From invasions and migrations to slavery and trade, history is embroidered with events that led to interactions between previously separate populations — and, in many cases, hanky-panky. By mining genetic data from living people, researchers have now created a historical atlas of instances of such mixing.
The study, published today in Science, uses statistical methods to make inferences about which populations interbred, and when, over the past 4,000 years. The findings are also presented as an interactive map. The authors sequenced DNA from 1,490 people from 95 genetically distinct populations around the world, and tested almost 500,000 single-letter variations in DNA known as single nucleotide polymorphisms, or SNPs. Read more.
Researchers have discovered a gene duplication related to the human brain that may have been responsible for adaptive evolutionary changes leading from ancient primate ancestors to modern humans. According to the scientists who participated in the study, two gene duplications occurred that were related to brain development, an aspect of change that was key to the emergence of ancestral and, ultimately, modern humans.
"There are approximately 30 genes that were selectively duplicated in humans," said Franck Polleux, a study participant and expert in brain development at The Scripps Research Institute. "These are some of our most recent genomic innovations."
Polleux and Evan Eichler, who is a genome scientist at the University of Washington, focused on a key gene known as SRGAP2. This gene was apparently duplicated at least twice over the past four million years, once about 3.5 million years ago and again about 2.5 million years ago. Read more.
Genetic analyses of individuals buried in funereal monuments near a volcano in southern Peru have revealed the family relationships and burial traditions of ancient Peruvians that lived before Christopher Columbus sailed to the Americas.
The ancient Peruvians buried their dead in “chullpas,” structures resembling vertical tombs, which can be up to 6.5 feet (2 meters) high. Researchers hadn’t known how the individuals buried within one chullpa were related.
Families were organized into “ayllu,” a group of relatives that shared common land and responsibilities. Historians think that men retained the ancestral land, and they traded their sisters for wives, in a sort of “sister exchange.”
In the new study, researchers from the University of Warsaw, in collaboration with Universidad Catolica de Santa Maria, retrieved and analyzed genomic sequences of 41 individuals buried in sixchullpas located 13,000 feet (4,000 meters) up the side of the Cora Cora Mountain in southern Peru. Read more.