Nature has found some pretty fantastic solutions to equally fantastic problems. It is no coincidence that we see all sorts of patterns both in the world around and the world within. Have you recognized these before?
Some patterns are pretty easy to spot.
2, 4, 6, 8, 10…. you can guess the next number.
0 1 10 11 100 __ 110 111 (fill in the blank.) Others, not so much.
Now, I’m the complete opposite of a fashion guru, but these earrings represent a particularly wonderful pattern: nature’s solution to the “How do I maximize the amount of input I get?” problem.
And this is where neurons come in. Anyone who’s ever had to learn the anatomy of a neuron has yawned, and then has read that dendrites (traditionally, the part of the neuron that receives information from neighboring neurons) look as if they were “branches on a tree.” Well, they actually really do look like tree branches. Maybe this is a case of seeing shapes in clouds where there are none, or maybe it’s something deeper that can tell us a lot about how nature solves particular problems.
Neurons come in all shapes and sizes, as do trees, partly because not all environments are created equal: some provide a constant source of input (e.g., sunlight, nutrients, neurotransmitter, oxygen, etc) while others abound with competition for that source of input, and so on.
Here are Ramon y Cajal’s (the Lady Gaga of neuroscience) famous sketchings of neurons, dating back to the early 1900s:
Let’s zoom out by a few factors of ten to start seeing some patterns. Bacteria have solved the problem with regards to optimizing their contact with a nutrient-rich environment:
We can leave the microscope at about the same factor of ten at the level of leaf venation:
Let’s drive the point a bit closer to home. How about human venation? Just replace the water in leaf venation with blood:
Our lungs, too, branch out to increase the amount of gas-exchange that alveolar sacs can provide:
Zooming out some more — because of its uncanny resemblance to dendrites and every other picture here, I responsibly took a picture of a tree while driving:
Often, clouds build up and exchange charge with the air and ground beneath in the form of lightning, which branches while “searching” for the “path of least resistance”:
Zooming out a few more factors of ten: running water in rivers, too, shows a similar draining pattern.
The theme is this: when there is some input, one optimal solution nature has found is to have the target “branch” its extremities to increase the amount of surface area in direct contact with the input. Kinda neat, since this occurs on every order of magnitude observable — not unlike what mathy-people call a “fractal phenomenon.” There are thousands of these branching patterns occurring in nature — converging from neurons to landscapes — as they are striking examples of nature’s redundancy.