Many wildlife biologists believe tigers are basically loners with no social or family life. But Thapar has had his eye on the tiger for most of his life, spending hours at a time watching tigers hunt, sleep and play. He is one of the world's leading tiger experts, and works to preserve their habitats and pass laws to protect them.

Thapar has noticed that when their habitat is left undisturbed, tigers are far from solitary. They form communities to share food and to hunt. Tiger cubs wail and cling to their mother after she's been gone, just as human infants do. Thapar believes that the loss of tiger habitats and the loss of prey is what forced tiger families to live apart.

When Thapar saw Kublai's family that afternoon, he knew the scene would change many scientists' minds about the way tigers live. "My heart missed a beat," he says.

Saving the Tiger to Save People
Just 100 years ago, India was home to 500,000 tigers. Now, there are fewer than 6,000 in the entire world. Some were killed so their parts could be used in folk medicines. And in some very poor areas of India, tigers are poisoned by people who don't want to compete with them for food.

Thapar created the Ranthambore Foundation 11 years ago, named for a national park in India where tigers are protected. He leads kids from local villages into the park to see tigers up close. He teaches about the threats facing tigers, and what kids can do to help.

"People ask, 'Why worry about saving the tiger rather than taking care of India's people?'" says Thapar. "But if we save the tigers' habitat, we save the rivers where clean water comes from. We preserve the balance of other species in the habitat. Our lives are interconnected with the life of the tiger."