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."