My father, whom I called Bhayya, grew up in the early part of the last century in the city of Lucknow in northern India. This intersection of period and place was perhaps the acme of Urdu-speaking culture, known ever since all over the subcontinent not only for its sublime literary achievements and the refinement of its manners, but also for its high ideals of decency and civility. One of the many ways in which these were manifested in the tehzeeb or culture of Lucknow was in its uncommon aspiration to male gentleness. This can perhaps best be described as something akin to the opposite of machismo. Even the shadow of aggressiveness was to be suppressed by men, with those unable to do so being considered barbarians or, at the very least, riff-raff. [Photo shows the Husainabad Imambara in Lucknow.]
Bhayya was a near-perfect product of this enviable culture, and hence I never even heard him raise his voice. Ever. Instead, one glimpsed his manliness in random, small ways. For example, I remember once when I was a child we were driving somewhere in our family car when a huge bumblebee flew in through a slightly open window and proceeded to make our driver almost crash the car, so busy was he ducking and furiously swatting at it. As the bumblebee droned loudly, crashing back and forth between various surfaces, with the rest of us (mostly adults) in the car spastically and violently trying to avoid it, my father sat perfectly still. Then with a single quick and confident motion of his hand, he had grabbed the bee and crushed it to death in his fist. He threw it out the window and didn’t say anything, but the bee had been faster than he, and later at home I noticed his swollen hand.
Bhayya also had the simplicity and frugal habits of someone who has grown up without very much. Hence he would use the same basic bar of laundry soap to bathe, wash his hair and face, and whip into a lather with a small brush for shaving. (I have heard that before I was born, in his eccentric 
attempts at economy, he even once tried to make large quantities of soap at home with the help of his brother and some vats of fairly toxic chemicals, but luckily my mother put her foot down and that was the end of that.) And shaving gives us another rare instance of his appearing somewhat macho: he always shaved with a razor blade (of the kind in the photo on the right) held simply between his forefingers and thumb. Whether he chose not to use a proper holder for the blade as another step in his economizing campaign, or because of some other personal preference or secret to a good shave, I will never know since I never had the courage to ask him while he was alive. It was quite frightening to watch though, because one felt that if he were startled he might accidentally slit his own jugular, but then, as we know from the bumblebee incident, he wasn’t easily startled. (And no, he did not die in a shaving accident.) All I know is that because of him, every time I shave with my fancy Gillette razor, I feel like a bit of a sissy. But we’ll come back to shaving later.
A peacock’s tail presented an obvious problem for Charles Darwin, in that it doesn’t enhance its owner’s ability to survive. Indeed, it is such an expensive investment of precious resources (to grow it), not to mention an unnecessary burden to carry around, making it much harder to flee from predators, for example, that it is actually a significant handicap. And the peacock is by no means alone in possessing such costly ornament. 
Such ornaments must be costly to function effectively as advertisements of fitness and health, because if they were not, it would be easy to fake them. For example, males of a certain species might start growing fake muscles which only look like real muscles (but are cheaper to grow) to appear strong. If this were the case, females would quickly start using some other criterion (like seeing if the male can actually lift a heavy weight) to make their choices. A costly investment in ornament is more difficult for less-fit males (such as diseased ones, for example) to make, and it is this that makes the ornament an honest display of fitness. (Now you know why men feel the need to buy Porches!) So, while the tail of a peacock may start as an advertisement of health and overall fitness (“look at me, I am so good at finding food and avoiding predators that I can afford to grow and maintain this expensive tail, and am still strong enough to get away from that fox which wants to eat me!”), there is something more that can happen as was shown by Sir Ronald Aylmer Fisher: runaway sexual selection.
What Fisher showed mathematically was that once such a process of sexual selection (where a male develops a trait that causes at least some females to prefer him) gets started, this male trait and the female tendency to prefer it become genetically correlated in descendants, and will spread quickly through the population in what he described as a “runaway process.” And as they spread, both traits (the male ornament and the female tendency to prefer males who have it) tend to themselves become exaggerated. With peahens unable to resist the sight of an awesome male tail, peacocks try to outdo each other by growing bigger and bigger and fancier tails. Of course, a point is reached where the natural selection costs of the tail actually start outweighing the sexual selection benefits of being able to impress potential mates, and a kind of equilibrium is reached. But not before this process of evolution giving rise to such whimsically resplendent ornaments as the peacock’s tail we see today.
An interesting theory of the origins of the relative hairlessness of humans relies on such a process of sexual selection. In The Descent of Man, Darwin himself dismissed more utilitarian explanations for the human loss of hair in favor of a sexual selection process, believing that in our ancestral men there arose an arbitrary preference for less hairy women, and that was enough (in what we would now call a Fisherian runaway process) to eventually result in our almost total loss of body hair, especially in women. Others, like Alfred Russell Wallace, believed that less body hair, at least initially, arose for actual utilitarian reasons, such as getting rid of lice, and being able to see whether one’s potential mate has lice or other parasites and the condition and color of their skin–an important indicator of health, with a sexual selection process then following. Recent work suggests that Wallace was probably right, and that the invention of fire and clothing to keep warm without body hair made it possible for humans to lose it. (By the way, pubic and underarm hair may have been retained as a way of efficiently dispersing sexual pheromones, whose importance is much underappreciated in our society.)
So what does this have to do with shaving? Well, nothing much yet, though as you can see, our relative hairlessness may have much in common with a peacock’s tail, at least in terms of how they came about. Now, you probably know that in the realm of culture, memes often spread in ways that are analogous to the way that genes spread through populations. This is how fashions, for example, get started. An arbitrary preference for pants that are flared a bit at the bottom gets going somehow, and before you know it a huge runaway fashion-selection process is in full sway, and you see huge bell-bottomed pants everywhere. I believe our present overall cultural tendency to prefer being clean-shaven probably also worked something like this. At some point a century or more ago, when shaving technology was not very advanced, it may have been an indication of success (or “fitness”) for a man to be clean-shaven, just as clean and expensive clothes would be: it meant that he had the resources and the leisure to go to a barber regularly. Or maybe there just spontaneously arose a preference for shaved men among women (they look more youthful, after all), and then the practice (or meme) spread through the culture in a runaway selection process, no different in principle from the cyclical vogue for thin ties, or wide collars, or short(er) hair for men than for women.
And finally, I come full-circle back to shaving technology with a last example of a completely runaway process which came to my attention by way of this year’s Super Bowl show on TV. One of the truly great advances in shaving razors came in 1971 when two blades were put close next to each other on a razor. This resulted in a much smoother, more comfortable shave, and the age of the Gillette Trac II began. But as you may know, the preference for more blades was not to stop there. If two blades were better than one, then three had to be better than two: in 1998 we were given the Gillette Mach 3 with three blades. (This is the razor that I use, though I am not sure if it is really any better than two-bladed ones.) Not to be outdone, a few years ago Schick introduced its Quattro with four blades! Being a sucker for marketing, I immediately bought it, but found that the blade is so wide that it is hard to shave the small areas on one’s upper lip, under the nose, etc. But in an almost unbelievable move, and with a $100 million marketing campaign for its launch, Gillette is fighting back by unveiling its Fusion razor on TV during the Super Bowl. The Fusion is a true peacock’s tail with six blades! I wonder what my father would have thought of that.