http://www.extremetech.com/extreme/139973-curiositys-latest-discovery-probably-rules-out-life-on-mars

“Far, far away, on the diminutive, 4000-mile-wide Red Planet, Mars Science Laboratory (MSL) Curiosity has unfortunately found no methane in the Martian atmosphere. This puts a fairly large dent in the likelihood of there being life on Mars. In happier news, Curiosity has spent the last few weeks extracting delicious science from rock and soil samples at the Rocknest site, and the one-ton rover also took some time out to snap the coolest interplanetary self-portrait you’ll ever see.

“The methane discovery (or lack thereof) comes from the first analysis of Martian atmosphere, taken by the Sample Analysis at Mars (SAM) instrument aboard Curiosity. SAM took a small gulp of Martian air and analyzed it with the Quadrupole Mass Spectrometer and the Tunable Laser Spectrometer — and in both cases, the sensors failed to detect any methane. This does not mean that there’s no methane at all, but it means that there’s no more than a few parts methane per billion parts of Martian atmosphere.”

Obviously this doesn’t mean there has never been life on Mars, but that there’s no current life.