Dolphins' Ability to Switch Diabetes On and Off Could Point to a Similar Knack in Humans
A scientist's discovery that dolphins have a genetic ability to turn diabetes on and off, depending on the availability of food, could lead to research into whether humans might have a similar-although dormant-gene.
Dr. Stephanie Venn-Watson, a veterinary epidemiologist and director of clinical research at the National Marine Mammal Foundation in San Diego, recently told the American Association for the Advancement of Science that dolphins can induce type 2 diabetes when food is scarce, then immediately turn it off when food becomes abundant.
Venn-Watson made the discovery after analyzing blood samples from dolphins that she was studying off the coast of San Diego. She theorizes that dolphins acquired the ability to control diabetes when they evolved from land animals into sea animals about 55 million years ago. Because their fish-only diet provided no carbohydrates and their large brains demanded constant nourishment, dolphins developed the ability to induce a condition of high blood sugar during lean times, then switch it off once they found food.
Venn-Watson said that some evidence suggests that humans had a similar ability during the last ice age because their diets were almost entirely protein-based. Because humans depended on the luck of the hunt, like dolphins they had to find a way to keep their large brains sufficiently nourished in between animal kills. If so, that "fasting gene" probably still exists in humans, although in a dormant form.
Studying this gene could provide a much deeper understanding of how to control the disease or thwart its onset. Eventually, scientists could begin experimenting with chemical "switches" that could turn the dormant gene on. In several current lab animal studies involving the genetic origins of diabetes, scientists have succeeded in controlling certain genes through the use of chemical messengers that instruct them to turn on or off.
One problem that researchers might face is resistance from animal rights organizations concerned that further study of the dolphin gene could involve taking dolphins into captivity. However, Venn-Watson said that when she took blood samples from dolphins, they "volunteered" her access to them by approaching her on the beach and presenting their tails.
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