Grizzly End: Prehistoric Bears Were Cannibals

Scientists discover ancient cave bears feasted on their den mates.

MOIA, Spain — Researchers have revealed that cave bears were actually cannibals — they ate their cave mates and their young.

The cave bear (Ursus spelaeus) bones, found at the Paleolithic site of Cova del Toll, in Moia, Spain, were discovered in the 1950s. However, no research on them was undertaken until 2014, according to Jordi Rosell, from Rovira i Virgili University and the Catalan Institute of Human Paleoecology and Social Evolution (IPHES).

The research, conducted by experts from those two schools, as well as the National Centre of Investigation for Human Evolution, Alcala University and Complutense University, coupled with new data, has just been published.

The findings compare the archeologic remains of cave bears with modern research into the behavior and remains of brown bears in the Pyrenees, the mountain range between Spain and France. Specifically, it set out to determine the origin of a bone modification known as “peeling,” which can be produced by both bears and humans.

“This time of year is the most critical one for the bears. If they have not eaten well during the other seasons of the year, or if they are too young or too old, they could die during hibernation and the body then remains inside the cave, ready for scavengers,” Rosell said.

The Cova del Toll is located near another cave where Neanderthals lived, and cave bears hibernated there.

Neanderthals visited the cave at different times of year. It was believed the marks found on cave bears bones had been left by them. However, it has now been revealed the cave bears made these marks in order to get at the entrails of their cave mates. (Remains of hyenas were also found.)

“With that information, the hypothesis that the cave bears were cannibals has been confirmed, they eat individuals of the same species,” Rosell said.

What is unclear is if they were killed by other hungry bears, or whether they were already dead.

The goal of the research was to discover more about the behavior of cave bears, which lived in the area between 150,000 and 12,000 years ago. The species lived in Europe and Asia during the Pleistocene and became extinct about 24,000 years ago. The Pleistocene Epoch began about 2.6 million years ago and lasted until about 11,700 years ago.

The remains found in the cave were also compared with previous studies of bone fractures caused by chimpanzees in captivity and modern human bone fractures done by the Khoikhoi, a traditional, nomadic tribe in Namibia.

“We wanted to know what the bears do when they eat a whole body. We monitored the brown bears in the Pyrenees for 10 years, collecting the remains of animals they ate and checking for marks” on their bones.

“Brown bears use their front paws as if they were hands, folding and pushing the thorax until the ribs and the vertebrae break so that they can get to the entrails, which is their favorite food,” said Rosell. “The main characteristic of the bone fractures is that the edges are left jagged, similar to the ones left when a fresh tree branch is broken.”

Cave bear skull recovered in the Toll Cave in 2015. The Cova del Toll, or Toll Cave, is located near another cave where Neanderthals lived, and cave bears hibernated there. (Florent Rivals-IPHES/Real Press)

Until now, the marks had always been attributed to human activity, but assigning the marks to bears is a game-changer. It happened so often that “a lot of archeological sites will need to be checked, especially those where there was a combination of animal and human activity. They ate their cave mates after they died,” Rosell said.

After hibernation, bears are starving and in a critical state where they will take “all they can eat. If there is the body of a bear in the cave, they eat them before leaving the cave to look for more food.”

But the motivation and circumstances that underlie the consumption are unknown.

“I am sure they also ate their dead offspring in the cave during this lethargic process, as bears are born very small and in a short time they grow a lot. Their bones are fragile, and we have found bones from bear cubs spread all over the cave, with lots of bite marks.”

Bear cubs are commonly are born in winter, during the hibernation process. At the end of the hibernation season, the mother and her offspring leave the cave in search of food, trying to avoid male bears, as they might try to kill the offspring in a bid to mate with the female and impregnate her with their own seed.

Prehistoric cave bears were more vegetarian than bears today, according to Rosell.

“Eating meat was not common, but like the Pyrenees brown bears, they are extremely carnivorous shortly after hibernation, as they leave that period starving and weighing around 100 kilograms (220 pounds) less. Over time, they tend to pay less attention to meat and prefer to eat fruit and grass in the area.”

Researchers also concluded cave bears hibernated in groups, in contrast to modern bears, which tend to be more solitary.

(Edited by Fern Siegel and Matthew B Hall)