They can't talk. They're not measurably intelligent. They can't even move on their own. Yet Katherine Freeman of Penn State University's geosciences department has been learning something from common marine algae.
"We're trying to look back in time," says Freeman, "to see if the level of carbon dioxide in the atmosphere was higher when the temperature was higher." By understanding Earth's ancient atmosphere, scientists hope to predict the consequences of modern-day greenhouse gas emissions.