When does history begin? Isn't it tempting to reply, "In the beginning", but like many obvious answers, this definitely turns out to be unhelpful. As one great historian once pointed out, history is the only subject where you cannot begin at the beginning. We can trace the chain of human descent back to the appearance of vertebrates, or even to the photosynthetic cells and other basic structures which are supposed to be the building blocks of life itself. We can go back further still, to almost unimaginable upheavels which formed our own planet and even to the origins of the universe. Yet, this is not "history".
Commonsense, as always, helps here. History is the story of mankind, of what it has done, suffered or enjoyed. Even when historians write about a natural process beyond human control, such as the ups and downs of climate, or the spread of an infectious disease, they do so only because it helps us to understand why men and women have lived (and died) in some ways rather than others.
This suggests that all we have to do is to identify the moment at which the first human beings step out from the shadows of the remote past. It is certainly not quite as simple as that, though. First we have to know what we are actually looking for. Most attempts to define humanity on the basis of observable characteristics prove in the end to be arbitrary and cramping, as long arguments about "ape-men" and "missing links" have shown.
Physiological tests help us to classify data but do not identify what is or what is not human. Some folks have suggested that human uniqueness lies in language, yet other primates possess vocal equipment similar to our own which they use as sounds to communicate with each other. At what point do they become speech? Another talked about definition is that man is a tool maker, yet observations have cast doubt on our uniqueness in this respect, too.
What is surely and identifiably unique about the human species is not its possession of certain faculties or physical characteristics, but what it has done with them; its achievements, or history, in fact. Humanity's unique achievement is its remarkably intense level of activity and creativity, its cumulative capacity to create change. All animals have ways of living, some complex enough to be called cultures. Human culture alone is progressive; it has been increasingly built by conscious choice. Of course, human beings have always only been able to make their history within limits. These limits are now very wide indeed, but they were once so narrow that it is impossible to identify the first step which took human evolution away from the determination of nature. We have, for a long time, only a blurred story, obscure, both because the evidence is fragmentary and because we cannot be sure exactly what we are looking for.
The roots of history lie in the pre-human past and it is hard to grasp how long ago that was. If we think of a century on our calendar as a minute on some great clock hanging in the air that records the passage of time, then white Europeans began to settle in the Americas only about five minutes ago. Slightly about 15 minutes before that, Christianity appeared. Rather, more than an hour ago a people settled in southern Mesapotamia (present day Iraq) who were soon to evolve the oldest civilization known to us.
This is already well beyond the furthest margin of written record. According to our new clock people began to write down the past much less than an hour ago. Some six or seven hours further back on our time scale, and even further remote, we can discern the first recognizable human beings of a modern physiological type already established in western Europe. Behind them, anything from a fortnight to three weeks earlier, appear the first traces of creatures with some manlike features whose contribution to the evolution which has followed is still in heated debate.
The bedrock of the story is the earth itself. Changes recorded in fossils of flora and fauna, in geographical forms and geological strata, narrate a drama of epic scale lasting hundreds of millions of years.
Climate was the first great pace-maker of change. About 40 million years ago - a reasonably early enough point to make a start from - a long warm climatic phase began to draw to a close. It had favored the reptiles, and during it Antarctica had separated from Australia. As the world grew colder and the new climatic conditions restricted their habitat, the great reptiles disappeared. Of course some have argued that there were other reasons for this phenomenon to have happened too.
Crudely summarized, the main lines of this transition were probably determined for millions of years by astronomical cycles. The changing position of the earth related to the sun gave rise to the varying climatic conditions that prevailed down below.
[extracted from History of the World by J M Roberts]