-derived elements like a low braincase profile, large brow ridges, and slight midfacial widening, but incorporates H. sapiens-like traits including a higher forehead and reduced , suggesting progressive gracilization in African lineages. These specimens, often classified under H. heidelbergensis or archaic H. sapiens, illustrate the evolutionary continuum without abrupt replacement. Genetic analyses of ancient DNA from African sites further support continuity between these archaic populations and modern H. sapiens, with no evidence of large-scale population turnover. Genome-wide data from 16 prehistoric Africans (spanning 8,100 to 1,400 years ago) reveal shared derived alleles and ancestry components—such as a deeply divergent lineage contributing up to 91% to modern Khoe-San groups—that link Middle Pleistocene ancestors to contemporary sub-Saharan populations, indicating evolution from H. erectus-derived groups. This continuity is accompanied by morphological trends toward reduced robusticity, evident in the decreasing thickness of cranial bones and brow ridges in later fossils, reflecting adaptations to dietary shifts and reduced masticatory stress over time. Environmental drivers, particularly climate fluctuations during the Middle Pleistocene, played a crucial role in prompting these changes. Oscillations in and across , including periods of and wetter phases from 1 million to 200,000 years ago, correlated with increases in hominin (e.g., -2.7% per unit of long-term precipitation variability), favoring cognitive enhancements for resource tracking in unstable habitats. These pressures also drove refinements in tool technology, such as more efficient handaxes and early prepared-core techniques, which supported larger brains by improving foraging efficiency in low-productivity environments.

Timeline of early Homo sapiens

The timeline of early Homo sapiens is marked by key fossil discoveries in Africa, primarily dated using radiometric techniques such as uranium-thorium dating for associated materials and optically stimulated luminescence for sedimentary contexts, which provide precise age estimates for hominin remains and associated artifacts. The earliest evidence comes from Jebel Irhoud in Morocco, where fossils including skulls, jaws, and teeth exhibit a mix of modern and archaic features, dated to approximately 315,000 years ago through thermoluminescence on heated flints and electron spin resonance on enamel. These remains suggest an early pan-African origin for the species, with populations persisting regionally before wider dispersal. Subsequent African fossils reinforce this timeline, highlighting persistence across the continent. The Florisbad cranium from , dated to approximately 259,000 years ago using electron spin resonance, shows transitional features between archaic and modern humans. At Omo Kibish in , the Omo I partial skeleton—one of the most complete early H. sapiens individuals—has been redated to about 233,000 years ago using argon-argon on volcanic tuffs bracketing the stratigraphic layer. Further east in Ethiopia's Middle Awash, the Herto skulls (including three partial crania) represent more derived forms and are dated to around 160,000 years ago via argon-argon dating of associated layers. These sites indicate a phase of initial African persistence from roughly 300,000 to 100,000 years ago, characterized by regional adaptations and limited evidence of out-of-Africa movement, during which anatomical changes toward modernity, such as rounded crania and reduced brow ridges, began to consolidate (see Physical anatomy). By approximately 120,000 years ago, early H. sapiens made incursions into the , as evidenced by burials at Skhul and Qafzeh caves in , dated to 120,000–90,000 years ago using , electron spin resonance, and uranium-series methods on associated sediments and shells. These remains show fully modern morphology and suggest brief, unsuccessful dispersals beyond during a period of climatic warming. Analyses reported in 2019 have proposed early H. sapiens presence in based on a fragmented skull from in , dated to more than 210,000 years ago using uranium-series dating, though this identification remains controversial due to the fragmentary remains and methodological debates. This would indicate potential failed migrations predating Levantine evidence and complicating models of African isolation, but further validation is needed.
Key EventSiteApproximate Date (years ago)Dating MethodSource
Earliest H. sapiens fossils, 315,000, ESRNature (2017)
Florisbad craniumFlorisbad, 259,000ESRJHE (1996)
Omo I skeletonOmo Kibish, 233,000⁴⁰Ar/³⁹ArNature (2022)
Herto skullsHerto, 160,000⁴⁰Ar/³⁹ArNature (2003)
Levantine incursionsSkhul/Qafzeh, 120,000–90,000, ESR, U-seriesNature (1989)
Proposed early Eurasian presence, >210,000U-seriesNature (2019)

