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Michigan Turtles On Immortality

Hanging out above like a bump on a log is a classic Chrysemys picta, or Painted Turtle, sitting just above the shallow, weedy pond on my southwestern Michigan land. Truth be told this specimen moved nothing like a lump, as did his aquatic band of brothers or bale – the classic collective term to refer to a group of turtles. At shutter speed, a half dozen of them did just that, diving ‘neath the bright green surface and disappearing in the marsh’s murky depths. Save this one here, caught by my camera with his proverbial turtle neck out.

Michigan’s reptiles of the order Testudines – characterized more by their special bony, shield-like shells- were in the collective viewfinder recently, with a Detroit Free Press article focusing on – as it read – Turtle Habitats Revealing Clues Into Our Longevity. Gaining energy by absorbing it from the sun like a solar panel, the females of this cold-blooded animal reproduce better at 80 years old than at 20, with more frequency,  larger clutches (groups of laid egg) sizes, and eggs that are slightly larger. The Painted Turtle, Blanding’s Turtle and Snapping Turtles are all common species in Michigan, all having an unusually large range in which they mature and begin breeding — for Blanding’s turtles, it’s between ages 14 and 21; for painted turtles, 6 to 11; for snappers, 11 to 16.Painted turtles tend to live until about age 40 to 42; snapping turtles and Blanding’s turtles into their 90s.

But here’s the weird part: They don’t seem to age.The reason a man or woman looks different at age 75 from the way he or she did at 25 has to do with senescence, the process of cells’ deterioration with age. There are up to 75 trillion cells in the human body, and they are constantly living, dying and being replaced. But that process of replication seems to work something like a copy machine making a copy of a copy of a copy — over time, it becomes more and more imperfect.

Research on Michigan Turtles basically shows that, “Unlike humans and mammals in general, turtles don’t senesce”, said Kim Scribner, an evolutionary ecologist at Michigan State University.  “There are a lot of people who are interested in turtles as a model of aging, because they apparently age quite gracefully.”  A slow but steady pursuit, given The Giant Tortoise having been known to live to age 200 and beyond.

It will be most interesting to study turtles at a sort of  genomic level, to understand what makes them different. Why aren’t they going through this cellular dying?  Do they have lower mutation rates? Perhaps there are more timely life lessons to learn from the tenacious turtle.