The oldest fossil record of Panthera Leo dates back 3.5 million years and was discovered in Tanzania. Lions had a huge range historically and were found in Europe and America as early as 10,000 years ago. The Eurasian Cave Lion, followed closely by the American Lion, was perhaps the largest cat to have existed. Both these great cats became extinct during the last ice age with the eradication of their prey animals. Widespread hunting also contributed to their downfall as lions disappeared from North Africa and major parts of Asia, limited today to Sub-Saharan Africa and Gir forest in India.

Lions usually have a uniform coloration, varying from golden to brown. Cubs frequently have spots on their coat that disappear as they age. Sometimes they persist and are visible on limbs and belly, that usually is whitish in color (particularly in lionesses). Male lions are the only cats to sport a mane, though male tigers frequently have mane-like hair surrounding their skull. However, mane in case of lions extends to their neck, shoulders and belly. The evolutionary origin of the mane is a subject of some controversy with some authorities maintaining that is an indication of sexual prowess and testosterone levels while others argue that its chief function is protection against other lions in fights. Both views appear to be true, however mane is frequently seen to be linked with environmental conditions. Captive lions in cooler climates of Europe and North America sport heavier manes whereas the lions of bushy Tsavo region in Kenya are maneless. Lions have the largest skull amongst all cats, with strong jaws and canines designed to suit their carnivorous lifestyle.

Lions have a social lifestyle unique from all other cats. They live in groups, called prides, that vary in number from 3-5 in case of Asiatic lions to up to 30-40 in African lions' case. Group living offers them several advantages including cooperative hunting and protection for the cubs. A pride usually consists of 1-3 adult male lions and 10-20 lionesses and their cubs. Female lionesses usually stay in a pride for the entirety of their lives, wheres males are removed from the pride by the adults as they reach maturity, and must search and take over a pride of their own. Lions are excellent hunters and are capable of taking down prey of any size owing to their specialized hunting skills. Females are the chief hunters and owing to their sleek yet immensely strong body structure are one of the most fearful hunters in all of animal kingdom. Usual approach is to circle the targeted prey and close in gradually. Couple of lionesses initiate the charge with the specific purpose of scaring and confusing the herd as they run straight towards the remaining members of the pride that stalk the prey's exit routes. Death is usually by suffocation however, lions are fully capable of killing up to medium-sized animals by swats from their giant forepaws. In fact lionesses often specialize in killing even large prey like zebra by breaking their neck through shear momentum as they try to avulse it during their leap. Contrary to popular belief, recent research shows that males partake in up to 50-60% of all hunts - particularly for big prey like the cape buffalo. However, the chief function of the big males is protection of the pride from outside threats. With a big mane, immensely strong forequarters and powerful jaws - lions are perhaps the best fighters amongst land mammals. The other predominant feature of the male lion is his bravery. Great hunters and historians maintain the lion as the king of beasts because of its great strength and courage. While the tiger slinks away through the forest, the lion stands his ground, at times showing incredible daring. There are few things more fearful than a hungry lion and at times his mere roar has caused many a hunters to fall from the machan to lion's hungry jaws. Lion's roar is in fact the loudest amongst all cats and on a clear day carries over several kilometers.

Lions usually prey on antelope, gazelle, zebra, wildebeest, warthog and buffalo. However lions have been known to prey on elephants and hippos in Botswana. There are accounts of black rhinoceros kills in Etosha national park by lions. At times lions, driven by disease, lack of prey or habitat encroachment by humans, turn to man-eating. Man-eating lions display supreme cunning and daring and are highly feared by African natives, considered demons and supernatural spirits. Apart from all his savagery, lion displays nobility too and unlike the leopard, rarely attacks humans unless driven by extreme hunger.