Physical anatomy

Anatomical modernity

Anatomical modernity refers to the suite of derived skeletal and cranial traits that define early modern humans (Homo sapiens) and set them apart from archaic hominins, including a , , reduced brow ridges, and . These features reflect a lighter, more slender postcranial build with thinner cortical bone and smoother contours compared to the robust skeletons of earlier species like . Key hallmarks include the globular braincase and facial retraction, which positioned the face more inferiorly beneath the cranium, facilitating an expanded capacity averaging around 1,350 cm³—substantially larger than the approximately 900–1,100 cm³ typical of H. erectus. Specific details of braincase globularity, such as increased vault height and parietal expansion, further underscore this derived morphology. These traits evolved in a mosaic fashion, with modern facial features appearing before full neurocranial globularity. Relative to H. erectus, early modern humans show a higher cranial index (breadth-to-height ratio exceeding 75 in sapiens versus under 70 in erectus), indicating a taller, more rounded vault, alongside marked reductions in facial through retraction of the midface and smaller alveolar dimensions. The earliest indications of anatomical appear in the fossils from , dated to about 315,000 years ago, which exhibit modern facial architecture despite a more elongated braincase; approaching the complete suite of traits, including increased globularity, by around 100,000 years ago in Levantine specimens like those from Skhul and Qafzeh, with full modern morphology evident in later fossils.

Cranial and skeletal features

Early modern humans exhibit a distinctive cranial morphology characterized by a high, rounded vault and the absence of an occipital bun, contrasting with the more elongated and projecting occiputs of archaic hominins like Homo erectus and Neanderthals. This high vault contributes to a globular neurocranium, a derived feature that evolved gradually in Africa after ~300,000 years ago, becoming more pronounced by ~100,000 years ago, resulting from parietal expansion and increased vault height relative to cranial length. Parietal bossing, marked by bulging along the midline of the parietal bones, further accentuates this rounded profile and is linked to the development of the precuneus region in the brain. Braincase volumes in early modern humans typically range from 1,200 to 1,500 cm³, with averages around 1,450 cm³ in specimens like those from Skhul and Qafzeh, comparable to recent humans but achieved through reorganization rather than absolute enlargement beyond archaic levels. Facial features of early modern humans show an orthognathic profile, with retracted midfaces and reduced facial projection relative to the braincase, departing from the prognathic faces of earlier hominins. A prominent , often in an inverted-T shape, develops on the , providing structural support without the robust projecting jawlines of archaic forms. Dentally, early modern humans display reduced sizes and a parabolic dental arcade, forming a rounded arch rather than the U-shaped arrangement seen in apes and earlier species; this configuration accommodates smaller postcanine teeth adapted to a varied diet. Postcranially, early modern humans possess longer limbs relative to trunk height and a narrower compared to Neanderthals, facilitating efficient bipedal locomotion and heat dissipation during activity. These proportions, including elongated distal limb segments, are adaptations for running, enabling sustained pursuit of prey over long distances in open environments. Average male height reached approximately 170 cm, reflecting a stabilization of stature from Middle Pleistocene levels and supporting increased mobility. Regional variations exist among early modern human populations, with individuals from sites like Skhul and Qafzeh (dated ~100,000 years ago) showing more robust cranial and postcranial features, such as prominent supraorbital tori and larger teeth, compared to the gracile forms that became predominant after ~35,000 years ago. For instance, Skhul V displays a thick and robust limb bones, while later European specimens trend toward slimmer builds.

Dispersal and admixture

Out-of-Africa migrations

The Out-of-Africa migrations of early modern humans represent the primary dispersal events that populated , , and eventually the , with the earliest evidence of dispersal out of Africa dating to approximately 180,000–120,000 years ago at sites like Misliya and Skhul/Qafzeh, followed by the major successful expansion around 70,000–50,000 years ago. These movements occurred in multiple waves, facilitated by climatic windows that lowered sea levels and opened land bridges or narrow straits. The northern route, through the , saw early dispersals approximately 120,000 years ago and another around 60,000 years ago, with fossil evidence from sites like Skhul and Qafzeh in the dated to about 100,000 years ago, indicating temporary occupations in the region. In contrast, the southern route across the Strait from the to the supported the major successful expansion between 70,000 and 50,000 years ago, enabled by coastal adaptations such as exploitation of by "beachcomber" populations, which allowed rapid movement along shorelines. Genetic evidence from (mtDNA) haplogroups underscores these dispersals, with originating in around 70,000–60,000 years ago and giving rise to non-African lineages and , which trace the southern route's spread into . This pathway faced environmental challenges, including the Toba eruption approximately 74,000 years ago, which may have contributed to a genetic bottleneck reducing to 3,000–10,000 individuals, though the causal link remains debated and some groups survived through adaptive strategies. The eruption's ashfall and climate cooling likely intensified selective pressures during early phases of the migration. From the , migrating groups rapidly colonized and reached (Sahul) by around 65,000 years ago according to archaeological at rock shelter, though recent 2025 genetic studies suggest a possibly later arrival around 50,000 years ago, marking one of the earliest seafaring achievements with crossings of at least 90 kilometers. Further expansions continued into and by 45,000 years ago, with populations adapting to diverse environments. The final major leg involved crossing into the between 23,000 and 15,000 years ago via coastal or inland routes during the , supported by footprints and artifacts in dated to 23,000–21,000 years ago. These migrations involved limited admixture with archaic populations encountered en route, contributing to without halting the overall dispersal.

