Early Human Migration – An Exploration

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Closing my eyes in bed my inner-eyes started to visualize many events of the past. I was able to visualize the Homo erectus who were living in the old world nearly two million years ago inhabiting the planet.

The Homo erectus was extant in Africa, Asia, and Europe. Their migration was made possible by a greater intelligence and new cultural technologies, probably including better hunting skills and the ability to create fire. Homo erectus were very successful in creating cultural technologies that allowed them to adapt to a new environment.

They were the true pioneers in developing human culture and in moving out of Africa to populate tropical and subtropical zones elsewhere in the Old World. This territorial expansion most likely began around 1, 800, 000 to 1, 700, 000 years ago.

Space images taken by NASA reveal a mysterious ancient bridge in the Palk Strait between India and Sri Lanka. The recently discovered bridge currently named Adam's Bridge is made of a chain of shoals, nearly thirty kilometers long. Its unique curvature and composition by age reveals that it is man made.

Archaeological studies reveal that the first signs of human habitation in Sri Lanka dates back to the bridge's primitive age, about 1, 750, 000 years. I surprised when Homo erectus built such a bridge so that they could migrate across the Palk Strait from India to Sri Lanka.

The research of the Center for Cellular and Molecular Biology in India captivated my mind. The center has undertaken a very large program on human genetic diversity in tribal populations of India and has come out with very interesting theories of modern human evolution.

Their three theories of human evolution, which have emerged out of the efforts of various research workers in the field was so mind-boggling to me, that it took on an obsessive interest.

The multi-regional theory was again and again haunting me.

According to this theory there was no single geographical origin for modern humans, but that after the migration of Homo erectus from Africa into Europe and Asia nearly 800,000 to 1,800,000 years ago, there were independent transitions in regional populations from Homo erectus to Homo sapiens.

But the "Recent African Origin" theory rests on a more scientific basis according to which all non-African populations descended from a Homo sapiens ancestor that evolved in Africa from Homo erectus 100,000 to 200,000 years ago. These ancients then spread through the world, replacing the archaic Homo-populations, the Neanderthals and the Homo erectus. The perspective is that all genetic lines derive from a recent common African ancestor and that non-African populations should carry a subset of the genetic variations present in modern African populations.

But a more fascinating theory to me was the one of hybridization. It suggests some gene flow between modern humans that migrated from Africa with the archaic populations of the Neanderthals and the Homo erectus outside Africa.

So, the evolution of modern humans could have been due to a blending of modern characters derived from the recent African populations with local characteristics of the archaic populations.

It was very much impressing the findings, which support the 'out-of-Africa' theory based on the molecular genetic evidence on the affinities of the Andaman Islanders in the Indian Ocean, arguably the most enigmatic people on our planet.

Mitochondrion is the powerhouse of every cell of our body. However, the mitochondrial DNA is a genetic element passed down only through women, while DNA of Y-chromosome is passed down to the next generation only through men. Studies of protein polymorphisms and of mitochondrial and Y-chromosomal indicate that African populations are the most variable and ancestral as expected under the "Recent African Origin" theory.

The center's finding was so exciting, which indicate that after an initial transformation from Homo erectus to Homo sapiens in Africa, the humans spread across a broad geographical region and rapidly increased in population in the past 50,000-100,000 years.

I was enthralled by the 'Journey of Man' by Spencer Wells, the geneticist from Oxford University, in the National Geographic Channel, where he asserts that: "All of us are literally Africans underneath the skin, Brothers and Sisters separated by mere 2000 generations "

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