ELIXIR OF LIFE
Even though immortality was an exclusive privilege of the gods (in Christianity, even humans were immortal, created as they were in the image of god, but they lost it after Adam and Eve tasted the Forbidden Fruit), it did not deter cultures across the world from concocting all kinds of elixirs and panaceas in order to defy or deceive death forever.
The quest for immortality may appear antithetical to the spirit of modern science, but it didn't deter its apologists (who by the way always happened to be men) from dreaming and theorising about it. Francis Bacon wrote a book of recipes that allegedly prolonged life. French philosopher Rene Descartes longed for it as he entered the autumn of his life. Marquis de Condorcet, a luminary of the Enlightenment, prophesied a day when "the duration between the birth of man and his decay will have no assignable limit".
While that day is yet to come, the scientific imagination has been busy conjuring up fanciful theories about the causes of ageing and how to get around them. The Russian biologist and Nobelist Ellie Metchnikoff proposed in 1914 that we die of the poison made by the bacteria in our guts.
Even more outlandish, Charles- douard BrownS¸quard, a neurologist at Harvard, allegedly injected lots of men, including himself, with fluids from the testicles of dogs and pigs to restore youth (women, presumably, never aged or their ageing was of little consequence). And then there was Austrian doctor Eugene Steinach, who in the 1920s did vasectomies to make men feel and look younger. The idea became such a fad that even wise old men like Freud and W B Yeats fell prey to it.
These early flights of fancy bit the dust soon. However, one idea that endured till the end of last century was the rate of living hypothesis, according to which animals that expend more energy tend to age faster. In 1954, Denham Harman at Berkeley University, California, proposed that lifespan was limited by free radicals, small molecules with an unpaired electron that can potentially damage a cell. Denham's free radicals explained how burning more calories could make you age faster and hence made the hypothesis more plausible. However, as happens in science so often, the rate of living hypothesis went out of favour as subsequent evidence on more species contradicted it.