The origins and migrations of modern humans around the world are a hot topic of debate. Genetic analyses have pointed to Africa as the continent from which our ancestors dispersed in the Late Pleistocene epoch, which began about 126,000 years ago. Various dispersal routes have been suggested.
As a group of scientists who have been studying human evolution, we propose in a recently published review paper that the coast of southern Africa was likely where Homo sapiens began this worldwide journey. We suggest that some people started leaving this area about 70,000 years ago, took a route along the east coast and left the continent about 50,000 to 40,000 years ago.
We base this hypothesis on various kinds of evidence, including geography, climate and environment, marine food resources, genetics, trace fossils, and the technical and cultural abilities of people in that region at that time. The reasons for migration and the advantages of a coastal route out of Africa, compared to an inland route, are outlined in our review.
This proposed route is counter to the current belief among most scientists that the Out-of-Africa migration began in eastern Africa and not southern Africa.
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A southern Cape origin?
In our review we accepted that modern humans arose in Africa during the Middle Stone Age about 200,000 years ago and then replaced populations of hominins outside the continent between 60,000 and 40,000 years ago.
We suggested that their African origin was in the southern Cape region of what’s now South Africa, and that their migration along the eastern African coastline and onto the Arabian Peninsula may have happened over a period of less than 20,000 years.
In reviewing available evidence, we focused on the possibility that our ancestors in coastal South Africa were ideally placed to colonise the world. They had an enabling culture that allowed them to survive almost anywhere.
The Pinnacle Point cave complex and other sites in this area are a UNESCO World Heritage Site because they provide the most varied and best-preserved record known of the development of modern human behaviour, reaching back as far as 162,000 years.
Food from the sea, like shellfish, set southern Cape Homo sapiens on their evolutionary path to becoming advanced modern humans. They had an advantage over those who relied solely on hunting and food gathering inland, especially during cold and dry periods on the African subcontinent. The harnessing of bow and arrow technology was also key for their success when compared to other hominins during the same period.
Climate and culture
Episodes of global cooling, also known as ice ages, resulted in a global lowering of sea levels, and had two main effects in Africa. One was that the width of the Red Sea between the Horn of Africa and the Arabian Peninsula narrowed. The other was that in the southern Cape, a vast coastal plain was exposed, providing extra habitat and plenty of food.
Increased cognitive capacity to interpret lunar cycles would have allowed ancestral humans to undertake timed excursions to the shore over spring tidal periods. The predictable coastal food sources might also, however, have led to inter-group conflict and territoriality, which could have played a role in the exodus of groups of people from the southern Cape.
In other parts of the world, there was a cold, dry period from 190,000 years to 130,000 years ago. And the dark, long “winter” after the Mount Toba (Indonesia) super-eruption 74,000 years ago would have reduced food resources in tropical regions. Hominins in the southern Cape appear to have survived these major global climate change events and continued to advance both culturally and technologically. We know something about these advances from research at cave sites such as Klasies River, Blombos and Pinnacle Point. Forms of ancient art have been found in these caves, indicating cognitively advanced humans.
Technical advances meant that the tools carried by these people on their journey were “state of the art” for 70,000 years ago – more advanced than those possessed by other humans encountered on their migration northwards.
Evidence mounts
In summary, the idea of a coastal migration out of Africa is based on:
- the earliest evidence for humans consuming seafood and developing adaptations for living close to the sea shore about 162,000 years ago
- the first evidence of dedicated coastal foraging for seafood, which may have enhanced our ancestors’ cognitive capacity
- the first “recipes” in early human food preparation around 82,000 years ago
- among the earliest reports of bone tool technology from around 100,000 years ago, which may have been used to make complex clothing and shoes
- the regular use of pigments such as red ochre as early as 162,000 years ago
- palaeoart in the form of engravings in ochre dated 100,000 to 85,000 years ago, and a drawing using an ochre crayon dated to 73,000 years ago
- the earliest evidence for making small stone blades around 71,000 years ago
- the earliest evidence for heat treatment of stone to produce advanced tools and weapons
- use of jewellery for adornment
- survival during a period of climate change following the Mount Toba eruption
- complementary evidence from the trace fossil (ichnology) record from the same region and time period. This includes the oldest reported use of sticks by humans, and the oldest reported evidence of humans jogging or running.
When the era of global cooling ended about 18,000 years ago and sea levels rose again, almost all of this Pleistocene landscape would have been covered by water. So it’s remarkable that so much evidence still exists.
There is no equivalent evidence of an advanced modern human presence from eastern Africa or anywhere else in the world.
Why migrate?
Why would some people choose to move and migrate? It is likely that increasing pressure from successful, growing, competing bands of humans, combined with climatic and environmental changes and a limited number of suitable cave occupation sites, provided a trigger for an initial eastward and then north-eastward migration.
At the same time, advanced cognition skills would have permitted increasing intra-group co-operation, enabling these humans to make their remarkable journey.
We think a coastal migration up and out of Africa was more likely to succeed than an overland migration. The reasons include the availability of seafood, fresh water, level ground, warm temperatures and fewer big, dangerous animals along the intertidal coastline. It seems there weren’t other people in the way either: for example, there is no evidence of an equivalent culture associated with the sea on the eastern coast of Africa.
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The lack of suitable coastal caves to live in north of South Africa may have encouraged human clans to keep moving up the coast.
Out of Africa
The exit from the Horn of Africa into the Arabian Peninsula was distinctly feasible from 60,000 years ago onwards. Records from the Red Sea indicate that sea levels in the region were about 100 metres below present levels 65,000 years ago.
Our examination of the available evidence points to the southern Cape coast as a cradle of modern human development. The people of this region were ideally placed 70,000 years ago to undertake a quick and effective migration out of Africa, and then around the world.
Alan Whitfield, Emeritus Chief Scientist, NRF-SAIAB, National Research Foundation
Charles Helm, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela University
Francis Thackeray, Honorary Research Associate, Evolutionary Studies Institute, University of the Witwatersrand
Renee Rust, Research fellow, Department of Geography, Archaeology & Environmental Studies, University of the Witwatersrand; Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela University
Willo Stear, Research Associate, African Centre for Coastal Palaeoscience, Nelson Mandela University
