A study of two Martian meteorites led researchers to the conclusion that Mars has never been warm for the past 4 billion years. They also claim Mars probably never had warm wet conditions that could harbor life.
This report contradicts earlier theories which stated Mars may once have been warm enough for life to have arisen. The scientists studied the amount of argon gas in the meteorites, this is a gas which slowly leaks out of rocks depending on the temperature. The cooler a rock has been the more argon it will contain.
"The small amount of argon loss that has apparently taken place in these meteorites is remarkable. Any way we look at it, these rocks have been cold for a very long time," Shuster said in a statement.
But they don't completely rule out life on Mars as geothermal activity may have created small areas on Mars that could harbor life. More details at CNN