When Dr. Laurance Doyle lectures to undergraduates, he tells them "math is not in the chalk," it is a tool they can use to understand the universe. Doyle finds math everywhere; in the signatures of radio waves that might reveal communication technology on other worlds; the distribution and orbits of planets circling distant stars; and in the calls of marine mammals.

At first glance, studying an endangered species may seem off target for the SETI Institute astronomer, whose special expertise is planet detection. Doyle, however, has exceptionally varied research interests. He has written extensively on circumstellar habitable zones (cosmic real estate that is bio-friendly), is a scientific collaborator on the NASA Kepler mission, and teaches a course on Native American history.

He also works with biologists Brenda McCowan and Sean Hauser, of the University of California, Davis, studying non-human communication systems to better understand the nature of language and intelligence, which in turn has direct relevance to the search for extraterrestrial intelligence (SETI). Quantitative tools for intelligence studies are and few and far between, making the Drake Equation term F_i (fraction of planets on which intelligence develops) one of the most elusive facets of SETI research.

Doyles team uses statistical tools from a field known as "information theory" to measure the complexity of different species communication systems and thus learn how much information individual animals can transfer between each other. This allows the scientists to draw inferences about the intelligence of the communicating species, which in turn gives F_i researchers a better understanding of intelligence as an evolutionary adaptation.

Information theory may also teach us how to approach the analysis of a signal from distant worlds should SETI astronomers make a confirmed detection. And -- as a surprising "SETI spin-off" -- information theory may also help protect one of the planets best-loved marine mammals.

Doyle explains the connection. "I was watching a television show about whales." It was the late 70s, and he was working at JPL, processing image data from Voyager. "The researchers were having trouble picking out individual signals from the animals. I wanted to help." Doyle knew his signal processing experience with Voyager could be useful. "We were using a Hough transform to pick out signals from the noise."

Realizing that this signal processing technique could be applied to the marine mammal calls, he contacted the Hubbs Research Center at Marine World and was connected with researcher Sheldon Fischer. The pair began to identify individual signals using the JPL technique. Unfortunately, the analysis required intensive computational power which, unlike today, was not practical for all but the largest research budgets. The project was ultimately dropped, but the experience sparked Doyles interest.

He "sat on it for seven years" before joining the SETI Institute in 1987, where he first encountered the small network of researchers interested in dolphin intelligence and SETI. "We all intuited that the study of dolphins may have something to do with SETI," Doyle explains, "but we didnt know how to tie it all in."

Eventually, the right combination of research expertise would coalesce into a collaboration between Doyle, McCowan, and Hauser. In the late 1990s a paper appeared in the journal Science, describing a novel use of information theory to analyze the "language" of DNA. An Institute colleague made "an off-hand comment" on the paper over lunch with Doyle, and the germ of an idea took root.

"I went home that night with preprints of Brendas dolphin signal paper, and did a Ziff plot." The Ziff plot is a tool within information theory that shows the relationship between repetitive and novel units of communication within a system. Language, Doyle explains, has a characteristic Ziff slope of 45 degrees. So did the dolphin. The results astounded the astronomer, who remembers, "First I had to have a cup of tea to make sure I got the figures right, then I called Brenda!"

Over the next year, the group pursued this line of research. In 2000, Doyles group, which also included Institute colleagues Dr. Christopher Chyba and Taylor Bucci, launched an expedition to Glacier Bay, Alaska. The researchers lowered hydrophones from their kayaks and gathered signals from the feeding whales. In the course of the studies, says Doyle, "we heard a lot of shipping noise, and decided to look for it in the data."

Before returning home, the team gave a talk in the Glacier Bay community, and caught the interest of local scientists who offered to share several years of recordings with the California researchers. This bonanza included data gathered during feeding sessions free of shipping noise, allowing the team to build a baseline against which they could compare the "noisy" recordings.

The results showed quantitatively that the boat noise was impacting the communication. The humpbacks were having to "shout" above the noise, repeating and simplifying their calls to each other, much like humans trying to converse above the din of a noisy party. "We detected an information decrease of about 28 percent in the presence of boat noise," says Doyle.

In the limited visibility environment of the ocean, humpbacks rely upon vocalization for their social behavior, which includes feeding. Shipping traffic was disrupting their communication, and by inference, their social activities. The researchers will soon be collaborating with the Alaskan Whale Foundation to gather more data, and coordinate the communication studies with other research on the humpbacks, such as studies of their physical health.

The future offers compelling research opportunities -- and challenges. "There is plenty of work that needs to be done," says Doyle. Asked about next steps, he explains, "Wed like to set up an array of hydrophones so that we can triangulate individuals." Identifying individual whales by their signals is highly sought goal of many marine mammal researchers.

Doyle smiles as he contemplates the road ahead. The research team would like to build upon their work with whales and dolphins to include many species in a survey of non-human communication systems. "We know how to do it," he says earnestly. "All we need is the funding."

For now, Doyles colleague Hauser looks forward to another season in Alaska with the Whale Foundation. The more data the group has to analyze, the more they can learn about the communication system, the behavior, and the effects of the environmental context in which the humpbacks socialize.

"Its a start," says Doyle. And a wonderful way to think about the utility of math as we celebrate Earth Day.