Scientists are continually trying to trace the origin of humans. A new study says Africa was homeland of modern man. According to the study, the area Makgadikgadi-Okavango in the southern part of Africa was the home to a large population of Homo sapiens until the advent of climate change. The fingered region is around northern Botswana.
About 200 thousand years ago, there was an enormous lake in the region. The lake was roughly twice the size of modern-day Lake Victoria. Thus, modern humans settled there for at least 70 thousand years. However, as a result of climate change, the area is now reduced to salt plains. Consequently, the human population began to migrate roughly 130 thousand years ago. The first set of migrants ventured northeast while the second wave went southwest. However, some remained in the homeland until today.
According to the researchers, it was this migration that triggered the development of human’s genetic, cultural and ethnic diversity in modern man. Speaking about the new study, Vanessa Hayes from the Garvan Institute of Medical Research and the University of Sydney, and Extraordinary Professor at the University of Pretoria said,
“We’ve known for a long time that modern man originated in Africa roughly 200,000 years ago. But what we hadn’t known until the study was where exactly this homeland was.”
The role played by mitochondrial DNA in the research
To reach the conclusion, the researchers analyzed DNA samples for about 200 Khoisan people. The ethnic group lives in modern-day Namibia and South Africa. They are known to carry a high proportion of mitogenomes called ‘L0’ lineage which are the earliest genomes of modern man. Explaining the importance of mitogenomes, Hayes said,
“Mitochondrial DNA acts like a time capsule of our ancestral mothers, accumulating changes slowly over generations. Comparing the complete DNA code, or mitogenome, from different individuals provides information on how closely they are related. Our work would not have been possible without the generous contributions of local communities and study participants in Namibia and South Africa, which allowed us to uncover rare and new L0 sub-branches.”
Subsequently, the researchers linked the L0 lineage timeline with the cultural, linguistic, and geographic distribution of different sub-lineages. This led to the finding that the ‘homeland’ of modern man was south of the Greater Zambezi River Basin which covers entire northern Botswana and stretches into the west of Namibia and east of Zimbabwe. Lead phylogenetic analyst, Dr. Eva Chan from Garvan Institute of Medical Research said,
“We merged 198 new, rare mitogenomes to the current database of modern human’s earliest known population, the L0 lineage. This allowed us to refine the evolutionary tree of our earliest ancestral branches better than ever before.”
The uniqueness of the new study on modern man
Unlike previous studies, the uniqueness of the present study lies in the combination of disciplines namely climatic physics, geology, and genetics. Geologist, Dr. Andy Moore from Rhodes University investigated existing fossil, archeological, and geological evidence to establish the one-time existence of Lake Makgadikgadi, Africa’s largest lake system. He said,
“Prior to modern man emergence, the lake had begun to drain due to shifts in underlying tectonic plates. This would have created, a vast wetland, which is known to be one of the most productive ecosystems for sustaining life.”
The range of error of previous studies was 150,000 to 250,000. However, the new study has a range of error of 165,000 to 240,000.
Not everyone agrees with the study
Some scientists have their doubts about the authenticity of the study. For example, Sarah Tishkoff of the University of Pennsylvania argues that mitochondrial DNA (mtDNA) alone is a poor tool for tracing the history of ancient Africa’s population. Others argue that the female ancestors of the Khosian speakers with the L0 lineage could have migrated from somewhere else.
Another researcher who expressed doubt about the findings of the study was Chris Stringer. Stringer is a researcher of human evolution at the Natural History Museum in the UK. He highlighted the complexity of human origins study. In a statement posted on Twitter, Stringer said,
“I am very cautious about using modern genetic distributions to infer exactly where ancestral populations were living 200,000 years ago, particularly in a continent as large and complex as Africa. Moreover, like so many studies that concentrate on one small bit of the genome, or one region, or one stone tool industry, or one ‘critical’ fossil, it cannot capture the full complexity of our mosaic origins, once other data are considered.”
Notwithstanding the divergence in the opinion of different researchers, one thing remains clear; Africa had an important role to play in the history and evolution of modern man. We will like to know what you think about this study in the comment box.