We often find ourselves divided into caste, creed and further in different families. Everyone around us belongs to different family backgrounds. Moreover, we tend to differentiate between people belonging to a rich class background and the ones whose entire generations have been poor. But, let me give you a rude shock, every person alive today descended from a woman who lived in modern-day Botswana about 200,000 years ago.
This recent discovery says that the ancestors of humans lived in the Botswana region, south of the Greater Zambezi River Basin, for good 70,000 years until climate change forced them to move out of Africa and settle around the globe.
Much debated topic is the location – where exactly do we trace back our origins? For this, scientists such as Hayes and her colleagues have analyzed mitochondrial DNA passed along the maternal line of more than 1200 people currently living across Africa. Mitochondrial DNA is studied to know the ancestors because it is separate from paternal DNA and changes less over time. That means it consists of genes only passed by the mother. It tells a single story: that of one’s mother, and her mother, and her mother’s mother.
The research focused on a branch of DNA known as the LO- a subdivision of the L- macro haplogroup present in all modern humans. This resulted in a list of more than 1000 mitogenomes including the LO lineage and another set of 198 new, rare mitogenomes that were not tapped before were added to the mitogenomes database. Using the existing and new data, they associated the entire LO timeline with the sub-lineages and their culture, language and geography suggesting a single lineage of LO stretching back to 200,000 years. All of this helped them to draw an evolutionary tree which had its origin from a single woman in Makgadikgadi-Okavango, once home to an enormous lake, roughly twice the area of modern-day Lake Victoria
But this theory of Hayes and his colleagues doesn’t go without criticism. They did not analyze the entire human genome but only a small part that is transferred from the mother to the child. Their study doesn’t tell us the origin of the human genome but the place and time where our mitochondrial DNA appeared. Consider the study of only the chromosomes passed on from father to son, it might tell us a different story of where and when we originated. We cannot say for sure that we are descendant of a woman in Botswana by just studying mitochondrial DNA when we are not even taking other components of our DNA into consideration. Consider the scenario where the Y chromosome in all men is passed on from a man who might have existed 400,000 years ago. How can we say the woman from whom all of us have inherited the X chromosome has met the man from whom all the men have inherited the Y chromosome?
Moreover, modern genetic technologies have proven that our ancestors interbred with other species, such as Neanderthals, who contributed to our DNAs. Our species also interbred with the Denisovans and there is evidence that both these species, the Neanderthals and the Denisovans were hybridizing with each other. It also leaves the possibility that the people might have migrated in the ancient past and mated with some other species in some other geographical area as the only basis they have to say migrations started 130,000 years ago is that there was a significant divergence in the first maternal sub lineage.
Although the research by Hayes and her colleagues leave room for debate, it did certain commendable value additions to the field of science. The discovery of 200 new and rare mitogenomes is valuable to the field of science. Moreover, identification of a prospective area where we might have our roots has given an open end to archaeology. It tells the archaeologists that more areas have to be explored to conclude where we come from. So, when anyone sounds very proud of “who” they are, “where” they come from and undermines someone else for the same, the joke is on them as no one really knows their true origin.