• Question: Where did life start. I know we came from apes etc all the way down to evolving from creatures in the sea, but how did life get in the sea?

    Asked by silverfox to Charlie, Eoin, Jemma, Julian, Steve on 18 Mar 2011.
    • Photo: Charlie Ryan

      Charlie Ryan answered on 16 Mar 2011:

      hi silverfox, i don’t know, and i think no-one’s really sure. Maybe some of the biologiest on this website can help yuo out further!!

    • Photo: Julian Rayner

      Julian Rayner answered on 17 Mar 2011:

      Hi silverfox. Great question. If we want to go way back, you need to think about how evolution works. For evolution to happen, all you need is an information code that copies itself (so there get to be more of them), and sometimes makes mistakes (so natural selection can act – some variants survive, and some die off). That way things multiply, and some multiply faster than others and take over – that is life.

      What was the first life on earth? There is a theory that it was naked replicating RNA (similar to DNA, but just a single strand) – ie not life as we know it, with cells, but just information repeating itself, the so-called RNA world. Some of the organic building blocks for RNA seem to be able to form in stars, and could have been dumped on earth by comets early in the history of the Earth (came up in Brian Cox’s recent TV series, if you saw it).

      Sounds cool, and I like the idea of a planet of replicating RNA, but we’ll never know for sure of course.

    • Photo: Jemma Ransom

      Jemma Ransom answered on 17 Mar 2011:

      I think scientists are divided on this one, there are many many many different theories. It is thought that life began in the sea, in the form of unicellular organisms (creatures that are just one cell). They lived in extreme conditions at very high temperatures in structures called thermal vents on the sea bed. These created the perfect environment for complex molecules necessary for life to come together to form living organisms. This is backed up by fossil evidence. The oldest fossils are of these unicellular microbes that date to around 3.5billion years ago, which is around 1 billion years after the creation of the Earth.

    • Photo: Stephen Moss

      Stephen Moss answered on 17 Mar 2011:

      Hi Silverfox
      This is one of the most important questions in biology. The most popular view is that because all life needs water, the very first organisms developed in the sea. These were probably similar to todays bacteria, so single cells living independently. There is evidence that the extreme chemical instability of the earth at that time (billions of years ago) led to the synthesis of all the organic chemicals necessary to create proteins and so on, and that these gradually assembled and reacted with one another to form life.

    • Photo: Eoin Lettice

      Eoin Lettice answered on 18 Mar 2011:

      Hi silverfox,
      This is a great question.
      Before life began, there was just pools of chemicals lying about the place. One of the things that defines life is the ability to reproduce and for life to begin, these chemicals must form some other chemical which was able to replicate and reproduce itself.
      Some scientists believe that this first replicating chemical might have been RNA (or something like it). RNA is very similar to DNA and life forms still use it to produce proteins to this day!
      Once life began, evolution ensured that it developed into all of the different and complex animals and plants and microbes that we see today!

      Eoin

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