"Dennis Taylor" <noemail@nospam.org> wrote in message
news:F_VRa.454323$3C2.12374723@news3.calgary.shaw.ca...

I'm just throwing this out for the sake of argument, but here goes: 1)

It's

generally accepted that Venus and Mars have no plate tectonics, while

Earth

does. You can maybe excuse Mars because of its size, but not Venus. 2) Any
number of  books have made reference to the importance of plate tectonics

in

the creation and maintenance of the Earth's biosphere, because of
outgassing, recycling of deposited carbon materials, etc. 3) The biggest
difference betwen Earth and the other two is the presence of the moon,

which

also is probably a major reason for the continued existance of an active

and

molten core, due to heating from tidal action.

So, given this, what if one of the primary requirements for life, for a

long

enough period to allow evolution of intelligence, is the presence of a
satellite big enough or close enough to maintain a molten core and ongoing
tectonics? That would certainly reduce the probability of life in the
universe, without requiring a mystical explanation.

This argument is covered in "Where Is Everybody" by Stephen Webb, and I

find

it particularly convincing. It's certainly something that would get around
the principle of Mediocrity.

Doesn't the moon also keep the earth's axis from wobbling around any more
than it does, such that if we didn't have the moon, there would be way more
climate
variation than we now have?

rj