Are we alone?
This has been a question that has often been asked. Given that so many science-fiction stories feature encounters with alien beings, it's an important question for science fiction.
A while back, a book titled "Rare Earths" made the news. Its bold
hypothesis was that in a typical galaxy, there was only a narrow ring in
which solar systems would have enough heavier elements so that planets
which could bear life could form, on the one hand, and those planets would
not be so constantly pummelled by asteroid impacts so that it could never
get past the stage of single-celled microorganisms.
While there was certainly some plausibility to its arguments, this sort of argument is... too contingent for my liking. That is, it seems to me that
it's entirely possible that if some facts were overlooked, it could turn
out to be mistaken.
But it seems to me that there is an argument - and, in fact, a fairly well- known one - that the kind of life that writes books and builds spaceships
is indeed very rare in the Universe.
How did human intelligence evolve?
Our big brains have a high metabolic cost. And while human intelligence
has obvious survival benefits... _now_... it took time for us, with our
large brains, to develop all this technology that we now have.
It seems quite unlikely that our large brains yielded enough in the way of *immediate* benefits to permit them to evolve in the face of their
metabolic cost.
This question was faced at a _very_ early stage by biologists studying evolution.
Charles Darwin, after _The Origin of Species_, went on to write a second
book on evolution, with the title _The Descent of Man, or Selection in Relation to Sex_.

And so we've known *all along* that the giant brain of Man came into being
to facilitate social interaction among humans... and thus this giant brain came into being through the same process as the tail of the peacock or the horns of the Irish Elk.

And, since the targets of sexual selection are essentially random - we wouldn't expect creatures with giant horns like the Irish elk to
necessarily exist on other planets, or creatures with tails like that of
the peacock - it reasonably follows that far from being a common and inevitable result of evolution if it has time, brains of the kind needed
to venture out into space... are likely to be rare indeed if they're just
one random choice out of so many that sexual selection might happen to enhance.

John Savard

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On Sun, 24 Aug 2025 05:42:21 +0000, John Savard wrote:

While there was certainly some plausibility to its arguments, this sort
of argument is... too contingent for my liking. That is, it seems to me
that it's entirely possible that if some facts were overlooked, it could
turn out to be mistaken.

On further reflection, I realize that my reasoning was mistaken, and that intelligence is likely a product of sexual selection is not one of the strongest arguments that we are alone in the Universe, or nearly so.
A friend of mine recently got a fish with very colorful fins for her
aquarium.
So the tail of the peacock is not entirely random: the products of sexual selection fall into certain common patterns. Things that enhance social interaction could be one of those patterns.

John Savard

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John Savard <quadibloc@invalid.invalid> wrote or quoted:

A while back, a book titled "Rare Earths" made the news. Its bold
hypothesis was that in a typical galaxy, there was only a narrow ring in >which solar systems would have enough heavier elements so that planets
which could bear life could form, on the one hand, and those planets would >not be so constantly pummelled by asteroid impacts so that it could never >get past the stage of single-celled microorganisms.

I had come across different stories about unlikely twists in the
history of life, the kind where if they had not lined up, there
might not have been any life at all. I never got around to laying
all that out in a way others could follow, but it left me with the
sense that life might be more improbable than the sheer number of
planets is large. I think it is possible that life on Earth is the
only life there is. But since there are stretches of the universe
we will never be able to see, we will never know for sure.

On Earth, not only did life show up, but out of life
came consciousness, which is still a huge mystery!

What hardly anyone considers is that there could be other phenomena
on the same level as life and consciousness. Things we do not even
have words for. Or, as a Secretary of Defense once said:

|As we know, there are known knowns. There are things we know
|we know. We also know there are known unknowns. That is to say
|we know there are some things we do not know. But there are
|also unknown unknowns, the ones we don't know we don't know.
..



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