Life without oxygen is possible
This is a super exciting question that preoccupies many scientists. The answer they currently give is: Yes, life that functions completely differently from the one we know is probably conceivable.
Let’s start with oxygen. It’s pretty clear that there are life forms that can survive without oxygen – they still exist today, namely anywhere where oxygen can’t reach, in wet areas or in deeper lakes, for example, where the water is quite still. From a certain depth there is no more oxygen, but there are still bacteria that can live without oxygen.
And don’t forget: the first living things on earth didn’t have green leaves, nor did they need oxygen – on the contrary, oxygen was a waste product and a poison for them. Plants, but also us humans and animals that use oxygen, came much later. So life without oxygen and green, no doubt, exists.
Water is essential to life as we know it
But what about water? That’s always been the big question with missions to Mars: Is there liquid water there? At least today we know that there were. And that of course raises the question: if there was water, was there life?
Water is absolutely necessary for life as we know it. It is a living medium par excellence, transferring nutrients to organisms and toxins from them. The question is, is there another substance that can do the same? Maybe somewhere much colder than ours, where there is definitely no running water.
For example, the planet Saturn has a moon called Titan. There’s ice there, definitely no liquid water there, but what could be lakes of liquid methane. And it is quite possible that there are life forms in which the source of life is not water but methane.
A life world based on silicon instead of carbon imaginable
It goes further: the basic building block of life on earth is carbon. Everything organic – proteins, carbohydrates, fats to our genetic material, DNA – is made up of carbon atoms, at least the basic structure. Carbon is one of the few elements that is so versatile that it can build many very complicated frames and structures. But there’s another element that could theoretically do the same: silicon. Therefore, some biologists consider it possible that a silicon-based environment is at least conceivable. And primarily on other planets.
But there are also serious researchers who say: in theory, these life forms can exist even on Earth, maybe even in our bodies, we just haven’t discovered them yet. This does not mean green people, but microorganisms that can hardly be distinguished from bacteria from the outside. But if they functioned completely differently from life as we know it, they wouldn’t be so easy to find among all the other organisms.