Adam And His Child Found
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As the coveted fossil of an ‘Eve’ continues to elude palaeoanthropologists, a group of fossil hunters has perhaps stumbled onto her partner ‘Adam’, and child in a dry and dusty valley bordering the Middle Awash River near Herto, a village in the Afar region of Ethiopia. So far, the fossil hunters have unearthed only fossilized skulls of Adam and his child. The skulls have been dated at 160,000 years. The elusive ‘Eve’ also lived around this period, according to scientists who studied a stretch of DNA from mitochondria, which is passed from mother to daughter.
The fossilized skulls are also shedding light on what happened during the transition from pre-humans to modern humans. “We have lacked intermediate fossils between 100,000 and 300,000 years ago when the transition was taking place, and that is where the Herto fossils fit,” said palaeoanthropologist Tim White, a professor of integrative biology at the University of California, Berkely, and a co-leader of the team that excavated the skulls. “Now, the fossil record reconciles with the molecular evidence.” He added, “With this new crania, we can now see what our direct ancestors looked like.”
In this research, Berhane Asfaw of the Rift Valley Research Service in Addis Ababa, Ethiopia and Giday WoldeGabriel of Los Alamos National Laboratory in New Mexico have supported White and his colleagues. The results of the find have been reported in two papers published in a recent issue of Nature.
The fossil-rich site of Herto was first identified on November 16, 1997. At the site, White first encountered stone tools and a fossil skull of a butchered hippopotamous. Excited White came back to the site eleven days later. Meanwhile, heavy rains eroded soil and exposed many more fossils. Crushed and scattered pieces of two adults’ braincases protruded from the ground. The ground close to where the adult skulls found was littered with pieces of bones of a child’s skull. Asfaw painstakingly pieced together the child’s bones. From its teeth, it has been guessed that the child died at the age of seven. The child’s skull bore marks indicating that, after death, the muscles had been removed from the base of the skull. The adult skulls also bore cut marks. This proves that Herto people had elaborate mortuary practices. The Herto skulls were not found with other bones from the rest of the bodies, which is unusual, White said. “This leads researchers to infer that the people were moving the heads around on the landscape.” They probably broke the skulls to extract the brain. “But, we have no way of knowing whether it was a part of a cannibalistic ritual,” White added.
Around two hundred thousand years ago, it was a shallow lake where is now Middle Awash River. The lake was home to hippos, crocodiles and catfish, while Buffalo roamed the land. The Herto people lived along the shores of the lake. This gave them opportunity to hunt animals like hippos and buffalo. Hippos’ bones found alongside the skulls speak volumes of their hunting skill. They used sophisticated stone tools like hand axes, flake tools, cores, and rare blades. “Using chipped hand axes and other stone tools, they were butchering carcasses of large animals like hippos and buffalo and undoubtedly knew how to exploit plants,” White said.
The reconstructed fossil skulls have sounded death knell for many theories. The anatomical features of the skulls prove that we are not descended from Neanderthals. “Neanderthals split off from the main branch of human family tree more than three hundred thousand years ago and died out about thirty thousand years ago,” White said. The Herto fossils provide strong support for the hypothesis that modern humans evolved in Africa and subsequently spread into Eurasia. The fossil evidence, said Asfaw, clearly shows that modern humans were living at around 160,000 years ago with full-fledged Homo sapiens features.
The Herto finds shift the focus of human evolution once again to East Africa, writes Chris Stringer, an anthropologist from the Natural History Museum, London, UK in a commentary article in the same issue of Nature. Because, in this single study area, the research team has found fossils dating from the present to more than 6 million years ago, painting a clear picture of human evolution from ape-like ancestors to present-day humans.
The descendants of Herto people and other contemporary African people spread across the continent and did not venture out of Africa until seventy thousand years ago, according to a new study by geneticists from Stanford University and the Russian Academy of Sciences. The results of the study have been published in a recent issue of American Journal of Human Genetics. In their study, the research team compared three hundred seventy seven snippets of DNA called microsatellite markers. These snippets of DNA were collected from one thousand fifty six individuals representing fifty geographic sites in Africa, the Middle East, Europe, Central and South Asia, East Asia, Oceania and Americas. The study revealed that only about two thousand wanderers left Africa. “This study, however, does not preclude the presence of other populations of Homo sapiens in Africa,” said Marcus W. Feldman, an anthropologist from Stanford University and co-author of the study. “Although, it suggests that they were probably isolated from one another genetically and that contemporary worldwide populations descend from one or very few of those populations.”
According to Feldman, their results support out-of-Africa theory, which says a small group of sub-Saharan African population gave rise to all populations of anatomically modern humans through a chain of migrations to the Middle East, Europe, Asia, Oceania and America. For migrating people, hunting and gathering was an uncertain way of living. “They faced a severe population bottlenecks during which their numbers crashed – possibly because of limited resources, diseases and, in some cases, the effects of long-distance migrations,” Feldman explained.
A few genetic mutations might have fuelled the meteoric shift in technological and cultural innovations. “The technological innovations increased the overall survival and birth rate of hunter-gatherers,” write Feldman and his colleagues. As a result, peoples scattered all over the globe bounced back in numbers. Richard Klein, an anthropologist from Stanford University has also linked the emergence of innovative and creative humans to genetic mutation. “There was a biological change – a genetic mutation of some kind that promoted the fully modern ability to create and innovate,” said Klein at a recently held symposium on Revolution and Evolution in Modern Human Origins: When, Where and Why? The American Association for the Advancement of Science organized the symposium in Denver, US. The ancestors of modern sub-Saharan African farming populations increased in numbers around thirty five thousand years ago. The peoples of Eurasia and East Asia also show evidence of population increase starting about twenty five thousand years ago.
About ten thousand years ago, retreat of last ice age and advent of farming made our ancestors to abandon the life of hunter-gatherers. Since then, we have never looked back. From a couple of thousand we are now over six billions inhabiting every patch of habitable land on earth. But, we cannot contradict our long forgotten African relatives. Fossils and genes remind us that we are indeed “Africans under the skin”.
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