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100 Years of Drift, Part 3: the invention of Pangaea

The invention of Pangaea. And why the Appalachians continue in Scotland

The Mountain Mystery

wegener pipe outdoorsIn today’s blog post, we continue our story of the development of the theory of continental drift – an idea which just celebrated its 100th birthday. Before Alfred Wegener’s 1915 book on contintents in motion, a few others had the idea, yet no one had developed it as thoroughly. In Part 1 of this series, we covered a bit of Alfred Wegener’s early life and some of his initial work. Yesterday, we showed how fossils and palaeoclimate figured into his continental drift theory. Today, we continue with Wegener by looking at his idea in a little detail.

On Saturday, January 6, 1912, Wegener presented a lecture that unveiled his hypothesis of a supercontinent and the idea that it fractured into our modern continents. He gave his talk to the German Geological Society at the Senckenberg Museum in Frankfurt.  Probably no one in attendance believed his notion – they…

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100 Years of Drift, Part 2: the evidence mounts

The evidence mounts: glacial striations, coal in Antarctica, and the distribution of dinosaurs (and others)

The Mountain Mystery

It’s been 100 years since Alfred Wegener proposed his idea of continental drift. Today’s blog continues the story we began yesterday – the tale of Wegener’s life and the development of his grand idea of mobile continents. This time, we’ll look at the significance of fossils and climate and how these contributed to the drift theory. 

By 1900, most geologists and biologists accepted Darwin’s description of species evolution. Darwin noted that the offspring of various creatures, isolated from each other and exposed to different environments, evolve into quite different beings with the passage of time. For example, bison arose on the American plains while the wildebeest fills a similar ecological niche in Africa. Both form huge herds, mostly survive by grazing (eating grass and seeds), but also by a little browsing (munching on the odd shrub). Both animals have manes, wild beards, and both look like trouble.

2 beasts

But you would…

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100 Years of Drift, Part 1: from meteorology to moving continents

Wegener is not the only scientist for whom meteorology has been the starting point on the path to other major discoveries. It influenced Dalton’s thinking in the development of atomic theory, while writing computer programs for meteorology was Paul Crutzen’s first step towards discovering how CFCs were destroying the ozone layer.

Wegener himself gets a supporting role in the admirable Horrible Science book (reviewed here), Evolve or Die.

The Mountain Mystery

Alfred Wegener, in Greenland, 1930Alfred Wegener, in Greenland, 1930  (photo by Fritz Loewe)

Fifty years ago, we finally figured out why the Earth has mountains. But one hundred years ago, Alfred Wegener had already offered an explanation – it took those extra 50 years for his grand idea to catch on. The continents, Wegener said, wander about. They bump into each other. Accidents cause mountains.

Yea, it’s been a hundred years since Wegener first wrote about continental displacement. A few other people had similar notions earlier. In the 1600s, Francis Bacon speculated that the southern hemisphere’s continents were arranged “like an opening blossom.” Some say Bacon was wondering if they had drifted from an original supercontinent, though Bacon never really said that.

In the 1800s, a few notable geologists (particularly Antonio Snider-Pelligrini, in France, and Richard Owen, in the USA) claimed that the continents were mobile. But their cases weren’t as compelling…

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Darwin vs today’s creationists; Eugenie Scott in Glasgow

GenieIntro

Lady Hope; Darwin on religion; varieties of creationism; creationist activity in UK; Petition 1530; Intelligent Design and the varieties of creationism; the eye; continental drift and biogeography; Mendelian inheritance; ancestry of whales; varieties of creationism; the “missing link”; Q&A

This is my personal selection from the talk that Genie gave to the Glasgow Skeptics on Monday February 15, as best I recall it. I thank her for a copy of her slides, and any misinterpretation is entirely my own fault (I have added some comments of my own in parentheses).

the title of the talk was: “What Would Darwin Say to Today’s Creationists?” The answer is just this:

Haven’t you been paying attention during the last 156 years?

