Wasn't it Paul Bramscher who wrote:

Mike Williams wrote:

Wasn't it Paul Bramscher who wrote:

So it may be that larger clusters of intelligence (large cities) will be 
one of the earlier potentially remote-sensible artifacts of 
intelligence.  For example, cities might be approached as (often, in 
today's modern sense) having some signature (chemical, albedo, 
geometric, etc.) which make them often stand out.

We may never be able to pick out an alien's brain waves, but we just 
might detect a city on an earthlike planet in the next century or two...

That's a rather anthropomorphic concept of aliens. I'd guess that most
intelligent civilisations wouldn't build cities.

Why?  Intelligent, mammalian and non-mammalian cooperative life on Earth 
 all developed along social considerations.  Herds, tribes, cities, 
hives, etc.  Clusters or communities may be better hallmarks (though not 
exclusive) of intelligence and cooperation than most.

In any case, we should first go by life as we know it on earth, not some 
hypothetical alternative.

Humans build houses because they're used to living in caves, and there
aren't enough caves for everybody unless you build fake ones. Uplifted
chimps and dolphins probably wouldn't build anything that we would
recognise as a city.

-- 
Mike Williams
Gentleman of Leisure