Could humans have contaminated Mars with life?

Doubtful. The only kind there may be is the "contamination" of what is inside the actual rovers we have on the planet. All the surface contamination would be quickly eliminated by the radiation that bombards Mars every day. I also doubt that we will find any life of the surface of Mars. Even extremophiles couldn't last long with the kind of radiation that Mars is subjected too every day and night. That said there may be some kind of extremophile life below the surface. We will see when and if we ever get there.

Thanks for sharing

After ready the article, I believe it is entirely possible.