Lady Hope and the myth of deathbed conversion

The first thing that would surprise Darwin if he could come back to life today would be the legend of his death-bed confession, to a certain Lady Hope, of reversion to Christianity and renunciation of evolution. Lady Hope is real enough. An evangelist and temperance crusader, she was a colleague of the philanthropist James Fegan, who ran a mission to London’s street urchins. Fegan corresponded with Darwin, who in 1880 gave him permission to use the reading room at Downe House for his work, and it seems plausible that Darwin and Lady Hope might have met around then.

In 1915, we have Lady Hope being reported at a Baptist revival meeting as having said that she spoke with Darwin in his death bed, and that Darwin had confessed to a love of scripture, and to regretting things he had said when younger. More specifically, that as a young man with unformed ideas he had thrown out suggestions that to his surprise spread like wildfire. (I note that Darwin in his autobiography confessed to an initial love of Paley’s natural theology, and in The Descent of Man to surprise at the speed with which evolution had been accepted, and remarks of this kind may be the seed of Lady Hope’s account.) In 1915, Lady Hope was over 70, so knowing how memories are reworked, and how stories grow in the telling, we can see how the totally false story that we have today could have arisen without conscious mendacity.

Darwin’s religious views

As for Darwin’s own views, he referred to belief in the punishment of unbelievers as “a damnable doctrine”, and may well have turned away from the idea of a benign deity after the death of his dear daughter Annie. (However, if I understand his Autobiography correctly, he continued to regard “this immense and wonderful Universe” as more than the product of mere chance[1], and eventually retreated into agnosticism only because he regarded the matter as beyond human understanding; I have discussed this here, and how more sophisticated modern creationists misdescribe his views here) .

Young Earth and other varieties of creationism

Crossbedding

The Cococino sandstone layer, showing the cross-bedded structure.  This, when examined together with small-scale and granular texture, identifies it as a wind-swept dune deposit.

Darwin, who was a geologist before he became a naturalist, would be very puzzled by Young Earth creationism, since in his time the Churches accepted (and churchman geologists contributed to) the geological column and the implication of many millions of years. Young Earth creationism and “creation science”, as a claimant to speak for mainstream Christianity, only arose in the mid-20th century. “Creation science” needs to account for the plain facts of geology, and does so in extraordinary ways, asserting for example that the entire Colorado Plateau, successive strata with a depth of over a mile, were laid down and drained within a year by the waters of Noah’s Flood. Hence creationists’ obsession with the Coconino Sandstone, whose texture and cross-bedded structure (as known since before 1945; see here and references therein) are characteristic of a wind-blown desert dune, and their extraordinary attempts to rationalise the claim that it was laid down under water.

Creationism is invariably associated with religion, and with those schools of religious thought that place great emphasis on the sanctity of a particular text. (Since such texts are ancient, they could hardly do other than adopt a creationist viewpoint.) Darwin probably never considered Islamic creationism, Turkey (despite still being a great European power) being seen as remote and exotic. Acceptance of evolution seems to vary widely throughout what one might call the Muslim world, but is a worryingly low 35% in Turkey. Turkey is home to the prolific publicist Adnan Oktar (Harun Yahya), publisher of the Atlas of Creation, which attempts to deny that evolution has occurred by comparing present-day forms with fossils. The Atlas’s scientific methodology, however, leaves much to be desired. Its “caddis fly” image is a photograph, not of an insect, but of a fishing lure. (I fear the problem of Muslim creationism may be deep-seated and widespread. I have written about the emerging alliance between Intelligent Design creationism and conservative Islam in Scotland, while in 1985, the then nominally secularist Turkish Government invited the Institute for Creation Research to help draft the school curriculum.) In the UK, according to a Theos/Comres 2009 survey, only 37% of those surveyed said that humans are the result of purely naturalistic evolution, 28% said we are the result of evolution according to God’s plan, 11% believed in evolution guided by divine intervention, and only 17% embrace separate creation. (The authors of the Theos report on the survey, themselves, describe evolution as “uncontestable”[2].)

