In an earlier post, I talked about the guards in Persian reliefs from Susa who are 17 bricks tall and have spears 19 or 21 bricks tall. Artists often ‘improve’ human proportions according to different ideas of what the well-formed body looks like: these guards are 5 2/3 bearded faces tall (17/3), Cennino Cennini would have them 6 1/2 bearded faces tall (26/4).
When I visited the Louvre in July I had a chance to look at some of those reliefs for the first time since 2016 (a few are on display behind glass in Tehran). As you see, my hand and the hand of the sculpture are about the same size (and I am not particularly tall or short). My hand is slightly closer to the camera than the sculpture is, so it is slightly enlarged.
We can’t test the length of the spears in these sculptures against surviving spears, because the wooden parts have rotted away or were broken before they were placed in graves. But we can compare the bodies against human bodies today. I came away from Susa convinced that the sculptures show warriors about 170 cm tall holding spears 190 or 210 cm long, about a head taller than their bearers, the length of the longer kind of spear in Greek vase paintings and sculptures. You can use that rule one brick high = 10 cm (4″) to estimate the size of the spearheads, thickness of the spear shafts, and other details. For example, the blades of the spears are a bit more than 1 1/2 bricks tall, so a spear with a blade about 15-18 cm/6-7″ long would be a good choice for Plataia 2021.
Edit 2019-10-26: On the same scale, most soldiers with a hoplite shield in Greek art would have spears from 15 to 23 bricks high (so the short, common kind is shorter than any of the spears at Susa, and the longest, rarest kind is longer).
People who have measured bones find that most ancient populations were only a few centimetres shorter than people in the same area today, but that is another story.
You can see more photos of these reliefs on livius.org under ‘Susa, Soldiers’ Mosaic’ (Dutch is his native language).
Some of the earlier Neo-Assyrian reliefs add some more important details:
These earlier Medes also carry spears with rounded ferules, and the shafts were painted red. Were the original spears painted or just varnished? Trusting colours in ancient art is a slippery business, but it might be worth trying, since some Scythian arrowshafts appear to have been painted bright colours.