One has the feeling of, "Here we go again." Virtually every time explorers or colonists here on Earth land on a new island or continent, they take with them other species that came along for the ride. This includes infectious diseases that can wipe out indigenous populations. So, perhaps we are at it again, assuming that the hostile environments we are crossing and discovering allow our microbial stowaways to survive the trip. And wouldn't it be at least ironic if there wasn't any life on Mars until we put it there? One reason we invest so much effort and resources to go to Mars is to discover new, alien life, but just maybe what we will discover is us. At least, as the article points out, we will eventually discover whether or not life on Earth is hardy enough to survive interplanetary travel, and that in and of itself will be worth learning.
And if those microbes do survive the trip and are able to live on Mars, what we may be witnessing is the beginning of what could be the greatest engineering project in human history, the terraforming of Mars. Eventually, we are going to leave Earth and learn to live in space, which means taking life on Earth with us to the stars. This sounds like science fiction, but maybe the very beginnings of our migration into the universe are already happening. Or not. But the possibility is intriguing.