Armed conflict in the Sahara, ~13 thousand years ago

An interesting story from the Independent:

Scientists are investigating what may be the oldest identified race war 13,000 years after it raged on the fringes of the Sahara. French scientists working in collaboration with the British Museum have been examining dozens of skeletons, a majority of whom appear to have been killed by archers using flint-tipped arrows.

...

Parallel research over recent years has also been shedding new light as to who, in ethnic and racial terms, these victims were.

Work carried out at Liverpool John Moores University, the University of Alaska and New Orleans’ Tulane University indicates that they were part of the general sub-Saharan originating population – the ancestors of modern Black Africans.

The identity of their killers is however less easy to determine. But it is conceivable that they were people from a totally different racial and ethnic group – part of a North African/ Levantine/European people who lived around much of the Mediterranean Basin.

The two groups – although both part of our species, Homo sapiens – would have looked quite different from each other and were also almost certainly different culturally and linguistically. The sub-Saharan originating group had long limbs, relatively short torsos and projecting upper and lower jaws along with rounded foreheads and broad noses, while the North African/Levantine/European originating group had shorter limbs, longer torsos and flatter faces. Both groups were very muscular and strongly built.

Rivers across the Sahara

PLoS ONE 8(9): e74834. doi:10.1371/journal.pone.0074834

Were Rivers Flowing across the Sahara During the Last Interglacial? Implications for Human Migration through Africa

Tom J. Coulthard et al.

Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times.

Link

Saharan dairying 7,000 years ago

Pottery shards put a date on Africa’s dairying

Yoghurt may have made it on to the menu for North Africans around 7,000 years ago, according to an analysis of pottery shards published today in Nature1.

The fermented dairy product left tell-tale traces of fat on the ceramic fragments, suggesting a way that the region’s inhabitants may have evolved to tolerate milk as adults.

The same team had previously identified the earliest evidence for dairying in potsherds nearly 9,000 years old from Anatolia2. But the findings from 7,000 years ago still predate the emergence and spread of the gene variants needed for the adult population to digest the lactose found in milk, says biomolecular archaeologist Richard Evershed of the University of Bristol, UK, who led the study with archaeological scientist Julie Dunne. He suggests that making yoghurt may have made dairy products more digestible.

Related: Earliest evidence for milk in the Near East and Southeastern Europe

Nature 486, 390–394 (21 June 2012) doi:10.1038/nature11186

First dairying in green Saharan Africa in the fifth millennium bc

Julie Dunne et al.

In the prehistoric green Sahara of Holocene North Africa—in contrast to the Neolithic of Europe and Eurasia—a reliance on cattle, sheep and goats emerged as a stable and widespread way of life, long before the first evidence for domesticated plants or settled village farming communities1, 2, 3. The remarkable rock art found widely across the region depicts cattle herding among early Saharan pastoral groups, and includes rare scenes of milking; however, these images can rarely be reliably dated4. Although the faunal evidence provides further confirmation of the importance of cattle and other domesticates5, the scarcity of cattle bones makes it impossible to ascertain herd structures via kill-off patterns, thereby precluding interpretations of whether dairying was practiced. Because pottery production begins early in northern Africa6 the potential exists to investigate diet and subsistence practices using molecular and isotopic analyses of absorbed food residues7. This approach has been successful in determining the chronology of dairying beginning in the ‘Fertile Crescent’ of the Near East and its spread across Europe8, 9, 10, 11. Here we report the first unequivocal chemical evidence, based on the δ13C and Δ13C values of the major alkanoic acids of milk fat, for the adoption of dairying practices by prehistoric Saharan African people in the fifth millennium BC. Interpretations are supported by a new database of modern ruminant animal fats collected from Africa. These findings confirm the importance of ‘lifetime products’, such as milk, in early Saharan pastoralism, and provide an evolutionary context for the emergence of lactase persistence in Africa.

Link

Back to (North) Africa (Henn et al. 2012)

A great new paper has just appeared, presenting new data, new conclusions about African prehistory, and new methodologies. I'll have to read it before I comment on it, but since it's open access you can read it for yourselves.

UPDATE I:


The new data are publicly available here, with information about samples here.
The new PCADMIX software is also available.

