Darwin’s missing evolution link discovered in Ontario

Charles darwin

 

If his theory of evolution was true, the world must have “swarmed with living creatures” more than 540 million years ago, Charles Darwin wrote in 1859. But the lack of evidence of this early life remained the missing link in Darwin’s theory for more than 100 years, until the first confirmed fossils of microscopic life that had lived in the Precambrian eon were discovered in Ontario on the shores of Lake Superior. Portrait by George Richmond (1809-18967), Wikimedia Commons.

 

Following is an excerpt from my current work in progress, Fossil Fire: A social history of the Fuels that empower and imperil.

A discussion of fossil fuels should start with a discussion of fossils. To begin at the beginning, we need to go back billions of years in search of the missing fossils in Darwin’s theory of evolution. When Charles Darwin published On the Origin of Species, or the Preservation of Favoured Races in the Struggle for Life on November 24, 1859 it became an instant bestseller. It also triggered a social upheaval, roiling Christendom ever since. Yet even Darwin acknowledged the missing fossils threatened the credibility of his theory. It took 95 years to find the first recognized missing fossils—at a remote site in Ontario on the northern shore of Lake Superior—and another decade before the discovery was widely confirmed and acknowledged.

At age 22, Darwin clambered aboard HMS Beagle at London for a five-year voyage around the world. An embryonic naturalist, he was charged with exploring the flora, fauna and geology of the lesser-known coastal regions of the world, most notably South America, the islands of the Pacific, and, famously, the Galapagos Archipelago. The Beagle’s captain, 25-year-old Robert FitzRoy, was an ardent Christian fundamentalist who hoped the expedition would conclusively confirm the Biblical account of creation. After the voyage, and for the rest of his life FitzRoy was one of the most strident and persistent critics of Darwin and his theory.

Darwin arrived home on the Beagle with new botanical and geological insights, including a breakthrough theory on the formation of coral reef atolls, and a bounty of natural specimens—birds, plants, animals, and fossils, among others. Twenty-three more years would elapse before he would publish On the Origin. He spent several years sorting and examining his collection, developing his theory of evolution, and penning the first of six drafts of his opus. But for most of the 23 years since his return from the Galapagos, he kept his manuscript under lock and key.

Darwin knew the distress and fury his book would create among millions of devout Christians to whom the Biblical account of creation was sacred. Even most naturalists believed animal life, humans in particular, first appeared on Earth fully developed. Not that the idea of evolution was entirely new; several writers had already thought of it, including his grandfather Erasmus. Edinburgh publisher Robert Chambers, carefully hiding behind an anonymously published book, had suggested that humans were evolved from apes.[1]

Chambers’ book caused fury enough. The manuscript that Darwin kept under lock and key would be far more explosive. His book would provide the first fully-developed and well-documented theory of evolution, supported by a plethora of scientific evidence. Darwin was “tormented” by the upheaval his idea would create, according to author Bill Bryson, since his wife was a devout Christian believer. Darwin “referred to himself as ‘the Devil’s Chaplain,’ and said that disclosing his theory ‘felt like confessing a murder.’”[i]

Another reason for Darwin’s hesitation in publishing his theory may have been the missing fossils. For at least 2,500 years, people have collected and written about animal fossils, from giant reptiles to the smallest fossilized seashells. All the known fossils found by 1859 once existed as fully developed organisms, whether plants, clams, dinosaurs, or apes. Such complex life forms, Darwin argued, evolved from very simple organisms. The core of Darwin’s theory is that life evolved from primitive, much less developed organisms. Darwin insisted that ancient oceans had once been alive with early, primitive ancestors. But where was the evidence?

Darwin faced the problem in his first 1859 edition of On the Origin, and more explicitly in his subsequent five editions:

“If the theory [of evolution] be true, it is indisputable that before the lowest Cambrian stratum was deposited… the world swarmed with living creatures. To the question why we do not find rich fossiliferous deposits belonging to these earliest periods I can give no satisfactory answer. The case at present must remain inexplicable, and may be truly urged as a valid argument against the views here entertained.”

All known fossils when Darwin wrote came from little more than one-tenth of the Earth’s history. The oldest came from the Cambrian, a brief period from about 540 million to 485 million years ago, marked by the sudden appearance of a wide-ranging great number of marine critters, living on, in, or swimming above shallow beds of the seas. The missing fossils of earlier forms would apparently have to be discovered somewhere in the rocks of the first four billion years of Earth preceding the Cambrian, in the rocks of the Precambrian eon. The search was already underway.

