1. Prehistoric people wore early underwear made of animal hide. Over 5,000 years ago, ancient humans wore leather loincloths wrapped around their waists! When scientists discovered the famous ice-mummy Ötzi the Iceman preserved in the Alps, they found he was wearing a neatly tailored loincloth crafted from woven goat leather.

2. Ancient Egyptians wore linen loincloths to stay cool. In ancient Egypt, people wore light, breathable loincloths called schenti made from flax plant fibers (linen). Even King Tutankhamun was buried in his tomb with over 140 pairs of custom-fitted linen underwear packed for the afterlife!

3. Medieval undergarments were long, baggy tunics called braies. During the Middle Ages, men wore loose, sack-like linen drawers called braies that wrapped around the waist and tied at the knees. They acted as a soft protective barrier between sensitive skin and heavy, itchy wool outer garments or metal knight armor!

4. Cotton fibers absorb sweat using natural capillary action. Most everyday underwear is made of cotton because of its microscopic structure. Hollow, tube-like plant fibers absorb moisture from the skin through capillary action, trapping liquid inside while allowing air to flow freely so your skin stays dry and healthy.

5. King Henry VIII popularized padded codpieces. In the 16th century, European men's fashion featured a decorative, padded pouch attached to the front of hose called a codpiece. King Henry VIII of England famously wore giant, padded codpieces filled with fabric layers to show off power, wealth, and status!

6. Astronauts wear high-tech liquid-cooled undergarments. Before stepping outside the Space Station for a spacewalk, astronauts put on a Liquid Cooling and Ventilation Garment (LCVG). This special underwear is threaded with 300 feet of flexible plastic tubing circulating chilled water to absorb excess body heat in space!

7. Seamless underwear is knit in 3D without cut fabric edges. Modern seamless underwear isn't cut out from flat fabric sheets and sewn together! Instead, advanced circular knitting machines weave tubular garments in three dimensions using continuous nylon loops, eliminating bulky side seams that cause skin friction.