The human species is exceptionally widespread, mainly due to our superior capacity in overcoming changing climatic conditions. We have colonised almost the entire land mass of the earth, a tremendous achievement in itself. We are the most formidible and successful coloniser amongst the mammals, in planet earth's history, and are exceptionally adaptable, innovative and creative which is a useful ability in the dynamic environments of our planet.
We are distinct from all other animals in many important ways, such as bipedal locomotion (walking upright), large brain size-to-body mass ratio. In addition our complex behaviours and advanced culture as well as our abilty to communicate by language or other means distinguish's us.
But we were not always like this. Evidence suggests that the physical and behavioral traits shared by all humans originated from ape-like ancestors and evolved over time. But the journey between walking upright and walking on the moon did not take a huge amount of time. Probably only about 5 million years. But when exactly was the dawn of humanity? When did the species with at least some claims to human characteristics first emerge?
Its difficult to give an exact time when humans stepped out from the shadows of the apes. There is no exact point in time when we can say the observable characteristics, such as bi-pedalism, are definately human. Neither can we base it on language, since other primates, also communicate and signal to each other (which can be called language) with vocal apparatus similiar to our own. And language is not just confined to primates.
Tool making and use must also be ruled out as a requirement to be considered human. We now realize that many animals have this skill. Jane Goodall observed chimpanzees in the wild carefully trimming twigs, inserting them into termite mound openings to 'fish' for termites, a favourite food of chimpanzees. Some chimpanzees use stones as hammers to crack nuts and obtain the food inside.
New Caledonian crows have shown tool making ability, using twigs to get to out-of-reach food in the wild. In experiments on crows in captivity, scientists have confirmed that the performance of these crows was comparable to the performance of the great apes in similar experiments. They were actually using human-like reasoning.
We do know the humans species first evolved in Africa and much of the story of human evolution occurred on that continent. The fossils of all human ancestors that lived between 2 and 5 million years ago come from Africa. For millions of years, finding food and shelter for survival was the main concern of humans, and our primitive ancestors (and sadly and unbelievably still is today for many).
Climate was a great pace-maker of change in the way species evolved. Significent climatic changes such as the ice ages had enormous effects on the environments. This presented great challanges for survival. Perhaps these are the challenges that ignited our intellect!