Victoria Beach, Lake Winnipeg, 2014
Along Lake Winnipeg in July it felt like business as usual. At Victoria Beach we rode our bikes down narrow gravel lanes through swarms of dragonflies and clouds of midges, basking in the perfect warm air and golden sunlight. The shop, bakery, tennis courts, and playground were busy. But what about the beach? If you listened to the residents, beyond the usual small talk, this question remained: what about the beach? And what about the scarps behind it?
Manitoba’s lakes have been having issues of one sort or another for decades. Most summers Lake Winnipeg has trouble with algal blooms as a result of increased nutrient flow from farms and cities, though the extent of this problem varies from year to year. In 2011 the shores of Lake Manitoba were devastated by high lake levels, after Assiniboine River flooding resulted in heavy use of the Portage Diversion channel. This year water has again been very high on Lake Manitoba and Lake Winnipeg, after heavy precipitation in the late spring and early summer.
On Lake Winnipeg, cottagers always reckon that their shorelines suffer from increased erosion because Manitoba Hydro keeps water levels high, the better to power dams on the Nelson River system. This could certainly be a cause, particularly when this high lake level is augmented by unusual rainfalls. But there is another factor, a geological one, which most people ignore because of its subtlety and complexity.
The land of Manitoba has been slowly rising for the past 10,000 years or so, as the crust rebounds from being pressed down by glacial ice that was hundreds or thousands of metres thick at the height of the last ice age. The ice melted away from south to north, so the southern part of the province is now closer to equilibrium and is rising slowly. In the north, the rebound is still more rapid (even farther north, near Churchill, the rate of rise is close to a metre per century!).
Postglacial rebound may seem like an interesting if remote phenomenon, but its effect “on the ground” is this: Lake Winnipeg’s outflow is at the northern end of the lake, and since this is the part that is rising more rapidly, the basin is gently tilting southward (imagine what happens as you tip a dish full of water). The lake is gradually moving across the flat lands at its southern end, reclaiming the marshes of the Red River Delta and the beachfronts of Ponemah and Matlock. Given enough time (before this land is again subject to large-scale glaciation), the lake will surely arrive where downtown Winnipeg stands today.
But this will take centuries or millennia. Meanwhile, whenever there is high water the lake will take advantage of it, moving just a bit farther southward and chewing away at the wonderful shorelines of Grand Beach and Victoria Beach. These shores are soft, being composed largely of sediment left behind by that glacial ice. The waves readily remove sand and gravel from the beaches and scarps, leaving behind only the larger boulders, and the shoreline continues to retreat. From a human standpoint this seems unfair and a great shame, but we can only hope to slow down nature. It will always win in the end.
A lot of detail on the geology of the Lake Winnipeg basin was published in: Lake Winnipeg Project: cruise report and scientific results; Todd, B J (ed.); Lewis, C F M (ed.); Thorleifson, L H (ed.); Nielsen, E (ed.). Geological Survey of Canada, Open File 3113, 1996, ; 656 pages, doi:10.4095/207501
© Graham Young, 2014
Ah, Mount Sylvan. Such a magnificent sight. And nearby, those huge rocky cliffs reach up to the sky!
I admit this is not really such a grand landscape as it might first appear. In Manitoba’s Interlake you have to take your topography where you can find it, and heaps of quarried limestone may well be the tallest features from one horizon to the other. The quarry at Sylvan is not a particularly good fossil locality, but in contains a fascinating succession of shallow-water carbonates that represent deposition under fluctuating environmental conditions.
Bryozoan-containing cherts at the base of the quarry are succeeded by a variety of other units including thin-bedded dolostones, microbialites, beds showing internal brecciation, and some intriguing clay-like horizons. One stromatolitic interval has yielded odd phosphatic bits, and we periodically revisit the site with the hope that more diagnostic phosphate components will show up (ideally parts of early fishes, but other things would be fine too). So much depends on how active the quarrying has been in the intervening months, and how much of the faces we can see. Last Monday, when I took these photos, the faces were muddy and we could not get to them very easily, but we will be back. We just have to be patient . . .
