The current "mile", the "International Mile", is very close to the 1593 "statute mile", going through a lot of history, but ultimately coming from 1,000 (a "mil") paces.
The kilometer: As part of the widespread rationalization that occurred during the French revolution, the meter was defined in 1791 as 1 ten millionth the distance of a line drawn from the equator to the north pole, through Paris.
The distance from pole to equator is 90*60 = 5400 nautical miles, and the same distance is 10,000 km. So for a long time the km was exactly 0.54 nautical miles.
Considering pre-metric France didn't use the mile, and the meter was originally meant to be 1/10,000,000 of the distance from the north pole to the equator, it seems almost impossible that it's intentional.
So it is, but the way that these units connect together is much closer than you'd think and amounts to a sort of mass distribution on the leg.
The kilometer is a thousand meters of course. And a meter was defined the way it was to match the length of a pendulum with a period of 2 seconds.
The mile was defined the way it was to match a different thousand: a thousand Roman paces, measured as two steps. (They didn't like the fact that if you go from left foot to right foot the measurement is slightly diagonal, so they measured from left foot to left foot.) So if you figure that a Roman had a leg length, measured from the ball of the hip joint to the heel, say, as 80cm, and you figure that they marched like equilateral triangles, then the full pace is about 160 cm or 1.6 m, and the Roman mile is then ~1.6 km.
But, my point is, these two numbers are not totally disconnected like it seems at first. So the second is a precise fraction of a day which has no direct connection to a person's leg. But, the decision to use this precise fraction is in part because when someone was looking at the 12 hours on the clock and placed the minutes and seconds, 5 subdivisions of the 24th part of the day looked and "sounded right." It is somewhat likely that this in part sounded right due to the standard Roman marching cadence, which was 120bpm (between footsteps) or 60bpm (left-foot-to-left-foot), set by your drummer, chosen presumably to maximize average efficiency among the whole unit.
So then if we treat everyone's legs as a pendulum that is being driven slightly off-resonance, then the period of this leg motion is ~1 second and the leg behaves like a pendulum that is ~25cm long. And this kind of tracks! Measuring from the hip socket down 25cm gets near most folks' knees, the thigh is heavier than the calf so one would expect the center of mass to be up a little from the kneecap.
So then you get that the leg is 80cm long from hip-socket to tip, but 25cm long from hip-socket to center-of-mass, and so you get some pure geometric ratio 2.2:1 that describes the mass distribution in the human leg, and that mass distribution indirectly sets the 1.6 conversion factor between km and miles.
If we could only connect the human leg's evolutionary design to the Golden Ratio! Alas, this very last part fails. The golden ratio can appear in nature with things need to be laid out on a spiral but look maximally spread out given that constraint (the famous example is sunflower seeds), but all of the Vitruvian Man and "the golden ratio appears in the Acropolis" and whatever else aesthetics is kind of complete bunk, and there doesn't seem to be any reason for the universe to use the golden ratio to distribute the mass of the muscles of a leg. So you get like 98% of the way there only to fail at the very last 2% step.
But this one isn’t a coinicidence - the idea of having the unit of length be the length of a seconds pendulum predates the meter we have. (It doesn’t work because the period of a pendulum depends on your latitude.)
You're kidding me! That's a fact I had no idea about. I thought I was damned clever for having figured out the thing as a child and then found out all the other kids knew it too. I never thought to check the origin. Made my day. Thank you.
Is it really just a coincidence? Genuinely curious.