Photo Gallery: Big Cats

An adult male lion walks through grasslands in Botswana's Okavango Delta. Biologists think one of the reasons males evolved their impressive manes was to provide neck protection during fights.

National Geographic is working to avert the lions' extinction with the Maasailand Emergency Fund. Donations will be used to support animal husbandry education and job creation for the Maasai, among other endeavors.