1.   Infections newly acquired during this tail will therefore be under selection pressure.

2.   Selection pressure operates on all stages of life cycles and has profound effects on the physiology and biochemistry of parasites.

3.   If they do, the computer flowers will have evolved under exactly the same selection pressure as caused real flowers to evolve in the wild.

4.   As a side effect of these selection pressures, human evolution crossed a threshold at which language became possible.

5.   Hence the continuing use of any one antibiotic may maintain the selection pressure for the whole plasmid, keeping levels of resistance to all the other drugs high.