Question: How did life start out?

Achim Schmalenberger answered on 18 May 2020:

Hi Bethany,
this question is going around for as long as we can ask questions. We still don’t have a definite answer but there are a number of credible theories about how life started. One of them is the so-called primordial soup, which is one of the least likely ones but also one of the older hypotheses. It stated that if you chuck all the needed building blocks into one place and leave them there for long enough, something is going to fall in place. In this case the building blocks of life. This was not very convincing though. The other hypothesis is that life started from meteorites. However, this would mean that we just pass on the question as then we would have to ask how this developed outside our solar system. In my opinion, the most likely way how life started out is near chemical gradients such as underwater smokers. let me explain. We know that for life to form we need certain things, we need to have an enclosed bubble that we know now is a cell, we need certain molecules to make this first cell and we need ingredients to produce things like proteins and nucleic acids. The energy to produce such things needs to come from chemical gradients that we can see close to these underwater smokers. At that time there was no photosynthesis, so the first life forms were what we call chemoautotrophs, they generated energy from chemicals. Now, some of the ingredients needed may have come indeed from outer space. For instance water on earth has come from comets. There may be also a few ingredients in these comets and meteorites that helped to form the first molecules like basic proteins and nucleic acids. This form of life would have been developing on earth for over a billion years before we would have organisms similar to bacteria as we know them now and would have started doing photosynthesis It would take a few more billion years before bacteria would have passed on this ability to what we now know to be plants.