13 unusually-shaped skulls were recently unearthed in Mexico when workers were digging an irrigation system. They are about 1,000 years old. Time reported that researcher Cristina Garcia Moreno of Arizona State University said, “We don’t know why this population specifically deformed their heads.”
Tai-wiki-widbee said: "There's more information at the Artificial Cranial Deformation page at Wikipedia, where I found the image at right (Painting by Paul Kane, showing a Chinookan child in the process of having its head flattened, and an adult after the process) and these notes:"
Early examples of intentional human cranial deformation predate written history and date back to 45,000 BC in Neanderthal skulls, and to the Proto-Neolithic Homo sapiens component (12th millennium BCE) from Shanidar Cave in Iraq. It occurred among Neolithic peoples in SW Asia. The earliest written record of cranial deformation dates to 400 BC in Hippocrates' description of the Macrocephali or Long-heads, who were named for their practice of cranial modification.This is NOT the skull of an extraterrestrial alien