Please excuse the relatively poor image quality in these photos. It was my first day in the field this summer and I had somehow managed to forget to pack a camera, so the iPhone had to suffice!
© Graham Young, 2014
For every problem there is a solution that is clear, simple, and wrong.
– H.L. Mencken
Is the polar bear doomed on a warming Earth? In the past few years, there has been much public concern about the future of this magnificent creature, which is often seen as the symbol of the effects of climate change on the natural world.
The polar bear is considered a vulnerable species by the World Conservation Union (IUCN), and the US Government granted it protection as a “threatened” species in 2008. While it is unknown whether polar bear numbers are actually in decline, there are serious concerns that a reduction in Arctic sea ice would have a profound impact on their populations.
It has been projected that we could see a total absence of Arctic summer sea ice within our lifetimes.1 This would clearly have a devastating impact on entire ecosystems, and on Arctic marine mammals such as seals, narwhals, and bowhead whales. For many people, however,2 any concerns about the effects of global warming on Arctic environments are completely overshadowed by concerns about … polar bears. Just polar bears.
In real life polar bears may well be fearsome, devious, cold-hearted killing machines, but in photographs they often look like large white puppies or happy people in fluffy bear suits. What could be more compelling than photos of cute, cuddly, huggable bears standing on ice floes, wrestling playfully, or batting around old tires?
For those who see the polar bear, like the panda, as a teddy-like animal that must be saved at all costs (regardless of what happens to all the other life forms around it), I have been considering steps that might be undertaken to ensure that many wild polar bears will remain in the world far into the future. The white bear could thus continue indefinitely as a symbol of all that is clean and fluffy and easily anthropomorphized.
There have already been many ideas put forward for the salvation of the polar bear, some practical, some less so. Some writers have suggested, for instance, that bears be relocated to liberal cities on the North American mainland, where they can feed upon well-upholstered climate activists. Other wits have proposed that polar bears could be readily rounded up and moved to Antarctica, where there are suitable sea ice conditions and an abundance of fat-rich marine vertebrates upon which they could dine.
Either of these suggestions would, however, be scientifically indefensible. Sound scientific practice for the relocation of mammal populations requires that we should only move them to areas where they lived previously, from which they have been extirpated. Such areas are typically places that could benefit from the presence of the reintroduced species, at the same time as that species is benefiting from the features of the new area. The reintroduction of species is sometimes considered as a component of rewilding, the return of habitats to their natural state.
Considering this issue as a scientist, I propose that we relocate a sustainably-sized polar bear population (say, at least a thousand of the animals) to a place where they lived in the distant past, a place where the existing natural ecosystem has been severely disrupted by human activities, a place in drastic need of rewilding. It is also a place where there is a virtually endless source of fat-rich mammals of a species so abundant that they will never be “threatened”, no matter how many are consumed by voracious bears.
For this scientific assessment, let’s first consider where polar bears might reasonably be relocated. Their current range includes the Arctic Ocean and some of the nearby seas and land areas. Their prehistoric range is, unfortunately, poorly understood, but a few details are known.
It is thought that polar bears (Ursus maritimus) may have diverged from brown bears (aka grizzly bears; Ursus arctos) just a few hundred thousand years ago. Polar bears have a poor fossil record, so fossils shed little light on their evolution. The oldest fossil is a jaw from Spitsbergen that is about 110,000-130,000 years old.3 Among the few other known specimens is the ulna of a large animal that lived about 70,000 years ago, dug up at Kew Bridge, London, England. The paleontologist Björn Kurtén4 assigned this to a polar bear subspecies, U. maritimus tyrannus.5
Based on this admittedly limited data, it seems scientifically reasonable to suggest that polar bears be reintroduced to this part of their former range. This could be considered as a further step in the environmental rejuvenation of southern England, an extension of the clean air laws of the 1950s and the well-known cleanup of the Thames River in the 1960s. Certainly there are other major projects that should be undertaken to encourage native plants and to maintain species such as the curlew, but surely the return of a true apex predator would be the crowning achievement of Britain’s environmental renaissance.
