How does complexity relate to the age of a lineage?
Life necessarily started simple, and the average complexity of life has tended to increase over time. However, because all species alive today, whether simple or complex, have been evolving for the same amount of time, there is no relationship between age of a lineage and degree of complexity. For example parasites are often simpler than their more complex ancestors because of their way of life. In Carol Lee’s talk, the salt-water organisms that invaded freshwater lost the ability to live in salt-water. With pesticides, if an insect becomes resistant to pesticide A and we then use pesticide B, does the insect then become vulnerable again to pesticide A? An important evolutionary principle is that it impossible to remain good at everything: if a mutation arises to suit you better to your current environment, it will tend to increase in frequency even if that same change makes you less able to live in some other possible environment. This explains the fact that adaptation to freshwater c
