• Question: Why are humans warm blooded but lizards cold blooded?

    Asked by to Anna, Chris, Jane, Iain, Nick on 18 Mar 2014. This question was also asked by .
    • Photo: Anna Middleton

      Anna Middleton answered on 18 Mar 2014:


      Hi Fitzgeraldj10464
      The simplest answer to why we are warm blooded and lizards are cold blooded is to do with evolution. Different species evolve in different ways to adapt to their environment.

      You can find a discussion about this this here: http://www.scienceforums.net/topic/18572-why-are-we-warm-blooded/

    • Photo: Jane Charlesworth

      Jane Charlesworth answered on 18 Mar 2014:


      I wrote an answer to this to someone else-here it is:

      Warm and cold-blooded animals survive better in different environments. Warm-blooded animals, for example, can be active at night, because they don’t rely on the sun. They might do better in environments where food is scarce (or low in nutrients–if you think about it there aren’t many vegetarian lizards outside of the tropical rainforest). Being active for longer hours has also meant that warm-blooded animals were able to evolve larger brains (brains use a lot of energy). You might ask why cold-blooded animals still exist if it’s better to be warm-blooded. The answer to that is that many animals survive just fine being cold-blooded–perhaps they live somewhere with a lot of sun or don’t need to eat very much.

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