The release of polar bears to the Home Counties would, of course, provide wonderful wildlife-viewing opportunities for a very large population. People love to see live polar bears, but it is clear that the animals do not do well in zoos. Zoo bears exhibit abnormal behaviours and it is cruel to keep them there. Well-heeled people pay large money to see wild bears, travelling to remote places like Churchill, Manitoba.
This sort of travel is, sadly, out of reach of the great majority of the population. By taking the wild polar bears to the people, then, we would be greatly democratizing the entire ecotourism process. The opportunity for an exciting close encounter with a huge, sharp-toothed polar bear would be available to all, regardless of age or social standing; it would no longer be the preserve of the leisured rich. Further, we could be certain that the bears they encounter would be plump and well-fed. There are few sights as disturbing as a hungry, skeletal bear.
The greatest and most positive impact of the reintroduction of polar bears to regions such as the Cotswolds would be in the area of traditional English sports. Large bears were just one component of the diverse indigenous macrofauna of the British Isles. Like other creatures such as wolves and wild cattle, they have been extirpated due to the presence of humans, by the development of towns and agriculture, but also notably through hunting. As people have hunted out the larger and fiercer species, the need for “sport” hunting has caused a transition to the pursuit of smaller and less frightening creatures such as mink and hares. The end result of this movement “down the food chain” 6 was that particularly sorry spectacle of 19th and 20th Century Britain: the fox hunt, also referred to as “the unspeakable in pursuit of the uneatable.” 7
Now, in the 21st Century, fox hunters have had even this meagre pursuit taken away from them by legislation, and those who do it legally are reduced to pallid facsimiles such as drag hunting8, though there have been some rumblings that the hunt is really not quite dead yet.
Regardless of whether it is really deceased or just resting, one of the major issues with the fox hunt is that, when you get down to it, it is not the least bit sporting. There is a dreadful imbalance between the mass of dozens of hunters, horses, foxhounds, terriers, and various servants of the hunton one side, and an elegant but smallish fifteen-pound mammal on the other. The ending is generally predetermined, with the fox being ripped apart by hounds; where is the sport in that?
My suggestion of the re-introduction of a key component of the extirpated macrofauna could make for a far more entertaining sporting event, an unpredictable contest in which disaster and death are always just the slash of a gigantic paw away. In this era of Ultimate Fighting Championships and base jumping, the return of polar bears to Britain could permit the English hunt to take its place in the pantheon of internationally-televised sporting events.
Can you imagine the wonderful interactions between red-coated, horse-riding hunters and their new, dynamic “prey” species? Can you picture the scene, as a pack of baying foxhounds meets a devious, fearless 1000-pound mass of muscle, sinew, claws, and teeth? It is a fox hunt tradition that new hunters are “blooded” 9 from the first fox kill they are involved in; now all members of the hunt would have the opportunity to be blooded every time they go out.
Now that would be a sport. And the television shows could even include the disclaimer that “no polar bears were harmed in the production of this program”.
Of course, all that this “modest proposal” illustrates is that a species can never be looked at in isolation from its ecosystem and environment. Even if we were able to save the polar bear by moving it to a new location, few of us would really want to live in a world without an Arctic, that great cold attic of strange creatures and places somewhere over the top of our “civilized” world. And the cuddly polar bears would not be truly happy in the English shires, even if their presence might have certain beneficial effects. Unless, of course, we could consider relocating walrus there as well …
1 International Panel on Climate Change (IPCC), in their Fifth Assessment Report (AR5)
2 Possibly the same people who spend a lot of time online searching for cute cat pictures.
3 Ingólfsson, Ólafur and Wiig, Øystein. 2009. Late Pleistocene fossil find in Svalbard: the oldest remains of a polar bear (Ursus maritimus Phipps, 1744) ever discovered. Polar Research 28(3): 455-462.
4 Kurtén, Björn. 1964. The evolution of the polar bear, Ursus maritimus (Phipps). Acta Zoologica Fennica 108: 1–26.
5 More recently this bone has been re-assigned by some scientists to U. arctos, but we will ignore that finding for the purpose of the present discussion.