PLoS Genet 8(1): e1002397. doi:10.1371/journal.pgen.1002397 

Genomic Ancestry of North Africans Supports Back-to-Africa Migrations 

Brenna Henn et al.

 North African populations are distinct from sub-Saharan Africans based on cultural, linguistic, and phenotypic attributes; however, the time and the extent of genetic divergence between populations north and south of the Sahara remain poorly understood. Here, we interrogate the multilayered history of North Africa by characterizing the effect of hypothesized migrations from the Near East, Europe, and sub-Saharan Africa on current genetic diversity. We present dense, genome-wide SNP genotyping array data (730,000 sites) from seven North African populations, spanning from Egypt to Morocco, and one Spanish population. We identify a gradient of likely autochthonous Maghrebi ancestry that increases from east to west across northern Africa; this ancestry is likely derived from “back-to-Africa” gene flow more than 12,000 years ago (ya), prior to the Holocene. The indigenous North African ancestry is more frequent in populations with historical Berber ethnicity. In most North African populations we also see substantial shared ancestry with the Near East, and to a lesser extent sub-Saharan Africa and Europe. To estimate the time of migration from sub-Saharan populations into North Africa, we implement a maximum likelihood dating method based on the distribution of migrant tracts. In order to first identify migrant tracts, we assign local ancestry to haplotypes using a novel, principal component-based analysis of three ancestral populations. We estimate that a migration of western African origin into Morocco began about 40 generations ago (approximately 1,200 ya); a migration of individuals with Nilotic ancestry into Egypt occurred about 25 generations ago (approximately 750 ya). Our genomic data reveal an extraordinarily complex history of migrations, involving at least five ancestral populations, into North Africa.

Link

Activity patterns of Garamantes

A different paper on cranial nonmetric traits from the same team and on the same population (Garamantes).

From the current paper:

The study of the activity patterns of the Garamantes, a population that flourished at Central Sahara approximately 3,000 years ago, offers some interesting insights on the levels of stress imposed by a sedentary life in a hyper-arid environment. The population showed low bilateral asymmetry, possibly due to limited task specialization. Moreover, the Garamantes exhibited low sexual dimorphism in the upper limbs, which is consistent to the pattern found in agricultural populations and implies that the engagement of males in warfare  and construction works was not particularly intense. In the lower limbs, males were stronger in TA possibly as a result of their involvement in herding and mobility on the uneven terrain of Fezzan. Finally, the Garamantes did not appear systematically more robust than other North African populations occupying less harsh environments, indicating that life in the Sahara did not require particularly strenuous daily activities.

AJPA DOI: 10.1002/ajpa.21597

Activity patterns in the Sahara Desert: An interpretation based on cross-sectional geometric properties

Efthymia Nikita et al.

The Garamantian civilization flourished in modern Fezzan, Libya, between 900 BC and 500 AD, during which the aridification of the Sahara was well established. Study of the archaeological remains suggests a population successful at coping with a harsh environment of high and fluctuating temperatures and reduced water and food resources. This study explores the activity patterns of the Garamantes by means of cross-sectional geometric properties. Long bone diaphyseal shape and rigidity are compared between the Garamantes and populations from Egypt and Sudan, namely from the sites of Kerma, el-Badari, and Jebel Moya, to determine whether the Garamantian daily activities were more strenuous than those of other North African populations. Moreover, sexual dimorphism and bilateral asymmetry are assessed at an intra- and inter-population level. The inter-population comparisons showed the Garamantes not to be more robust than the comparative populations, suggesting that the daily Garamantian activities necessary for survival in the Sahara Desert did not generally impose greater loads than those of other North African populations. Sexual dimorphism and bilateral asymmetry in almost all geometric properties of the long limbs were comparatively low among the Garamantes. Only the lower limbs were significantly stronger among males than females, possibly due to higher levels of mobility associated with herding. The lack of systematic bilateral asymmetry in cross-sectional geometric properties may relate to the involvement of the population in bilaterally intensive activities or the lack of regular repetition of unilateral activities.

Link

Cranial nonmetric traits of Garamantes

Am J Phys Anthropol DOI: 10.1002/ajpa.21645


Sahara: Barrier or corridor? Nonmetric cranial traits and biological affinities of North African late holocene populations

Efthymia Nikita et al.

