A fun and systematic way to think about alien life is to imagine of how their central nervous system might work. I will discuss different aspects of ours from the lowest to highest levels and mention some possible ways an alien’s might be different.
- The neuron: At the very lowest level, the sensory processing, movement, and memory functions of complex life on Earth is built on neurons. For our purposes, neurons are cells that can quickly send messages between one another. (All cells send messages to each other in multiple ways, but on a much slower time scale than neurons.) The chemical processes that mediate this operate in millisecond range. Interpretation of high-bandwidth sensory input like humans have requires a lot of computational processing by the brain and each channel of sensory input is processed in parallel. The computational requirements of balancing and moving bodies with as many joints as we have are massive and also done in parallel. Finally, human memory requires a lot of ‘wetware.’ Thus, to support all these functions, humans have billions of neurons with trillions of connections. Perhaps an alien race possesses neurons that operate either faster or slower than ours do. Perhaps their neurons are somehow more or less metabolically ‘expensive’ so that they may have a lot larger or smaller brains. There are any number of variations.
- Sensory systems: Humans and animals have a host of sensory receptors that tell them about the world around them. Here is a list of many of them (not exhaustive):
- Photoreception: In humans these receptors support vision and synchronization of our circadian rhythms. We have four channels of vision. Rods convey information about light intensity, edges, and movement and cones convey color (red, green, or blue). These photoreceptors respond to a fairly narrow band of electromagnetic radiation called ‘visible light.’ One could imagine alien species being more tuned to different ranges on the spectrum from radio, to microwave, and to infrared (e.g. predator and pit vipers), as well as ultraviolet and higher frequencies. It just so happens the visible spectrum is the most useful on Earth evolutionarily speaking, but maybe it would be different spectra elsewhere. It seems logical that whatever vision system an alien might have, it would likely be placed close to the brain to reduce latency and protect delicate structures.
- Chemoreception: In human this includes our senses of taste and smell. To stoke the imagination, one does not have to look far. Catfish have olfactory receptors on their whiskers and many insects have exquisitely sensitive chemoreceptors on their antennae. Chemoreception is about finding food, avoiding danger, finding a mate, and rejecting toxic material. Imagine an alien race with chemoreceptors on their appendages. Perhaps they ‘shake hands’ to exchange chemical signals of good or ill will. The possibilities are endless.
- Mechanoreception: Includes the sense of touch, hearing, and acceleration and comes in many forms. Read about it.
- Thermoreception: The temperature sense.
- Magnetoreception and electroreception: Some Earth species have evolved these. Be creative.
There’s much more, so I’ll continue in another post.