• Question: how did species form?

    Asked by to Joe, Juan, Kate, Rosie on 21 Mar 2014. This question was also asked by .
    • Photo: Juan Carlos Lopez-Baez

      Juan Carlos Lopez-Baez answered on 21 Mar 2014:


      Well, it is said that we all have a common unicellular ancestor (unicellular = made of one cell only), that lived billions of years ago.Different species have descended from it thanks to two processes: evolution and natural selection. Evolution is the process by which a group of living organisms can develop a new characteristic and then (say, for example the ability to fly, like birds) are able to keep that characteristic for many generations. Natural selection is very tightly linked to this and it is the process that “selects” whether that new characteristic is beneficial or not (for example, an animal that develops the ability to have a very thick layer of fat will be very well suited for the North Pole, but if the same was to happen to an animal in Australia, it will not be a beneficial characteristic to have and it will mean it won’t survive the heat).

      Of course, you have to think that this has happened through billions of years (one billion = 1,000,000,000…<–that is a lot of 0's) and small characteristics have accumulated to make the big differences that we see in the animals, plants and bacteria (to mention a few) that we see today. Some, like us, have accumulated many changes and for that reason we are very evolved. Others, like viruses and bacteria have hardly evolved and that's why they have hardly changed in millions of years.

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