In Africa is a five-year research programme to investigate the origins of our species – Homo sapiens – and its diversity in Africa, and aims at making new discoveries of early human fossils, archaeological sites and their environmental context in East Africa to test models of human origins and diversification in Africa. In Africa has two field projects in Kenya – one focused on the Turkana Basin and one on the Central Rift Valley.
Genetic and fossil evidence tells us that our species, Homo sapiens, evolved in Africa in the last 200,000 years, and spent the first 70% of its history within the continent. So to try to understand what selective pressures gave rise to human adaptations – both biological and behavioural, as well as the demographic circumstances that shaped our history, we need to understand (1) what happened in Africa before modern humans evolved, (2) the conditions, competition and resources available in different parts of the continent when modern humans first lived there, and (3) why, when and how the ancestral human populations began to diversified into different groups that looked and behaved differently from each other. Understanding all three of these aspects of our history is critical for piecing together the story of how we became the species we are, how we came to look different from each other, and why some people left Africa while others did not. Yet, while evidence for other aspects of the history of our species continues to grow – such as the dispersal of humans out of Africa, information about Neanderthal adaptations and their interactions with H. sapiens, or our understanding of the selective effects of high latitude palaeoclimates, the knowledge of what happened in Africa during this time remains a challenge.
Part of this challenge is because the African continent is so large. The area of Africa is approximately 30,200 million km2 – the equivalent of the sum of the areas of China, Japan, India, the United States, and most of Europe. Considering this size, what we know of the prehistory of the continent is extremely small. Indeed, Africa is probably the continent with the least known fossil and archaeological record of Homo sapiens.
We do not know where in Africa modern humans evolved. The earliest fossils of Homo sapiens were found in Ethiopia, but the earliest evidence of complex behaviours – technical innovations in stone-tool technology, the use of ornaments and bone tools, etc. – have so far been found in North and South Africa. These suggest complex mechanisms of social, cultural and cognitive change, and understanding their roots in the earlier archaeological record is again critical to understand why and how early humans were changing their behaviour.
In East Africa there are very few known fossil and archaeological sites dating to this period. Yet, knowing what happened in East Africa at the time is particularly important. With its unique mosaic environment structured by lake basins, highlands and plains, East Africa continuously offered alternative niches to foraging populations, while the timings of tropical droughts may have set in place push-pull mechanisms for the local survivorship of populations and subsequent expansions elsewhere. Also, the little that is known from East Africa in the last 200,000 years suggests that early human populations lived there. The challenge is to find the sites where evidence of these early people can be recovered – their stone tools, the animals they hunted, their ornaments, ultimately the fossils of the people themselves.
Why in Africa?
Current research in modern human evolution in Africa stresses the exciting potential for understanding how climate change, African palaeo-environments and human demographic adaptability interacted to shape the biological and behavioural evolution of our species. However, comparatively little is know about the prehistory and biological variation of early modern humans in Africa, and even less about the early history of African populations. Many projects are devoted to the study of human evolution and to finding new fossils and archaeological sites in Africa. But with a 5, and perhaps 7 million year history, and a huge continent, the task is vast. A major scientific initiative is needed to discover new fossils of Homo sapiens in Africa and the material record of their behaviour – our project, ‘In Africa’, contributes to this initiative through its field expeditions to the Turkana Basin and Central Rift Valley of Kenya.