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Humanity out of Africa

Genetic tracking has taken researchers back to a woman who is described as our common ancestor. She has been given the name Mitochondrial Eve. In male genetics – the Y Chromosome, passed from father to son – a common ancestor has been traced to someone today named Mitochondrial Adam. The scientists have not been so exact that they believe they have found a couple.

Science is sometimes approximation. Researchers went as far back without a break in lineage (matrilineal and patrilineal) as they could. They assume that their genetic Eve and genetic Adam had parents – as opposed to having appeared on earth with some kind of magic, like converted from a toad. The geneticists recognize that mutations (changes in gene structure) were involved. There were mutations that moved creatures to what we now call human, and there were mutations that continued among humans that would change eye and skin color and other minor characteristics.

Science's Eve is estimated to have come into being perhaps as long ago as 200,000 years. And according to the journal Nature, science's Adam "did not live too far apart in time" from Eve. These two early humans have been placed by paleo-anthropologists as living in East Africa, leaving us with a theory called monogenism, that humans appeared at one point in time and place – opposed to polygenism, which includes the idea that humans of different races are descended from different ancestors. The idea of a single origin of humans in East Africa is the predominant position held within the scientific community.

The transition to human in Africa has been described as a response to climate change, to periods of cooling and drying, to dense forests thinning out, producing woodlands and grasslands. The primate that became human has been described as having climbed down from the trees across a time span of thousands of years and exploring beyond the edge of dense forest. Trying to survive, people followed the animals that they hunted, and they gathered edible plants where they could. It is assumed that they moved about in small extended family groupings – as seen in hunter-gatherer societies still around in modern times – the group small enough in size that they knew each other well. People were social creatures, surviving through team work and sharing.

Humans moved from East Africa into nearby Arabia, where tools have been found that dated back 125,000 years. People moved into what today is China, where human teeth had been discovered that date back to 80,000 years ago. Migrants to be known as aborigines are believed to have reached Australia at least by 65,000 years ago (according to ABC News in July 2017, 18,000 years earlier than archaeologists previously thought). A migration into Europe has been described as occurring 45,000 years ago. Meanwhile genetic changes had begun that contributed to different physical racial characteristics.

When the last Ice Age was reaching its peak around 25,000 years ago, a movement of people was underway from Asia to the North American continent. People were surviving on land between Siberia and what today is Alaska as a result of the low sea levels that accompanied the Ice Age. In the thousands of years that followed, people moved deeper into the North American continent. Stone spearheads and human DNA found in Oregon caves indicate "that at least two cultures with distinct technologies shared the continent more than 13,000 years ago." (New York Times, July 12, 2012.)


CONTINUE READING: Hunter-Gatherers and War

Copyright © 2016 by Frank E. Smitha. All rights reserved.