Rocks evolve too, geologists claim

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Rocks evolve too, geologists claim

http://www.nationalpost.com/news/story.html?id=992895

 

Rocks evolve too, geologists claim

Randy Boswell, Canwest News Service Published: Tuesday, November

25, 2008

Peter Wilson/Canwest News Service

 

A new geological study argues that rocks actually involved in tandem

with plants and animals.

A landmark scientific study co-authored by a Canadian geologist has

identified a sudden explosion of mineral diversity after the emergence

of life on Earth, and advanced a " revolutionary " theory that rocks have

been evolving -- much like plants and animals -- throughout the planet's

history.

Wouter Bleeker, an Ottawa-based researcher with the Geological Survey of

Canada, is one of eight members of an international team whose theory of

" mineral evolution " -- the idea that many of the Earth's rocks are

dynamic " species " which emerged and transformed over time, largely in

concert with living things -- is generating a major buzz in the global

scientific community since its publication last week in a U.S. journal.

 

" The key message, " Mr. Bleeker told Canwest News Service, " is how

closely intertwined the mineral world is with life and biology. " He said

human teeth -- with their key ingredient of apatite -- are vivid

reminders that the " seemingly static, inorganic " physical Earth should

be viewed more like a " living organism " underpinning the biosphere.

But the new theory is also being hailed as a potential tool in the

search for life on other planets since it offers new ways of perceiving

the interactions between rocks and living things. Probes of distant

planets should be seeking evidence of biological processes that may have

shaped alien landscapes, the scientists contend.

 

The study, published in the latest edition of American Mineralogist,

chiefly proposes a new way of understanding Earth's natural history and

teaching the geosciences -- particularly how plant processes have

altered the planet's atmosphere and its rock chemistry, and how the rise

of complex life forms with shells and skeletal features " irreversibly

transformed Earth's surface mineralogy. "

The research team, led by U.S. geologists Robert Hazen and Dominic

Papineau of the Washington, D.C.-based Carnegie Institution, recounted

how just 12 minerals are believed to have been present among the dust

particles swirling through space at the dawn of planetary formation some

five billion years ago.

 

As the materials that formed Earth " clumped " together and were subject

to thermal pressures and other forces, the number of distinct minerals

increased to about 250, the study says. Then, due to volcanic activity,

plate tectonics and other processes that churned the surface of the

planet before life emerged, the population of mineral " species " had

grown to about 1,500 by four billion years ago.

That's when changes to ocean chemistry and atmospheric conditions,

coupled with the emergence of life, sparked an unprecedented

diversification of the world's minerals.

Among the best known examples of how living things transform the Earth's

rock layers is limestone, which is accumulated from the dissolved shells

of tiny marine creatures. But the new study provides the first

comprehensive analysis of the multitude of rock-life interactions and

documents how mineral evolution unfolded rapidly as life took hold early

in the planet's history.

 

" Biochemical processes may thus be responsible, either directly or

indirectly, for most of the Earth's 4,300 known mineral species, " the

study states.

" Mineral evolution is obviously different from Darwinian evolution --

minerals don't mutate, reproduce or compete like living organisms, " said

Mr. Hazen in a statement announcing the study's findings. " But we found

both the variety and relative abundances of minerals have changed

dramatically over more than 4.5 billion years of Earth's history.

 

" For at least 2.5 billion years, and possibly since the emergence of

life, Earth's mineralogy has evolved in parallel with biology, " Mr.

Hazen added. " One implication of this finding is that remote

observations of the mineralogy of other moons and planets may provide

crucial evidence for biological influences beyond Earth. "

Stanford University geologist Gary Ernst is quoted in a Carnegie

Institution summary of the study describing the research as

" breathtaking " in its scope and adding that " the unique perspective

presented in this paper may revolutionize the way Earth scientists

regard minerals. "

 

The study's proposed theory of mineral evolution is also highlighted in

the latest edition of Nature as " an exciting concept that will do much

to stimulate debate and enliven thinking in the usually staid field of

mineralogy. "