Human pre - history is filled with terrifying brute our ancestors had to contend with , but even among these , cave bear ( Ursus spelaeus ) stand out , having sometimes reached a MT in weight . For all their fearsome defenses , fresh evidence suggests their paranasal sinuses , the air - fill cavities at the front of the skull , may have been their undoing .
undermine bear fossils are comparatively common across Europe and Asia because so many go while hibernating . Yet we know less than we would wish about them , let in their dieting . They have been suggested as everything from powerful marauder to cowardly scavenger or gentle herbivore .
“ acknowledge the feeding behavior of the cave bear is not a piffling aspect,“Dr Borja Figueiridoof Spain ’s Universidad de Malaga said in astatement .
The cause of their experimental extinction is also under debate with the two usual suspects – climate variety ( in this fount , a particularly cold part of the water ice long time ) andhuman competition . InScience Advances , Figueirido andDr Jack Tsengof the University of Buffalo have brought these together , proposing the bear ' were made vulnerable by their motive to log Z’s through longer winters .
Large paranasal place can be used to hold nitrogen oxide , which hibernating brute use to deject their metabolism – more space allows greater metabolic control . As a import , U. spelaeussported some telling holes in its skull , larger than survive bear species the source equate them against . In the case ofU. spelaeus ' even larger easterly European cousinU. ingressus , these reached 60 pct of the skull book , but it seems in the long trial these holes in their head were not what they needed at all .
" Mechanically speaking , being ' thickheaded ' may not be a defective affair because more bone mean more geomorphologic military capability , " Tseng enunciate . " However , our finding back the interpretation that requirement for sinus system occasion in cave bear call for a trade - off between sinus ontogeny and skull intensity level . "
Adding large sinuses helped undermine bear slow up their metamorphosis during hibernation , but it melt off their jaw force , reducing their dietary flexibility and probably leading to their death . Alejandro Pérez - Ramos
The authors used the emerging field of biomechanical mold to estimate the strength of the former bear ' jaw muscles . They concluded that as the bear developed bigger sinuses to last the frosting historic period , they give up some of their chewing mental ability , restricting their diet .
This ineluctably made the bears more vulnerable to anything that affected their solid food provision . If the climate changed again or man started competing with them for nutrient , they were unable to fall back on alternative sources of nutriment . No doubt human rivalry for cave , a popular account for their demise , deport some of the blame , butU. spelaeusmay have gotten stuck at an evolutionary deadened end .
Tseng think identifying what led to the demise of other large mammals can help us understand what allowed our ancestors to live in the same shape . That , in spell , could be helpful in get wind what is essential for next success in a changing surroundings .