6 The concept of hunting of foxes in Britain could be compared to current ideas that we should be fishing and eating more jellyfish. In both cases, this is not because they are the best animals for the particular function; rather, they are all that is left as a result of humanity’s rapacious harvesting of creatures that are much larger and fiercer in one case, and much tastier in the other. The ritual aspect of fox hunting, however, has few parallels even among the many bizarre forms of human “harvesting” behaviour.
7 Oscar Wilde, A Woman of No Importance.
8 The mind boggles at the diverse potential meanings of this term.
9 Blood (tr.v.).– to smear the cheeks or forehead of (a person) with the blood of the kill as an initiation in hunting. (The Free Dictionary)
© Graham Young, 2014
One Reason Geoscience May Fail to Connect with the Public
It is often difficult for a true believer to understand people who do not share those beliefs.
A few weeks ago, when I attended the annual Geological Association of Canada – Mineralogical Association of Canada meeting (GAC-MAC), I noticed a certain recurring theme in conversations. Several times during the meeting, I heard geologists from the industry or government sectors complaining about how little the general public thinks about or values the resource extraction sector.
In particular, they were concerned that teenaged schoolchildren are quite apathetic about the obvious benefits of the mining and petroleum industries. The general observation was that teens tend to be ignorant and apathetic about Earth resources, and that they may express antipathy to the very idea of resource extraction. The suggestion I heard from some geoscientists is that the teens have been “brainwashed” by the environmental movement, and that as a result they are not embracing the real nature of the world in which we live.
All of this left me wondering whether many geoscientists have also been brainwashed – whether we have “drunk the Kool-Aid” of the develop-at-all-costs-and-the-environment-be-damned movement. Don’t get me wrong: there is no question that modern society needs tremendous resources, both renewable and non-renewable, and that civilization as we know it would collapse without a steady supply of petroleum and minerals. But geoscientists also need to recognize that these things come at a cost, and there may be situations where many in the rest of society are not prepared to pay that cost.
Considering some of my fellow geoscientists, I am reminded of the story of the great Mississippi bluesman Robert Johnson, who supposedly met the devil at a crossroads at midnight. The devil gave him the gift of guitar mastery, but in return Johnson gave the devil his soul. Presumably this was a conscious decision on Johnson’s part, with his soul considered a fair price for the great gift he was receiving. I fear that many geoscientists are hardly slowing down as they pass through their own crossroads, and as a result they don’t even notice that they have arrived at the other side. Geoscience has received tremendous gifts from industry and vice versa; is scientific objectivity the price of those gifts?
An absolute buy-in to industry’s objectives makes things highly problematic when it comes to spreading the word to society of the tremendous importance of geoscience. Geology seeks an understanding of all aspects of the Earth, and in the practical world this knowledge is applied to a wide variety of endeavours including earthquake and landslide mitigation, land use planning, environmental management, and mining and petroleum exploration. It is easy for us to see resource extraction as a good thing, but considered in the broadest possible scientific context it is clear that it is more of a necessary evil than a pure positive. It is something we have to do to keep humanity going and developing, but it can also have many bad side-effects, on environment and on some people.
We will never convince people who hold differing opinions if we start off by telling them that they are wrong about the world. They are not wrong, and geoscientists, government, and policy makers need to be more prepared to accept and include other perspectives. Under the current system, it often appears that corporate, economic, or political interests are steamrollering environmental protection, so it is little wonder that we meet a public antipathy to resource geoscience. Calling those supporting environmental interests “radical groups”, as was done by Canada’s recent Minister of Natural Resources, is a sure way to achieve push back from a broad sector of the public.
The environment should be comprehensively included in the balance sheet whenever any project is contemplated, and it needs to be made clear to the public that a complete assessment is being done. There may, in fact, be some resources that should not be developed with the technology currently available, because the true cost of their development may be far too high. To a considerable extent the search for resources is now moving into environmentally risky frontier areas such as iron mines in the Arctic islands and oil wells on the outer continental shelves. We should be able to reject projects that are not supportable on the grounds of excessive deleterious environmental effects.