Genetic interbreeding with archaic populations

Genetic evidence indicates that early modern humans interbred with archaic hominins during their dispersal out of , resulting in the incorporation of archaic DNA into modern human . This admixture is detectable through comparisons of ancient and contemporary DNA sequences, revealing contributions from , Denisovans, and unidentified "ghost" populations. Non-African populations carry approximately 1–4% ancestry, stemming from interbreeding events in approximately 50,000–60,000 years ago. This occurred after modern humans exited and encountered groups, with the introgressed DNA persisting in varying proportions across Eurasian-descended lineages. The Vindija genome, sequenced from Croatian fossils dating to around 46,000 years ago, provided key reference data for identifying these shared sequences, confirming that the admixing were closely related to late Eurasian populations. Denisovan admixture is prominent in populations of Oceanian and Asian descent, contributing up to 5% of their genomes in some cases, with evidence of multiple interbreeding pulses. A notable adaptive outcome is the Denisovan-derived variant of the EPAS1 gene, which enhances high-altitude adaptation by regulating hemoglobin levels and is prevalent in Tibetan populations. This introgression likely occurred in eastern Eurasia following initial Neanderthal admixture. Detection of archaic admixture relies on ancient DNA sequencing of reference genomes, such as those from Vindija Neanderthals, combined with (LD) analysis in modern genomes to identify long haplotypes indicative of recent . These methods quantify archaic segments by measuring excess sharing and decay patterns in LD, distinguishing admixture signals from incomplete lineage sorting. Within Africa, modern populations show evidence of admixture with unidentified archaic "ghost" populations, contributing approximately 2–8% to West African genomes based on refined LD-based inferences from recent studies. These events, estimated at 43,000–124,000 years ago, involved unknown hominins not represented by Neanderthal or Denisovan fossils, highlighting complex interbreeding dynamics on the continent prior to major out-of-Africa migrations.

Behavioral and cultural evolution

Emergence of behavioral modernity

refers to the suite of cognitive and cultural traits that distinguish anatomically modern Homo sapiens from earlier hominins, including abstract thinking, symbolic expression, complex planning, and innovative tool use. This transition is often associated with the shift from the (MSA) in to the in , occurring broadly between approximately 50,000 and 40,000 years ago, though evidence suggests a more protracted development. Two primary theoretical frameworks explain this emergence: a gradual model rooted in African MSA contexts and a punctuated "" hypothesis centered on Eurasian innovations. The gradual model posits incremental advancements in symbolic and technological behaviors over hundreds of thousands of years in , driven by environmental pressures and cumulative , challenging earlier notions of a sudden around 40,000 years ago. In contrast, the "," originally proposed to describe a rapid explosion of art and tools in , has been largely critiqued for , with recent syntheses emphasizing 's primacy in behavioral complexity. Influential factors include cognitive fluidity—the integration of modular intelligences (social, technical, , and linguistic) into flexible problem-solving—and rising population densities that facilitated idea exchange and cultural ratcheting. Preconditions for were laid by anatomical modernity, which emerged around 300,000 years ago and enabled larger social networks, enhanced communication via , and greater ecological adaptability. These biological foundations, including expanded brain regions for , allowed early H. sapiens to form cooperative groups exceeding 150 individuals, promoting the transmission of complex knowledge. Globally, signs of appeared earlier in than in ; for instance, engraved ochre pieces from , , dated to about 77,000 years ago, indicate symbolic thought predating the by tens of millennia. In , similar traits manifested later, around 45,000 years ago, possibly due to migration dynamics and local adaptations rather than a novel cognitive threshold. This African precedence underscores a pattern of development, where behavioral traits diffused variably across populations.

