As the above photo clearly shows, someone has been drinking beer on Mars.
The photos was actually taken by NASA's aptly named Spirit Rover in November of 2007. It wasn't until recently that one of those people who has nothing better to do than look at NASA's old Myspace photos in excruciating detail found the item.
Clearly this indicates some level of intelligent life on Mars. They might be drunk, but by golly, they are drunk on Mars!
Now, some might argue that this is simply a trick of the light on the rocks or something like that, but we see it as clear and undeniable proof of an Interstellar Beer Industrial Complex that not only runs this planet, and this solar system, but the whole of this galaxy, at least. What remains to be uncovered is whether or not there is a brewery on Mars, Where are the hops grown? and what is the ABV (alcohol by volume) content? We suppose it might also be interesting to find out who drank this beer, why did he/she leave the bottle laying there, what was the price of the beer (including taxes), and what did it taste like? Furthermore, without a closer examination we don't even know if it was light beer or even a lager. It could be an intergalactic IPA or deep space dark brown ale for all we know.
One thing is certain. We can rest assured that when we do find the aliens, we will be able to sit down and share nice cold brew with them.