Dating Old Bones

Article excerpt

THE OLDEST HUMAN skull in the Americas has been found and dated to be nearly thirteen thousand years old, confirming that humans lived in the Americas a thousand years earlier than scientists thought. The age and the shape of the skull are raising new questions about who the first Americans were and from where they came.

Although the skull was discovered in the vicinity of Mexico City in 1959, it had not been dated until geologist Sylvia Gonzalez, of Liverpool's John Moores University in England, and anthropologist Jose Concepcion Jimenez, of the National Institute of Anthropology and History in Mexico, took an interest in its origin. The skull was part of a collection of twenty-seven early hurrahs that was stored at the National Museum of Anthropology in Mexico City.

"The museum knew they were very ancient, but they did not have the exact age," Gonzalez says. Advances in radiocarbon dating techniques enabled Gonzalez and a team of scientists from England and Mexico to date several skulls using less than two grams of bone fragments. Gonzalez was delighted with the results. The oldest skull--referred to as Penon III Woman--was 12,700 years old. "[If] you look at how many human skeletons there are that are more than 8,000 years old, you can count no more than twenty people," Gonzalez says. "These four that we got from Mexico are really very precious."

Because the skulls are intact, Gonzalez and her team were able to take their measurements and compare their shape and size to both ancient and modern-day Native Americans. The skulls are dolichocephalic--meaning long and narrow headed--which is the opposite of the short, broad-headed shape of previous Mexican remains and of modern-day Native Americans. According to Gonzalez, these skulls suggest that there was a race of long, narrow-headed people living in central Mexico long before the descendants of today's Native Americans arrived. …

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