In the long process of evolution, these bacteria obviously look like "successful people". They gradually lose the ability to decompose toxic substances such as hydrogen peroxide (H2O2) and let other creatures do these "rough jobs" for themselves. This kind of interspecific relationship is very common in nature, but sometimes we don't know how these relationships were originally formed. Now, researchers have proposed a new evolutionary theory to help explain how this dependence is formed. They call this theory "Black Queen Hypothesis", which is as ingenious as its name.