Revolution: Usually violent and not permanent
Evolution: Non violent (though there can be conflict involved) long lasting, usually a permanent change.
Revolution: Usually violent and not permanent think 1776 and WW1
Evolution: Non violent (though there can be conflict involved) long lasting, usually a permanent change think red queen's race.
The paradox of sex: The "cost" of males
- For more details on this topic, see Evolution of sex.
Science writer Matt Ridley wrote a book The Red Queen in which he discussed the debate in theoretical biology over the adaptive benefit of sexual reproduction to those species in which it appears. The connection of the Red Queen to this debate arises from the fact that the traditionally accepted theory (The Vicar of Bray) only showed adaptive benefit at the level of the species or group, not at the level of the gene. By contrast, a Red-Queen-type theory that organisms are running cyclic arms races with their parasites can explain the utility of sexual reproduction at the level of the gene by positing that the role of sex is to preserve genes which are currently disadvantageous, but which will become advantageous against the background of a likely future population of parasites.
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 fact, in some species, such as lions, males pose a positive threat to live young fathered by other males (although this could be viewed as a manifestation of Richard Dawkins' so-called selfish gene, whose goal is to reproduce itself, which may as a consequence suppress the reproduction of other genes). Obviously there are species which are exceptions to this rule, such as humans, seahorses, and penguins, amongst others. In addition, males and females must spend resources to attract and compete for mates. Sexual selection also can favor traits that reduce the fitness of an organism, such as brightly colored plumage in birds of paradise which increases the likelihood for an individual to be noticed by both predators and potential mates. Thus, sexual reproduction can be 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 alleles. Some instances of genetic variation might be advantageous only when paired with other mutation, 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.
