Lions kept in zoos have a higher rate of malformed skulls, scientists say, which puts the cats at greater risk of brain damage. When researchers compared the noggins of captive lions to those of their wild counterparts, they uncovered a potentially life-threatening problem: In zoos, lions were more likely to have smaller openings at the bottom of their skulls.
This hole at the skull's base, called the foramen magnum, lets the brain connect to the spinal cord. And if this opening is too narrow, pressure on the brain stem causes tremors and loss of balance -- symptoms that have been observed in zoo lions.
It's not quite clear why these captive cats have improperly shaped craniums, but Joseph Saragusty, a biologist at Berlin's Leibniz Institute for Zoo and Wildlife Research who lead the skull study, has a few ideas. He tells New Scientist that zoo lions might be genetically disposed narrower foramen magnums -- and the lack of hard bone and gristle in captive cats' diets, in turn, worsens the problem. But, he says, "without knowledge of the cause behind the disease, there can be no real solution."