As a child I had a fascination with science fiction. That fascination lasted well into adulthood. I loved the stories of space travel and the colonization of other planets and star systems. I watched Star Trek and loved it like I was being paid to. Lo these many years (decades) later, real science and careful thought made me aware of something the stories I was reading/watching largely ignored.
There is an irony that I feel obligated to acknowledge. One of the most well known stories - one that was certainly known to me - had that ignored issue as a central component. Basically, we were warned. We ignored it.
Certain well known and very wealthy (monetarily) individuals have talked about expanding humanity’s presence across the solar system and beyond. Superficially, it is a desirable goal. Superficially, we are but a few significant scientific advances from being able to accomplish that goal. Hollywood is even producing movies that an uncritical analysis would lead one to reasonably believe that expansion is fairly near. I have some doubts.
According to science, humans did not always exist on this planet. The planet itself existed as a distributed cloud of gas, dust and the detritus from the deaths of stars that preexisted our Sun. If one accepts the truth of evolution - change over time - one should acknowledge that evolution on this planet did not start with the biological. The distributed cloud evolved into a planet and the evolution continued. When biology evolved, it continued to do so. Eventually humans appeared.
Evolution as I understand it has multiple possible modes. Small changes randomly take place as cells are dividing and multiplying. Those changes can either be survival positive, survival negative or survival neutral. The impact on survival can be immediate or effective on a much longer timeline. It would not be unreasonable to suggest that some evolutionary changes are an effort of nature to address a specific problem. I have no idea what problem or problems there might have been to instigate the evolution of humanity but, at some point, the planet evolved us to deal with something. Nature can be a touch lazy. She refused to do work that has already been done. As such, humans have DNA sequences and biological traits in common with other living things on this planet, flora, fauna and fungi.
Of course, I will acknowledge that there are those who reject the evidence of evolution. Some of them insist that the entirety of the Universe was intentionally constructed by a Divine entity generally referred to in Western culture as “God”. Their understanding says God put us here and put other stuff here for us to use. In reference to such things as I allege in this essay, it makes no fundamental difference whether we accept the scientific or the religious understanding.
According to your wilful understanding, humans were either evolved by this specific planet or a Divine entity intentionally placed humans on a planet that had been prepared specifically for humans. Either way, the only reasonable conclusion is that the planet, Earth as it is known, is beyond integral to the existence of humanity as we know it.
We know that water is necessary for human life. We can see water, we can feel humidity. But adding water to the lunar regolith will not turn it into soil. That requires a lot more in the way of physical and chemical processes that simply do not occur on the Moon. Millions of years of those physical and chemical processes were necessary on Earth prior to the evolution of any sort of life and billions of years of those processes preceded humanity. Soil has evolved, or was created, to enable the uptake of nutrients into plants and fungi that can then be used by internal human processes. Things that we generally consider to be pests turn out to be integral to human life in any of an actual myriad of ways.
In “War Of The Worlds” by H.G. Wells, (circa 1896) the invading force is killed by microbial pathogens that evolved on Earth and as such, the alien invaders had no biological defenses against those pathogens. The aliens were killed by the presence of those microbes. Humans would be killed just as effectively by the absence of all of those microbes.
Think of it like your car. Picture the seats, windshield, steering wheel, brakes, paint, the road and more. Your car will start and run without those things but you cannot safely operate the vehicle without them and its continued existence gets less likely with each of those you delete. Delete them all and your car is effectively useless.
For billions of years, microbes, plants, insects, arachnids, fungi, reptiles, fish, mammals and stuff that is extinct have been consuming and processing each other and creating the environment that allows us to flourish. Perhaps we could terraform the Moon or Mars in a shorter time than Ma Nature took here on Earth but, I am absolutely sure we can’t do it in a human lifetime and possibly not in humanity’s lifetime.
Regardless of what Hollywood presents, we honestly need our magnetic field which helps protect us from cosmic radiation. We honestly need our atmosphere, thin though it may appear, for the many things it does for us. We honestly need the things that feast on dead and decaying biological mass. We honestly need for all those things to have existed for millions of years before we show up.
I do not know of one single scientist, engineer or reasonably serious person who espouses a belief that we can exist longterm anywhere without those things. If we are particularly unlucky, we would get to a place that had microbes already. We would die as Ma Nature (or God if you prefer) is unlikely to have given us immunity to microbes we were unlikely to encounter. Either we need thousands to millions of years of terraforming or we are dead on arrival. Those are pretty much the options.
