Science!

« Transit of Mercury | Main | Mythbusters »
Saturday Nov 25, 2006

Somehow makes even The Lord of the Rings seem short


It is hard to overemphasize the shocking suddenness of life's proliferation in the seas and on the lands of Earth.  Suppose some galactic civilization had evolved on planets of stars older than the sun, and they had sent out a dozen expeditions to visit Earth, spaced evenly throughout Earth's history.  The first ten expeditions would have found only lifeless craters, lavas, sand dunes, and highly eroded river channels on Earth's land surfaces.  The eleventh expedition would have arrived 380 My [million years] ago and would have found the land mostly covered by flourishing Devonian forests.  The twelfth expedition would find us.

From William K. Hartmann & Ron Miller's The History of Earth.  Recommended as a highly readable summary of the geological and biological evolution of the planet.  Mostly geology, since that's actually most of Earth's history--6/7ths of it, in fact, without any life whatsoever.  Human history is even more absurdly short, about 10,000 years, compared to 4,500,000,000 years of Earth history.  Which is to say the Earth has been human-free for 449,999/450,000 or 99.9998% of its existence.  (By comparison, dinosaurs were around for something like 150,000,000 years--15,000 times as long as us.)

Anyway, if at this point in your life you're not completely blown away by the staggering scale of geologic time, this is a nice book to fix that.

Comments:

Nice post, but I do have one pet peeve that always irks me every time I see it: we've been here for 10K years and the dinosaurs were around for 150M. Apples and oranges have more in common than humans and dinosaurs. Humans are a species, and dinosaurs are a class.

A fair comparison would be dinosaurs and mammals. Of course mammals (at least protomammals) have been around since the dawn of the dinosaurs. Unless you count birds as dinosaurs, then we've both been around for about the same amount of time.

If you're going to compare humans to dinosaurs, then you must compare us to a specific species of dinosaurs. The problem then becomes how you define when a species emerges and when it has evolved into something else (I'm not even going to get into my objection to the use of 10,000 years for humans).

Anyway, sorry for the rant. I really do understand the point you're making, but that "humans vs. dinosaurs" analogy is so, so bogus that it just upsets me every time I see it.

Posted by The Science Pundit on November 29, 2006 at 08:21 PM EST #

Thanks for the comment, that's an excellent clarification. I don't agree that the analogy is useless, but your note about comparing a species to a class is very important. While my point was really just to compare human recorded history with dinosaur fossil history, I should also have elucidated the qualifications of using the 10K year figure--modern humans, modern history only.

Posted by Josh on November 30, 2006 at 09:37 AM EST #

Post a Comment:
Comments are closed for this entry.