system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How did STD's begin?

How did they very first originate?
gpt
Like most disease, it started with the constant contact of livestock and the vermin that surround them like birds, bats, rats, insects and the like. As time passed, certain bacteria and virus mutated to essentially jump species. They did not have sex with these animals (they actually may have) but most likely came into contact with excrement like feces, urine, saliva, sweat, ect allowing transmission.