There are varieties of creationism. Young Earth creationists accept biblical chronology, and think that present and extinct species coexisted. Old Earth creationists accept versions of the scientifically agreed chronological sequence, but regard each stage as a separate phase of the Creator’s activity. Guided evolution accepts common descent, but treats successive changes as the result of divine intervention (perhaps by intervention at the molecular level). Intelligent Design considers mutation as a random process, and, neglecting the role of selection, improperly infers that it cannot generate meaningful novelty. (In the US, Intelligent Design advocates are generally Old Earth creationists, but in the UK leadership and allies are more often believers in a young earth.)

Creationism in the UK and its opponents; the current Petition

Creationist bodies are very active within the UK. Creation Ministers International has a UK branch (which caused furore by sending a speaker to the publicly funded St Peter’s Academy in Exeter, a mistake by the school that will not be repeated). There is Truth in Science (which sent copies of the creationist pseudo-text book, Explore Evolution, to every school in the UK), and others. Various bodies, such as Skeptics, Humanists, and the British Centre for Science Education, actively work to restrict their influence, and the Scottish Secular Society’s Public Petition PE01530 (with which regular readers will be very familiar) aims to keep creationism from being presented as valid in schools.

The eye, continental drift and biogeography, Mendelian inheritance, the ancestry of whales, and the mythical missing link

GenieEyeDarwin would have been very interested in the direction of creationism in the UK, and the revival of the design argument, which he regarded as refuted by natural selection. When he considered the eye as a structure that at first appeared too complex to have arisen naturally, he pointed out that it could have arisen from a photosensitive spot, through a directional cavity, to an enclosed structure whose fluid would concentrate the light, and eventually, via the development of the enclosing membrane into a lens, to the complexity of the mammalian eye in its present form. We now know that all these imagined stages are actually evident in molluscs.

He would have been delighted by continental drift, which solves long-standing puzzles in biogeography. Biogeography is one of the most convincing arguments in favour of evolution. It explains, as separate creation can not, why the flora and fauna of continental islands are closely related to those of the adjoining land mass, while those of oceanic islands are restricted and exotic. And yet, how come there were marsupials in Australia and in South America, but nowhere else? (North American marsupials crossed from the south, after the relatively recent closure of the isthmus between the two continents). We now know that marsupials appeared when present-day Australia, Antarctica, and South America were joined together in the supercontinent of Gondwanaland, allowing migration of marsupials from their original South American home, and indeed marsupial fossils have been discovered in Antarctica.

He would also have been delighted to learn of Mendelian genetics, which solve the “dilution problem”. Under blending inheritance, a favourable variation would appear in less intense form in the offspring of the favoured individual, but genetic inheritance avoids this. Instead of the character being passed on with half the intensity, it is passed on with the same intensity to half the offspring.

Darwin was ridiculed (still is, by particularly ignorant creationists; see here) for speculating that the behaviour of a bear swimming with his mouth open to catch prey was a clue to the ancestry of whales, which clearly are mammals. Yet within the past 40 years, we have accumulated detailed fossil knowledge (free access review article, from which the image below is taken, here)  of all the intermediate stages linking present-day whales to their even-toed terrestrial ancestors. This is part of a general phenomenon. Darwin famously lamented the gaps

https://i2.wp.com/static-content.springer.com/image/art%3A10.1007%2Fs12052-009-0135-2/MediaObjects/12052_2009_135_Fig27_HTML.gif

Whale evolution ;the first 10 million years

 

in the fossil record, and present-day creationists echo these laments, as if they were still warranted. Thus they commonly repeat a remark made some decades ago, to the effect that all known human ancestral fossils would fit onto a small table. Not any more. The human fossil record is now so rich, that we have more specimens of the relatively obscure species Homo habilis than we have of Tyrannosaurus rex.

