Answer:
It is believed that the origination of microbial life took place on the planet Earth much before the origination of intelligent life, that is, in an enormously distinct environment. It is known that the origination of microbial life took place about three billion years ago when not much oxygen was present and the environment was warmer than found at present.
This shows that the microbial species can thrive in different kinds of surroundings in comparison to more composite forms of life. This also shows that the development of microbial life generally takes place more easily in comparison to the development of intelligent life, as it requires less range of chemical and physical surroundings for their development. Hence, it can be said that they can be more generally found in extraterrestrial planets in comparison to intelligent life.