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"the aviator" – a vision of the future that’s a little too close for comfort Alison Campbell Jan 09

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I found the Herald’s front page this morning a sad and depressing read. My heart goes out to all those affected in some way by the terrible bush fires ravaging so much of Tasmania, Victoria, & New South Wales.

I also had a certain sense of deja vu as I read of the fires – for I’d read something similar last year, in blog-buddy Gareth’s book The Aviator, Book One of the Burning World series. Except that in the book, the scale of events is much greater than is (thankfully) the case at the moment, and Melbourne is destroyed by a fire storm. Gareth’s vision of a not-too-distant future in which our global ecosystems have been irreparably affected by anthropogenic greenhouse warming, is both an alarming foretaste of how things could become**, and a rather good read (another blogging friend, Ken Perrott, reviewed the book very favourably when it first came out, & I’ve been meaning to write my own review for quite a while). The story follows the key character (& narrator – well, one of them), an airship pilot called Lemmy, in his travels around a world in which ecosystems and societies have collapsed, or changed – in many instances, beyond recognition. (There are actually 2 narrators: the second is Jenny, the artificial intelligence who actually runs the airship. Their commentaries alternate, & it’s interesting to see the differences in perspective, especially given that the AI is to some degree self-aware.)

As the series title suggests, in this future world it’s not only Australia that suffers from fire. Lemmy also witnesses huge fires in the Arctic, where massive methane deposits originally locked under the ocean in the form of methane clathrates have been ignited and the flames burn seemingly endlessly. I’ve recently read more about these deposits in Bill McGuire’s Waking the Giant: we are talking significant carbon stores here, at around 2000 billion tonnes of carbon trapped in the form of clathrates: something that is highly attractive to energy companies & of deep concern to climate scientists.

The first time I read The Aviator, I thought it would be a rather good classroom resource for senior students. And that hasn’t changed on a subsequent re-reading. Its engaging focus on a current, extremely relevant topic means that the book could be used in many different areas as the basis of discussion and to provoke further student research: how do individuals, and societies, cope with change? What happens when the technologies we rely on so heavily are no longer available, or are concentrated in the hands of relatively few people? How would a rise in average global temperature affect various ecosystems? Is a future such as the one Gareth describes, something that we can yet avoid?

Highly recommended.

 

Gareth Renowden (2012) The Aviator (The Burning World). Limestone Hills Ltd.

Bill McGuire (2012) Waking the Giant: how a changing climate triggers earthquakes, tsunamis, and volcanoes. Oxford University Press. ISBN 978-0-19-959226-5

 

** In some ways it reminds me of Richard Cowper’s The Twilight of Briareus - though having said that, Cowper’s world has been sunk into an ice age, and his story has a strong mystical feel to it. But the themes of societal and ecological break-down, and how people cope with these, are common to both books.

 

 

 

 

skulls & braaiiinz – what’s not to like? (also, plants) Alison Campbell Jan 03

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The intrepid reporters from Number 8 Network e-mailed the other day. “What are you reading?” they asked; “after all, it’s the holidays & you must have heaps of time to put your nose in a book.” Which is sort of right, it is the Christmas/New Year break, but the days just seem to fly by when you’re doing not very much at all.

However, as it happens I’m working my way through several books at the moment, so I was able to oblige.

First up is Skulls, by Simon Winchester. Strictly speaking it’s not actually a book but an interactive iPad app, based on the enormous personal collection of Alan Dudley. I bought it because I find skulls fascinating (though not so obsessively fascinating as I think they must be for a collector of same) & the blurb at the app store offered me the ability to zoom in, out & around a whole bunch of bony brain protectors. This, I figured, would be quite fun & could also be a useful teaching tool (I’m looking forward to showing it to a colleague who teaches 3rd-year zoology).

And the ability to examine skulls in such detail really is great, although – a minor quibble! – I would have liked to be able to look at them from beneath & above as well as from all sides. You lose some definition at high levels of zoom but apart from that, wow! I would otherwise not have known that the Atlantic wolffish has quite so many teeth (shades of an aquatic Red Riding Hood villain) & such a wonderfully architectural skull. Or that a rabbit could somehow have lived long enough for its incisors to grow backwards & inwards in curves reminiscent of reversed (& miniature) elephant tusks.

