A group of researchers have revealed that cave bears were actually cannibals that had the unsociable tendency of eating their ‘cavemates’ and their young.
The cave bear (Ursus spelaeus) bones, found at the Palaeolithic site of Cova del Toll, in the municipality of Moia, in the eastern Spanish province of Catalonia, were discovered in the 1950s. According to Jordi Rosell, from Rovira i Virgili University and IPHES, hundreds of cave bears were found in the cave, but no research was undertaken until about a decade ago.
The research, conducted by experts from the Catalan Institute of Human Paleoecology and Social Evolution (IPHES), the Rovira i Virgili University, the National Centre of Investigation for Human Evolution, Alcala University and Complutense University, has been published in the magazine Quaternary Science Reviews, and has compared the archaeological remains of cave bears with contemporary research into the behaviour and remains of brown bears in Pyrenees.
The cave is located near another cave where Neanderthals used to live, and cave bears used to hibernate there. “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”, he said.
Neanderthals also visited the cave at different times of year and so far it was believed that the marks found on cave bears bones had been left by them. However, it has now been revealed that the cave bears themselves did these marks in order to get at the entrails of their cave mates. But it is still unclear if the eaten were killed by other hungry bears, or whether they were already dead.
The goal of the research project was to find out more about the behaviour of cave bears, magnificent animals that lived in the area between 150,000 and 12,000 years ago. The researchers used the cave bear bone remains found in the cave and compared them with the behaviour and the marks left by brown bears (Ursus arctos) in the Pyrenees mountains nowadays.
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.
Jordi Rosell said: “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 favourite food”.
The expert said that “the main characteristic of the bone fractures is that the edges are left jagged, very similar to the ones left when a fresh tree branch is broken.
Until now, the marks had always been attributed to human activity, but with the new research it was found that the bears made the marks, and so often that “a lot of archaeological sites will need to be checked, especially those where there was a combination of animal and human activity.
The expert said: “With that information the hypothesis that the cave bears were cannibals has been confirmed, they eat individuals of the same species”.
“They ate their cave mates after they had died”, Rosell added, explaining that after hibernation, bears are starving and are in a critical state where they will take “all they can eat”. He said that “if there is the body of a bear in the cave, they eat them before leaving the cave to look for more food”.
However, he also said that “we cannot say if they were responsible for the death of the individuals or only ate their dead bear friends in the cave after they had already died during hibernation”.
He added: “I am sure that 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. The mother is in a lethargic state, and they are breastfed. 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 made with the female and impregnate her with their own seed.
According to Rosell, prehistoric cave bears were more vegetarian than bears today, so “eating meat was not very common, but like the Pyrenees brown bears, they are extremely carnivorous shortly after hibernation, as they leave that period starving and weighing around 100 kilogrammes (220 lbs) less”.
“Over time, they tend to pay less attention to meat and prefer to eat fruit and grass in the area.
The experts’ research also concluded that cave bears used to hibernate in groups, which is in contrast to modern bears, which tend to be more solitary.