The Garamantes flourished in southwestern Libya, in the core of the Sahara Desert ∼3,000 years ago and largely controlled trans-Saharan trade. Their biological affinities to other North African populations, including the Egyptian, Algerian, Tunisian and Sudanese, roughly contemporary to them, are examined by means of cranial nonmetric traits using the Mean Measure of Divergence and Mahalanobis D2 distance. The aim is to shed light on the extent to which the Sahara Desert inhibited extensive population movements and gene flow. Our results show that the Garamantes possess distant affinities to their neighbors. This relationship may be due to the Central Sahara forming a barrier among groups, despite the archaeological evidence for extended networks of contact. The role of the Sahara as a barrier is further corroborated by the significant correlation between the Mahalanobis D2 distance and geographic distance between the Garamantes and the other populations under study. In contrast, no clear pattern was observed when all North African populations were examined, indicating that there was no uniform gene flow in the region.

Link

Is Jebel Irhoud the Father of mankind?

The redating of the human Y-chromosome phylogeny to about 142 thousand years ago and the relocation of its most ancient lineages from east and south Africa to the Northwest marks a watershed moment in our understanding of human prehistory.

It is a fortuitous coincidence that there actually is a sample of humans from Northwest Africa from around the same time: Jebel Irhoud, about 160 thousand years ago from Morocco:

Jebel Irhoud is a cave site located about 100 km west of Marrakech, Morocco. The site is known for the numerous hominid fossils discovered there. Currently, the site has yielded seven specimens. The best known of these are portions of two adult skulls, Irhoud 1 and 2, a child’s mandible (Irhoud 3), and a child’s humerus (Irhoud 4). Fossils 1-3 were discovered while the cave was being quarried for barytes and thus their exact context and age has been subject to debate. Originally the Irhoud hominids were considered North African Neandertals. It is now clear that they are best grouped with other early anatomically modern humans such as Qafzeh (Israel) and Skhul (Israel).

A 2007 article by Smith et al. is extremely important for this population:

Earliest evidence of modern human life history in North African early Homo sapiens

Tanya M. Smith et al.

Recent developmental studies demonstrate that early fossil hominins possessed shorter growth periods than living humans, implying disparate life histories. Analyses of incremental features in teeth provide an accurate means of assessing the age at death of developing dentitions, facilitating direct comparisons with fossil and modern humans. It is currently unknown when and where the prolonged modern human developmental condition originated. Here, an application of x-ray synchrotron microtomography reveals that an early Homo sapiens juvenile from Morocco dated at 160,000 years before present displays an equivalent degree of tooth development to modern European children at the same age. Crown formation times in the juvenile's macrodont dentition are higher than modern human mean values, whereas root development is accelerated relative to modern humans but is less than living apes and some fossil hominins. The juvenile from Jebel Irhoud is currently the oldest-known member of Homo with a developmental pattern (degree of eruption, developmental stage, and crown formation time) that is more similar to modern H. sapiens than to earlier members of Homo. This study also underscores the continuing importance of North Africa for understanding the origins of human anatomical and behavioral modernity. Corresponding biological and cultural changes may have appeared relatively late in the course of human evolution.

In the recent paper on the Ceprano calvarium, Irhoud 1 clearly belonged in the modern human cluster, and so it was in my re-analysis of that data, as were skulls from the Sudan and Tanzania in Africa, and the Qafzeh/Skhul early skulls from the Levant.

It thus seems to me, that the earliest modern human skulls are found in North/East Africa and West Asia, while the root of the Y-chromosome phylogeny is provisionally in Northwest Africa and seems to be in agreement with the autosomal evidence for a bottleneck in the human population at around 150,000 years ago.

Here is the interesting part: Irhoud had been once seen as a Neandertal. Indeed, it displayed some Neandertal-like leanings in a previous analysis. The consensus now (supported by the results of Mounier et al.) seems to be that it was modern human, but the Neandertal connection does not stop there:

The lithic industries of Jebel Irhoud were Mousterian, the same as Neandertals. Mousterian industries link European Neandertals, with modern humans in North Africa and the Near East. The Mousterian industries represented a genuine progress over the Acheulean tools that archaic humans had been using for hundreds of thousands of years before, and they, in turn, were replaced by the Aurignacian at exactly the time that Cruciani et al. date the main Y-chromosome CT clade that encompasses all Eurasians and most Africans.

