Have you noticed that some South American tribes have huge heads? The mystery has been solved! Usually, environmental pressures drive evolution (biotic factors like predators and disease or abiotic factors like altitude, UV radiation, or climate). In the case of the Amazonian Xavánte tribe, sexual selection and isolated cultural practices led to significant changes to their morphology (shape). A full quarter of the tribe’s population was made up of sons of a single chief, Apoena, who had five wives. You can see how being more reproductively successful means that any traits of theirs can quickly come to dominate the population.
This photo was released in May 2008 by a group called Survival International. The caption read, “Uncontacted Indians in Brazil Seen From The Air”. Since then, there have been lots of criticism that the whole thing was a hoax and suspicions about the organization’s motivations and the authenticity of the scene were raised. On June 22, The Observer, a London-based newspaper, ran a story called “Secret of the ‘Lost’ Tribe That Wasn’t” saying that the tribe’s existence “has been noted since 1910.”
Survival International released a statement to try to clarify things, including: “The story is not a hoax, and none of those involved in working to protect these Indians’ rights have ever claimed they were ‘undiscovered.’”
I guess language is subjective after all.
