According to the Bible, God commanded Homo Sapiens to “fill up planet Earth” (Gen. 1:28), and as a species we have most certainly done that. But what motivated prehistoric mankind to spread out throughout the entire world, in the evolutionary rapid time of less than 60-80,000 years?  

Homo Erectus originated somewhere in East Africa almost two million years ago, and then slowly spread out to inhabit South Africa, the southern parts of Europe (Spain and Italy), the Caucasus, India, China, and Indonesia over the next million years. Homo Sapiens reached Indonesia and Australia within 40-50,000 years of its exodus from Africa. New research by a paleoanthropologist at the University of York suggests that moral and emotional reasons, especially betrayals of personal and communal trust, are the best way to understanding the rapid spread of our own species around the world. 

Dr. Penny Spikins says that the speed and character of human dispersals changed significantly about 80-100,000 years ago. Before then, movements of pre-Homo Sapiens species were slow and largely due to environmental events, population increases or ecological changes. Then, relatively quickly, human populations spread with remarkable speed and across major environmental barriers.

Dr. Spikins relates this change to changes in human moral, spiritual, and emotional relationships. In research published in Open Quaternary (PHYS.org November 24, 2015), she says that neither population increases nor ecological changes provide an adequate explanation for patterns of human movement into new regions which began around 80-100,000 years ago.

Spikins suggests that as social and personal commitments to others became more essential to group survival, human groups became more motivated to identify and punish those individuals who cheat. Moral disputes motivated by broken trust and/or a sense of betrayal became more frequent and motivated early humans to put distance between themselves and their rivals.

The religious and emotional bonds which held populations together in crisis, had a darker side in heartfelt reactions to betrayal which we still feel today. Larger social networks made it easier to find distant allies with whom to start new colonies, and more efficient hunting technology meant that anyone with a grudge and a weapon was a danger, but it was human values and emotions which provided a force of repulsion from existing occupied areas, which we do not see in other animals.

The expansion of Homo Erectus out of Africa into Asia around 1.8 million years ago appears to have been caused by the need to find more large scale grasslands. After 80-100,000 years ago, however, dispersal into distant, risky and inhospitable areas became relatively more common compared with movements into already occupied regions. Human populations moved into very cold regions of Northern Europe, crossed significant river deltas such as the Indus and the Ganges, deserts, tundra and jungle environments and even made significant sea crossings to reach Australia.

In other words, God’s commandment to “fill up planet Earth” is followed by Eve and Adam’s decision to internalize (eat) the fruit the morality tree, and gain knowledge of good and evil. This leads to moral or religious conflicts that often provoke substantial mobility—the furious ex ally, mate or whole group, intent on seeking revenge or justice, are a strong motivation to run away, and to take almost any risk to do so.

While religion is a powerful force binding people together, it also can be a strong force that gives courage and hope to small groups of dissenters, who abandon their birth community and go forth to a strange far away land, as was the case with Abraham and Sarah: “The Lord had said to Abram, ‘Go from your country, your people, and your father’s household, to the land I will show you, and I will make you into a great nation. I will bless you, I will make your name great, and you will become a blessing.’” (Gen. 12:1-2.)

For more information: “The geography of trust and betrayal: moral disputes and Late Pleistocene dispersal,” Open Quaternary, doi.org/10.5334/oq.ai.

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Rabbi Allen S. Maller is the Rabbi Emeritus of Temple Akiba in Culver City, California. His website is: www.rabbimaller.com.  Earlier versions of this article may have appeared elsewhere.

The views expressed by Rabbi Maller are his own and not necessarily those of the Blogmaster. They are published in order to promote this blog’s mission to provide information and foster discussion about matters of faith and science. The Blogmaster thanks Rabbi Maller for his contribution to this forum.

1. Gnarlodious says:

   December 6, 2015 at 8:08 pm

   Interesting theory, but I think there is more to it. In one story, Abraham smashes the idols of his father. This iconoclastic attribute of certain humans gives rise to an extreme divergence of thinking and territory, as described in the Abraham story. In modern times we see the same instinct as cult leaders desperately trying to peel off populations of believers to build their own group of followers. Genetically this has been shown through certain haplogroups that are more widely distributed than other haplogroups which seem to remain clustered in their location of origin. In geneaology one can discover that certain lineages have an aversion to their parents and strive to put as much distance as possible between themselves. For plants and animals it is easy to explain, the instinct is called “territorial”. Some species are not social, they thrive when there is adequate distance between themselves and others of their species. I believe the story of Sarah sending Hagar away shows Sarah to have this quality. I believe this constant distancing of Jews from other people is a major theme of Judaism that is still with us today, and is why we are so genetically distinct.

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