ELI5: In nature, why is there no opposite to “disease”, for example, a kind of virus or pathogen (but the opposite) that mentally or physically enhances our abilities?

There is, it is called mutualism. Our intestines are lined with millions of bacteria, they help us break down our food and make it easier to digest. Oral flora can, for some people, prevent cavities or plaque buildup. There are many other bacterium and parasites that can benefit us. If you’re at the store, take a look at the “probiotics” section.

Explain Like I`m Five: good questions, best answers.