 

Skulls

A sample of the skulls of species intermediate between modern humans and other apes

 

So the scientific record (including much not even touched on here), ever since the publication of On the Origin of Species, has been one of steadily reinforcing the central concepts of common descent, and of natural processes driving evolution.

What, then, would Darwin set to today’s’s creationists? Simply this: “Haven’t you been paying attention during the last 156 years?”

Q&A:

GenieFbImageQ: Is there a risk that so uncompromising a talk would put off those sympathetic to creationism?

AS: I would not give this talk to such an audience. There are those whose identity is bound up with creationist religion, whom I cannot hope to reach; those uncertain, to whom I would present the arguments for evolution; and those, like tonight’s audience, who need no convincing.

Q: Are creationists dishonest?

A: Most ordinary creationists are either misinformed or muddled. The higher echelons go through considerable mental contortions, but I have no reason to doubt their sincerity.

Q: How can we respond to those who consider “Goddiddit” a satisfactory explanation?

A: Science is highly valued socially and culturally. So any ideologue tries to recruit science. Hence “creation science,” and devices like imagining the speed of light to have been much higher in the past, so as to allow light from galaxies billions of light years away to have reached us within 6,000 years. “Creation science” is a procrustean bed, on which all observations are distorted until they fit the initial biblical assumptions.

This is contrary to the key moral value of science which is the admission of fallibility. Science as process depends on critical examination and revisability. We need to impart this, not by telling but by showing, and showing by asking. The dandelions on our lawn have short stems, but those over there have long stems. Why might that be?

1] This idea of overall cosmic design is of course the very opposite of the kind of piecemeal meddling that goes by the name of “Intelligent Design theory” today.

(2] Theos is funded by the Templeton Foundation, making it anathema to some exponents of evolution. I have argued that such doctrinal purity is misguided.)

Evolution, the Horrible Science – antidote to creationism

EvolveOrDie1For some time I have been looking for a good way to immunise children (and others) against the absurdities of creationism, as the virus spreads  across the Atlantic. I may have found what I’m looking for in the children’s section of my local public library.

Horrible Science – Evolve or Die. Horrible Science is a sister series to Horrible Histories, popular on both sides of the Atlantic, but especially in the UK. This book promises, and delivers, “science with the squishy bits left in”. We learn, for example, what “coprophagous” means, and that rabbits are coprophagous, and why. And what coprolites are. And how this relates to the personal habits of leaf-eating dinosaurs and why we think they must have produced thunderous farts.

All part of a calculated strategy of demystification, which is one of the most delightful things about this book. Scientists are shown disagreeing, admitting ignorance, being proven wrong, being mean to each other, and you could be a scientist too. Children (and adults) who read this book will end up less frightened of science, more impatient with the pomposity, complexity, and jargon that goes with bad science teaching, sceptical about authority, and aware that any scientific claim must be based on evidence and could be overturned by further evidence.

EvolveOrDie2The book does this by example, rather than by exhortation. For example, we have Alfred Wegener being laughed at by his contemporaries, although we now know he was right about how continents drift and even about how molten rock beneath them makes this possible (I never knew he got that bit right too, although as I said in an earlier post it was Arthur Holmes who explained what drives the process). We are given four separate theories about what wiped out the dinosaurs, and when we are told which one is correct (or rather, as the book says, “the one most scientists favour”) we are given a quick rundown of the evidence; cratering on planets and asteroids, other collisions between Earth and smaller asteroids, the monster crater off the coast of Mexico, and the iridium-rich layer laid down some 65 million years ago all over the world. When we are told that the adder’s tongue fern has 630 pairs of chromosomes, we are also told that no one knows why.

We hear about mosquitos, malaria, and mutations, and the evolution of drug resistance by malaria parasites. We are given numerous other examples of evolution, with discussion of how complex organs originated. The wings of pterosaurs could have started out as temperature control membranes, and the lungs of land animals are directly related to those of lungfish. The eye, of course, elaborated in stages from a simple pinhole like the one still found in snails. I would have liked a page or two here on dinosaur feathers, still a rare novelty when the book was first published (1999), but well established by the time of the current (2008) edition.

