Uneven bars used to be the men's parallel bars adjusted so it was asymmetrical.
The days when gymnasts would beat the bar, causing men to cringe at the sight of the 'bar beats' were around until the mid-1980's when uneven bars evolved to mimic the men's horizontal bar more.
After the Seoul Olympics, uneven bars became wider set, so that bigger swinging skills can be accomplished. Here's one of the stand outs of the mid 1990's on unevens.
The early 21st century was dominated by American gymnasts, and since then we have really made our mark on the international competition.
Finally, we arrive at today, where bars looks easy when Madison Kocian (USA) reigning world champion on the bars competes.