Natural history of the bible
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The last ice age
People have been migrating all over the earth for tens of thousands of years. During these movements, once in a while, new mutations arise in the Y chromosome. If these mutations spread through a local population, they become markers that allow researchers to track migratory movements and consumers to reconstruct their ancestry using genetic tests.
During the tail end of the last ice age, temperatures varied widely. Initially, temperatures rose quickly during the Bølling–Allerød period, when the Levant was warm and lush. However, temperatures dropped again during the Younger Dryas, and conditions worsened for another millennium until our geologic era started: the Holocene.
The people who lived in the area during the tail end of the last ice age were the Natufians. Their early settlements date back to the Bølling–Allerød, the late settlements are from the Younger Dryas, including Jericho.
During the geologic era we live in, the Holocene, the earth still changed in numerous ways. The Sahara dried out, and the Black Sea expanded, perhaps inspiring the flood myths of the Middle East.
Numerous areas around the world had enough biodiversity so that humans were lucky in their management of natural resources and stumbled across species with which they developed more and more intimate relationships: domestication. One of these areas was the "fertile half-moon" to which the Levant belongs. Agriculture led to higher population densities, more division of labor, and social stratification, enabling the development of organized religion.