Why don’t we have woolly mammoths anymore? Was it climate change? Did early humans eat them to death? Maybe. Or maybe they just fell down. A new paper suggests that bone disease weakened the prehistoric giants until they could no longer support their own body weight.

Theories on the mammoths’ disappearance have long jockeyed for supremacy. Most attention has focused on two likely culprits: global warming and hunting. Each new study refutes the last, leading to headlines like “What Killed Off the Woolly Mammoth? Climate Change,” followed just a few months later with “Humans Definitely Killed Off Woolly Mammoths.”

What if everybody’s right?

Paleontologist Sergei Leshchinskiy of Russia's Tomsk State University believes that a shifting climate led to changes in the landscape, which in turn caused a decline in available minerals. In a recent paper in the journal Archaeological and Anthropological Sciences, Leshchinskiy argues that these nutrient deficiencies weakened the mammoths’ bones, making them slower and weaker, and therefore easier to hunt. 

Image Credit: ©TSU

Leshchinskiy analyzed more than 23,500 mammoth bones and teeth using a magnifying glass, stereomicroscope, and scanning electron microscope, as well as x-rays and densitometry. The bones had been collected from mineral-rich sites in the Czech Republic, Poland, and Russia. These areas are called the beast solonetz,which Leshchinskiy translates as "a ground surface area characterized by a high content of certain macro- and micro-elements." Like nutrient watering holes, the rocks and soil of the beast solonetz sites provided animals like mammoths with the minerals they needed. 

But something went wrong. Leshchinskiy found signs of osteoporosis and other bone diseases in a full 90 percent of the specimens he examined. Holding up a mammoth is a big job, and these bones were just not strong enough. Even the bones from baby mammoths were brittle and weak, which suggests their mothers weren’t getting the nutrients they needed.

So what changed? The landscape. Over thousands of years, as continents shifted and the planet warmed, some areas were swamped, and others went dry. Floods leached essential nutrients like calcium, magnesium, zinc, and sodium from the soil of the beast solonetz. The supply of dirt-flavored multivitamins dried up, says Leshchinskiy, and the mammoths’ skeletons began to weaken.

Conquering a mammoth in its prime would have been no easy feat for our ancestors. A mammoth with a broken leg, on the other hand, was as good as dinner. Leshchinskiy’s results are specific to Eurasia, but he believes the same scenario may have been true elsewhere in the world, including North America.