Eli5 I’ve always wonder why when you “step” in germs they don’t try to make their way to your mouth, and how is it different, when you touch your mouth with germs on your hand they know they have to go inside, but not when they’re on your elbow or leg.

Question

Eli5 I’ve always wonder why when you “step” in germs they don’t try to make their way to your mouth, and how is it different, when you touch your mouth with germs on your hand they know they have to go inside, but not when they’re on your elbow or leg.

In: Biology

Answer 1

Germs don’t “know” anything. They’re not sentient and have no objectives other than surviving, eating and reproducing. The insides of our bodies are extremely favorable environments for bacteria, so we have a lot of defenses to keep them out- namely, our impervious skin and immune system.

Touching your mouth or any part of your face just transfers the bacteria that are happily puttering around on your finger to that area. The mouth and eyes are notable in that they’re gateways to our insides that some bacteria could exploit to gain a foothold inside us.