Readers who know of Centauri Dreams‘ fascination with ‘deep time’ will not be surprised that I am working on a side project involving past, not future time. Specifically, a study of the Eocene, that remarkable period beginning some 55 million years ago during which the ancestors of most modern mammals — including the higher primates, such as apes, monkeys and man – appeared.
And if the Eocene, 2/3 of the way back to the age of the dinosaurs, seems like a long reach from interstellar travel, ponder this: the more we learn about how life adapts to changing planetary environments, the better we’ll be able to carry out the hunt for life around other stars. On that score, it’s interesting to see that a team supported in part by NASA’s Exobiology program has determined that Earth’s continents were in place soon after the planet formed. The Earth was not, in other words, a purely ocean world in that era, or a barren, inhospitable place like the Moon.
Analyzing the occurrence of a rare metal element called hafnium in ancient minerals from the Jack Hills in Western Australia, the team, led by Stephen Mojzsis (University of Colorado), found evidence that the rocks it studied dated back 4.4 billion years. “The view we are taking now is that Earth’s crust, oceans and atmosphere were in place very early on,” said Mojzsis, “and that a habitable planet was established rapidly.”
A 2001 study led by Mojzsis and published in Nature had shown the presence of water on Earth 4.3 billion years ago. For more on the scientist’s earlier work, see this NASA story. The current paper is Harrison, Blichert-Toft, Mojzsis et al., “Heterogeneous Hadean Hafnium: Evidence of Continental Crust at 4.4 to 4.5 Ga,” published online November 17, 2005 and available as a preprint via Science‘s ScienceXpress service. A University of Colorado press release is here.
Plate Tectonics May Grind To A Halt, Then Start Again
ScienceDaily (Jan. 7, 2008) — Plate tectonics, the geologic
process responsible for creating Earth’s continents, mountain
ranges, and ocean basins, may be an on-again, off-again affair.
Scientists have assumed that the shifting of crustal plates has
been slow but continuous over most of Earth’s history, but a new
study from researchers at the Carnegie Institution suggests that
plate tectonics may have ground to a halt at least once in our
planet’s history — and may do so again.
Full article here:
http://www.sciencedaily.com/releases/2008/01/080103144448.htm
Bio-Earth Planetology: Planets as Living Super-Organisms
Japan’s Maruyama Shigenori, one of the world’s leading geophysicists, is working on a global formula for a vast new field of study that would include dozens of disciplines collaborating to produce an overall picture of the Earth.
Maruyama is creating a new institute called the Center for Bio-Earth Planetology will be launched in 2009 and fully dedicated to creating a new conception of life in space.He wants to find out if the continents will merge again in 250 million years to form a single super-continent; how meteorites change the chemical composition of the Earth; and what the connection is between the temperature of a planet and its magnetic field, which protects plants and animals from being bombarded with cosmic radiation, which in turn influences the rate of mutations and thus the development of new forms of life.
As he connects the dots from astronomy to life sciences, the outlines emerge of an all-encompassing image of entire planets, which appear as living super-organisms.
He believes that expanding the study of life sciences to the core of our world and the depths of outer space will help us find distant relatives of our own Earth — planets that could also sustain life.
Maruyama is also provoking controversy in the with his bold hypotheses a new fascinating theory on the lifecycle of the Earth’s crust.
Full article here:
http://www.dailygalaxy.com/my_weblog/2008/01/bio-earth-plane.html
First Rule Of Evolution Suggests That Life Is Destined To Become More Complex
Bath, UK (SPX) Mar 18, 2008 – Scientists have revealed what may well be the first pervasive ‘rule’ of evolution. In a study published in the Proceedings of the National Academy of Sciences researchers have found evidence which suggests that evolution drives animals to become increasingly more complex. Looking back through the last 550 million years of the fossil catalogue to the present day, the team investigated the … more
http://www.terradaily.com/reports/First_Rule_Of_Evolution_Suggests_That_Life_Is_Destined_To_Become_More_Complex_999.html