Tuberculosis was rampant in North American mastodons during the late Ice Age and may have led to their extinction, researchers say.
Mastodons lived in North America starting about 2 million years ago and thrived until 11,000 years ago—around the time humans arrived on the continent—when the last of the 7-ton (6.35-metric-ton) elephantlike creatures died off.
Scientists Bruce Rothschild and Richard Laub pieced together clues to the animals' widespread die-off by studying unearthed mastodon foot bones.
Rothschild first noticed a telltale tuberculosis lesion on a bone at an excavation site in New York in 2001.
"His eye was caught by a particular bone—a metacarpal, the equivalent to one of the long bones in the palm of the hand," said Laub, who is also curator of geology at the Buffalo Museum of Science.
"He noticed a feature on the bone indicative of tuberculosis."
Rothschild, a practicing physician and an expert on ancient diseases, went on to study 113 mastodon skeletons across the continent. He found that 59 of them, or 52 percent, had the tuberculosis lesions.
Based on the finding, it's likely that virtually every late Ice Age mastodon in North America had tuberculosis, Laub says.
Tuberculosis causes grooved erosion in bones. While the disease didn't kill the ancient animals directly, it certainly weakened them, Rothschild says, likening their deaths to events that lead up to an airplane crash.
"You don't have a crash from one thing going wrong," he said. "It's multiple factors."
The research findings were published recently in the German science journal Naturwissenschaften.
Large, Adaptive Animals
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