If ‘Why?’ is the first question in science, ‘Why not?’ must be a close second. Sometimes it’s worth thinking about why something does not exist. Such as a truly three-legged animal. At least one researcher has been pondering the non-existence of tripeds.
“Almost all animals are bilateral,” he said. The code for having two sides to everything seems to have got embedded in our DNA very early in the evolution of life — perhaps before appendages like legs, fins or flippers even evolved. Once that trait for bilateral symmetry was baked in, it was hard to change.
With our built-in bias to two-handedness, it can be hard to figure out how a truly three-legged animal would work — although that has not stopped science fiction writers from imagining them. Perhaps trilateral life has evolved on Enceladus or Alpha Centauri (or Mars!) and has as much difficulty thinking about two-limbed locomotion as we do thinking about three.
This kind of thought experiment is useful for developing our ideas about evolution, Thomson said. (1)
Everything started with Nothing.
Then One came into existence.
We are still in the phase of Two…
And there is no way to get any further.
For going further means that we get to three.
And from there infinity is one step away.
Leading to nothing more than zero once again…
But there is no infinity.
There is no two.
Not even One.
For only everything exists.
In the palm of a small kid…