This is an idea I’ve thought about for decades, ever since it was first pointed out that mitochondria within eukaryotes (for example) may originally have been independent bacteria-like organisms that established residency within larger microbes (through ingestion or by invasion, it matters little in the end) and found the accomodations of that environment tolerable, if not agreeable. It certainly automatically offered another layer of protection against the external slings and arrows of outrageous fortune.

A completely dispassionate and preconception-free alien visiting the Earth today would note that the basic naked human unit habitually ensconces itself within a vast range of both sedentary and mobile “garments”, from houses and buildings and cities to cars, trains, planes and spacecraft, all of them modularly designed to extend the reach and capacity of the basic unit and support them to perform tasks which in turn supports the metabolism of that vastly greater critter those units call “civilization.”

Which is why I often regard Los Angeles as “Locust Land” (especially while sitting in a nominal traffic jam). Everybody knows that people put their cars on to commute, and when they do, the resulting creature that runs along rubber tires on prepared pathways is something else. What’s a “human”? That question depends on what they happen to be occupying at any given moment.

Just a random bit of food for thought I guess.