Population history of West Africa

The population history of West Africa is composed of West African populations that were considerably mobile and interacted with one another throughout the history of West Africa. Acheulean tool-using archaic humans may have dwelled throughout West Africa since at least between 780,000 BP and 126,000 BP (Middle Pleistocene). During the Pleistocene, Middle Stone Age peoples (e.g., Iwo Eleru people, possibly Aterians), who dwelled throughout West Africa between MIS 4 (71,000 BP) and MIS 2 (29,000 BP, Last Glacial Maximum), were gradually replaced by incoming Late Stone Age peoples, who migrated into West Africa as an increase in humid conditions resulted in the subsequent expansion of the West African forest. West African hunter-gatherers occupied western Central Africa (e.g., Shum Laka) earlier than 32,000 BP, dwelled throughout coastal West Africa by 12,000 BP, and migrated northward between 12,000 BP and 8000 BP as far as Mali, Burkina Faso, and Mauritania.

During the Holocene, Niger-Congo speakers independently created pottery in Ounjougou, Mali – the earliest pottery in Africa – by at least 9400 BCE, and along with their pottery, as well as wielding independently invented bows and arrows, migrated into the Central Sahara, which became their primary region of residence by 10,000 BP. The emergence and expansion of ceramics in the Sahara may be linked with the origin of Round Head and Kel Essuf rock art, which occupy rockshelters in the same regions (e.g., Djado, Acacus, Tadrart). Hunters in the Central Sahara farmed, stored, and cooked undomesticated central Saharan flora, underwent domestication of antelope, and domesticated and shepherded Barbary sheep. After the Kel Essuf Period and Round Head Period of the Central Sahara, the Pastoral Period followed. Some of the hunter-gatherers who created the Round Head rock art may have adopted pastoral culture, and others may have not. As a result of increasing aridification of the Green Sahara, Central Saharan hunter-gatherers and cattle herders may have used seasonal waterways as the migratory route taken to the Niger River and Chad Basin of West Africa. In 2000 BCE, "Thiaroye Woman", also known as the "Venus of Thiaroye," may have been the earliest statuette created in Sub-Saharan West Africa; it may have particularly been a fertility statuette, created in the region of Senegambia, and may be associated with the emergence of complexly organized pastoral societies in West Africa between 4000 BCE and 1000 BCE. Though possibly developed as early as 5000 BCE, Nsibidi may have also developed in 2000 BCE, as evidenced by depictions of the West African script on Ikom monoliths at Ikom, in Nigeria. Migration of Saharan peoples south of the Sahelian region resulted in seasonal interaction with and gradual absorption of West African hunter-gatherers, who primarily dwelt in the savannas and forests of West Africa. In West Africa, which may have been a major regional cradle in Africa for the domestication of crops and animals, Niger-Congo speakers domesticated the helmeted guineafowl between 5500 BP and 1300 BP; domestication of field crops occurred throughout various locations in West Africa, such as yams (d. praehensilis) in the Niger River basin between eastern Ghana and western Nigeria (northern Benin), rice (oryza glaberrima) in the Inner Niger Delta region of Mali, pearl millet (cenchrus americanus) in northern Mali and Mauritania, and cowpeas in northern Ghana. After having persisted as late as 1000 BP, or some period of time after 1500 CE, remaining West African hunter-gatherers, many of whom dwelt in the forest-savanna region, were ultimately acculturated and admixed into the larger groups of West African agriculturalists, akin to the migratory Bantu-speaking agriculturalists and their encounters with Central African hunter-gatherers.

With the emergence of the West African Iron Age, iron metallurgy developed in ancient West African civilizations, such as Tichitt culture and Nok culture. Following the flourishing of Iron Age West African civilizations, periods of mass enslavement, such as the Trans-Atlantic slave trade, contributed to the depopulation of West Africa. At least 6,284,092 West Africans are estimated to have been enslaved and taken captive during the Trans-Atlantic slave trade; along with Africans enslaved and taken captive in other embarking regions of Africa, such as Central Africa and Southern Africa, as well as between at least 12% and 13% of enslaved Africans taken captive estimated to have died during the Middle Passage, the overall number of Africans enslaved and taken captive during the Trans-Atlantic slave trade is estimated to have been at least 12,521,335. During the modern period, the population of West Africa is estimated to have increased from 69,564,958 in 1950 CE to 413,340,896 in 2021 CE.

Climate

Early Stone Age

In the Falémé River Valley zone, with the exception of stadial phases and interstadial phases, there has been a fairly steady state of humidity and temperature throughout a span of 120,000 years. Additionally, for at least the previous 100,000 years, the presence of flora (e.g., trees) has remained quite consistent. Consequently, this region has remained habitable for human populations, from the Early Stone Age, through the Middle Stone Age, to the Later Stone Age. Furthermore, for the previous 100,000 years, compared to the climate of East Africa, the Pleistocene climate in West Africa has been more steady and humid.

In the Atakora mountainous zone, the Pleistocene climate has supported continuity in human habitation, from the Early Stone Age, through the Middle Stone Age, to the Later Stone Age, which spanned the previous 120,000 years.

Middle Stone Age

In the Falémé River Valley zone, with the exception of stadial phases and interstadial phases, there has been a fairly steady state of humidity and temperature throughout a span of 120,000 years. Additionally, for at least the previous 100,000 years, the presence of flora (e.g., trees) has remained quite consistent. Consequently, this region has remained habitable for human populations, from the Early Stone Age, through the Middle Stone Age, to the Later Stone Age. Furthermore, for the previous 100,000 years, compared to the climate of East Africa, the Pleistocene climate in West Africa has been more steady and humid.