Somehow, modern western society is going to have to become more transparent and we will need to develop systems that permit fair solutions, as we move forward toward what may still be hoped will be a greener yet prosperous future.
© Graham Young, 2014
Catacomb.—An underground cemetery consisting of a subterranean gallery with recesses for tombs, as constructed by the ancient Romans. (Oxford Dictionary)
Like sedimentary strata that record long-gone events, the past itself is layered. Within a single place you may encounter many pasts, each resting on top of another: fragments of your own memory, evidence of the passage of other people and creatures, and vestiges of the Earth’s deep history. Unlike strata, these layers of time may not be visible and you may not be able to touch them. They may nonetheless be quite tangible.
I spent the first part of last week contemplating a many-layered place as I worked on collections at the New Brunswick Museum in Saint John. Visitors to Saint John are encouraged to visit the museum’s exhibits, located at Market Square in the tourist centre of the city. But those of us who examine the museum’s diverse and historic collections have the pleasure of doing so at the old museum building; collections are stored within a grand stone pile on Douglas Avenue, which also housed the exhibits from 1934 to 1996.
Simply entering the building on Monday morning was enough to transport me into the uppermost layer of past time. For a New Brunswick school child of the 1960s this was the New Brunswick Museum, a beloved and much-anticipated stop on our special tour of Saint John. To me it is still the only genuine museum building in that town; constructed partly as a make-work capital project in the 1930s, it is a classically-influenced centre hall edifice, a compact sandstone-clad structure modelled on the grand museums of Europe and America.
Climbing the tall steps and stepping through the front door, I could still see it just as it had been. Past the reception desk and the various archive and collection offices, I could envision the gallery that had housed lovely examples of New Brunswick furniture, and the rather incongruous displays of Oriental porcelain. Up the black slate stairs would be the splendid exhibits about Saint John shipbuilding and the settlement of New Brunswick, and downstairs would be . . . well, we will get to that.
I was graciously met by Dr. Randy Miller, the Curator of Geology and Palaeontology, who escorted me down to the basement and oriented me with what I would need to know for my work there. Many of the collections are in an area that was “back of house” way back in the 60s, but as is the case in all museums the collections have inflated and expanded over time, so that what used to be exhibit space in the rest of the basement is now filled with zoological and paleontological items.
Between my work station and the men’s room, I walked first past rows of cabinets labelled “Type Fossil Collection”, then through a maze of boxes, stuffed creatures, and racks of whale vertebrae. These were marvellous things, but in my mind’s eye I could also see what had been here long ago. Here were the cabinets of taxidermied mammals; we were always particularly entertained that the French label for the moose had been mis-translated as “l’Original”! Over there was the exhibit of the Hillsborough Mastodon, and I seem to recall some Carboniferous fossil fish from the Albert Mines area. And somewhere up high (I cannot recollect where but it was either hanging from the ceiling or resting on top of a cabinet), was the most remarkable item: an immense preserved sturgeon pulled out of the St. John River a century ago.
But now this reverie had passed. I was back at the data entry computer and had to return to the digital age. I was in Saint John to add data to the records of specimens I had donated there about 20 years ago, specimens of Silurian fossil corals that had formed part of the suite for my Ph.D. thesis at the University of New Brunswick. Randy had been patiently waiting for years for me to live up to my promise to get this collection in order,since museum collections that lack data are almost worthless. And now I was finally digging in and sorting them out.
I would scroll to the next record in the database, read it to see what information was lacking, then wander down the row of cabinets to see if I could locate the specimen in its drawer. After looking through almost all of the seventy-something specimens I had donated, I would eventually discover the one I sought. I would then carry the fossil in its cardboard tray back to the computer desk, where it could be contemplated as I checked through the identification and locality data fields.
Most of the corals are pieces I had collected some 30 years ago, in fieldwork along the New Brunswick and Gaspé shores of Chaleur Bay. Holding a fossil and chasing down a satellite image of its locality on Google Earth, I again found myself time travelling.
