Expert: John J. Shea - 1/22/2008

Question
Hi, my name is Brandon and I've always been fascinated with the field of archaeology, and most other sciences in general.  My question is, is there any scientific basis for the theories that man was at one time more advanced than we are today?  That perhaps this isn't the first time we as a race (although vastly different from our ancient ancestors thanks to evolution) have achieved things like flight, atomic warfare, and perhaps even space exploration?  As a scientist, I was hoping you could provide me with scientific answers, as I've only been able to uncover far-fetched speculations in my research so far.  Logic tells me it's not impossible since most of the things in our world today would deteriorate within 100 years without us, but without proof or scientific basis, I have to question the likelihood.  Thanks for your valuable time!

Answer
Brandon
The idea of a lost civilization like our own is a popular theme in science fiction.  There is no evidence to support the hypothesis that there was a past civilization with technical abilities comparable to our own.
It is true that a lot of our technology would decompose, but there would still be a signature.  For example, if they relied on metallurgy, they would have depleted the earth's surface of gold, silver, copper, tin and other non-ferrous metals in the same way we have done.  They would likely have domesticated animals and plants, and this ought to show up in genetic bottlenecks (reductions in genetic variability) among species descended from those domesticates.  Lasty, if they had nuclear power, there ought to be radioactive traces of this technology.  Space exploration is extremely expensive, even today it costs something like $40,000 per lb to put a payload in orbit.  The economic activity required to support even rudimentary space exploration would probably bankrupt any pre-modern civilization and, again, there would be traces of the economic activity and support technology.
There are plenty of civilizations that rose and fell in antiquity, but none comparable to the present one in terms of technological complexity.
I hope this answers your question.
Cheers,
John Shea