Craters and Origins of Life Down Under
by Mark Lowenthal
A brief but detailed look at the science behind the hypothesis.
Did complex life on Earth begin in what is today Australia? In light of
three recent discoveries that will be briefly discussed in this chapter,
such a theory is becoming increasingly plausible. Perhaps equally notable,
however, is the small number of professional researchers who are aware
of these discoveriesand more importantly, the implications of them
when considered as a whole.
In the beginning...
Of course the origin of life is a mysteryperhaps the mysterythat
has most fascinated both professional scientists and laymen since... well,
since humans walked upright and gained the capacity to ponder the question.
In order to place the relationships between the three following discoveries
in a tangible context, however, it would be useful to briefly discuss
the evolutionary timeline as previously understood.
The era to which these discoveries are relevant is known as the Archaean
period. The Archaean period is considered the earliest and most important
era of geological time and pertains to the period prior to 2,500 million-years
ago. This period is thought to be significant for two reasons. First,
it was this era that gave rise to the first evidence of complex life on
Earth. Secondand equally significant, is that virtually nothing
else is known about it.
So fair enough, this Archaean period acted as the cradle of complex life as we now know it. But what kind of complex life are we talking about? Compared to cats, dogs and humansnot very complex.
Dr. Roger Buick
School of Geosciences
Edgeworth David Building FO5
University of Sydney
NS W 2006, Australia
Phone: 61-2-9351 2032
Fax: 61-2-9351 0184
Phone: 61-2-9351 3682
Dr. Andrew Glikson
Research School of Earth Science
Australian National University
Canberra, ACT 0200
Dr. Ray Binns
Dr. Dave Dekker
Parkroyal, Port Moresby
Phone: 675 3212266
Dr. Peter Franzmann
Parkroyal, Port Moresby
Phone: 675 3212266
But in biological terms, these ancient life forms were infinitely more complex than the organisms that had existed before them. Unlike simple cells such as bacteria, these new molecules, known as eukaryotes, possessed nucleiand these nuclei contained DNAthe building blocks of complex life that eventually evolved into plants and animals.
Next we are faced with three pertinent questions: When, specifically, did these eukaryotes first appear? Where did they first appear? And perhaps most importantly, how did they suddenly come into existence?
Here is where our three recent discoveries become relevant.
When? As for the when? question, the first of our three recent discoveries has shed some new light. Up until quite recently, the first evidence of eukaryotes suggested that complex life on Earth began approximately 1.7 billion-years ago. This understanding changed dramatically however, when in August of 1999 a team of Australian scientists, led by paleontologists Jochen Brocks and Dr. Roger Buick of the University of Sydney, and Dr. Graham Logan and Dr. Roger Summons of the Australian Geological Survey Organization (AGSO), discovered traces of molecular fossils indicative of eukaryotes in the Pilbara Region of Western Australia. The discovery was published in the international journal Science, in August of 1999.
The molecular fossils extracted by the researchers were discovered 700 meters below the Earths surface in a drill hole created by the team beneath the Karijini Range. This discovery proved to be monumental in that it revealed molecular evidence of eukaryotes that have since been dated at more than 2.7 billion-years old. The molecular fossils we report are the oldest preserved biological molecules in the world, noted Brocks shortly after his teams discovery.
This discovery has not, of course, established the exact beginning of complex life on Earth, but it now provides evidence that it existed about one billion-years earlier than previously believed.
Where? The second discovery to which this chapter calls attention pertains to the next question of significance pertaining to the origin of complex life on Earth: Where did this complex form of life first appear?
On this question, three important characteristics help to narrow the range of potential breeding grounds for the birthplace of complex life. While we may never know precisely what these first complex life forms looked like, we know that the birthplace had to be characterized by the presence of water and most probably, extreme heat, lack of oxygen, and intense electromagnetic activity. Most commonly, such an environment is only found in an active volcanic region, but a secondand uniquecircumstance is also thought to be capable of creating such a breeding ground: the impact of a meteor or asteroid colliding with the Earths surface long ago, before oxygen was abundant in the atmosphere.
As is well known, the impact of an asteroid creates a sizeable divot in the Earths surface and is known as an impact crater. It is believed that in such craters the enormous impact causes an unusual heating of groundwater and spurs hydrothermal activity and highly charged electronic pulses. It is precisely such circumstances that may have encouraged the development of microorganisms like eukaryotes.
