To eke out even the barest subsistence on Mars, a living thing would have to adapt to a formidable set of environmental challenges: an arid, often extremely cold landscape with miniscule amounts of oxygen in the atmosphere and no organic matter to eat. During a recent foray into a similarly inhospitable part of our own planet, scientists have discovered several species of bacteria that hint at what life on Mars, if it exists, might look like. These microbes survive on minerals in the surrounding rocks—minerals also found in the Martian surface.
Life finds a way and it is perfectly possible that there are living organisms on Mars. The climate was more amenable aeons ago and this work shows that even current conditions could sustain a sort of life.
I do not expect we will find any intelligent life but there are all sorts of possibilities.