A closer look

While higher organisms have to go through the lengthy, exhausting process of reproduction to mix genetic traits, single-celled organisms just pass them around like trading cards. Plasmids are tiny, rogue circles of DNA that exist completely separate from the main genome, allowing cells to casually swap them on the go. If one cell figures out how to resist a deadly threat, it just hands copies of the instructions to its neighbors, ensuring the entire block survives.