A genetic study has revealed the history of pygmy tribes scattered across western and central Africa, and it's a story that might surprise the the people themselves. Pygmies are defined as groups of people whose adult men are typically less than 4 feet 11 inches in height, but they have little in common besides that physical characteristic and the word pygmy, which was foisted on them. But a genetic analysis of pygmies living in Gabon and Cameroon suggests that the first group of pygmies split off from other humans at least 50,000 years ago, and that ancestral population
survived intact until 2800 years ago when farmers invaded the pygmies' territory and split them apart [ScienceNOW Daily News].
European explorers first encountered pygmy populations in the 19th century and lumped them together under a name that Homer used in the Iliad to describe an African tribe of diminutive crane-fighters.... Many of their languages are also very varied, and the populations do not view identify any of the others as an ancestral group. "There is no such thing as a pygmy civilisation or identity" [New Scientist],
says lead researcher Paul Verdu. Even today, the various populations often don't know of one another's existence. The genetic analysis of 604 individuals in nine pygmy groups and 12 nearby non-pygmy populations showed that the pygmy groups are now very genetically different from each other, but that they share a recent common ancestor. This indicates that people of short stature evolved once in central Africa and then spread out, and puts to rest the notion that
shortness evolved independently in each tribe because it was advantageous for life in the forest [ScienceNOW Daily News].
Exactly why pygmy populations diverged from one another is unclear, Verdu says. He hypothesises that an ancient migration of farmers and herdsmen across sub-Saharan Africa – dubbed the Bantu expansion – might have segmented pygmies living in West Africa [New Scientist].
Once they were scattered and isolated, the groups rapidly accumulated genetic differences, researchers say. The study, published in Current Biology [subscription required], also found a strange twist: All the pygmy populations had genes from non-pygmy populations, but the outside groups had no pygmy genes. The researchers suspect this is because
pygmy women tend to marry nonpygmy men and move to their homes, not vice versa. But these marriages often fail because of discrimination against low-status pygmy wives, Verdu says, and the pygmy women return to their pygmy groups with children who have DNA from their taller fathers [ScienceNOW Daily News].
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