These bacteria love volcanic environments and post-impact environments, observed Dr. Andrew Glikson, a geologist from Australian National University, and who also happens to be the focus of the second significant discovery touched upon in this chapter.
In the spring of 2000, Dr. Glikson, who specializes in the study of asteroid impacts and early evolution of the Earth, led a research team that uncovered what is now known as the Woodleigh impact crater, under the plains east of Sharks Bay in Western Australia. The Woodleigh crater is in fact the worlds fourth-largest impact crater with a diameter of 120 kilometers, and was created by a massive asteroid colliding with the Earth about 360 million-years ago. The asteroid that formed the crater was six to eight kilometers in diameter, says Glikson.
Together with Franco Pirajno of the Geological Survey of Western Australia (GSWA), I also found that the chemistry of shocked rocks has been modified and material from the exploding asteroid has actually penetrated the sub-crater floor in the form of melt and vapor, adds Glikson. It is only the second time that such effects have been observed anywhere.
Gliksons discovery is significant in that it portends a host of additional evidence yet to be unearthed due to the geological history of the region. As it happens, the canyonlands and impact craters of western and central Australia contain the largest and oldest surface record of ancient volcanoes and impact craters ever discovered. The climatic and atmospheric characteristics of the region and its history were ideal for the formation of the first complex life-forms. There was groundwater, intense heat due to both volcanic activity and the aforementioned asteroid impacts, and an atmosphere that at the time contained little or no oxygen and tremendous bursts of electronic charges.
How? While these discoveries have certainly introduced some intriguing new evidence as to when and where complex life may have first appeared, there is still the equally fascinating question of how such life forms were initially created.
We have already touched upon the climatic and biological circumstances necessary for such an occurrence. And we have also discussed the possibility of asteroid impact as the catalytic event that may have given rise to the creation of complex organisms such as eukaryotes. But is the impact of an asteroid the only possible explanation? Perhaps not.
As noted earlier, the only other natural phenomenon that would be associated with the necessary characteristics is volcanic activity. This scenario is also inextricably connected to the canyonlands and craters of western and central Australia. As it happens, the nature of this ancient volcanic activity is also the focus of the third and final recent discovery that will be discussed here.
Our understanding of the relationship between ancient volcanic activity and its potential role in the creation of complex life-forms was bolstered in the spring of 1999, by the discovery of a huge undersea chimney in the Bismarck Sea, north of Papua New Guinea.
The chimney was discovered by the Research Vessel Franklin, operated by the Commonwealth Scientific and Industrial Research Organization (CSIRO) and was located in an eerie landscape nearly two kilometers below the surface of the ocean. It is thought to be part of a vast hydrothermal system on the ocean floor that spews out plumes of superheated mineral-rich fluids from deep in the Earths crust into the surrounding seawater.
According to CSIRO expedition leader Dr. Ray Binns, our first examination (of the chimney) indicated it was teeming with bacteria and archae (very ancient and primitive life-forms).
The microbiologists aboard the Franklin were delighted, as one of the CSIRO expeditions primary goals was to identify particular microbes that could be used to process minerals on dry land in order to develop more efficient and cleaner ways to win metals.
We believe that microbes such as these deep sea bugs may enable Australias miners to exploit lower grade ore deposits, extract metals more cheaply, clean up waste streams and may even improve mine safety, explained CSIRO Dr. Dave Decker.
Most significant for this discussion, however, the discovery of this undersea chimney may provide a link to the formation of the ever-elusive eukaryotes.
According to CSIRO microbiologist Dr. Peter Franzmann, these mineral-mining bugs may be relatives of some of the earliest forms of life to emerge on the planetmore than three billion-years ago.
Back then, conditions were similar to what we now see in these seafloor hydrothermal ventshigh temperatures, lots of volcanic activity, and darknesswith the nutrients to sustain life pouring out of the Earth itself.
So what can be ascertained from these three discoveries?
In isolation, each discovery is intriguing, to say the least. Considered in relation to one another, however, these three suggest something infinitely more excitinga vast, unexplored region that may hold the key to unlocking the mystery of the origin of complex life on Earth.
The canyonlands and impact craters of western and central Australia seem to possess the necessary geological and environmental history to have hosted this momentous event. Now its up to research scientists, national governments and private industry to finance a full-scale search.
For those who wish to pick up the trail, contact information for the researchers mentioned in this chapter is furnished.
The answer to the worlds greatest mystery waits.