In the intensive search for extra-terrestrial life scientists always look for water because of its crucial role in supporting life. They recognize that without liquid water, physical life is impossible because water has a number of unusual properties that are crucial to maintaining life.
There is no evidence that any other simple molecule exists that can mimic the essential biological functions of water. And remember that while water is just one of hundreds of different physical and chemical ingredients necessary for life’s existence, none of them either individually or together explain life’s origin.
It was recently recognized that water molecules within the internal structure of proteins preserve the shape and structural strength of these proteins. In addition only water allows proteins to achieve the optimal stability that is critical to life functions.
Remember the mere existence of life’s components does not mean that the life they are made from and depend on, will actually be found. The presence of water does not guarantee life, any more than the amount of silicon, the seventh most abundant element in the universe, means that there will be portable computers everywhere! And computers are much less complex than life.
So next time you wonder about extraterrestrial life, come down to earth and be thankful for the abundant supply of life sustaining water that we have right where we live.