Natural Selection Image Map

Success Stories

Environmental Hazards Can be Eliminated: Unleaded Gasoline

For about 80 years, lead was used as an additive in gasoline to make car engines run smoother. It became the primary source of lead pollution in the United States. Lead poisoning causes serious effects, especially on the brains of babies and young children. See our Hazards discussion of lead.

In about 1986, laws were fully implemented to phase out the use of lead in gasoline.  Benefits occurred quickly. One study shows that US blood-lead levels declined by 78 percent from 1978 to 1991. Today, the European Union has banned the use of lead in gasoline and the World Bank has urged all countries to do so. Click here for a quick overview of the history of lead use in gasoline.

Endangered Species Can Be Saved

In an earlier lesson, we talked about how conservation efforts seem to have saved the American Bald Eagle and the Whooping Crane from extinction.  There are other modern-day examples of preserving species.

For several decades, biologists at various institutions in Mexico and Texas developed programs to save the Ridley Turtle species. Humans had nearly destroyed the species by harvesting the eggs that the turtles laid on the Gulf Coast beaches. Click here for more information.

Back to Previous PageNext to Following Page




Introduction | Why It Matters | How We Find Out | What We Know | Story Time
Common Hazards | Activities | Self-Study Game | Teachers Pages | Standards (TEKS)

Peer Curriculum | Ecosystems Home Page | Communication Exercises
Copyright 2001-2003
Web Site Privacy Statement