Three Major Hypothesis

I. Location of the Transition to Modern Humans

By the Middle Pleistocene, Homo heidelbergensis was spead out in Africa, Europe and Asia. Into modern humans evolved one or more of these populations. There is an argument weather modern humans originated in Africa, or the transition to modern humans was a worldwide phenomenon. Multiregional evolution model shows that human evolution took place within one lineage over the past 2 million years, from H. erectus, to H. heidelbergensis, to H. sapiens. Opponents say that human anatomy took place piecemeal across the Old World, with some changes, and modern humans resulting through the mixing of these changes through gene flow. The hypothesis of African origin states that human anatomy appeared first in Africa and then spread across the Old World. Fossil record supports the African origin hypothesis.

II. Replacement

According to African replacement model, modern humans emerged as new species in Africa about 200, 000 years ago and started to spread through the Old World, replacing preexisting human populations outside of Africa which became extinct and are not part of our ancestry.

III. Assimilation

Assimilation model proposes that the initial change took place in Africa, however changes were spread to other populations outside of Africa through gene flow. Genes got mixed, but not replaced.

Homo Neanderthalsis has been considered as a separate branch of human evolution. We do not have enough evidence to make any conclusions about Sahelanthropus tchadensis, so far, it is the one and the oldest specie with human like features. They are very important for understanding hominin evolution. We need to know where did we come from, so sometime we can understand where do we go. It is very important to know about our early ancestors and other human-like creatures which lived in the past for our own evolution and understanding of who we are and what makes us special, how can we survive and not extinct like they did.

A fossil of a 24,500-year-old early modern human child unearthed in Portugal shows distinctive Neanderthal characteristics, possibly the result of interbreeding. After that, all record vanish. Although DNA tests show that modern humans and neanderthals diverged from a common ancestor more than 500,000 years ago and that modern humans do not carry neanderthal genes and so did not interbreed when they encountered each other 50,000 years ago, the discovery of possible hybrids suggests that we still have not fully completed the Neanderthal story.

There is not much record about Saelanthropus tchadensis and his relatedness to modern humans. However, more we study and search, more we find out and with every single thing our world outlook can become 100% different.