The chapters comprising the ‘book’ struck me as a bit of an eclectic mix: we’ve got an interview with the collector himself, followed by an essay on the nature of collecting. Then, after learning about what a skull actually is & the bones that make it up, we find out about the dodo, or the pseudoscience relating to skulls – wherein we can learn about Piltdown man & phrenology but not, to my surprise, the various claims about ‘alien skulls’ from South America. Or the iconography of skulls, or skulls in art & in Mexico, & so on. One of the nice things about apps like this is that – even less than with a ‘real’ book – you don’t have to follow a linear progression through the text but can dip in & out, & that there are nice little visual cues to guide you in your choice of where to go next.

Not a lot in the text that was completely new to me, but well worth the price (at $17.99 this is one of the more expensive iPad apps) for the sheer enjoyment to be gained from viewing the images.

As for the brains – I’m also working my way through a Kindle edition of Carl Zimmer’s Brain Cuttings. Zimmer is one of my favourite science writers & this collection of essays (mostly written originally for Discover magazine) hasn’t disappointed me. The first essay’s title is from a question asked by Charles Darwin of one of his many correspondents. Wondering whether people around the world expressed emotions in the same way, Darwin asked, “Does shame excite a blush?” From this starting point, Zimmer takes us through scientists’ current understanding of the evolution of the face, a feature that began to form around half a billion years ago with the appearance of the earliest fishes. He asks why primates, in particular, have such complex, expressive faces – something that has to do with the complex social behaviour of this group of mammals. It turns out that facial mimicry is part of that social behaviour – and apparently the ability to mimic someone else’s facial expression, however briefly, may well be important in allowing us to understand how that person is feeling. An interesting experiment certainly suggests this:

[Researchers] had volunteers bite down on a pen and then look at a series of faces. They had to pick the emotion they thought the faces were expressing. The volunteers could recognise sad faces and angry ones with teh same accuracy as test subjects who did not have pens in their mouths. But they did a worse job of recognising happy faces.

Biting a pen, it just so happens, requires you to use the same muscles you use to smile. Because the smiling muscles were active throughout the experiment, [the research] subjects apparently couldn’t reel themselves start to mimic happy faces. Without that feedback, they had a more difficult time recognising when people were happy.

And that’s just the first chapter! The second essay, “The googled mind”, is an exploration of just where the mind stops. As Zimmer remarks,

[we] tend to think of the mind as separated from the world. We imagine information trickling into our senses and reaching our isolated minds, which then turn that information into a detailed picture of reality… In fact, teh mind appears to be adapted for reaching out from our heads and making the world, including our machines, an extension of itself.

In other words, it looks like the ‘mind’ is more of a complex system that comprises both the brain and various bits of its environment – books, for example, or computers, iPads – and even the tools we use.

This book’s both entertaining & informative & I’m enjoying reading it, one chapter at a time.

Third on my list is an actual, print-on-paper, hardcopy book: Fifty plants that changed the course of history, by Bill Laws. I bought this on a colleague’s recommendation, because of all the topics I teach at first-year level, botany seems to be the one that students are least engaged with, & I was hoping for some nice new examples to add my list of ‘cool stuff about plants & how they changed our world’.

My impression of this book is that it’s a bit like the curate’s egg: good in parts. My copy is a beautifully presented hard-cover edition, with lovely illustrations & some fascinating snippets of information (for example, that pineapples were grown in England over pits full of fresh dung! (This generated heat as it rotted, & augmented the warmth from stoves.) And the idea of a bamboo bicycle is an intriguing one. I’m enjoying dipping into it, a couple of plants an evening.

But unfortunately that enjoyment is tempered by moments of irritation. OK, I know I’m simply being greedy in wanting to know more about some topics than can be fitted into the 2 or 3 pages accorded them here. That’s a minor one. But saying that plants “absorb carbon dioxide and exhale oxygen” glosses over the fact that plants need that oxygen for cellular respiration as much as we do. (All too many of my first-years share this particular misconception.) And what am I to make of the following statement ?

The oldest names for the coconut are in Sanskrit, pointing to India as the source [of this plant]. However, the discovery of the fossilised remains of a tiny proto-coconut on New Zealand’s North Island suggests it might have been first taken into service here 5,000 years ago.

