The animal known to have the longest gestation period is the African elephant. Female African elephants carry their young for about 22 months, longer than any other land mammal. The extended gestation period allows the developing fetus to grow sufficiently to thrive in the wild upon birth. These majestic creatures typically give birth to a single calf, although twins can occasionally occur. The long gestation also reflects the complex social structures of elephant herds, which rely on cooperation and support among females for calf rearing, thereby ensuring the survival of the species.