Exploding Population

Before agriculture, the population of the earth was unlikely to have exceeded five or ten million people. It has been calculated that in England there were probably five, maybe, ten thousand inhabitants. This is nearly ten thousand times less than the population of England today. The adoption of agriculture led to a demographic explosion. World population has increased one thousandfold in the last ten thousand years. Even in traditional African societies, those tribes who became cultivators several thousand years ago now number many millions of people. The tribes that stuck to the oldest syle of living, hunting and gathering, are still small in numbers even now.

Hunter-Gatherers

All of today's hunter-gatherers have certain customs in common. They live in small groups, have no social or political hierarchy, are normally without leaders, and base their social contacts on reciprocal respect.

Genetic Variability

Any group, even the most "primitive", is genetically highly varied. Customs preventing inbreeding help keep even the smallest human population rich in genetic variations.

Convincing Historical Interpretations

To be convincing with any historical interpretation, there must be an accumulation of as much evidence as possible. However, there will always be those who ingrained prejudices and bias will lead them to refuse to accept certain concepts, even in the face of the strongest evidence to the contrary. Historical sciences are therefore subject to a greater degree of uncertainty than empirical sciences. This is one reason to study human origins from many different view points such as paleoanthropology, biology, archaeology, social anthropology, linguistics, and so on. It is essential for research to take into account all related fields and accumulate evidence from many perspectives.

Order of Things

• The first hominids may go back to 5+ million years ago. By about 4.0 million years ago, bipedality was taking shape and a ground adaptation was a dominant theme. These early hominids began to emerge as a savannah adapted rather than forest adapted primate between 3.0 and 2.0 million years ago.
• Early forms of Homo migrated out of Africa to other parts of the world perhaps as early as 1.8 to 1.6 million years ago. There may be several migrations that followed to provide home lands for Homo Erectus and early forms of Homo Sapiens (Archaic Homo Sapiens) in Africa, Europe, Asia, and Southeast Asia.
• The first modern humans lived about one hundred thousand years ago, perhaps numbering between twenty and one hundred thousand people (estimates are problematic.) They inhabited limited geographical areas in Africa and the fringes of the Middle East.
• Modern humans expansion reached full impact after 60,000 years ago when modern humans appear in Asia, Australia, and Europe (around 40,000 years ago). Their expansion ended about ten to fifteen thousand years ago having reached virtually all the parts of the globe inhabited today. Their numbers probably reached about 5 million.
• Livestock and crop-raising activities began nine to ten thousand years ago. This revolution in food production happended in different areas of the world over the next three or four thousand years. This precipitated an unprecedented increase in population. As populations grew, there was a move toward higher density as people began to live in settled communities and eventually cities.
• Certain animals provided special opportunities for further expansion. The horse was used for food, transport, and eventually as an instrument of war. Nomadic herders began to expand about five thousand years ago from southern Russia into Europe, central Asia, and India. The camel helped the Arabs to expand into northern Africa.
• The invention of iron pushed agriculture into areas that were unfavorable without it. This enabled people to spread throughout Europe and Africa.
• The wheel, the sail, the outrigger canoe, and the compass enabled further expansion.
• Military innovations facilitated expansion through conquest. The use of the horse with a wheel created the chariot for example. Metals could be used for defense and offense.

Impulses for Innovation

• The development of language permitted better communication between individuals and groups. This enabled initial expansions because it clearly provided selective advantages through increased effectiveness in adaptations.
• Improvements in transport were probably essential for travel to distant regions.

The Bottom Line of Expansion

Expansion to areas with profoundly different climates and environments led to significant biological and cultural adaptations. Expansion relied on small groups of people moving into new areas. This provided a mechanism for significant changes in the genetic makeup of populations caught in the spread. This is the founder effect, a random process leading potentially to large changes in genetic makeups in small time frames.

Ability of Learn

Knowledge cannot be gained without the ability to learn. The basis of culture is the ability to accumulate knowledge, receiving it from previous generations and handing it on to the next so that each new generation need not reinvent the same things. Communication between individuals is the glue of any cultural structure.

Humanity

Much of our life depends on our cultural background as well as on our genetic structure. We are contingent upon both and the legacy of change in both over millions of years. Humanity deeply wants to understand itself better.