When I was young, the United States of America was still known by that name but Russia was called the Union of Soviet Socialist Republics. Ronald Reagan called them the Evil Empire and in 1984 he "outlawed Russia forever." This was odd because they weren't called Russia then. They were the Union of Soviet Socialist Republics. Throughout the latter part of the 20th Century both countries built nuclear warheads like they were going out of style - the bigger the better. It seemed pointless to build such monsterous weapons in order to kill such fragile animals as human beings. As any sociopath can tell you, a simple knife will do.
Sociopathy never goes out of style. Since those heady Cold War days, Pakistan was seen trotting its atomic weapons down the cat walk. A nuclear device remains the dream of every rogue dictator whose potassium nitrate looks hopelessly passe. Fortunately the gap between desire and possession is not due to the rhetoric of George W. Bush. Complexity and price have done more to limit nuclear proliferation than policies and treaties. Nuclear weapons are god damn hard to make.
Throughout the decades of the 70s and 80s, the United States and the Soviet Union had honed the art of nuclear arms proliferation. I expressed little interest the nuclear arms race until I recieved my very first paycheck. "TAXES!--What the fuck?" The largest deduction on the check was called "Federal." Suddenly the fiscal policies of the United States government became important to me. "How many fucking bombs do you people need?"
Many who argued against nuclear proliferation chose a different tactic. Rather than emphasize financial burden, they calculated the ramifications of nuclear war. Peaceniks tallied the number of times the superpowers could blow up the earth then ran around with their hair on fire. The arms race, they shouted, would end all life on this planet. What a bunch of arrogant bastards.
Only a human could be so self-centered to think that humans have the potential to destroy life on this planet. Sure, they may end human life but organic matter will continue to propagate long after the humans are gone. Bacteria are't going anywhere. Neither are germs nor ciliates nor flagellates nor protozoans. Life is incredibly durable. It will surely survive humanity.
That durability causes me to believe that if life ever existed on Mars, then it's probably still there. Life adapts. It is flexible and changes through time. If there was life on Mars, then it probably followed water underground.