Five thousand years ago, there weren’t any people in New Zealand; hence no-one to take anything ‘into service’… (Interestingly, Sir Charles Fleming notes that a fossil coconut dating to the middle-late Miocene was discovered in Hawkes Bay; this would give an age of around 5-10 million years.)

So, I’m accumulating some new stories to tell in class, and I am enjoying the read, but – unlike Skulls and Brain Cuttings – I probably won’t be recommending Laws’ book to students looking for a bit of extra reading. At least, not until I’ve finished it & identified any other potential pitfalls. Although… I guess the error I’ve picked up on here would be a useful jumping-off point for a discussion of New Zealand’s botanical history.

B.Laws (2010) Fifty plants that changed the course of history. Firefly Books. ISBN: 978-1-742372-18-1

S. Winchester (2011) Skulls. Touch Press.

C.Zimmer (2010) Brain Cuttings: fifteen journeys through the mind. Scott & Nix Inc. NY ISBN (Kindle): 978-1-935622-16-1

teaching what you don’t know Alison Campbell Sep 10

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I’ve just finished writing & delivering a new set of lectures; next week we’re moving back into what is – for me anyway! – more familiar territory. At the same time I’ve been reading Therese Huston’s book Teaching what you don’t know. Huston’s examples are drawn from the US tertiary system, and as you begin reading it quickly becomes apparent that ‘teaching what you don’t know’ is a common occurrence for teachers in that sector. (And I really do mean, ‘what you don’t know’: a science lecturer teaching a general writing course, for example. At least I’m still teaching biology!)

One of the Big Questions in a situation like this is, what & how much do you tell your students? Huston notes that in some circumstances a lecturer might not want to let on that they’re teaching at the fringes of their expertise – perhaps they’ve previously felt that their authority or credibility have been challenged by students, & letting on now isn’t going to help the classroom dynamics.

Personally, I prefer to put a positive spin on this experience. First up – I’m still teaching biology, albeit an area that’s moved on a bit since I studied it. I’ve had to do a lot of extra reading, but I have the considerable advantage over the students in that I’ve already got the mental constructs into which I can scaffold my new learning. Now that I think about it, the immediacy of that learning helps me to help my students make sense of this new material as they encounter it themselves.

There’s also the fact that the pace of scientific discovery is such that it’s highly unlikely anyone could keep up with it. We don’t have the luxury of reading papers all day, every day, so we try to read the key papers, especially those in our own areas of expertise, and know with regret that there are bound to be others that we’ve missed. So the odds are good that every now and then, a curious, deep-thinking student is likely to ask a question that challenges & stretches your own understanding. The big thing is not to be thrown by this.

Huston gives a number of strategies for dealing with the challenge of teaching what you don’t know, drawn from interviews with a number of expert teachers who routinely teach outside their immediate field of expertise – & relish the challenge of doing so. One of these teachers, speaking of how quickly our knowledge of science moves on, comments that

“… we know different kinds of things, things that were unknown in 2005 we’re certain of now. And now we know that some of what was true in 2005 was wrong. They were hypotheses and we now have the data. It’s a lot of fun because students know I’m learning along with them, and we’ll say “What have we learned? What are people thinking about right now? What are the big questions that are left?”

As that lecturer said, learning new things – while challenging – is also stimulating & fun. If that sense of excitement and enjoyment carries through to your actual classes, then you’ll speak with passion and enthusiasm – how better to in turn enthuse your students?

What’s more, the mere fact of expressing uncertainty can help students learn something of the nature of science. Don’t stop at saying ‘I don’t know’ to that curly question; take it further: ‘I don’t actually know the answer to that question, it’s a bit outside my field of expertise. But I do know that in these circumstances so-&-so would happen, so I can hypothesize that such-&-such might happen in the circumstances you describe.’ And that’s a rather satisfying learning experience for everyone :-)

T.Huston (2009) Teaching what you don’t know Harvard University Press

quirks of human anatomy Alison Campbell Feb 06

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I’ve just started browsing through a book with the promising title, Quirks of human anatomy: an evo-devo look at the human body. (Held, 2009). (The Science librarian does a great job of sifting through new titles & running them past the various departments in our Faculty to see what people would like to see added to the shelves.) Held says that he wrote the book as

a kind of amusement park. Its thematic ‘pretend game’ is to inspect each body part through the eyes of an alien visitor who asks, “why is it this way and not that?”

