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17 #1 Fall 2008 Engineering an End to Aging Michael Anissimov Age-defying creams and lotions, esoteric herbs and elixirs, Botox and plastic surgery -- what do they all have in common? None of them will actually increase your life span. Usually, they're snake oil. At best, they improve external appearance without actually extending life. We deserve better, and we'll need it if we want to live longer than the typical three score and ten years. e first thing to realize is that nature doesn't specifically want us to die. ere is no "death gene." For any species in any environmental context, there is an ideal life span from an adaptive point of view -- an evolutionary optima. One evolution- ary strategy includes species that reproduce quickly and die off fast. Another includes species that reproduce slowly and live for a long time. Call it quality versus quantity. ankfully for humans, we're squarely in the quality column, but many would agree that 80 to 90 years is not enough. We perish not because of some internal clock that says, "Time to die now!," but be- cause of a lack of attention and self-healing -- mere neglect. Once we've reproduced a few times, in the eyes of nature, our useful- ness has run its course. We are cast aside, onto a pile of skeletons 600 million years deep. is is unacceptable, and we need to find a new way, but since nature isn't ac- tively working against us -- just neglecting us -- the challenge is surmountable. LONGEVITY IN NATURE First, let's look to nature for inspiration. Are there any animals with extraordinarily long life or regenerative capacities? Absolutely. ere is one animal that scientists be- lieve is immortal -- the lowly hydra, a sim- ple, microscopic freshwater animal, shaped something like a tiny squid. Apparently, the challenges of indefinite tissue regeneration are simple enough for such a small organ- ism that nature has solved them. American biologist Daniel M. Marinez did a study of mortality in three colonies of hydra for four years straight, and barely any of them died . Death rates were random, uncorrelated with age. is means they weren't display- ing senescence (aging), and died from other causes. In almost all other known species, death rates increase with age. Not in hydra. ey die from getting eaten, or infected by a virus, or squished, but not from ag- ing. ere could be a thousand-year-old hydra out there, maybe in a small lake right in your neighborhood. We don't know, be- cause there is no way of telling their age by looking at them! Planarians -- those odd animals that look like a slug squished in a microscope slide -- are another organism that scientists suspect may be immortal. No detailed stud- ies have been conducted yet. In many cases, if you cut a planarian in half, it becomes two planarians. ese live as long as one born by conventional means. If you kept cutting a planarian in half, it might never die, be- cause each piece would go on living. What about more-complex ani- mals? ere are our friends in the order Testudines: turtles, tortoises, and terrapins. Scientists have examined the internal or- gans of young and old turtles and found that they look exactly the same. Something in a turtle's physiology prevents these organs from breaking down. An article in Discover magazine asked, "Can Turtles Live Forever," and came to the conclusion that it's entirely possible. Like hydra, turtles experience no increase in mortality rates and no decrease in reproductive rates as they grow older. ere are turtles 150 years old that exhibit no signs of aging. Harriet the Turtle, a pet of Charles Darwin's, was born in 1830 and died only in 2006. It seems turtles can die from disease, injury, or predation, but not aging. is quality is called "negligible se- nescence." Sign me up. From these animal examples, we see it would be premature to state that negligible senescence is biologically impossible, as is frequently assumed. Nature seems to be uninterested in our quaint notion that all organisms must age. e question is -- how can we make this work for humans? e oldest person who ever lived, Jeanne Louise Calment, kicked the bucket at the age of 122 1/2. Can we push that boundary? I m a g e b y K ΓΈ b e n h a v n s U n i v e r s i t e t (continued next page)