The fossil record places human origins in Africa to some date over 200,000 years ago, but science continues to search for details about the incredible journey that took Homo sapiens from Africa to the far reaches of the Earth. How did each of us end up where we are? Why do we have such a wide variety of colors and features?

Through the eons of time, the full story of human ancestry remains written in our genes. When DNA is passed from one generation to the next, most of it is recombined by the processes that give each of us our individuality. But some parts of the DNA chain remain largely intact through the generations, altered only occasionally by random mutations, which become what are called genetic markers. The order in which these markers occur allows geneticists to trace our common evolutionary timeline back many generations.

Different populations carry distinct mutations, or genetic markers. Identifying and following the markers back through generations reveals a relationship shared by all humans, best conceptualized in the form of a genetic tree. Today, thousands of diverse branches, corresponding to unique human groups, can be followed backward to their common African root more than 100 millennia ago.

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