Human Origins and Ancestry

Genomics is illuminating human and family origins at a level not previously possible. 


Did you know that your genome helps uncover the history of your ancestors, both near and distant? Advances since the Human Genome Project allow us to compare genome sequences among humans, living and long-deceased, and to trace our collective ancestral history.

Where did different humans come from and how are we related? These are among the most common questions that humans ponder. The Human Genome Project produced a reference human genome sequence that scientists now regularly use to compare with newly generated genome sequences. This reveals genomic changes that have occurred in different populations over time, which provides a more powerful way to decipher the various stories of human origins and ancestry.

Ancient DNA Tells Our Species' History

Nearly 20 years ago, scientists developed techniques for extracting small amounts of DNA from ancient samples, like bones or fur or even soil, and used very sensitive methods for sequencing the extracted DNA [see DNA Sequencing]. Genomic studies like these have allowed us to examine human genomes from around 500,000 years ago when our ancestors (the species Homo sapiens) were diverging from other similar species, such as Homo neanderthalensis or Neanderthals.

So far, we have learned that Neanderthals took a different path than humans in their migrations around the world, but there are still traces of Neanderthal DNA sequences in our genomes today. These small stretches of DNA may influence traits that have helped people survive in some way, making it more likely to then be passed on to their children. For example, a 2017 study found that some Europeans still carry Neanderthal-like sequences that influence their circadian rhythms, making them more likely to be a morning person or a "night owl." In contrast, some DNA variants might have just happened in one population and not another. The same study found variations in the MC1R gene that lead to red hair were extremely rare or nonexistent in Neanderthals, so that trait seems to be human-specific. As we find better ways to isolate DNA from ancient remains and improve our DNA sequencing technologies, we will learn more about our species' history.

Human Migrations Out of Africa

What happened when humans began to migrate out of Africa and move around the world? Genome sequencing of Africans living in different times - from as long as 6000 years ago to today - has revealed that humans divided into different groups and moved around the world at multiple times. In Southern Africa, local hunter-gatherers and then herders appear to have been replaced by Bantu farmers around 2000 years ago. As humans migrated into Europe, the genomes of different groups also began to retain different variants. One 2008 study looked at about 200,000 specific places in the human genome where people are different from each other [see Human Genomic Variation], among a collection of Europeans. The patterns of genomic variants among different groups could be used to reproduce the map of Europe with 90 percent accuracy. Even more surprising, when a new European person's genome was analyzed, the researchers could predict where that person was from within a few hundred kilometers. More recent studies in the United States also show that genomic variation coupled with genealogical records can be used to infer birth location quite accurately.

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