In Western society, shoes are a truly ubiquitous item of clothing, but they still might not be something you ponder too often. That’s not exactly an issue; on a technical level you’re probably not missing out on any indispensable information. Still, it is nice to get yourself better acquainted with your footwear, so here are five things you didn’t know about shoes that are sure to knock your socks off.

1. Nine out of every ten of shoes end up in landfills

It may sound depressing to the sartorially or environmentally inclined, but the shoes among us aren’t going to last for too long — and after their useful life ends, they often up in landfills, where they can take a shockingly long time to decompose (the plastic and rubber in your shoes are not very biodegradable). In recent years, there has been a movement to make shoes that will at least recycle better, and about a decade ago one company released a shoe whose midsole was designed to “biodegrade 50 times faster than conventional athletic shoes.”

2. The earliest known shoe was found in Oregon

There was a time when people referred to America as the “New World,” but I hope cobblers never made that mistake. We’ll never know when the first shoe was developed, but the earliest known shoe was actually found in Oregon. Discovered in 1938, these sandals seem to date back some 10,000 years. If you’re a stickler for leather, the oldest known leather shoes were found in a cave in Armenia, and are believed to be around 5,500 years old.

3. Some cultures in history took shoes insanely seriously

Honestly, to me, shoes are just an article of clothing, and one of my goals in life is to think about them as little as possible. Good thing I’m not living in Greece around 2,000 years ago, when the type of shoes you wore could indicate your role in society (newly married women wore white shoes; in general, paler shoes were an indication of wealth). Meanwhile, in Arab societies, showing the sole of your shoe to someone is considered a major insult.

4. The 19th century was a major century for shoes

Transportation and many other things changed dramatically over the course of the 1800s, but one of those “other things” was shoes. Around the year 1800, shoemaking was a skilled trade. By 100 years later, many (perhaps most) shoes were being made in factories and being purchased off the shelf. The 19th century also saw a variety of landmarks in shoe history, including the first known pair of athletic shoes, track spikes, which were leather shoes with metal cleats.

5. Shoes can sometimes be a symbol of mourning

In some societies and contexts, shoes can be used to convey a sense of mourning. This phenomenon seems to have its roots in Greece, but it can be seen in other countries, as well. In fact, shoes — or, more specifically, empty shoes, which call to mind the wearers who perished — can be found as powerful symbols of mourning at memorials to both 9/11 and the Holocaust.