Key archaeological evidence

In Africa, some of the earliest indicators of symbolic behavior among early modern humans come from in , where engraved ochre pieces and perforated kraussianus shell beads, dated to approximately 75,000 years ago, suggest deliberate use for personal adornment and possibly ritual purposes. These artifacts, recovered from layers, include ochre slabs with crosshatched incisions and shells showing wear from suspension, indicating sustained cultural practices. Further evidence of abstract design appears at Diepkloof Rock Shelter, also in , where over 270 fragments of engraved ostrich eggshells from around 60,000 years ago reveal a tradition of geometric patterns likely used on portable containers, pointing to organized symbolic expression during the Howiesons Poort period. In , the arrival of early modern humans is marked by the techno-complex, spanning roughly 43,000 to 26,000 years ago, which introduced refined stone tools such as blades and bladelets, alongside bone and antler implements, reflecting advanced craftsmanship across sites from to . Artistic representations flourished, exemplified by the from Cave in , a dated to about 40,000 years ago that depicts exaggerated female features, representing one of the oldest known portable sculptures associated with culture. Similarly, the wall art in , , features over 1,000 engravings and paintings of animals like lions and , radiocarbon-dated to approximately 36,000 years ago, showcasing sophisticated use of shading, perspective, and movement in a deep cave setting. Technological innovations during this period included widespread bladelet production, where small, sharp flakes were struck from prepared cores to create efficient cutting edges for tools and projectiles, evident in Aurignacian assemblages across Europe. Bone tools, such as awls and needles for hides, and composite weapons like points hafted with stone inserts, demonstrate resourcefulness in material use and strategies, with residues on artifacts confirming adhesive bindings from resin or birch tar. These advancements, appearing shortly after modern human dispersal into , highlight a shift toward more versatile and specialized equipment. Burial practices providing insight into ritual behavior are documented at Qafzeh Cave in , where graves of early modern humans from around 100,000 years ago contain red ochre applied to bodies and , such as shells and deer antlers, suggesting intentional ceremonies to honor the deceased. At least 15 individuals were interred in flexed positions with ochre-stained remains, including a child with ochre and antler, indicating symbolic associations with color and life force in contexts.

Recent developments

Post-dispersal evolution

After early modern humans dispersed from around 60,000–70,000 years ago, their populations encountered diverse environmental pressures that drove localized genetic and morphological adaptations. One prominent adaptation was the evolution of , allowing adults to digest from , which emerged in approximately 10,000 years ago alongside the domestication of dairy animals and the spread of . This trait provided a nutritional advantage in regions with seasonal food scarcity, leading to strong positive selection on specific genetic variants, such as the -13910*T in the MCM6 enhancer. Variations in skin pigmentation also arose as adaptations to ultraviolet (UV) radiation levels post-dispersal. In high-UV equatorial regions, dark eumelanin-rich evolved to protect against folate depletion and skin damage, while in low-UV higher latitudes like and , lighter skin independently developed around 8,000–10,000 years ago to facilitate synthesis from limited sunlight. These changes involved selection on genes like SLC24A5 and SLC45A2, resulting in regional clines where pigmentation gradients align with annual UV exposure. Regional morphological divergences appeared in cranial features among early modern humans. For instance, Pleistocene and early Australians, such as those from Kow Swamp and Cohuna, exhibited slight cranial robusticity—including thicker vault bones and more pronounced supraorbital tori—compared to the more gracile crania of contemporaneous Europeans like individuals, possibly reflecting responses to local diets, climates, or rather than archaic admixture. Recent genomic studies from the 2020s have identified signatures of post-dispersal selection pressures related to pathogens and diet. Analyses of reveal positive selection on immune-related genes, such as those in the HLA region, driven by regional pathogen exposures like in , enhancing resistance but increasing autoimmune risks. Similarly, dietary shifts selected for variants in genes affecting metabolism, including those for digestion (AMY1) and fatty acid processing, as humans adapted to and varied food sources across continents. Recent findings as of 2024 have further clarified admixture patterns, showing instances of back-migration and higher in some Eurasian populations, influencing immune and metabolic traits. These findings underscore how local environments accelerated adaptive evolution after dispersal.

Pace of progress in human history

The history of early modern humans shows a gradual emergence of technological and cultural complexity starting around 300,000 years ago in , with the featuring increasing innovation such as hafted tools, pigment use, and symbolic artifacts, building on traditions comparable to those of archaic populations like the . This development of occurred incrementally, with evidence from sites like indicating abstract thinking and artistic expression by 100,000 years ago or earlier. Around 70,000–50,000 years ago, coinciding with major out-of-Africa dispersals, there was an acceleration in cultural diversification, seen in the in and the in , with refined tools, implements, and evidence of seafaring, long-distance , and artistic expression. This phase marked enhanced adaptive capacity compared to contemporaneous Neanderthals, whose toolkit endured with limited changes for over 250,000 years, from about 300,000 to 40,000 years ago. Key drivers included the development of cumulative culture, in which innovations accumulated across generations through social learning; the evolution of complex language, with evidence suggesting protolinguistic capabilities by 100,000 years ago; and the expansion of social and trade networks facilitating idea exchange. These factors created a feedback loop of , enabling effective adaptation to diverse environments. By the Holocene transition around 12,000 years ago, the cumulative base of refined foraging strategies, plant knowledge, and versatile tools provided the essential groundwork for agriculture's emergence, as stable climates permitted intensive plant management and in regions like the and . This shift from nomadic systems to sedentary farming societies marked a further intensification of progress, building on the foundations laid during the .

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