“It’s a milestone in human evolution” — Human’s ancestor were isolated for 100,000 of years and now experts find “genetic variation”

Human evolution is like the world’s most difficult puzzle; only small pieces of evidence remain on Earth.  These few remains of our predecessors are searched for by many researchers to get a clearer picture of how humans evolved to what we are now. However, immense progress has been made over many years of archaeology, and the puzzle is filled with many visuals of what ancestors might have looked like and information on how they behaved.

Diving into our isolated predecessors’ past and the role they played in human evolution

For many years, the origin of humans was centered around movement: the spread of people across continents, expansion, and migrations. A discovery published this year reveals that the moments of no activity or movement also contributed to the evolution of humans.

In South Africa, ancient DNA was discovered by scientists in a group of sedentary humans called the Khoisan that lived in isolation for almost 100,000 years. At the time that the Khoisan people lived, there were no countries or even territories established yet, but evidence of their existence is found in a huge portion of modern-day South Africa, some parts of Namibia, and Botswana.

The time frame that the group lived in solitude allowed for unique genetic variation to occur. Researchers uncovered a lineage that separated from other human groups roughly 300,000 years ago, through sequencing genomes of the individuals who lived in South Africa over the last 10,000 years.

The researchers’ findings unveiled that this specific population of humans remained genetically separate from the rest of the continent up until only 1,400 years ago. During this period, they evolved distinct characteristics such as UV protection as well as kidney function adaptation. These ancient humans adapted to their environment, which was the first of its kind to be discovered and shaped Homo sapiens miraculously. This discovery made scientists revise the old theory that stated that all humans evolved from one unified population in a specific region in Africa.

The genomes in the Khoisan that scientists are fascinated by, and how Isolation shaped human biology

These genomes did not develop overnight; they developed over centuries of generations as they adapted to their environment, making them more suited to survive the conditions. The UV protection genome developed as the Khoisan experienced strenuously hot and sunny weather, and the kidney genome, also known as the “Water-wise” genome, developed due to the scarcity of water in the dry inland.  This process is called natural selection, and this is when a specific species’ biological makeup alters due to its environmental conditions. Some pressures that shape genomes include:

• The climate conditions (hot, dry areas)
• diseases (modern example: COVID)
• lifestyle (hunting, mobility)

Scientists revealed that when groups stay separate from each other for an extensive period of time, their DNA develops a unique pattern different from that of previous generations. This is called a genetic drift.

How were different groups kept apart for so long?

Natural features such as rivers, massive lakes, mountains, and seas kept groups separate from one another for over 100,000 years. The Zambezi River basin served as a natural barrier between the southern and the central part of Africa, prohibiting long-distance movement. Simultaneously, the changing sea levels on the southern coast created a huge coastal plain, which attracted people to settle in this area and kept them apart from other groups. This area of land functioned as a continental island that allowed for unique human lineage adaptations to occur in southern Africa.

How does this discovery impact the study of evolution going forward?

This discovery unveiled ancient humans with adapted genomes that resided in southern Africa hundreds of thousands of years ago. This gives mankind a bit of a clearer understanding of how we evolved and what conditions contributed to it, and shows that the evolution of early humans was not only reliant on nomadic people moving outward. The extended period of the group living in solitude allowed for miraculous adaptations of their genomes to take place. Even though this discovery is a milestone, the puzzle of evolution is still incomplete, which encourages optimism for future findings.

NOTE – This article was originally published in Ecoportal.net and can be viewed here