Very early in the book there’s an image of vertebrate ‘morphospace’, which moves from the familiar to the seriously strange, and from reality to things – like Dumbo & ET – that can be conceived of but which are unlikely to exist due to various physical constraints. Cool!

As I said, I’ve only begun dipping into Quirks, but I’ve already come across a couple of examples that I’ll probably use in class. One is of a set of twins, born in France in 1844, who seemed on the basis of various tests (done when they were 17) to be monozygotic – yet one child was a boy & the other, a girl. Seems impossible… When cells from each twin were karyotyped, the boy was (as expected) XY i.e. he had 23 pairs of chromosomes, 22 of them ‘somatic’ & the 23rd pair the typical ‘sex’ chromosomes of a male mammal. His sister, however, was XO: 22 pairs of somatic chromosomes & just a single X, characteristic of Turner’s syndrome.

How could this be? The original zygote must have been XY. Presumably a Y chromosome was lost from one or some of the embryo’s cells before it split to form 2 embryos, with all the XO cells cohering & thus giving rise to the female twin.

Just as strange is the story of one Daniel Burghammer, who’d been married for 7 years when, in 1601 he gave birth to a child (doubtless to the extreme confusion of his poor wife!).  According to the contemporary account, Daniel ”was half man & half woman” & had at one point slept with a another man, an act which resulted in his pregnancy. You might think that this is just a fantastical tale, were it not for another example reported in the New England Journal of Medicine in 2004: an infant who

had a penis (with hypospadias) and scrotally enclosed testis… on the right, but a hemiuterus, oviduct, and ovary internally on the left.

Where this gets really weird is that cells on the ‘male side’ of this child were all XY, but those on the ‘female side’ were XX. Held suggests that the child may be a chimera, where 2 sperm fertilised 2 eggs, but the resulting zygotes then fused to produce a single embryo. But as he says, without DNA analysis we’ll never really know.

I am really looking forward to my bedtime reading for the next few days!. And this will certainly enliven my lectures on reproduction!

L.L.Held, Jr. (2009) Quirks of human anatomy: an evol-devo look at the human body. Cambridge University Press ISBN 978-0-521-73233-8

the mind’s eye Alison Campbell Jan 18

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I always enjoy reading Oliver Sacks’ books, not least for the wonderful anecdotes but also with the humane, compassionate way in which he described & discusses the various problems that his patients present with. And so I was delighted to get my hands on another one, The Mind’s Eye – as the title suggests, this volume examines the ways in which neurological problems manifest themselves in the way we see the world. One reason the book caught my eye was its cover: red with yellow font – & a font that’s deliberately fuzzy & blurred in places, by way of mimicking how some people see the world. Another reason was that as a child, I remember being fascinated by the question of how other folks perceived colour. I mean, was their ‘red’ the same as the ‘red’ that I saw? And if it was different, how would we actually know, given that we’d both use the same name for the colour of fire-engines & ‘red delicious’ apples. (I didn’t think of traffic lights – there weren’t any in Wairoa when I was a kid.)

The Mind’s Eye set me thinking about that second reason again, because with at least some of the patients he describes, their self-developed coping mechanisms mean that you wouldn’t necessarily know. People without the ability to see in 3-D, for example. This is something that most of us take for granted, & so we assume that everyone else (except, perhaps, those unfortunates who’ve lost an eye to accident or disease) also sees the world in glorious stereopsis. But they don’t; it’s just that in many cases they deal with it in ways that mask what we ’3-D viewers’ would see as a deficiency – & may well have adapted so well that even the possibility of 3-D vision is not attractive to them. And indeed, having monocular vision need not be seen as a handicap: Sacks comments that the first person to fly solo around the world, Wiley Post, did so with only one eye. (The other was removed surgically, following an infection, when Post was in his mid-20s.)

An individual with an uncorrected squint (strabismus) may also lose the capacity for binocular vision, & in the past it was generally thought (based on observations & experiments on other animals) that if a squint wasn’t corrected early in a child’s life, that person would forever after see the world ‘flat’, lacking the depth perception necessary for stereoscopy. But Sacks relates how he received a letter from a neurobiologist, Sue, who’d gone for most of her life in just such a ‘flat’ world after a childhood squint had not been properly corrected. When she was in her late forties, Sue’s sight began to deteriorate and, with the support & advice of a developmental optometrist, had practiced & done exercise after exercise until she acquired the ability to see the world in 3 dimensions. Take a moment & think about how this might feel… frightening? terrifying? wonderful? (It was definitely the latter, in her case.)

