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Evidence from a prehistoric mastodon hunt
Manis specimen. This image is a close-up view of the bone point fragment that is embedded into the mastodon rib.
[Image courtesy of Center for the Study of the First Americans, Texas A&M University]
A controversial mastodon rib, found with the tip of a bone point lodged inside, is 13,800 years old, researchers report in a new study.
The findings suggest that the hunters who killed this animal lived before the emergence of the Clovis culture, which was until recently thought to be the earliest well-established human culture in North America.
The fossils were discovered in the late 1970s near Manis, Washington. Though researchers initially dated the skeleton at about 14,000 years, other scientists have questioned this age and debated whether the rib was related to the other remains found at the site.
To clear things up, Michael Waters of Texas A&M University and colleagues used a precise technique called mass spectrometry to date the carbon in samples of bone collagen extracted from the rib, the embedded point and a pair of tusks found nearby. Their results show that all of these fossils are the same age, roughly 13,800 years old.
The researchers also used high-resolution X-ray CT scanning (the same type of technology used in hospitals to see inside patients' bodies) to visualize the part of the bone point that was embedded in the rib. They report that the point was probably at least 27 centimeters long, which is comparable to the length of later, Clovis-age points used in throwing or thrusting weapons.
Finally, Dr. Waters and his colleagues analyzed genetic material from the rib and the bone point, concluding that the point was itself made from mastodon bone. These findings, along with evidence from other sites, suggests that people were hunting mastodons and mammoths at least two millennia before Clovis.
Some of the most common artifacts from the Clovis culture are stone arrowheads used for hunting. Archaeologists have proposed that the Clovis hunters played a major role in driving large ice-age animals to extinction. While this may be true, we now know that the Clovis hunters weren't the first humans in the Americas to hunt huge animals like mastodons.
The study appears in the 21 October issue of the journal Science.