1900 Air Pollution

Examine this graph from FRONTLINE/NOVA: "What's Up with the Weather?" Web site to see dramatic increases in three greenhouse gases over the last two hundred years.

The Advantage of Sex

Why did sex evolve? The likely answers, in this essay for the Evolution Web site by science journalist Matt Ridley, may surprise you.

All in the Family

In this Evolution Web feature, test your skills at judging who's who on the tree of life while you learn about the tools and methods of cladistics.

Allopatric Speciation

These images from the Smithsonian Institution depict Nancy Knowlton's work with snapping shrimp in Panama. Knowlton found that the closing of the isthmus -- dividing the Pacific Ocean from the Caribbean -- resulted in new species of shrimp.

Ancient Farmers of the Amazon

This video segment from Evolution: "Evolutionary Arms Race" tells the story of the leafcutter ant and the fungus it farms -- an example of mutually beneficial symbiosis.

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Arctic Tundra

This video segment from Wild Europe: "Wild Arctic" explores the struggle for survival in one of Earth's most extreme environments.

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Biological Invaders

This video segment from Evolution: "Extinction!" shows the impact of invasive species on native ecosystems.

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Biomes

This interactive resource adapted from NASA describes the different temperature, precipitation, and vegetation patterns in seven biomes: coniferous forest, temperate deciduous forest, desert, grassland, rainforest, shrubland, and tundra.

Build-a-Fish

In this interactive activity from Shedd Aquarium, build a fish and then release it into the reef to search for food and evade predators. Try different combinations and observe how each kind of fish has unique adaptations that help it survive in its habitat.

Carnivorous Plants of Texas

In this video adapted from Texas Parks and Wildlife Department, learn about carnivorous plants that act as both producers and consumers in an ecosystem. See sundews and blatterworts capture and digest insects.

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Caves: Extreme Conditions for Life

This video segment adapted from NOVA raises the provocative idea that if life can exist in the most extreme environments on Earth — such as in dark, toxic caves — then perhaps living things can also survive in harsh environments on other planets.

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Changing Arctic Landscape

In this video adapted from the Arctic Athabaskan Council, learn how warmer temperatures in the Arctic are transforming the landscape, triggering a host of effects such as permafrost thawing and insect infestations.

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Chris Schneider: Rethinking Conservation

In this interview filmed for Evolution: "Darwin's Dangerous Idea," biologist Chris Schneider discusses the relationship between conservation and speciation.

Compare the Poles

Explore the defining features of the Arctic and the Antarctic in this interactive activity adapted from the Woods Hole Oceanographic Institution.

Complex Relations

In this text excerpted from chapter 3, "Struggle for Existence," of Charles Darwin's On the Origin of Species, Darwin draws on firsthand and historical information for his observations about evolution.

Contaminants in the Arctic Food Chain

The levels of contaminants found in particular animals vary widely depending on where they fit into the Arctic food chain, as described in this video segment adapted from LOKE Films and the Arctic Monitoring and Assessment Programme.

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Contaminants in the Arctic Human Population

In this video segment adapted from LOKE Films and the Arctic Monitoring and Assessment Programme, learn how human populations in the Arctic are affected by industrial contaminants in the food chain.

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Continental Divide: The Breakup of Pangaea

Examine geological evidence found in fossils, rock deposits, and ancient mountains that supports the theory of continental drift in this interactive activity adapted from the Exploratorium.

Darwin: Reluctant Rebel

This video segment from Evolution: "Darwin's Dangerous Idea," together with interviews with Daniel Dennett and James Moore, depicts Darwin struggling with publicizing his revolutionary theory.

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Darwin's Diary

Delve into the private thoughts of a reluctant revolutionary in this Evolution Web feature.