The Red Queen or "Red Queen's Race" is an evolutionary theory explaining the existence of sex. By making every individual an experiment when mixing mother's and father's genes, sex may allow a species to adapt quickly just to hold onto the niche that it already has in the ecology.
Accordingly, the metaphor Red Queen represents the situation in nature where creatures must adapt quickly to changing environmental threats just to survive from generation to generation. In Through the Looking Glass, Alice complains that she has to run just to stay in the same place.
- "Well, in our country," said Alice, still panting a little, "you'd generally get to somewhere else -- if you ran very fast for a long time, as we've been doing."
- "A slow sort of country!" said the Queen. "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!" [1]
Men seem quite useless. Why should there be men?
Sex is an evolutionary puzzle. In most sexual species, males make up half the population, yet they bear no offspring directly and generally contribute little to the survival of offspring. In addition, males and females must find each other to mate, and sexual selection often favors traits that reduce the survival of organisms. Thus, sex is highly inefficient.
One possible explanation for the fact that nearly all vertebrates are sexual is that sex increases the rate at which adaptation can occur. This is for two reasons. First, if an advantageous mutation occurs in an asexual line, it is impossible for that mutation to spread without wiping out all other lines, which may have different advantageous mutations of their own. Second, it mixes up genes. Some genes might be advantageous only when paired with other genes, and sex increases the likelihood that such pairings will occur.
For sex to be advantageous for these reasons requires constant selection for changing conditions. One factor that might cause this is the constant arms race between parasites and their hosts. Parasites generally evolve quickly, due to their short lifespans. As they evolve, they attack their hosts in a variety of ways. Two consecutive generations might be faced with very different selective pressures. If this change is rapid enough, it might explain the persistence of sex.
