For most of us who were a little attentive at elementary school. You must have heard of the cradle of mankind and how it is located somewhere is Africa. To be more specific there are two regions in Africa that claim that title. The Afar depression, that spans through the countries of Eretria, Djibouti and Ethiopia has been commonly been considered the first human ancestral home. However, findings from other parts of Africa tend to dispute this point of view. Such as, the UNESCO world heritage site located 50 km northwest South Africa that comprises a series of limestone caves that account for over 1,500 H. naledi Fossils and a 2.3-million-year-old hominid fossil. These findings have helped give the 47,000-area region the name “Cradle of mankind”. Despite being given the name, the region did not host the oldest ever hominid fossils, which were found in Chad and date as old as 7.0 million years. Since hominin fossils are distributed all around Africa, it is hard to pin point the actual cradle land for human kind.
If we first lived in Africa, how did we find ourselves in the other parts of the world. How did we move to Europe, Asia, and places as distant as the Americas? More importantly why did we move to these locations?
One big problem with dealing with prehistory is that we are explaining things that have not been historically documented. Furthermore, even the documented part of history might be biased as it only tells the tales of the victor. The interpretation can also be affected by the evolution of language where our interpretations may differ with the authors interpretations. Nevertheless, fairly accurate historical narratives can be formed from the study of fossils, linguistics, and genetics.
The evolution of early hominids can be explained by the savannah hypothesis which argues that climate change forced early hominids from trees, thus making them more adaptable to living on the ground. It was at 2.3 million years ago that the first hominid (Homo erectus) started moving out of Africa into the Eurasia Subcontinent.
Where are all the other hominids? That’s the principal question that most creationists will attack me with as I try to create this narrative of human movement. To answer that question, I would like to address the issue of extinction. Simply other early hominids might not be visible due to extinction events. Extinction can occur due to predation or even unfavorable environments. The most recent extinct species include St Helena Olive tree (2004), The Golden Toad (1989), and Tasmanian wolf (1936). Currently, there are over 15,000 endangered species whose extinction rate may be 100X or 1000X above the baseline rate. The discovery of H. Naledi also helped bring out a new perspective on the existence of hominid species. In this case, the dating of H. Naledi coincided was traced back to 300,000 years, a time period when H. Sapiens still roamed the earth’s surface. The existence of multiple species of man at the same time period shows the graduality of evolution and how it relates to adaptability and extinction.
Most significant, were the hunting strategies of some of the extinct hominid species. Archeological evidence showed that Hominids, such as the Neanderthal man used direct hunting methods where they ambushed large animals with man made spears. These hunting methods not only increased their survival risk, but also accelerated the decline of these food sources. As food sources became scarce so did their ability of surviving the environment.
The extinction of Neanderthals could also be attributed their social characteristics. It has been hypothesized that Neanderthal population was less than <100,000. These population were not localized but dispersed in different groups. Thus, there was low genetic diversity among these species. More interesting is how the mass extinction of Neanderthals corresponded with the arrival of H. Sapiens in Europe. The extinction could be attributed to a series of factors such as increased competition or even incidence of new diseases. Genetic evidence gives a different story. The analysis of Neanderthals showed that they shared many genes such as the FOXP2 which is responsible for the development of linguistic skills. Further, the neanderthal genes are still present in most European and Asian population. However, these genes are not present in native Africans.
The case of Neanderthals helps clarify the movement of H. Sapiens from Africa to the rest of the world. The movement is believed to have started between 70,000 – 100,000 years ago. The reasons for the movement can never be established, lest if the death can talk, but can be attributed to a series of factors. One of the key factors for the migration is the drying in the horn of 70,000 years ago that can be observed in some of the sediments derived from the Gulf of Aden. The examination shows that there was a significant climatic shift that saw the deterioration of weather conditions from a warm to a much drier climate.
Now that were have clarified why the Neanderthals are missing let’s try mapping our movements in early history. The first migrations out of Africa were those of the Homo Erectus who were then followed by the later hominids such as the H. heidelbergensis, (assumed to be the ancestors of Denisovans and Neanderthals). The Denisovans dominated the Asian regions. Evidence of Denisovans can be proved through DNA analysis whereby their DNA have been found in Papuan, Micronesian and aboriginal Australians. The Neanderthals, on the other hand, dominated most of the European regions. The migration of H. Erectus is believed to have proceeded through the Levantine corridor and the Horn of Africa. These migrations could account for the H. Erectus fossils observed in Gongwangling, China, Riwat, Pakistan and Ubeidiya, Jordan.
The modern man, H. Sapiens is believed to have emerged between 260 – 350 after the merging of Africa and South Africa Hominids. Expansions were mostly dominated to the to the Southern and central Africa regions. These expansions led to the recording of two major Ancestral clusters, one associated to southern Africa and another associated with Eastern Africa. A theory on expansion to west Africa cannot be clearly formulated owing to the Scarcity of Archeological Evidence.
Migration to the levant and Europe has been dated between 115,000 and 300,000 years ago. These expansions have been hypothesized to have reached China as early as 125,000 years ago. Though archeological evidence is still limited. Nonetheless, expansion of modern human populations were dominant starting 50,000 years Ago. For instance, H sapiens colonized Australia as early as 50, years ago surpassing the boundaries reached by H. Erectus. On the hand, expansion to the American Subcontinent is estimated at 25,000 – 15,000 year ago.
Overall, it is evident that the expansion of Humans was not structured but occurred in phases. However, it is evident that the ancestry modern human can be traced back to East African and Sothern African roots. Thus, if we wanted to understand the first man, then these would be the areas we would look at. But again, there’s that grand dilemma. When can we fully classify a species to be human like enough to be identified as one of us?
Sources
Waltham, T. (2009). Afar triangle: rift valleys and volcanoes over plate divergence. In Geomorphological Landscapes of the World (pp. 183-190). Springer, Dordrecht.
The Tjay pod 