horseshoes and harnesses -- 5/19/21
Today's selection -- from How to Invent Everything by Ryan North. Before horseshoes, horses would need to take time off for their hooves to regrow. And before harnesses that worked for horses, people had to use the less efficient ox, or pull things themselves. "Horseboots" were invented around 400 BCE, with a metal-bottomed version first appearing around 100 CE. Nailed horseshoes didn't emerge until about 900 CE:
"Horses' hooves are made of keratin -- just like human nails -- but unlike us, if their hooves become too worn down, they won't be able to walk. This isn't a problem in the wild, but in a domesticated setting -- where horses work on different terrains from what they evolved on, carry many more people and loads of cargo on their backs, and pull farmers' plows, carts, and even chariots around -- horse hooves face increased wear and tear. The solution is to protect them with shoes!
"The earliest horseshoes were more accurately called 'horseboots': leather or rawhide wrapped around the feet. These evolved into metal-bottom boots around 100 CE, and into bronze or iron shoes that were nailed directly into the horse's hoof -- there are no nerve endings in keratin, so the horses don't feel anything -- a few hundred years later. Nails are hammered in from the bottom of the hoof up out the top, where they're bent back so they lie flush with the hoof. This holds the shoe in place while also preventing the nails from catching on anything. You want to nail at the edges: go in too deep and you will cut the quick, which does cause pain and will prevent a horse from walking until it heals.
"Horse hooves never stop growing for as long as the horse lives. In a sense, horseshoes do their job too well, because any horse that wears shoes must have them removed every six weeks or so, so that their nails can be filed back down to an appropriate size before their shoes are reattached. If you have a lot of horses, this can become a full-time job -- early on it's usually the blacksmith who specializes in both producing the iron shoes and attaching them, but when you reach a level of specialization where it's a separate vocation, that job is called 'farrier.' Farriers sometimes have their own furnaces so that they can heat their shoes, bending them for a better fit! …
"Harnesses were originally invented: 4000 BCE (yokes), 3000 BCE (throat-and-girth harness), 400 CE (collar harness)
"Harnesses seem like a simple invention: tie a rope around your animal, ideally around its shoulders, and it'll pull your load, right? For oxen -- dense, sturdy animals with heads positioned beneath their shoulders -- it really is that easy. The best oxen harnesses are called 'yokes,' and they're made from wood. To have two oxen work side by side, lay a beam of wood on their necks in front of their shoulders, and strap it loosely in place: this will keep the animals aligned, and you can attach your load to the beam at the midpoint between the two animals. Put cloth between the wood and animal for comfort, and you're done! With just one ox, you can attach a curved piece of wood directly in front of the horns, and attach your load at the side -- oxen 'head yoked' can't pull as hard, but two oxen can also be head yoked individually, then held together with another rope.
"But horses are trickier. The most obvious way to harness a horse -- a loop around the base of the neck connected to a loop around the chest to hold it in place -- may seem like it'll do the job, but it's actually one of the worst ways you can harness these animals! This throat-and-girth harness lets a horse pull something, but as it pulls, the straps cut into the horse's windpipe, carotid arteries, and jugular veins, all at the same time. Any horse harnessed this way is clearly not going to be working at peak horse efficiency. To get them there, and to reap the benefits of not accidentally choking your horses all the time, you'll want to invent the collar harness.
"A collar harness is simply a padded piece of wood or metal that fits around the base of the horse's neck, with points to attach the load near the bottom, on either side of the horse. This distributes the force of the load away from the neck and onto the shoulders. Instead of just pulling the load with its front, the horse can fully engage its rear end to also push against it. This (finally!) allows the horse to exert its full strength against a load, and your horses will go from being (accidentally) artificially constrained to operating at full efficiency, simply by changing the way they're harnessed.
"This will be revolutionary. Wherever horses with collar harnesses appear, they quickly replace oxen: freed from the physical penalty of an inferior harness, a horse can do the work of an ox in half the time, with greater stamina. The increased power of a horse (or 'horsepower,' if you will) allows not only more fields to be plowed in a day but for harder fields to be plowed, transforming previously unproductive terrain into productive farmland. Assuming you have horses, the simple invention of the collar harness is enough to greatly increase your farming efficiency; and therefore also the size of the population your civilization can sustain. Humans took more than three thousand years to figure out this simple piece of wood that would finally let their draft animals and civilization reach their full potential."