Fossils and other archaeological evidence provide many clues about where humans came from, but the picture is far from complete. Genomics helps us find the missing pieces of our distant past by looking at genomic differences between people living today. These small genomic changes that were passed down connect us to our ancestors – preserving the story of their journey in our DNA.
The genomes of modern African populations are far more diverse than those of Asians and Europeans.
Our species, Homo sapiens, evolved in Africa about 200,000 years ago. Genomics shows that early Asian and European populations originated from small African groups who started moving to the Middle East about 60,000 years ago. Those small groups carried only a small fraction of Africa’s genomic diversity. Even today, the genomes of modern African populations are far more diverse than those of Asians and Europeans.
Our DNA also reveals that our species mixed with ancient human species that are now extinct – Neanderthals in Europe, and a mysterious Asian group called Denisovans. Small amounts of Neanderthal or Denisovan DNA sequences are found in the genomes of some 21st century people.
Small differences … are reminders of how our ancestors were shaped by different environments on their journeys
Through migration and mixing populations, all the while encountering new environments and diets, DNA variants spread across many populations. Nevertheless, the genomes of any two unrelated people today are about 99.9 percent alike, and small differences in our appearance, or our risk or protection from disease, are reminders of how our ancestors were shaped by different environments on their journeys across the world.
As you explore DNA, you may start to wondering about human origins and your own family’s genomic journey.