|The remnants of what was once Africa's largest lake could be the starting point of human ancestors, according to a new study / Photo by: rawpixel via 123RF|
The remnants of what was once Africa's largest lake could be the starting point of human ancestors, according to a new study.
Researchers believe that all modern humans are descendants of those who once lived in what is now known as Botswana. They said that, for the first time, they have discovered the "cradle of humanity" where the first modern humans evolved before they began to travel and spread across the world.
Tracing the Ancestral Tree
In the study, the researchers examined the DNA records and migration patterns of 1,217 people from southern Africa representing a "particularly important and poorly studied slice of human genetic diversity," American magazine and multi-platform publisher The Atlantic said.
These people are known as the Khoe San and people genetically linked to them. They live in rural Africa and are known to be the most closely related to ancient humans.
The Atlantic added that the DNA records were used to create a family tree, which allowed the team to determine that anatomically modern humans first emerged in the Makgadikgadi wetlands about 200,000 years ago.
Found just south of the Zambezi River, the Makgadikgadi wetlands used to be a warm, lush Garden of Eden where early humans thrived for about 70,000 years before they began migrating. The migration was driven by the drying climate when the Earth's axis wobbled 130,000 years ago.
The direct descendants of these ancient humans can still be found residing in the arid Kalahari desert today.
"It has been clear for some time anatomically modern humans appeared in Africa roughly 200,000 years ago," lead researcher Vanessa Hayes said. "What has been long debated is the exact location of this emergence and subsequent dispersal of our earliest ancestors."
|Found just south of the Zambezi River, the Makgadikgadi wetlands used to be a warm, lush Garden of Eden where early humans thrived for about 70,000 years before they began migrating / Photo by: Rainer Lesniewski via 123RF|
Disputing Previous Claims
The results of the study add to the growing geological and fossil evidence that proves Lake Makgadikgadi was humanity's original homeland—debunking earlier claims that smaller groups of humans evolved in different African regions before migrating, British tabloid-style newspaper the Daily Mail reports.
"There was a very large lake," Hayes said. "By the time modern humans arrived, it was breaking up into smaller ones – creating a wetland."
She added that "green corridors" of vegetation sprung out of the wetland, which originated from a lake twice the area size of the 23,000-square-mile Lake Victoria in Tanzania and Uganda. This evolution allowed ancient humans to migrate going north-east and south-west.
According to the Daily Mail, a wetland is among the most suitable ecosystems for sustaining life and the one in Makgadikgadi "would have been abundant enough for the human species to become established."
However, the climate began to change and dried out the land. This caused the wetland to turn into a region of salt pans and desert, driving people to migrate from the area.
"The first migrants ventured northeast, followed by a second wave of migrants who traveled southwest," Hayes said. "A third population remained in the homeland until today. "In contrast to the northeasterly migrants, the southwesterly explorers appear to flourish, experiencing steady population growth."
The study is evidence that humanity began in the Makgadikgadi lake, but other researchers aren't impressed at the results.
Mark Thomas, a geneticist of University College London, said the problem lies in the fact that mitochondrial DNA doesn't hold much information about the ancient populations in the study.
Mitochondrial variants merely trace weakly onto specific populations, the New Scientist explained, adding that such a method provides worse results further back in time. The New Scientist is a London-based weekly English-language magazine that covers all the latest aspects of science and technology.
"When you go back to the mitochondrial common ancestor, around 200,000 years ago, at that point the tree must contain no information about our population history," Thomas said.
Another prehistory expert, archaeologist Eleanor Scerri, said the paper "is a convenient response" but not a convincing one as it doesn't consider evidence that the human species is over 200,000 years old.
Moroccan fossils, for instance, suggest that humanity is at least 315,000 years old. While it can be said that these fossils aren't modern enough to be classified as humans, Scerri said the same could be argued for many fossils found in southern Africa.
"The constellations of traits that define us today don’t appear in any single individual until sometime between 100,000 and 40,000 years ago," she said.
People in southern Africa are unlikely to be "evolutionary relicts who have neither changed nor moved geographically for tens or even hundreds of thousands of years," the archaeologist added. Migration or significant changes in populations through the years would make it difficult to determine where the human species began.
Hundreds of thousands of years of evolution have led to amazing developments for humans as a species. Such developments help in tracing back humanity's origins and the history of the world. But as evidence after evidence emerges, it is important to be cautious in making claims that will possibly change how humans see the world and its history.
|Mark Thomas, a geneticist of University College London, said the problem lies in the fact that mitochondrial DNA doesn't hold much information about the ancient populations in the study / Photo by: Sergey Nivens via 123RF|