A remarkably common pattern for the evolution of many things. You see it all the time in the evolution of technical things, but also many systems in general.

When you start to reach the top of the limits of what one system can do you’ll start to see a focus on efficiency, cost reduction and small improvements and optimisation. This is great because it forces a new creative solution to arise in order to make any real progress. An image search gives a few examples.

Also, see some related sketchplanations: The long nose of innovation, designing for adoption, understanding the chasm.

The S-curve.

I learned about 2.5D, or two and a half dimensions, from my engineering days. Turns out it’s really quite common to make 2.5D things because, for example, it’s easy to drill or mill down into something, and a pain to turn something on it’s side and drill from the other side. Or, as with vacuum forming it’s easy to suck plastic onto a mould, but a pain to get it off if you’ve got any overhangs as you can’t lift it straight up again. Hence the plastic sandpit in our garden is a 2.5D object rather than true 3D. Civilisation in general looks rather 2.5D from the air as we tend to build up, but don’t find overhangs that easy or practical eg the pyramids.

2.5D

There’s a famous photo series by Eadweard Muybridge that shows, unequivocally, that while galloping all four of a horse’s legs leave the ground. I’d always heard that’s what they trying to find out at the time, but from what I’ve read it was more a question of at what points do a horse’s legs leave the ground. The photos show the somewhat surprising state of leaving the ground while the horse’s legs are tucked, not when they are outstretched. It’s a lovely example of what Edward Tufte calls small multiples.

Do horses legs leave the ground at a gallop?