Another example Sacks discusses is ‘alexia’, or ‘word blindness’ – the inability to recognise written language, something that is due to damage to a specific part of the brain (say, by a stroke). As someone who reads & writes – copiously! – on a daily basis, both for pleasure & as part of my job, I simply cannot imagine what it would be like to lose this ability. It was something of a relief to read (heh) that at least one of Sacks’ patients was able – slowly and painfully – to recover some of his old skills in this area. A related disorder is ‘prosopagnosia’ – the inability to recognise faces (something that Sacks described in his 1985 book The Man Who Mistook His Wife For a Hat (Yes, seriously, that’s what happened in this particular case study).

Perhaps the most poignant example in the whole book is that of Sacks himself, in an extended essay that combines diary entries with self-reflection following on his diagnosis of a ocular melanoma – a tumour affecting his eye. The details of how the growing tumour encroached on his vision are both fascinating and awful (& if they’re bad to read, think how you would feel to have these things actually happening to you). Surgery to insert a radioactive plaque & subsequent lasering, both targeting the tumour, saw him lose his binocular vision – rather ironical given that Sacks at one point belonged to the New York Stereoscopic Society. Four years later, in 2009, bleeding behind the retina of the affected eye saw him lose almost all sight in it – including his peripheral vision. This meant that he experienced something that hitherto he’d only known through working with patients who’d suffered strokes in a particular region lf the brain – anything, any person, any object, on the affected side effectively ceased to exist for him. As Sacks describes it:

This came home even more forcefully when Kate [his PA] and I finished our walk and headed back to my office. I walked ahead and got into the elevator – but Kate had vanished. I presumed she was talking to the doorman or checking the mail, and waited for her to catch up. Then a voice to my right – her voice – said, “What are we waiting for?” I was dumbfounded – not just that I had failed to see her to my right, but that I had even failed to imagine her being there, because “there” did not exist for me.

Such personal anecdotes make The Mind’s Eye a compelling and affecting read.

O.Sacks (2010) The Mind’s Eye, pub. Picador. ISBN978-0-330-51399-9

‘the uncertainty of it all – understanding the nature of science’ Alison Campbell Nov 18

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With the implementation of the 2007 NZ Curriculum comes the need for teachers to think about how best to help their students to develop an understanding of the nature of science.

The Nature of Science is the overarching unifying strand. Through it, students learn what science is and how scientists work. They develop the skills, attitudes, and values to build a foundation for understanding the world. They come to appreciate that while scientific knowledge is durable, it is also constantly re-evaluated in the light of new evidence. They learn how scientists carry out investigations, and they come to see science as a socially valuable knowledge system. They learn how science ideas are communicated and to make links between scientific knowledge and everyday decisions and actions. (from the NZ Curriculum, 2007) 

But to do this, teachers need resources. From time to time a colleague & I had tossed around the idea of writing a book for just this purpose, looking at how scientific ideas have developed over time and the relationship between science & society. Well, I’ve just finished reading through the book I’d have liked to write: The uncertainty of it all: understanding the nature of science, by Jane Young (2010).

(At this point I need to let you know that I could be a biased observer, having seen an earlier, draft, version of this book and its accompanying CD-ROM.)

Jane decided to write this book after her experiences with a Year 9 class who “had issues with science” and were quite hostile to her attempts to lead them to engage with topics such as evolution and global warming. “Scientists,” they said, “don’t know what they’re talking about.” This seemed to be a reflection of a wider lack of understanding of what science is all about: that it’s evidence-based, & that scientists’ understanding of the world is thus subject to change if the evidence demands this.

So,The uncertainty of it all begins with a chapter on what science is & what it’s not. (Apparently Ernest Rutherford once said that “science is what scientists do”, which isn’t particularly helpful when you’re trying to nail the idea for a bunch of young teenagers!) Next is a section on the history and development of science, before we move on to the language of science as distinct from pseudoscience (which is generally untestable, not particularly logical, lacks plausible mechanisms – homeopathy, anyone?, disregards or ignores existing data and theories, and often claims that its finds are ignored by ‘the Establishment’).

