It's no secret that red-headed females tend to hold a certain, mysterious allure for - at the very least - the male members of our community. They're a favorite subject of inflation stories and artwork alike (or at least I think they are, given all the threads I've seen on this and other forums discussing the trend), but to date, we've had little understanding of why. The closest thing to an explanation I've heard to date involves early exposure to toonish temptresses like Jessica Rabbit - whose buoyant, pneumatic curves could easily be blamed for sparking a fascination with round, bouncy, gravity-defying objects in impressionable young minds.
However, recent scientific studies may have finally shed some light on this phenomenon. Tests have shown that the sight of the color red triggers an increase in heart rate and brain activity in humans, similar to what we experience during heightened states of excitement. Experiments were conducted in which the researchers threw parties in a series of rooms - each of which was painted in a single, primary color. They observed that the majority of guests tended to gravitate towards the red room - though said guests also tended to get 'partied out' faster, and would often leave earlier, than the guests who favored the other rooms. Similarly, they found that women tended to get more attention at parties if they wore read, as opposed to other colors. This may offer some explanation for the seemingly mysterious appeal of redheads, or 'the woman in red'; the effect that the color red has on the human brain makes them seem more 'dangerous' - or at least more exciting.
I'm hardly a scientist, but it does seem to make a certain amount of sense to me. I'd be curious to hear what other people think.
I would say the default position is that blondes are the hottest, although my own preferences run to darker hair. Redheads may seem "exotic" to some because they are rare. Likewise, many Japanese people love blonde hair, and many Westerners have an "Asian fetish." Some celebrities, such as Angelina Jolie, may owe their "exotic" beauty and popularity to mixed genes. "The grass is always greener..."
There's no doubt that color plays a role, otherwise people wouldn't wear makeup. A blush on the lips or in the cheeks (or on the posterior, if you're a baboon) is part of our non-verbal communication.
But I see a woman as a gestalt effect, not parts. Everything must work together. Winona Ryder looked "wrong" in Edward Scissorhands with blonde hair, although the clash might have been intentional. Many years ago I met a beauty pageant winner with red hair, but I knew it was not natural for her. As I got to know her better, she admitted it. About 20 years later, she still tints her hair.
What I can't figure out is where Lt. Ellis and the other moonbase babes from Gerry Anderson's UFO fit into all this. :)