A damning new report published in the PLOSone science journal suggests that captive lions run a significantly higher risk of brain damage than their wild counterparts.

The report – authored by a team of scientists and captive research specialists from Germany, Israel, the U.S., and the U.K., headed by Joseph Saragusty – observes that “lions have been kept in captivity for centuries and, although they reproduce well, high rates of stillbirths as well as morbidity and mortality of neonate and young lions are reported. Many of these cases are associated with bone malformations, including foramen magnum (FM) stenosis and thickened tentorium cerebelli.”

What this means is that certain skull bones do not appear to form correctly in a high proportion of captive lions, leaving these lions more susceptible to fatal health conditions and brain-related illnesses.

Until now, it hadn’t been clear whether these brain malformations were specific to zoo animals or were just as frequent in the wild.

However, after comparing 575 lion skulls – 512 of which had come from wild lions and 63 former captive ones – Saragusty’s report came to the inescapable conclusion that the foramen magnum bone was significantly smaller in the captive animals. The skulls, which were sourced from museum collections all over the world, demonstrated that this captive-specific malformation was by news a modern phenomenon. Even a thirteenth-century captive lion skull excavated from the Tower of London showed signs of this foramen magnum deficiency.

The symptoms of this type of brain damage include tremors, loss of balance, and unusual head tilts – a condition that famously afflicted captive Israeli lion Samson until he underwent life-saving brain surgery back in 2005.

Saragusty theorizes that some lions may be genetically predisposed to the condition, which is then triggered by the inadequate diets they are fed in zoos. He says, “Unfortunately, without knowledge of the cause behind the disease there can be no real solution.”

One thing’s for sure: the knowledge that captivity could cause such alarming deformities in a lion’s skull is just one more reason never to visit a zoo or theme park that imprisons animals for the sake of profit. Instead, check out these five awesome ways to experience wild animals without the cruelty.

Image source: Wwarby / Wikimedia Commons