• Question: How did life start out?

    Asked by Bethany is @home! on 18 May 2020.
    • Photo: Aruna Chandrasekar

      Aruna Chandrasekar answered on 18 May 2020:

      Life, in General, started with the Big Bang. We do not know anything about life before that.

    • Photo: Simon Spichak

      Simon Spichak answered on 18 May 2020:

      Hi Bethany! Great question! There is a lot of evidence that life could have formed spontaneously from different molecules, chemicals and compounds coming together at just the right time! We may never know for sure but our best guesses come from replicating the conditions of the Earth billions of years ago in the lab to study how it may have come about. All living things have genetic material and these are building blocks for life. Scientists have shown that under the right conditions, with the material available on Earth billions of years ago, this material can form spontaneously. Eventually, some lipids may have formed some bags (primitive cell walls) around the molecules that contain what we need to make genetic instructions. By chance, some of these molecules were able to replicate themselves – creating life. Of course these are just from laboratory experiments, we may never know exactly how life started out!

    • Photo: Achim Schmalenberger

      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.

    • Photo: Aisling Ryan

      Aisling Ryan answered on 19 May 2020:

      No one is entirely sure, but there are a lot of possibilities that different scientists have suggested! The one that sticks with me the most is the evolution of cells. In short, animals (including humans) have different types of cells than bacteria or plants. Bacteria cells are called prokaryotic (pronounced pro-kaar-e-ot-ic) and animal and plant cells are eukaryotic (you-kaar-e-ot-ic).
      Many scientists believed that more simple prokaryotic cells evolved into eukaryotic cells. You can think of prokaryotic cells as a simple blue circle, but eukaryoic cells are multicoloured with a really cool design!
      At the very beginning these first animals were very simple and lived in the ocean. As time went on this population of simple animals could evolve into more complex animals, but the evolution happens so slowly that nobody notices it happening. It could start with a new trait like hunting to get food. Maybe the sea creature needs to swim fast or blend into something to escape a predator, so this population of sea creatures will evolve to have perhaps bigger fins or become a colour that is maybe the same as sand so a bigger sea creature won’t see them and eat them!
      Eventually these sea animals evolved to be able to breathe above water, and lots of them moved onto land. From this more animals evolved from the land animals and no longer had the ability to live in water. It took billions of years, but eventually humans evolved from primate animals such as gorillas or apes, and now here we are!
      Hope this makes sense! 🙂

    • Photo: Fiona Malone

      Fiona Malone answered on 21 May 2020:

      With a big BANG!

    • Photo: Roisin Jones

      Roisin Jones answered on 29 May 2020:

      There are some great answers to this already, so I’m not going to elaborate, just say that the phrase ‘primordial soup’ is one of my favourites, it’s so evocative!