Dear Sue Lee Hooker

A long time ago people thought that the difference between inanimate things (like rocks or icebergs or houses) and animate things (like trees or wallabies or mosquitoes) was that the living things had something magic breathed into them to make them alive.

No one knew how this worked--or how life was passed on from one generation to another.

Over the last hundred years or so people have started to change their minds about this. It seems that the main difference is that the living things are much more complicated than the non-living things.

There are lots of ideas about how and why life came about, but no one really knows for sure.

Some people think that when computers get smart enough and complicated enough then they will become alive, too.

Other people disagree very strongly with this. They think that there is something special about the way cells are made that lets living things react and learn in ways that a computer never could.

So, to summarise... Something is alive if it can adapt to its environment, if it metabolises (takes in food and uses it to do things and stay alive) and if it reproduces (makes new copies of itself).

Do these three things apply to you?

Yours sincerely 

Virginia R. Claire

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