It is generally believed that human life originated on the continent of Africa. Many fossils of hominid species have been found in African countries.
Fossils of Australopithecus afarensis, living around three to four million years ago, have been discovered in Ethiopia
in the Lower Valley of the Awash. Remains of another early hominid, Australopithecus africanus, were found in South Africa
in caves in the Sterkfontein Valley. Fossils of Homo habilis, dated around two million years old, were unearthed in Tanzania
by the Leakey family at Olduvai Gorge.
There are a number of theories about the migration of humans from Africa. The Multi-regional theory says that groups of Homo erectus, who appeared over one and a half million years ago, migrated from Africa and evolved into modern humans in Asia and Europe, as well as Africa, around the same time. An opposing theory, known as Out-of-Africa, suggests that small numbers of modern humans, who lived in Africa one hundred and thirty thousand years ago and migrated around thirty to fifty thousand years later, eventually spread throughout the world and replaced earlier humans.
A later theory proposed by Professor Alan Templeton says that migration from the African continent took place in three waves. This theory suggests that modern Homo sapiens from Africa may have interbred with the archaic species living in Asia and Europe who had left Africa in earlier migrations.
The Out-of-Africa theorists believe that Homo neanderthalensis, a close evolutionary relative of modern humans, died out around thirty thousand years ago. It has been discovered that a group of Neaderthals, named after the Neander Valley in Germany
, lived in caves in Gibraltar
about this time or perhaps even later.
Fossils of Homo sapiens sapiens in Cro-Magnon in the Dordogne in France
show that some of our ancestors were living in Europe thirty-five thousand years ago.
Many people think that a small number of modern humans left Africa and moved into the Middle East around a hundred thousand years ago. Exact dates are difficult to assess and it has even been suggested that the move may have taken place only sixty thousand years ago. Migrating groups followed the coastline of Asia; some journeyed to Australia
, arriving between sixty thousand and forty thousand years ago. Eventually people moved into Central Asia and then into Europe. It is thought that the Americas were the last continents to be populated, possibly around twenty thousand years ago, perhaps via the Bering Strait land bridge.
The migrations took place over long periods of time. In some cases each generation may have moved on just a short distance
. In other cases longer journeys were undertaken such as the Polynesian migrations.
Throughout our history numerous population movements have occurred through migration, invasion, exploration and trade. One of the largest involuntary population movements was brought about by the trans-Atlantic slave trade which flourished between the sixteenth and nineteenth centuries. African slaves were transported from countries such as Senegal
to work on plantations in the Caribbean and the Americas.
Other large migrations took place around this time as people moved to South Africa, the Americas and Australia. Again, we see that since the first people left Africa we have continued to migrate. At the end of the twentieth century, the United Nations estimated that one hundred and seventy-five million people lived outside their countries of birth. In London, alone, over three hundred languages were spoken.
Today, DNA testing can be used to look at the routes taken by our distant ancestors. Small changes occasionally take place in DNA sequence and it is these changes which help to identify our lineages, also known as haplogroups.
An example of the use of DNA testing to identify the origin of a group of people can be seen in the case of Polynesia
. Until the tests were carried out it had been thought that people living on the Polynesian islands might have migrated from South America but DNA testing showed that the Polynesians' ancestors came from Asia.
Around thirty-six ancestral clan mothers have been identified worldwide using the method of testing mitochondrial DNA, which is passed from mother to child. Ancestral clan fathers have also been identified using Y-chromosome DNA which is passed from father to son.
My mitochondrial DNA test, provided by DNAPrint Genomics in Florida, identified my haplogroup as Haplogroup H which is widespread throughout Europe and West Asia and may be more than twenty thousand years old. My particular sequence matched a sequence found in Northwestern Europe. Haplogroup H is the most commonly found haplogroup in Europe.
DNAPrint Genomics also carried out a DNA test on an English male volunteer whose family has lived in the United Kingdom for generations. The result showed that his Y-chromosome haplogroup is predominant in people from the Near East and Europe. His haplogroup is believed to have originated in the Middle East approximately twenty-two thousand years ago, dispersing into Europe and North Africa with the spread of Neolithic agriculture. Haplogroup J is divided into several subgroups. Subhaplogroup J1 is found in the Middle East, Northern Africa and Ethiopia, whereas, subhaplogroup J2 is more prevalent in Europe.
The test results remind us that a relatively short time ago we were all closely related. It was only a small number of our ancestors who took part in the early migration from Africa. As DNA testing progresses it will be possible to find out more about population movements and the history of people who lived thousands and tens of thousands of years ago.
We would like to thank Stan William Wright for participating in the Y-chromosome test
Thanks to DNAPrint Genomics Inc. in Sarasota, Florida, USA for providing the DNA test results. Visit www.ancestrybydna.com for more information.
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