Looking for Precambrian life

The century-long search for Darwin’s answer brims with wrong turns, mistakes, and disputes. One of the first in the field was Scottish-born John William Dawson (1820-1899), a protégé of Charles Lyell, the most famous geologist of his time. Dawson himself later became recognized as one of the world’s leading geologists and scientists, serving as principal of Montreal’s McGill University, the only person to have served terms as president of the Royal Society of Canada, the Geological Society of America, the American Association for the Advancement of Society, and its British counterpart. He was a devout Presbyterian and, like FitzRoy, a staunch believer in the Biblical account of creation. He saw no contradiction between the possibility of Precambrian life and his religious beliefs, and no reason to suppose any Precambrian life would be the progenitor of a more evolved form of life. He believed simple forms of life may have existed from earliest times, but under the Biblical account of creation, they could not change or evolve.

From the Banks of the Ottawa River, Dawson collected and examined specimens of limestone rock, later determined to be 1.1 billion years old.[ii] He concluded the unusual green and white thin markings were the first discovered Precambrian fossils, a claim immediately disputed. Dawson stuck to his guns, and expounded his claim in an 1875 book, The Dawn of Life; Being the History of the Oldest Known Fossil Remains, and their Relations to Geological Time and to the Development of the Animal Kingdom. Dawson vigorously defended his claim to his dying day, but he was mistaken. “Dawson’s famous and now infamous ‘dawn animal’ was nothing more than a curiously layered mineral deposits formed when hot molten rocks intruded into Laurentian limestone,” J. William Schopf writes in Cradle of Life, his first-hand account of the study of Precambrian life.[iii]

On the other hand, Charles Doolittle Walcott (1850-1927), “Founder of Precambrian Paleobiology,”[iv] really did find Precambrian fossils, but his discovery was dismissed and ignored for more than half a century. A high school dropout and largely self-educated “rock hound,” Walcott pursued his passion for finding and studying fossils to become the most acclaimed American geologist of his time. He served variously as director of the U.S. Geological Survey, secretary of the Carnegie and Smithsonian Institutions, president of the American Association for the Advancement of Science and the National Academy of Science, and science advisor to President Theodore Roosevelt. Walcott remains the reputed discoverer, and first major collector, of “the world’s most important animals fossils,”[v] found high in the Canadian Rockies.

In 1883, Walcott found algae fossils in exposed Cambrian rocks in the Grand Canyon, and in the Montana mountains. Sixteen years later he made a more startling find, also in the Grand Canyon, of small animal fossils in the much older “Precambrian carbon-rich shales… the first true cellularly preserved Precambrian organisms ever recorded.”[vi] The skeptics were quick to pounce. The authenticity of the Precambrian fossils was disputed four years after Walcott’s death, with seeming finality, by Sir Albert Charles Seward of Cambridge University, considered the final authority on the matter. “We can hardly expect to find in Precambrian rocks any actual proof of the existence of bacteria,” Seward wrote in 1931.[vii] Two decades later, it would be up to geologist Stanley A. Taylor and his associates, to prove Seward wrong.

The trail to Schreiber

Stanley Tyler discovered the first fully formed and acknowledged Precambrian fossils—microscopic algae and fungi bacteria—while on a Sunday fishing trip in August 1953. A mineral, or “hard rock,” geologist with the University of Wisconsin, Tyler was funded by the U.S. National Science Foundation to study the geology of a 500-kilometre stretch of Gunflint chert rock, so-labelled because it was once used to spark the fire of ancient flintlock guns. The iron-bearing Gunflint stretched from then active iron mines in northern Minnesota, up 175 kilometres into Ontario along the north shore of Lake Superior to Thunder Bay, with isolated remnants farther east for another 100 kilometres, to the lake shore near the small town of Schreiber, where the “best preserved”[viii] fossils lay waiting.

For his fishing trip, Tyler rented a dingy with an outboard motor, as recounted by Schopf in Cradle of Life.[ix] As he cast his line near the shore at Schreiber Beach, the jet-black rock of the Gunflint outcrop and the large stromatolites were clearly visible. Tyler scrambled ashore for a closer look. The rock was certainly Gunflint chert but not the red colour that would indicate the presence of iron. The stromatolites interested him, but were they as old as this Precambrian rock? He picked up a few specimens to add to the collection of Gunflint rocks he would soon take back to Madison and the University of Minnesota after completing his season’s fieldwork.

In his Madison laboratory, Tyler used a high-powered microscope to examine his sliced, paper-thin stromatolite samples. He saw that this section of rock somehow escaped millions of years of pressure and heat to remain close to its original condition when laid down as sediment on an ancient ocean bed, thereby “providing a glimpse through the Precambrian metamorphic veil,” as Tyler put it.[x] What really astounded Tyler was the presence of tens of thousands of microscopic, dark brown networks that looked like fossils—two-billion-year-old organic fossils. The fossils contained thin filament strands, bulb-shaped at one end and star-shaped at the other.

