Science & TechHow it works
How bacteria run evolution in a matter of days.
Take an antibiotic and most bacteria die. A few happen to carry a mutation that protects them. Those survive and divide, some every 20 minutes. Soon the population is almost entirely resistant. Bacteria even swap such genes with each other, across species.
Useful: Every dose is a round of selection: that's why each unnecessary use counts, in medicine and livestock farming alike.
Source: en.wikipedia.org