A small band of Homo Sapiens left our homeland with some failed forays before the species finally began to spread largely from Africa about 50,000 years ago, first going to Europe and Asia, and ultimately to the rest of the world.
So why did this transition succeed after it wasn't the previous one? New research offers insights. It documented how human African hunter-gatherers adopt diverse habitats, such as thick forests and arid deserts, and acquire adaptability that helps them tackle a wide range of conditions awaiting across the continent.
“Why the variance was successful 50,000 years ago is a major question in the study of human origin. Our results suggest that humans have developed ecological flexibility to survive in challenging habitats,” said Emily Hallett, an archaeologist at Loyola University Chicago, who is a co-leader of the research published in Journal Nature.
Looking at the array of archaeological locations in Africa, this study detailed how populations expand their range to central and West African forests and North African deserts about 20,000 years before this dispersion.
Some examples of archaeological sites at this point showing the expansion of human niches into harsh deserts include the regions of Libya and Namibia, while examples of expansion into forested habitats include the regions of Malawi and South Africa.
Homo Sapiens originated around 300,000 years ago and live in grasslands, savannas and various other African ecosystems.
“Starting about 70,000 years ago, they suddenly start to intensify this exploitation of diverse habitats and see that they are beginning to expand into new types of habitats in ways we don't see before.
“An ice age was upon us, meaning we are arid in parts of Africa. Learning how to adapt to a new niche could have made humans respond to this squeeze,” added Scerri.
Improved ecological flexibility of species appears to reflect cultural and social advances, such as passing knowledge from one generation to the next and engaging in collaborative behavior, researchers said.
“This must be accompanied by significant changes in interaction with the natural environment, as it can occupy not only a new environment in Africa but a whole new condition in Eurasia,” said research biologist and research co-leader Michela Leonardi, co-leader of the Natural History Museum in London.
“Another way of phrase this is that the ability to live in different environments in Africa is not an adaptation that allowed them to succeed from Africa, but rather a sign that at that point humans are the ultimate generalist who can tackle the environment that has progressed from deep forests to arid deserts.”
“This flexibility is an important feature that later allowed them to conquer novel challenges all the way to Siberia's coldest tundra.”
On trekking from Africa, Homo sapiens encountered not only new environments and unfamiliar animals and plants, but also other human species, including Neanderthals and Denisovan. The ecological flexibility learned in Africa may have provided an advantage when Homo sapiens encountered these other humans.
Genetic evidence shows that people outside Africa today can trace their ancestors to a human population that numbered only thousands of people engaged in pioneering migration from Africa about 50,000 years ago.
“I think adaptability and innovation are traits of our species and allowed us to succeed in every environment we encountered,” Hallett said. “At the same time, we are too good at adapting to different locations to undermine most other species on the planet.”
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