You can get a sense of this by looking at the three wings pictured above. Here on Earth, the wing evolved separately in bugs, birds and bats. Paradoxically, the possibility that evolution takes place elsewhere might simplify the search for life. Nature jealously guards ideas that work. Thus, focusing on the most basic similarities among all living organisms could provide the most important clue to the discovery of alien life.
Many scientists believe the best way to search for our origins is to begin with the basics.
Stripped to its fundamentals, the universe doesn't get any more basic than hydrogen. The hydrogen atom is the lightest and simplest atom you can think of. Put two hydrogen atoms together and you have the lightest, most abundant and simplest molecule. About 150 years ago, astronomers realized the space between stars was occupied by a thin dispersion of dust particles, smaller than the width of a human hair. First, it helps the formation of stars by carrying away some of the heat that is produced when gas rushes toward the core of a future star.