Skip to main content

By Studying Dolphins, Researchers Get New Insight into Human Medical Issues

When medical researchers use animal models to understand human illness, they usually turn to mice or monkeys. But now researchers are discovering that dolphins may provide insight into a range of human diseases, from cervical cancer and the effect of toxins to Type II diabetes.

In presentations Thursday and Friday at the AAAS Annual Meeting, researchers detailed the surprising medical parallels between humans and the big-brained, ocean-going mammals. And their research generated extensive news coverage, from blogs to newspapers and from North America to Europe.

Stephanie Venn-Watson, director of clinical research at the U.S. Navy Marine Mammal Program Foundation in San Diego, said in a podcast interview with Nicole Foley of AAAS that research into dolphins glucose-processing and blood-sugar levels could someday yield treatment of late-onset diabetes in humans.

A common dolphin | Public domain photo courtesy of NOAA, Scott Hill

[Public domain photo courtesy of NOAA, Scott Hill]
"Both dolphins and humans have big brains compared to their body size," Venn-Watson said. "Large busy brains need a lot of sugar, so scientists believe this could be why dolphins and humans have these common sugar needs."

Erik Stokstad, writing in Science NOW, detailed how the research emerged:

In 2007, Venn-Watson and veterinary pathologist Sam Ridgway of the University of California, San Diego, School of Medicine, "made a surprising discovery in bottlenose dolphins...owned by the U.S. Navy. After reviewing 7 years of routine blood samples from 52 dolphins, they found that the blood chemistry after fasting resembled that of people with diabetes—higher levels of glucose and other molecules, such as an enzyme called gamma-glutamyl transpeptidase—while the blood after a meal was like that of healthy people. This allows the dolphins to maintain adequate glucose levels while eating a high-protein diet, Venn-Watson said."

In her podcast interview, Venn-Watson explained that dolphins get little glucose from their fish diet; instead, they appear to manufacture their own glucose.  That, she said, suggests they "might have a genetic-fasting switch that turns diabetes on and off."

And that has potentially huge implications for humans. "If dolphins indeed have this genetic-fasting switch that can turn diabetes on and off," she said, "then control of such a gene could lead of to the cure of diabetes in humans."

Other researchers, meanwhile, are looking to dolphins for other insights.

"Another important human disease where the dolphin may be of help is cervical cancer triggered by the papillomavirus," Dick Ahlstrom write in the Irish Times. He quoted Hendrik Nollens, a marine biologist at the University of Florida: “We discovered that dolphins get multiple infections of [various] pilloma viruses which are known to be linked with cervical cancer in women."

Clive Cookson, writing in the Financial Times, also quoted Nollens: "Dolphins are the only species besides humans that we know of which can harbour co-infections, or infections of multiple papilloma virus types, in the genital mucosa...

"Even more surprisingly, some virus groups have shown the ability to cross the marine-terrestrial boundary, from sea to land," the researcher added. According to Nollens, there has been at least one case in which viruses underwent genetic recombination.

"So while it is exciting that dolphins can provide a unique window into the role of co-infection in human cervical cancer, we cannot rule out that the next high risk virus, such as SARS or West Nile, might actually come from the marine environment."

Leo Kretzner, writing for the Ground Report Web site, reported that dolphins may signal another threat to humans, as well.

"Lori Schwacke of the Hollings Marine Laboratory in Charleston, S.C.--part of the National Oceanic and Atmospheric Administration (NOAA)--has documented the highest levels of PCBs (polychlorinated biphenyls) ever seen in marine wildlife among dolphins living in estuaries along the coast of Georgia, with concentrations as high as 2900 parts per million.

"Using catch-and-release-based medical examinations of dolphins, Dr. Schwacke and her colleagues found signs of altered thyroid hormones, elevated liver enzymes, and suppressed immune function in these animals."

In Ground Report, Schwacke offered a grim assessment: “We can no longer assume or hope that these chemicals over time are completely buried in sediment or washed out to open sea to be diluted--they are clearly still entering the coastal food chain.”