On Candles

For those of you who don’t know, the candle lit at both ends is often taken as symbolism, among other things, of the Caltech student. “The candle that burns twice as bright burns half as long.” I originally heard of this quote through one of my all-time favorite movies, “Blade Runner,” and it was spoken in reference to the short-lived but physically and mentally superior replicants. I never took much stock in it: by this, I don’t deny that a physical phenomenon that a candle lit on both ends will last approximately half as long, but in the symbolic meaning that those who excel are doomed to early deaths. If anything, I believed the opposite: Humans are machines, and some machines are better designed and built than others. Given only that one machine is more efficient at doing what it does than another, one would conclude that the former would also likely last longer, simply because superiority of craftsmanship would usually correlate across all aspects.

Thus it was that I found one thought in Richard Dawkin’s “River out of Eden” particularly arresting. “Whenever natural selection favors a gene because of its beneficial effect in youth–say, on sexual attractiveness in a young male–there is likely to be a downside: some particular disease in middle or old age, for example.” The source of his (or rather, technically it is due to P. Medawar, G.C. Williams, and W.D. Hamilton) reasoning is that while mutations in genes generally have more than one effect, it is likely that ones which stay in significant numbers in the population have exactly one beneficial effect: the vast majority in the space of all possible mutations on existing genes that are those with no beneficial effect (and many harmful ones) would quickly be removed from the gene pool by natural selection, and the space of mutations having two or more beneficial effects is vanishingly small compared to that of exactly one, and would rarely if ever be sampled.

The one intrinsic assumption in this line of reasoning is that humans as a species are at equilibrium, or at least a steady-state: Genes that are successful at ensure their own propagation are already present in optimal or near-optimal concentration. This assumption is based on the idea that number of years that occur the life of a modern man pales in comparison to that of the length of the history of humans as a species. Yet here, inevitably, Dawkins made a flaw in reasoning, for his next chapter in “River out of Eden” claims exactly that we are not currently in an “average” decade/century of human growth. We are at the threshold of science, where many fields are intersecting which greatly prolongs the expected lifespan not only of individual humans, but also humanity as a species. In the past hundred years, the fitness of many genes have been violently skewed, due to the advent of modern medicine. Almost all genes that confer resistance to certain diseases have had their benefits diluted. Almost all genes that favor the buildup of fat in the body has suddenly been inverted from an advantage to a disadvantage. Almost all genes that favor longevity and delaying of menopause are much more valuable now (and possibly even more valuable shortly, with human cloning).

Thus, I believe there is hope. I remember once chatting with an old-aged Chinese seller of paintings, and he was saying he did not remember me (I’ve bought on the order of 5 from him). He said that he had great memory as a kid, but in life, often precocious perceptive and intellectual abilities are accompanied by stronger versions of senescence. It fits Dawkins’s theory, but it may not necessarily be true for everyone.