Has there always been a male female distinction in clothing? 800 years ago did all of the men wear pants while all of the women wore skirts? When did this dichotomy begin?
Men wear skirts in Scotland. 
(Running away very very very fast)
I think years ago men wore clothes that looked like skirts and dresses, such as togas and Fred Flinstone cavemen attire.
True! 
It depends on the soctiey (even cave men had fashion) and where they lived. Mostly clothes are for protection, so climate would be the biggest factor.
Wait… you were talking about gender distiction. Well I have no idea about that in reguards to cave men, but the example you give (800 years) is not that far ago.
So, it really depends on the soctiey, in Europian socitey in year the 1200AD I would think that gender would be a huge factor in your choice of clothes. However, at that very same time in say a small tribe in South America, they might have no need for such distictions.
See The Costume Page, for clothing in history:
All the below info is from “An Underground Education”, a fascinating, meticulously documented book by Richard Zacks:
In Renaissance Europe, high fashion for men were those ridiculous tights, with codpieces to enhance their genitalia (male falsies, you could say). During this time, standard dress for a woman was a long skirt.
In a reverse of today’s fashions, women’s legs were almost never seen in public, and men’s were. As Zacks says, Shakespeare would have thought a well-dressed businesswomen ca. 2002 was a hooker.
FWIW, one of the offenses for which Joan of Arc was burned at the stake was “dressing like a man” – away from the battlefield, Joan wore a short gray tunic with tights underneath – this was what men wore in those days.
Under the long skirts, women typically wore individual cloth stockings held up by garters, but no underwear – the crude hygiene practices of the day made it impractical. Bifurcal underwear (i.e., panties) didn’t become prevalent until (I believe) the late 19th century.
Most societies have shown some kind of distinction between masculine and feminine attire, but not necessarily in the same way as in modern western countries. For example, the traditional men’s clothing for men in Bengal is the dhoti; for women, the sari. Both are long pieces of cloth that are draped around the waist and body, forming skirt-like falls. However, the two are very different in style and appearance. In Arabia, it was the women that wore loose pantaloons, while the men wore long skirts and robes. Even in Europe, men wore long robes and skirt-like garmets up until only a few hundred years ago. The traditional attire for warriors in Greece and Rome were short skirts.
Around 1200, AFAIK, both mens and womens wore long robes (the clergy kept these robes when they went out of fashion and were replaced by shorter robes/tunics for men, which were considered as loosy by the church)
I was obviously refering to western europe in my previous post…
I figured men started wearing pants around the time a large proportion of them started riding horses everyday . . . whenever that was.
Trousers were invented by the ancient Scythians, a horse-riding people. They were the inventors of the steppe nomad empire, a pattern later followed by Huns, Turks, Magyars, Mongols, and Manchu. All these peoples wore trousers, naturally.
The ancient toga-wearing Mediterranean world thought trousers were only for barbarians (the Greek and Roman soldiers wore armored miniskirts). Likewise, ancient India wore only draped clothes. In the ancient Middle East, Persia was the first nation to adopt trousers because of their trading and cultural relations with Central Asia. The Iranian cultural world extended well into Central Asia in ancient times, and therefore through Iran the custom of wearing pants spread to the Middle East. The word pajamas comes from Persian pây jâmah (literally, ‘leg garment’), referring to loose trousers. India and probably also Russia got the custom through invasions by Central Asian steppe empires.
In western Europe, the Celtic peoples and their bifurcal garments (“trews” or “breeks”) were probably the first in ancient times. Ironically, it’s the Scots alone in Europe who have preserved kilt wearing. Them and those Greek regiments.
I ask because after recently hearing the explanation for why men have short hair and women long (LSS: Blame the Romans) I was wondering if the difference in costume also had such a definite begining.