We are also repeatedly reminded that science is a human activity, and that humans often make fools of themselves. So we have a Hall of Fame, with Lamarck, Darwin of course (not Wallace, though he does get a fair mention), Hippocrates who got inheritance wrong but at least had a go, Mendel, Wegener, Watson and Crick (I’d have liked to see Rosalind Franklin too, of course),[1] and Louis and Walter Alvarez, each of them fleshed out with details of their times, accomplishments (more varied than I’d realized), and at times shortcomings and absurdities.

You are invited to make your own observations; “Could you be a palaeontologist? You need a hammer, goggles, tons of patience!” There follows a very clear explanation of the difference between igneous, sedimentary, and metamorphic rocks, and reasoned advice that sedimentary rocks are what you should be looking at when fossil hunting. The section on Mendel is followed by a suggested experiment on pollen transfer using nasturtiums and a paint brush, and there is a very squishy suggested experiment (see below) to illustrate the principle of continental drift.

EvolveOrDie3An amazing amount of information is clearly and accurately presented in the book’s 142 pages. This includes an excellent account of the species concept, and “the way that one species separates into two” (the book successfully avoids jargon terms such as “speciation”), illustrated by the way that English has diverged between the two sides of the Atlantic. This is used later in a very clear explanation of how hominids and chimps have both diverged over the same length of time from a common ancestor. Not a trivial point. One of the most common and most irritating questions that creationists coach children to ask is “If evolution is true, why are there still monkeys?” A child (or teacher) who has read this book will immediately realise that this makes as much sense as asking “If I descended from my grandparents, why do I still have cousins?”

I particularly liked the way the book treats continental drift. You’re invited to test your teacher by asking for an explanation of the fact that identical mosasaur fossils are found in both South America and Africa (long distance swimming, or riding logs, or vanished land bridges – an explanation that was actually taken seriously for many decades – or identical evolution in both continents, or the two continents having once been joined together). This leads on to the idea of continental drift, and hence to what we grown-ups call biogeography; you find mosasaurs on both sides of the Atlantic, because they evolved before it opened, but the difference between Old World and New World monkeys is the result of evolution since that time.

I do have some criticisms. Much too much is made of “living fossils”, ignoring how far they actually differ from their ancestors. For example, it was already known when the current version of this book appeared that coelacanths are a diverse clade. Of the dozen pages in the section on hominid evolution, one is wasted on Piltdown Man, a forgery exposed 60 years ago. And while it is inevitable that the human evolution section has a rather old-fashioned appearance about it (in 2008, Ardipithecus was only represented by fragments, it was not yet known that humans and neanderthals had interbred, and Australopithecus sediba was still undiscovered), it is nonetheless too apologetic about the deficiencies of the (then) fossil record. After all, The Last Human, which lists 22 separate species, had appeared in 2007. I have already mentioned dino feathers as another development that should have been included in the 2008 update. However, all of these criticisms are at a high level, and reflect my sensitivity towards what the creationists call “weaknesses” in the science of evolution.

I particularly value this book because it builds on what every child knows; the poo-laden squishiness of reality, fascinating, beautiful, and cruel. Children who have read this book will have no difficulty in recognising the creationists’ prelapsarian perfection, with its vegetarian velociraptors and lamb-cuddling lions,  for what it is – so much dino dung. And they will know how best to respond – with a dino-size fart or if, like me, they are pretending to be grown-ups, with a philosophical and factual analysis, which will come to much the same thing.


[1] The central role of experimental crystallography in unravelling the structure of DNA was acknowledged by giving a share of the resulting Nobel Prize to Maurice Wilkins, Franklin’s nominal boss. Franklin herself was by then ineligible because she was dead. She is remarkable for having been involved with two separate Nobel prize winning enterprises, the other one being the structure of the tobacco mosaic virus.

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