The evidence seems to be in astonishing agreement with my hypothesis about the so-called "Neandertal admixture" in modern humans:

• Early modern humans originated in North Africa, or at least somewhere between North and East Africa. Their traces may very well be hidden under the sands of the once (or thrice) green Sahara
• They formed a clade with Neandertals, and used the same Mousterian tools, while humans elsewhere continued to use the older Acheulean ones. Both of them could very well have descended from Homo heidelbergensis, although the transition is not yet clear.
• They expanded briefly into West Asia after Marine Isotope Stage 5, 120,000 years or so ago, and appeared in the Levant (Skhul/Qafzeh). As the Sahara dried up, they must've spread both to West Asia, and deeper into Africa, and, not surprisingly, the next major branching of the Y-chromosome phylogeny dates to about that time; this accounts for the deep (but not deepest) Y-chromosome lineages in modern day San.
• Eventually (around 40,000 years ago, after the end of wet Marine Isotope Stage 3), they developed the even more advanced Aurignacian technology, and went on to conquer most of the world, driving the Neandertals to extinction. As the Sahara dried up, they expanded into Sub-Saharan Africa once again, and this time they inundated it with their genes.

Hence, the Modern-Neandertal affinity is not the result of any hypothetical admixture event between the two: Sub-Saharan Africans have also preserved some of the genetic legacy of the older Acheulean-using populations of the continent which shifts them somewhat away from other modern humans and Neandertals.

The model in brief

195 ka: Anatomically modern humans appear in East Africa (Omo skulls)

160 ka: Mousterian-using modern humans in North Afrca (Jebel Irhoud)

142 ka: Y-chromosome Adam

MIS 5 120-110 ka: Demographic expansion of modern humans in Sahara during this wet phase, followed by collapse as Sahara becomes dry; escape to West Asia and Sub-Saharan Africa; possible admixture with Neandertals and Acheulean-using Palaeoafricans respectively.

MIS 3 50-45 ka: Second demographic expansion of modern humans in Sahara, followed by collapse as Sahara becomes dry; development of Aurignacian

after 45 ka: Colonization of Eurasia and Sub-Saharan Africa by modern humans sensu stricto: anatomically and behaviorally modern people with advanced tools. Most human Y-chromosomes (belonging to C, DE, and F) coalesce to this period.

40 ka: Neandertals extinct after contact with modern humans (absorbed/killed?); some survive in periphery

Today: Most living humans descended from post 45-ka expansion people. Sub-Saharan Africans shift away from Eurasians due to a little archaic African admixture. Papuans shifted away from Eurasians due to "Denisovan" admixture. Contribution of other archaic hominins to regional Homo sapiens populations TBD.

mtDNA and trans-Saharan slave trade (Harich et al. 2010)

The main trans-Saharan slave routes are shown in Figure 1 (on the left). The paper also contains quite useful interpolation maps of the main Sub-Saharan African mtDNA haplogroups, who should be useful for future reference.

BMC Evolutionary Biology 2010, 10:138 doi:10.1186/1471-2148-10-138

The trans-Saharan slave trade - clues from interpolation analyses and high-resolution characterization of mitochondrial DNA lineages

Abstract

Background
A proportion of 1/4 to 1/2 of North African female pool is made of typical sub-Saharan lineages, in higher frequencies as geographic proximity to sub-Saharan Africa increases. The Sahara was a strong geographical barrier against gene flow, at least since 5,000 years ago, when desertification affected a larger region, but the Arab trans-Saharan slave trade could have facilitate enormously this migration of lineages. Till now, the genetic consequences of these forced trans-Saharan movements of people have not been ascertained.

Results
The distribution of the main L haplogroups in North Africa clearly reflects the known trans-Saharan slave routes: West is dominated by L1b, L2b, L2c, L2d, L3b and L3d; the Center by L3e and some L3f and L3w; the East by L0a, L3h, L3i, L3x and, in common with the Center, L3f and L3w; while, L2a is almost everywhere. Ages for the haplogroups observed in both sides of the Saharan desert testify the recent origin (holocenic) of these haplogroups in sub-Saharan Africa, claiming a recent introduction in North Africa, further strengthened by the no detection of local expansions.

