Sarah Holt

It's a mystery on a global scale: five times in Earth's past, life has been nearly extinguished, the vast majority of plants and animals annihilated in a geologic instant. What triggered these dramatic events? And what might they tell us about the fate of our world? Joins scientists around the globe as they unravel the mysteries of two of the most dramatic mass extinction.

In Japan, Europe and Russia, birth rates are shrinking and the population is aging. In parts of India and Africa, more than half of the still growing population is under 25. The world population is now careening in two dramatically different directions. China revs up examines China's booming economy and the impact its having on the environment.

Scientists are coming to understand fat as a fascinating and dynamic organ - one whose size has more to do with biological processes than personal choices. Through real life stories of hunter-gatherers, sumo wrestlers, and supermodels, Nova explores the complex functions of fat and role it plays in controlling hunger, hormones, and even reproduction.