The section on how science works includes ‘What are scientists really like?” This includes some of my own favourite examples, including the eccentric Henry Cavendish & also Beatrix Potter, who besides being a popular & successful author of stories for children was an accomplishd botanist. They’re mostly no more weird than anyone else, they don’t all wear white coats - and they get things wrong: the great physicist Lord Kelvin, for example, commented that ”X-rays will prove to be a hoax.” And the paths to scientific discovery are many and varied. While careful observation, experimentation and analysis are important, insight and plain old good luck have their place.

And I was happy to see “science and statistics” receive several pages :) A reasonably large number of students come into my first-year biology classes with no statistical knowledge (& sometimes no maths), which presents a few problems when they get into experimentation and data analysis. But even more importantly, students who’ve been exposed to experimental design & the concept of probability are better equipped to think critically about the multiplicity of pseudoscientific claims they’ll encounter over the years.

The final chapters of the book deal with people and science: ‘A love-hate relationship” begins by noting that while we use the outputs of science and technology on a daily basis, our human need for certainty doesn’t always sit well with the potential for change that is part of good science. What’s  more, science can challenge comfortable beliefs; it “asks people to see things as they are and not as they believe or feel them to be.” Jane then goes on to look at criticisms of science before dealing with the interplay between science, morals and ethics, using examples (the infamous Tuskegee study and our own ‘unfortunate experiment, among others) that should be good starting points for productive classroom discussion.

 ”A human endeavour” also offers these starters, covering misunderstandings about science, examples of using the scientific toolkit as a basis for making informed decisions (are cell phones implicated in cancer? does chelation therapy help ‘cure’ autism?), and highlighting some of the astounding achievements that science has made over the last few hundred years

 Jane’s hope for her book is that it will help “to communicate… both the excitement and the uncertainty of the human endeavour that is science.” I think it succeeds :)

Jane Young (2010) The Uncertainty of it all: understanding the nature of science. Triple Helix Resources Ltd www.biologyresources.co.nz

communicating science – an example of good practice Alison Campbell Jan 18

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The following is from the Young Australian Skeptics website – I’ve copied the whole post across because it’s a brief one (& I’ve added links to book reviews):

We probably have all encountered scientifically ignorant people, for some people knowing the complexities of the universe is simply not interesting. This ignorance is generally spawned within the Medias interpretation of science and scientists; however a scientist known as Len Fisher is doing something about this by communicating science to the general community. Earlier in Brisbane  this year (as part of the BrisScience and BWF Festival) he held a seminar on how science should be communicated to the public. Len Fisher is best known for his ignoble prize for physics; it related to the topic why biscuits go soggy when you dip them in your tea.

He was contacted by a biscuit company to conduct this research, much to the derision of his colleagues; however his aim was to show to the media how real scientists think about everyday problems. He made it very clear to the reporters that the research was not really “life or death” serious research but it was to illustrate that science is not just a collections of immaterial facts and figures, but the study of reality. This was also seen in his desire for the motto and aim of the ignoble prize completion to be changed; it was originally an award for “Science that should not and cannot be reproduced”, he morphed this to “Science that first makes you laugh, then makes you think”.

This aim was to elevate respect for science within the community and to inspire interest in education. Len fisher has also authored several novels on a variety of topics: Rock, Paper and Scissors: Game Theory in everyday life, How to dunk a doughnut: The science of everyday life, Weighing the soul: The evolution of Scientific ideas, The perfect swarm: The science of Complexity in everyday life. By illustrating common science to the community Fisher is attempting to stir interest within the community, young and old, and this approach might help fellow communicators to attract and maintain interest in how the world works.

As a result of reading the above I’ve come to a number of conclusions: a) I want to meet Len Fisher & learn stuff from him! b) I need to keep an eye open for future BrisScience events; & c) there isn’t enough time in the future timespan of the universe to read all the good science books I come across. (Well, OK, that last is pure exaggeration, but you know what I mean!) 

did ancient jellyfish sting? Alison Campbell Dec 12

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One of the nice things about going on holiday for a reasonable period of time, without computer, e-mail, cellphone etc, is that you can settle down for a bit of serious reading. In a fairly full 7 days I still managed to complete 2 books & start another. One was detective fiction (PD James rocks!). The other was Martin Brasier’s book Darwin’s Lost World.