Conclusions
The interpolation analyses and complete sequencing of present mtDNA sub-Saharan lineages observed in North Africa support the genetic impact of recent trans-Saharan migrations, namely the slave trade initiated by the Arab conquest of North Africa in the seventh century. Sub-Saharan people did not leave traces in the North African maternal gene pool for the time of its settlement, some 40,000 years ago.

Link

Wet phases in Sahara and migrations in North Africa

This is an open access article.

PNAS doi:10.1073/pnas.0905771106

Wet phases in the Sahara/Sahel region and human migration patterns in North Africa

Isla S. Castañeda et al.

Abstract

The carbon isotopic composition of individual plant leaf waxes (a proxy for C₃ vs. C₄ vegetation) in a marine sediment core collected from beneath the plume of Sahara-derived dust in northwest Africa reveals three periods during the past 192,000 years when the central Sahara/Sahel contained C₃ plants (likely trees), indicating substantially wetter conditions than at present. Our data suggest that variability in the strength of Atlantic meridional overturning circulation (AMOC) is a main control on vegetation distribution in central North Africa, and we note expansions of C₃ vegetation during the African Humid Period (early Holocene) and within Marine Isotope Stage (MIS) 3 (≈50–45 ka) and MIS 5 (≈120–110 ka). The wet periods within MIS 3 and 5 coincide with major human migration events out of sub-Saharan Africa. Our results thus suggest that changes in AMOC influenced North African climate and, at times, contributed to amenable conditions in the central Sahara/Sahel, allowing humans to cross this otherwise inhospitable region.

Link

Out of Africa via Libya and not the Nile?

Which way 'out of Africa'?
New evidence provides an alternative route 'out of Africa' for early humans

The widely held belief that the Nile valley was the most likely route out of sub-Saharan Africa for early modern humans 120,000 year ago is challenged in a paper published this week in the Proceedings of the National Academy of Sciences.

A team led by the University of Bristol shows that wetter conditions reached a lot further north than previously thought, providing a wet 'corridor' through Libya for early human migrations. The results also help explain inconsistencies between archaeological finds.

...

Anne Osborne, lead author on the paper said: "Space-born radar images showed fossil river channels crossing the Sahara in Libya, flowing north from the central Saharan watershed all the way to the Mediterranean. Using geochemical analyses, we demonstrate that these channels were active during the last interglacial period. This provides an important water course across this otherwise arid region." The critical 'central Saharan watershed' is a range of volcanic mountains formerly considered to be the limit of this wetter region.

...

Dr Derek Vance, senior author on the paper, added: "The study shows, for the first time, that monsoon rains fed rivers that extended from the Saharan watershed, across the northern Sahara, to the Mediterranean Sea. These corridors rivalled the Nile Valley as potential routes for early modern human migrations to the Mediterranean shores."

Climate history of the Sahara

Related press release

Reconstructing the climate of the past is an important tool for scientists to better understand and predict future climate changes that are the result of the present-day global warming. Although there is still little known about the Earth's tropical and subtropical regions, these regions are thought to play an important role in both the evolution of prehistoric man and global climate changes. New North African climate reconstructions reveal three 'green Sahara' episodes during which the present-day Sahara Desert was almost completely covered with extensive grasslands, lakes and ponds over the course of the last 120.000 years. The findings of Dr. Rik Tjallingii, Prof. Dr. Martin Claussen and their colleagues will be published in the October issue of Nature Geoscience.

...

The scientists were able to reconstruct the vegetation cover of the last 120.000 years by studying changes in the ratio of wind and river-transported particles found in the core. "We found three distinct periods with almost only river-transported particles and hardly any wind dust particles, which is remarkable because today the Sahara Desert is the world's largest dust-bowl," says Rik Tjallingii.

Nature Geoscience doi:10.1038/ngeo289

Coherent high- and low-latitude control of the northwest African hydrological balance

Rik Tjallingii et al.