As a mineralogist, Tyler needed some expert advice from a paleobotanist. He hooked up with Elso Barghoorn at Harvard University. Tyler and Barghoorn returned to collect more samples at several locations near Schreiber. Barghoorn confirmed these were, indeed, fossils of organisms that lived some two billion years ago. These were primitive blue-green algae, “the oldest structurally preserved organisms… which have yet been discovered in Precambrian sediments,” they wrote in a “preliminary statement” of their findings. As such, they said the fossils were “of great interest in the evolutionary scheme of primitive life.”[xi] The world of science shrugged and dismissed them: too much had already been heard about supposed Precambrian fossils. Nothing more would be said about the Schreiber fossils for the next 11 years.

Tyler and Barghoorn prepared a draft for a much more detailed and longer article about their Precambrian fossils. But, preoccupied with one thing or another, they left the draft manuscript, much like Darwin’s On The Origin of Species, sitting idle in a desk draw for six years. In 1963, eight months shy of the tenth anniversary of his discovery at Schreiber, Tyler unexpectedly died at age 57. That year 21-year-old Bill Schopf, an honours graduate of tiny Oberlin College in Ohio, with a degree in geology and a burning ambition to find out more about the mysterious life of the Precambrian, entered Harvard as Elso Barghoorn’s student and assistant.

Barghoorn and his new assistant were rushed into reviving the idle manuscript by another geologist, Preston Cloud, head of the Department of Geology at Tyler’s alma mater, the University of Minnesota. In their 1954 preliminary statement in Science, Tyler and Barghoorn intentionally omitted a precise location of the Precambrian fossil bed, other than marking it “near” Schreiber. Their statement even misspelled the name of the town as “Schrieber.” Cloud, however, managed to find the site, and spent three days carefully examining the outcrop. Now he was about to publish a detailed article in Science about what Tyler and Barghoorn had found and first examined a decade earlier. Barghoorn and Schopf spent a frantic two weeks preparing the draft manuscript and photos of the fossils for publication in Science, in advance of the Cloud article that threatened to steal the recognition of Barghoorn’s and Tyler’s earlier ground-breaking work.

“Micro-organisms from the Gunflint Chert,”[xii] by Elso S. Barghoorn and Stanley A. Tyler was published in 1965 in Science, a 10,000-word, 15-page article, with a substantial selection of the enlarged photos. They reiterated earlier claims of their preliminary statement. “These structurally preserved Precambrian fossils from Ontario,” they wrote, “are the most ancient organisms known… of unusual interest in the study of the history of life.” This time the world of science sat up. With the evidence in this article, there could no longer be any doubt about the existence of Precambrian life, and, moreover, life much older than that of the real but unacknowledged Precambrian fossils found earlier in the Grand Canyon and elsewhere by Walcott, as well as possible findings by others. “The Barghoorn-Tyler paper is a classic,” Schopf wrote 40 years later. “For all time it will probably stand as the most important article ever written in the field.”[xiii]

Still older Precambrian fossils were later found, particularly in Australia where Schopf played a leading role in the discovery and evaluation of larger stromatolites with their algae and fungi fossils—1.5 billion years older, and within one billion years of the birth of Earth. Yet the little-known, isolated and restricted area in the Schreiber Channel Provincial Nature Reserve where the outcrop of Gunflint cherts slopes into the placid blue water of Lake Superior is where the seeds for all life on Earth today were first found. It is difficult to envision a more historic world site than this neglected piece of Precambrian rock, in this isolated corner of Ontario.

Unfamiliar Canadian history stories 001

[1] Chambers was the maternal grandfather of Robert (Bob) Chambers Edwards (1860-1920), Western Canada’s best-known humourist and satirist, and publisher of the popular Calgary Eye Opener.

[i]Bill Bryson. A Short History of Nearly Everything. Toronto: Anchor Canada, 2003, p. 388.

[ii] William J. Schopf. Cradle of Life: The Discovery of the Earth’s Earliest Fossils. Princeton: Princeton University Press, 1999, p. 19.

[iii] Ibid., p. 21.

[iv] Ibid., p. 27.

[v] Stephen J. Gould. Wonderful Life: The Burgess Shale and the Nature of History. New York: W.W. Norton, 1989, p. 23.

[vi] Schopf. pp. 27-28.

[vii] Ibid., pp. 33-34.

[viii] Stanley A. Tyler and Elso S. Barghoorn. “Occurrence of Structurally Preserved Plants in Pre-Cambrian Rocks of the Canadian Shield. Science, New Series, Vol. 119, No. 3096 (Apr. 30, 1954), pp. 606-608. http://www.jstor.org/stable/1682018. Accessed: 02/03.2014.

[ix] Schopf. p. 37.

[x] Ibid., p. 38.

[xi] Ibid, p.606.

[xii] Barghoorn and Tyler. “Microorganisms from the Gunflint Chert.” Science, New Series, Vol. 147, No.3658, Feb. 5, 1965, pp 563-577. htpp://jstor,org/stable/171562. Accessed March 2, 2014.

[xiii] Schopf. p. 59.

 

Leave a Reply

Your email address will not be published. Required fields are marked *