Grasping one specimen of Cystihalysites encrustans, I saw us hunkered at Quinn Point as rising storm waves made it impossible to continue working at outcrops spread across the tidal flat. Placing a thin section of Heliolites interstinctus under the microscope, I could see my field assistant dropping an expensive chisel into the icy sea as we traversed a narrow ledge along cliffs by the Anse McInnis. And I’m sure this specimen of Syringopora minuta was in my heavy pack as we clambered up from the beach on one of the few sweltering days of a Gaspésien summer, disturbing topless sunbathers hiding among crevices near the Pointe aux Bouleaux.
With so many layers of time to contemplate, it is little wonder that two days in the collections passed quickly. The time ghosts did not slow me down; if anything, they helped me approach the tedious database work with enthusiasm and energy. But with so much to be done, there was no time to examine any of the wonderful and historic collections that also “live” in that basement (as Canada’s oldest continuing museum, the New Brunswick Museum has scientific specimens dating back to the mid nineteenth century!).
In fact, I was not able even to finish getting my own data into order. But that is a good thing, really, because it means that there will have to be another opportunity to visit those layers of time, and to take in all the details that I neglected to notice on this visit. I am really looking forward to that.
Many thanks to the New Brunswick Museum for permitting and encouraging my visit there. The museum has just launched a capital plan that will allow them to build an addition to the old building, and to retrofit that fabulous structure so that it meets modern collections standards. A news video explaining this plan can be found here; those with sharp eyes may notice that I make a brief cameo appearance, staring down a microscope at about the 1:38 mark.
© Graham Young, 2014
I realize that I have been very lax about posting here in the past month or so. I have been on the road a good bit lately (more on this soon), and when I have been around in Winnipeg I seem to have been occupied with other things.
One of those other things was the recording of a lengthy interview for Palaeocast, the first half of which was posted today. Palaeocast is a series of podcasts about paleontology, produced in the UK by Dave Marshall, Joe Keating, and their friends. It had been suggested to Dave that he interview me about fossil jellyfish (medusae), and we e-mailed back and forth for a while about the questions he might ask. Dave works some of the time on offshore oil rigs, so when he was back on dry land we tried to figure out when an interview might work, given a few issues such as the six-hour time difference between England and Manitoba, and my aforementioned absences.
We eventually fitted in the interview before I headed off to Brandon for a major specimen acquisition. It was done by Skype, which I had never used before in an interview setting. All rather strange, talking into a microphone attached to my computer, in the comfort of my home office. And it was also strange to do an interview for which there was virtually no time limit!
Dave’s approach to interviewing is to ask the question and then sit back and let the interviewee expand/ramble as s/he sees fit. I am mostly pleased with how this turned out – I think we have given a good overview of the fossilization of jellyfish and the geological occurrence of medusan fossils. Nevertheless, there are one or two places where I wish I could go back and tweak the answers to make them absolutely scientifically accurate – a combination of the gaps in my knowledge of this huge subject, and the natural incoherence that occurs when one is placed in front of a microphone!
If you listen to it, the interview itself begins at about the 4-minute mark; the link can be found here.
I was recently reminded of a piece I once wrote, which was published in the newspaper about 17 years ago. I was interested in re-reading it and was sure it must be available somewhere online. Since a reasonably diligent search revealed no trace of it (and since I had a hard time even finding a paper copy), I thought I would post it here. It still bears some relevance and I thought some of you might enjoy it (though it was hard to resist the urge to revise the occasionally clunky phrasing!).
The Biggies Died Out in Earth’s Mass Extinctions
A while ago, a local area computer network at the University of Manitoba in Winnipeg was knocked out by a computer virus that went by a very melodramatic name – something like “Avenging Angel” or “Dark Destroyer.” The virus jumped from the network onto the hard drives of personal computers as their users plugged into and off the network. It spread rapidly, like an epidemic; once it was in a computer, it incapacitated any software the user attempted to open.
Nevertheless, one machine was not affected. This computer was an old IBM clone running a version of DOS (disk operating system) that was apparently too primitive for the virus to deal with. The computer had an inherent immunity to the infection.