I found this particular volume both irritating & entralling, although the fascination won out. (The irritation was caused by some – to me, anyway – rather laboured metaphors.) One of the things I particularly enjoyed was that Brasier led me to think again about things we tend to take for granted. For example, the Burgess Shale and Ediacaran fossils are over 500 million years old, & yet show much better preservation of partially or wholly soft-bodied organisms than many more recent fossil specimens. Why should this be? (I’m embarrassed to say I’d never really thought about this…) And – did the ancient jellyfish that ballooned their way through the Pre-Cambrian oceans sting? (A topical question, given that the stinger nets were up in Port Douglas & anyone swimming outside them was regarded as dicing with a very unpleasant death by box jellyfish.)

On the Ediacaran & Burgess fossils, & other similarly well-preserved ancient sites - the ‘standard’ answer has always been that the fossils formed in a particular, narrow, set of circumstances. For example, the fossils of the Burgess Lagerstätte were thought to have formed when the animals were engulfed in a mudslide & carried deep into anoxic waters. With no available oxygen decomposition was very slow, & the fine silts entombing the corpses captured their soff tissues in exquisite detail over the long, slow process of fossilisation. But for the earlier, Pre-Cambrian soft-bodied fauna, Brasier suggests there’s another factor involved – a lack of worms (in the sense of ‘worm-like invertebrates, many of which actively burrow into the substrate’).

Take modern earthworms.Darwin devoted his last book to them, detailing how earthworms process soil & dead vegetation, rapidly turning over the soil, producing humus, and aerating everything into the bargain. Many modern marine worms do much the same, leaving characteristic burrows & galleries in the mud, & trace fossils formed from such burrows are found in Cambrian rocks & provide some of the first evidence of eukaryote behaviour. The burrows of those early worms would have helped to oxygenate previously ‘dead’ seafloor sediments, so that organisms falling to the sea floor would be more likely to decay rather than enter the process of fossilisation. And the worms would have processed the dead bodies, or the soft bits anyway, meaning that the odds of any non-skeletal body parts making it through to fossilisation were much reduced. So Brasier suggests that one of the reasons why the soft-bodied Ediacaran fossils (& others even earlier) is that there were no worms around to churn things up. How different the marine ecosystems must have been, way back then!

And the jellyfish? In this case, Brasier’s saying that it would be worthwhile to stop visualising the past in terms of the present. Modern-day jellyfish do indeed sting. Like all cnidarians they possess specialised cells called cnidocytes, that contain nematocyts: the structures that do the actual stinging. These structures enable jellyfish, sea anemones & their relatives to catch their prey – and their prey are generally ‘higher’ animals: arthropods, fish & the like. Yet these animals evolved more recently; whatever those Pre-Cambrian jellyfish were consuming, it was nothing like what modern jellies eat. Brasier makes the point that [j]ellyfish are not primitive beasts. They have co-evolved to prosper in a post-Ediacaran world. In other words, the stinging nature of modern cnidarians has evolved in response to the changing nature of potential prey, and the ecological niche of Pre-Cambrian cnidarians was very probably quite different from that which they occupy today.

I’d never really thought about that before…

M.Brasier (2009) Darwin’s Lost World: the hidden history of animal life pub. Oxford University Press.

hummingbirds & the high cost of s*x Alison Campbell Nov 18

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One of the nice things about reading books by great science writers is that I just know I’m going to learn lots. I’ve just got back into Nick Lane’s latest book Life Ascending (it’s been my lunchtime reading at work & recently other things have intruded…). Lane has a lovely lyrical way of writing that I really enjoy, & I thought I’d share a couple of paragraphs with you. They’re from the chapter titled Sex: the greatest lottery on Earth. in which he’s discussing how & why sexual reproduction evolved. At the heart of this excerpt is the idea that the biological costs of sex are quite hard to measure, but can be very high. The example here is hummingbirds – the go-betweens for sex in many species of tropical plant.

Rooted to the spot, plants are the most implausible of sexual organisms, yet the overwhelming majority of them are exactly that; only dandelions, along with a handful of other species, cock a snook at sex. The rest find a way, the most spectacular being the exquisite beauty of flowering plants, which swept through the world some 80 million years ago, turning the dull green forests into the magical painted glades we know today. Although they first evolved in the late Jurassic, perhaps 160 million years ago, their global takeover was long delayed, and ultimately tied to the rise of insect pollinators like bees. Flowers are pure cost to a plant. They must attract pollinators with their flamboyant colours and shapes, produce sweet nectar to make such visits worthwhile (nectar is a quarter sugar by weight), and distribute themselves with finesse – not too close (or inbreeding makes sex pointless). Having settled on a pollinator of choice, the flower and pollinator evolve in tandem, each imposing costs and benefits on the other. And no cost is more extreme than that paid by a tiny hummingbird for the static sex life of plants.

