When wolves were reintroduced to Yellowstone National Park in the United States after being absent nearly 70 years, the most remarkable "trophic cascade" occurred. What is a trophic cascade and how exactly do wolves change rivers? George Monbiot explains in this movie remix.

This is my "Change the World" project for my school environmental science class.

Biology teacher Ceri Evans gives a masterclass to students on what he says is arguably the greatest idea anybody ever had: evolution. He uses a series of activities to demonstrate genetic variation, mutation, competition, survival of the fittest, niches and adaptation through natural selection. He a...

A move towards sustainable energy is often talked about as an issue for big government, especially during the 2016 election. However, across the United States, progress is being made in biofuel, wind, and solar power at the grassroots. Atlantic national correspondent James Fallows and contributing w

In every female kobudai... is a male in waiting. Animals in the genus Semicossyphus belong to the wrasse family, or the Labridae. Other members of the family and some fish in other families can also change their gender. They develop the reproductive organs, external features, and behavior of the op...

Penn was built on the concept of innovation. “If it’s new, novel and holds promise to change the world,” says President Amy Gutmann, “you’ll find it at Penn.”

In this SCIENCE episode of Ask Dr. Bob we address Health and Politics. We discuss the use of PrEP to prevent acquiring HIV/AIDS and the need to continue the support of this medical treatment for all individuals at risk. We also discuss the political climate regarding abortion medication and the se...

HULC a human assisting robot will be available to the handicapped in 5-10 years and will alllow them to walk again!!!

We are living through unprecedented times. This pandemic has swept through our nations, communities and our homes, touching each and every one of us and changing the way we live in unimaginable ways. But we are not ready to accept this as the new normal. We know where this virus came from, just as w...

This edition of the series "Tapestry: The Faces of AIDS", profiles Dr David Fawcett author of "Lust, Men and Meth" a book that explores the relationship between gay men, meth, and other mood altering chemicals, and high-risk sexual behaviors. It also provides a sex therapist’s insight into sexual d