The machine’s fortunate owner, a paleontologist and friend of mine, suggested that his computer was like the survivor of one of those mass extinctions that have occurred on Earth, in which most forms of life are driven to their deaths over a relatively brief period of geologic time. It seemed to be a particularly apt analogy.
Scientists have identified up to 15 mass extinctions in the history of life. The disappearance of dinosaurs (and many other life forms) at the end of the Cretaceous Period is by far the most widely known. Evidence indicates that this event was probably caused by the impact of a large asteroid on Earth 65 million years ago in what is now the Yucatan Peninsula of Mexico [n.b., the end of the Cretaceous is now placed at 66.0 million years ago, or Ma]. Such a collision of asteroid and planet could have caused earthquakes and tidal waves and produced a cloud of dust that blocked sunlight and caused the death of plants, the basis of food chains.
Although this was one of the five largest mass extinctions, it was not, in fact, the greatest one of all. That honour goes to the one that occurred at the end of the Permian Period about 250 million years ago [currently dated at about 252 Ma]. In this catastrophe up to 96 percent of all species on Earth became extinct.
The major mass extinctions apparently had different causes (the other three majors occurred in the Late Ordovician Period 440 million years ago [the extinction is currently dated at about 443-445 Ma]; the Late Devonian 360 million years ago [currently dated at about 372 Ma]; and the end of the Triassic 210 million years ago [currently dated at 201 Ma]. Some of the earlier global deaths may have resulted, not from bombardment by an object from space, but from changes in global climate, in glaciation, or in sea-level and ocean-circulation patterns. There was considerable variation in the length of time for global extinctions to take place. If the asteroid scenario is correct, then much of the end-Cretaceous event could have happened in less than a year, while other extinctions may have been spread out over several million years.
Over the past two decades, much research has been directed at mass extinctions. Scientists have discovered that in, in each of the events, certain types of life forms disappeared while others came to predominate among the survivors. Animals that died off were typically large and/or complex, and had specialized needs for food and resources – dinosaurs are typical of these. Those that survived tended to be small and had simple needs.
Other survivors had relatively low food needs. They may have produced very long-lived seeds or eggs or gone into a state of suspended animation. Thus, the simple clam-like invertebrate Lingula, which lives in the sediment of tidal flats and would probably be considered a pretty dull sort of animal, has survived every mass extinction of the past 500 million years.
Perhaps the comedian’s suggestion that the survivors of a future holocaust will be cockroaches driving Plymouth Valiants is not far off the mark, since both animals and cars could be described as ecologic generalists. Similarly, my friend’s computer is a simple “life form,” and was able to survive a deleterious event that knocked out the more complex and specialized members of the computer ecosystem.
A stand-alone computer is much less likely to be infected by a virus than is a computer cabled into a network. In the same way, biologic systems that are largely separated from the rest of Earth’s food web are unlikely to be severely affected by mass extinctions. For instance, the ecosystems along deep-sea ridges don’t depend on the sun for energy but are based on bacteria that metabolize energy from hot, mineral-rich water flowing out of the ridges. These ecosystems are characterized by strange, giant tube worms and unique bivalves and crabs. Such organisms were probably largely unaffected when the dinosaurs vanished.
Other stand-alone or nearly stand-alone ecologic systems include some large cave networks, and microbes that have been discovered living in bedrock deep within the Earth’s crust.
If we take the analogy further, and consider the whole Earth as a single local area network, we have to ask the obvious question: is there a virus lurking out there that could cause a global system failure? If there is, then the systems likely to be extinguished are the big complex ones, which sadly include any organism that can read this.
This piece was previously published as:
Young, G. 1997. The biggies died out in Earth’s mass extinctions. The Globe and Mail, Toronto, Saturday, Feb. 1, 1997, p. D6.
Young, G. 1998. The biggies died out in Earth’s mass extinctions. In, G. Dasgupta and J. Redfern (eds.), Reading Writing: Essay Strategies for Canadian Students, Second Edition. ITP Nelson, Scarborough (Ont.), p. 135-136.(reprinted from The Globe and Mail).
© Graham Young, 2014