Duke University evolutionary biologist Peter Turchin, writing about the proposed cultural evolution of pants, says,
If we go back to the ‘Cradle of the Western Civilization,’ the Mediterranean region two thousand years ago, we will find that none of the civilized people there (notably the Greeks and the Romans, but also Phoenicians and Egyptians) wore pants.
But zipping forward in time for about a thousand years, all of a sudden pants are everywhere.
Why did the Italians switch from tunics to pants? The answer is the horse. Not only are the horses responsible for why we live in complex, large-scale societies (or, at least, how such large-scale societies first evolved), they are also the reason why males have to swelter in pants in summer, instead of wearing the cool kilt.
All around the world, societies which had mastered the art of horseback combat wiped out those that hadn’t. The theory goes that men in battle need protect their most sensitive organ, and riding sidesaddle is not particularly amenable to the chaos of combat.
Writing in The Atlantic, Alexis Madrigal adds to the discussion the similar history of the bicycle and the decline in long, frilly dresses. Madrigal says,
What all these examples suggest is that technological systems — cavalry, bicycling — sometimes require massive alterations in a society’s culture before they can truly become functional. And once it’s locked in, the cultural solution (pants) to an era’s big problem can be more durable than the activity (horse-mounted combat) that prompted it.
Read more: http://blogs.smithsonianmag.com/smartnews/2012/07/people-wear-pants-because-cavalry-won-wars/#ixzz2pj2w8aqq