In the Jos Plateau zone, the Pleistocene climate has fluctuated mostly during stadial phases and interstadial phases, throughout the previous 120,000 years; specifically, stable climate occurred between MIS 4 and MIS 2, and climate fluctuations occurred during the periods and sub-periods of MIS 1 and MIS 5. Consequently, the human habitation in Jos Plateau, which is only composed of Middle Stone Age sites, has been distinct in terms of culture and environment in comparison to the Falémé River Valley.

In the Atakora mountainous zone, the Pleistocene climate has supported continuity in human habitation, from the Early Stone Age, through the Middle Stone Age, to the Later Stone Age, which spanned the previous 120,000 years.

Later Stone Age

In the Falémé River Valley zone, with the exception of stadial phases and interstadial phases, there has been a fairly steady state of humidity and temperature throughout a span of 120,000 years. Additionally, for at least the previous 100,000 years, the presence of flora (e.g., trees) has remained quite consistent. Consequently, this region has remained habitable for human populations, from the Early Stone Age, through the Middle Stone Age, to the Later Stone Age. Furthermore, for the previous 100,000 years, compared to the climate of East Africa, the Pleistocene climate in West Africa has been more steady and humid.

In the Atakora mountainous zone, the Pleistocene climate has supported continuity in human habitation, from the Early Stone Age, through the Middle Stone Age, to the Later Stone Age, which spanned the previous 120,000 years.

In 15,000 BP, the West African monsoon transformed the landscape of Africa and began the Green Sahara period; greater rainfall during the summer season resulted in the growth of humid conditions (e.g., lakes, wetlands) and the savanna (e.g., grassland, shrubland) in North Africa. Between 5500 BP and 4000 BP, the Green Sahara period ended.

Pastoral Neolithic

By 4500 BP, sources of water in the Sahara had dried, and subsequently, drought occurred, which resulted in a decrease in the presence of humidity in the region. Concurrent with the decrease of humidity in the Sahara, between 3500 BP and 2500 BP, there was an increase of humidity in the Sahel.

Iron Age

During the 1st millennium cal BCE, between the Later Stone Age and Early Iron Age, the environment was conducive for the growth of pearl millet in the Lake Chad Basin.

Material culture and archaeological data

Early Stone Age

Acheulean tool-using archaic humans may have dwelled throughout West Africa since at least between 780,000 BP and 126,000 BP (Middle Pleistocene).

Middle Stone Age

Middle Stone Age West Africans likely dwelled continuously in West Africa between MIS 4 and MIS 2 and likely were not present in West Africa before MIS 5. Amid MIS 5, Middle Stone Age West Africans may have migrated across the West Sudanian savanna and continued to reside in the region (e.g., West Sudanian savanna, West African Sahel). In the Late Pleistocene, Middle Stone Age West Africans began to dwell along parts of the forest and coastal region of West Africa (e.g., Tiemassas, Senegal). More specifically, by at least 61,000 BP, Middle Stone Age West Africans may have begun to migrate south of the West Sudanian savanna, and, by at least 25,000 BP, may have begun to dwell near the coast of West Africa. Amid aridification in MIS 5 and regional change of climate in MIS 4, in the Sahara and the Sahel, Aterians may have migrated southward into West Africa (e.g., Baie du Levrier, Mauritania; Tiemassas, Senegal; Lower Senegal River Valley).

Later Stone Age

Earlier than 32,000 BP, or by 30,000 BP, Late Stone Age West African hunter-gatherers were dwelling in the forests of western Central Africa (e.g., earlier than 32,000 BP at de Maret in Shum Laka, 12,000 BP at Mbi Crater). An excessively dry Ogolian period occurred, spanning from 20,000 BP to 12,000 BP. By 15,000 BP, the number of settlements made by Middle Stone Age West Africans decreased as there was an increase in humid conditions, expansion of the West African forest, and increase in the number of settlements made by Late Stone Age West African hunter-gatherers. Macrolith-using late Middle Stone Age peoples (e.g., the possibly archaic human admixed or late-persisting early modern human Iwo Eleru fossils of the late Middle Stone Age), who dwelled in Central Africa, to western Central Africa, to West Africa, were displaced by microlith-using Late Stone Age Africans (e.g., non-archaic human admixed Late Stone Age Shum Laka fossils dated between 7000 BP and 3000 BP) as they migrated from Central Africa, to western Central Africa, into West Africa. Between 16,000 BP and 12,000 BP, Late Stone Age West Africans began dwelling in the eastern and central forested regions (e.g., Ghana, Ivory Coast, Nigeria; between 18,000 BP and 13,000 BP at Temet West and Asokrochona in the southern region of Ghana, 13,050 ± 230 BP at Bingerville in the southern region of Ivory Coast, 11,200 ± 200 BP at Iwo Eleru in Nigeria) of West Africa. By 11,000 BP, the late settlement made by Middle Stone Age West Africans and earliest settlement made by Late Stone Age West African hunter-gatherers emerged in the westernmost region (e.g., Falémé Valley, Senegal) of West Africa. Middle Stone Age West Africans and Late Stone Age West African hunter-gatherers likely did not become admixed with one another and were culturally and ecologically distinct from one another.