The hummingbird must be tiny, for no larger bird could hover motionless over the deep throat of a flower, its wings beating at 50 beats a second. The combination of tiny size and colossal metabolic rate needed to hover at all means that hummingbirds must refuel almost incessantly. They extract more than half their own weight in nectar every day, visiting hundreds of flowers. If forced to stop feeding for long (more than a couple of hours), they fall unconscious into a coma-like torpor: their heart rate and breathing plunge to a fraction of that in normal sleep, while their core temperature goes into free fall. They have been seduced by the enchanted potions of plants into a life of bondage, moving relentlessly from flower to flower, distributing pollen, or collapsing into a coma and quite possibly dying.

With costs like that, the benefits of sex have got to be significant. That, and the evolution of this complex practice, occupy the rest of the chapter. I am so enjoying this book :-)

N.Lane (2009) Life Ascending: the ten great inventions of evolution. Norton.

the lost city & life undersea Alison Campbell Sep 13

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I do love the fact that there is always something new to learn. And often, to pass on to my students. Like the ‘Lost City’ – a surreal landscape of ghostly white towers that’s formed around alkaline vents deep under the Atlantic Ocean. Now, I know about the ‘black smokers’ – fragile black towers belching superheated, chemical-rich waters into the icy ocean depths of the mid-Atlantic ridge, and the amazing biological communities associated with them. I talk about them in lectures, as (among other things) an example of ecosystems that don’t rely on inputs from the sun to power their producers. And colleagues of mine have the privilege of regularly diving to study these pockets of life. But alkaline vents?

I encountered the vents in Nick Lane’s new book Life Ascending: the ten great inventions of evolution. Lane introduces them in the context of his chapter on the origins of life. We’ve long known that life evolved in the water, & for a while now at least some scientists have been talking about the possibility that the black smokers were the actual venue for this event. More recent still is the proposal that the cooler, chemically different alkaline vents offered a place for life to evolve. As Lane says on his blog, The origin of life is one of biology’s biggest conundrums. How prebiotic chemistry gave rise to biochemistry, how the first cells formed, what kind of energy first powered metabolism and replication — all these questions are serious challenges. Remarkably, all are answered in broad brush stroke by the amazing properties of alkaline hydrothermal vents, which form naturally chemiosmotic, self-replicating mineral cells with catalytic walls. They concentrate organics, including nucleotides, in impressive quantities, making them the ideal hatcheries for life.

While black smokers form along zones of sea-floor spreading, alkaline vents lie some tens of kilometres back from these rifts in the planet’s crust. And the minerals expelled from alkaline vents precipitate from the water to form white filigree towers – shown below in an image from the the best-known field, the ‘Lost City’.

Why do some scientists think that these ghostly towers could have been incubators for the first living things on Earth? One factor is their age. Black smokers are relatively short-lived: they & their communities decline & die over perhaps a few hundred years as the rocks they are on move away from the crustal rift & the fresh magma that powers them. But the pale vent towers last much longer; in the case of the Lost City, around 40,000 years so far. This significantly increases the odds of life evolving on or in them. And internally, at a microscopic level the vent towers contain huge numbers of interconnecting compartments that trap & concentrate the organic molecules formed by the reaction of carbon dioxide with the hydrogen gas bubbling up from the rocks beneath the vents. This would make the formation of organic molecules, including polymers like RNA, much more likely than around the black smokers. It’s suggested that the most likely pathway for this to happen is by a reversed Krebs cycle, which rather than breaking organic molecules down into CO2 & hydrogen, builds them up. And significantly, while the reversed Krebs cycle is unusual, it’s fairly common in those bacteria that live in alkaline vents.

In other words, this is a plausible hypothesis & one that offers plenty of opportunity for modelling & testing. And I’ve learned something new :-)

N.Lane (2009) Life Ascending: the ten great inventions of evolution. Norton.

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