Abstract

The evolution of the northwest African hydrological balance throughout the Pleistocene epoch influenced the migration of prehistoric humans1. The hydrological balance is also thought to be important to global teleconnection mechanisms during Dansgaard–Oeschger and Heinrich events2. However, most high-resolution African climate records do not span the millennial-scale climate changes of the last glacial–interglacial cycle1, 3, 4, 5, or lack an accurate chronology6. Here, we use grain-size analyses of siliciclastic marine sediments from off the coast of Mauritania to reconstruct changes in northwest African humidity over the past 120,000 years. We compare this reconstruction to simulations of palaeo-humidity from a coupled atmosphere–ocean–vegetation model. These records are in good agreement, and indicate the reoccurrence of precession-forced humid periods during the last interglacial period similar to the Holocene African Humid Period. We suggest that millennial-scale arid events are associated with a reduction of the North Atlantic meridional overturning circulation and that millennial-scale humid events are linked to a regional increase of winter rainfall over the coastal regions of northwest Africa.

Link

Kiffians and Tenerians from the Sahara

From the NY Times:

From an analysis of the skeletons and pottery in those two seasons, scientists identified the two successive cultures that occupied the settlement. The Kiffians, some of whom stood up to six feet tall, both men and women, lived there during the Sahara’s wettest period, between 10,000 and 8,000 years ago. They were primarily hunter-gatherers who speared huge lake perch with harpoons.

...

Elena A. A. Garcea, an archaeologist at the University of Cassino in Italy, identified ceramics with wavy lines and zigzag patterns as Kiffian, a culture associated with northern Africa. Pots bearing a pointillistic pattern were linked to the Tenerians, a people named for the Ténéré Desert, a stretch of the Sahara known to Tuareg nomads as a “desert within a desert.”

Christopher M. Stojanowski, an archaeologist at Arizona State University, said the two cultures were “biologically distinct groups.” The bones and teeth showed that in contrast to the robust Kiffians, the Tenerians were typically short and lean and apparently led less rigorous lives. Perhaps, Dr. Stojanowski said, they had developed more advanced hunting technologies for taking smaller fish and game.

The shapes of the Tenerian skulls are puzzling, researchers said, because they resemble those of Mediterranean people, not other groups from the southern Sahara.

PLoS ONE 3(8): e2995. doi:10.1371/journal.pone.0002995

Lakeside Cemeteries in the Sahara: 5000 Years of Holocene Population and Environmental Change

Paul C. Sereno et al.

Background

Approximately two hundred human burials were discovered on the edge of a paleolake in Niger that provide a uniquely preserved record of human occupation in the Sahara during the Holocene (~8000 B.C.E. to the present). Called Gobero, this suite of closely spaced sites chronicles the rapid pace of biosocial change in the southern Sahara in response to severe climatic fluctuation.

Methodology/Principal Findings

Two main occupational phases are identified that correspond with humid intervals in the early and mid-Holocene, based on 78 direct AMS radiocarbon dates on human remains, fauna and artifacts, as well as 9 OSL dates on paleodune sand. The older occupants have craniofacial dimensions that demonstrate similarities with mid-Holocene occupants of the southern Sahara and Late Pleistocene to early Holocene inhabitants of the Maghreb. Their hyperflexed burials compose the earliest cemetery in the Sahara dating to ~7500 B.C.E. These early occupants abandon the area under arid conditions and, when humid conditions return ~4600 B.C.E., are replaced by a more gracile people with elaborated grave goods including animal bone and ivory ornaments.

Conclusions/Significance

The principal significance of Gobero lies in its extraordinary human, faunal, and archaeological record, from which we conclude the following:

1. The early Holocene occupants at Gobero (7700–6200 B.C.E.) were largely sedentary hunter-fisher-gatherers with lakeside funerary sites that include the earliest recorded cemetery in the Sahara.

2. Principal components analysis of craniometric variables closely allies the early Holocene occupants at Gobero with a skeletally robust, trans-Saharan assemblage of Late Pleistocene to mid-Holocene human populations from the Maghreb and southern Sahara.

3. Gobero was abandoned during a period of severe aridification possibly as long as one millennium (6200–5200 B.C.E).

4. More gracile humans arrived in the mid-Holocene (5200–2500 B.C.E.) employing a diversified subsistence economy based on clams, fish, and savanna vertebrates as well as some cattle husbandry.

5. Population replacement after a harsh arid hiatus is the most likely explanation for the occupational sequence at Gobero.

6. We are just beginning to understand the anatomical and cultural diversity that existed within the Sahara during the Holocene.

Link