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When did humans first start roaming the earth about how many years ago ?
Answer 1:

Well it depends somewhat on how one defines the term Human. A paleoanthropologist would say that the first true human goes by the name Homo sapiens. This gives the genus, the species and the variety, words that have very specific meanings in biology and evolutionary theory.

According to genetic and fossil evidence, archaic homo sapiens sapiens evolved to anatomically modern humans in Africa roughly 200,000 to 100,000 years ago. Members of one branch, perhaps driven by the quest for new environments and resources?, left Africa by 60,000 years ago and over time replacing earlier human populations such as Neanderthals and Homo erectus .

Before this time, paleontologists can trace the origins of the genus Homo back for 2 or three million years based on fossils and sophisticated work that can be done with fossil material. But these primates looked considerably different than modern man (Homo sapiens sapiens).

As an example of the nomenclature, consider the Neanderthals. Where do they fit in in detail? For some time, paleoanthropologists have debated whether Neanderthals should be classified as Homo neanderthalensis or Homo sapiens neanderthalensis, the latter placing Neanderthals as a subspecies of H. sapiens. Some morphological studies support the view that H. neanderthalensis is a separate species and not a subspecies. Others, say "no evidence has been found of cultural interaction” and evidence from mitochondrial DNA studies has been interpreted as evidence Neanderthals were not a subspecies of H. sapiens. This sort of disagreement between experts is part of the refining process of science in general. There is always a quest for more information and new studies. For example, discovery of new hominid fossils can change the present ‘best guess”.

The good news is that science operates by successive approximation and when things go well each new piece of information makes our understanding more complete.

Answer 2:

The oldest fossils of modern humans (Homo sapien sapien) were found along the Omo River, near the village of Kibish, in southern Ethiopia. We know the age of these fossils by using various geochronological (age-dating) methods to date the rocks in which these fossils were found. The Omo I and Omo II skeletons have been determined to be 195,000 years old.

So, we know that the latest that modern humans evolved was 195,000 years ago. It is possible it was earlier, but either we haven't yet found those fossils or those fossils have been destroyed by natural processes. Other fossil evidence (like the Laitoli Trackway) indicates that by 120,000 to 115,000 years ago, modern humans had spread throughout Africa. By 100,000 years ago, humans had made their way into Asia, and were established in Europe by about 60,000 years ago.

Answer 3:

Species of human-like animal (e.g. neanderthals) began leaving Africa in the last two million years. Our own species left Africa somewhere between 100,000 and 50,000 years ago. Whether you consider these other creatures to be humans depends on your definition of what is human and what is not.

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