Archive for biology

The Eocene in Antarctica

Posted in Science with tags , , on August 2, 2012 by davidnm2009

I’ve just become aware of what I think is a very interesting paper, albeit one from outside of my field: Persistent near-tropical warmth on the Antarctic continent during the early Eocene epoch (Pross et al 2012).

The executive summary, as it were, is that Eocene-era Antarctica (55-48 million years ago) may have been a lot warmer than is generally reckoned. It’s been known for quite a while that the southern-polar continent hasn’t always been glaciated, and certainly has been forested in the distant past. However, the impression I’d got (from what I’ve read, here and there) was that the general opinion was that non-glaciated Antarctica was still a fairly cold place. Intuitively, given its extreme latitude, that would seem to make sense.

This study is arguing that simple intuition is wrong in this case.

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Old Mars

Posted in Astronomy, Science, Space with tags , , , on December 31, 2011 by davidnm2009

“…Yet across the gulf of space, intellects vast and cool and unsympathetic, regarded our planet with envious eyes, and slowly and surely drew their plans against us….”

Yes, I’m listening to Jeff Wayne’s version on ‘War of the Worlds’.

Wells’s opening narration has to be one of the most wonderfully chilling things I think I’ve ever read. On the face of it, it breaks every narrative rule in the book (third person, passive voice, no dialogue, pure exposition) and yet, I find it impossible to read without shivering.

Interestingly, for its day, ‘The War of the Worlds’ was also scientifically-plausible. The Victorian Mars was believed to be a living world, if likely rather a dry and desolate one. Indeed there was even some evidence of supposed activity on the surface – the infamous ‘cannali’. (Actually ‘channels’ – the word was mistranslated into English as ‘canals’, which are a rather different entity from that which Schiapperelli meant to imply!)

Of course, Science Has Marched On (as it’s rather prone to). Our Mars is a nearly-airless, lifeless world. If anything does live on it – and there can’t be very much, else we would long since have known of it – then it couldn’t be more than a few microbes, perhaps huddling in some warm, wet reservoir beneath the surface. Our Mars almost certainly did have liquid water, warmth and air, but that phase was billions of years ago.

Our Mars is just too small.

Its core cooled and froze out aeons ago, stilling the planet’s internal dynamo. With no global magnetic field, there was nothing to shield it from the solar wind, and the storms of the Sun slowly stripped away its air. In addition, without plate tectonics, the atmospheric cycle slowly ground to a holt. Mar’s air was gradually lost to sediments deposited at the beds of the Noachian oceans. Then those oceans themselves gradually evaporated, their vapour rising into the stratosphere, where solar ultraviolet broke apart the heavy water molecules. The light hydrogen atoms would simply have escaped into space, Mars’s low gravity being too weak to hold them. The oxygen would have been lost into compounds by reaction with other materials in the Marian crust and air – oxygen is a notably reactive gas! (And as well it is – if it were any less reactive, our entire human metabolic system would be quite impossible.)

Over the millennia, these processes ran their course. Mars was left dry, desolate and lifeless. If there ever was anything living there, it does not seem to have been able to survive the transition from Blue Mars to Red Mars. Today, Mars averages something like -60 Celsius and it has a surface air pressure of a mere 7.6 millibars, or less than 1% that of the Earth. The only remaining water are some suspected permafrosts and the two small, bright caps of ice at either pole. There is also a breath or so of water vapour in the thin atmosphere, but not enough to form more than a single pond. Our Mars is a cold, cratered orb, staring blindly into the heavens.

Still, one has to wonder.

“…The chances of anything coming from Mars, he said, were a million to one…”

Image credit: NASA, via Wikimedia Commons

Gravity, Pt. 3

Posted in Science, Speculation with tags , , , on April 1, 2011 by davidnm2009

I was going to be writing a post about the implications of differential gravity for the body’s, ah, excretory systems next. (There are plenty, as it happens.) But then it occurred to me that there was a much more basic and much more obvious problem that should be considered first. It’s called actually being able to move in the first place!

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Gravity, Part. 2

Posted in Space, Speculation with tags , , , on March 31, 2011 by davidnm2009

It’s all about the bones.

Your bones are a central part of your physiology. They hold your body up. They also help you to move, by giving your muscles something to push against. They also house the marrow that amkes your red blood cells. And, like all systems in the human body, evolution has optimised them for 1 g of gravity. How are they going to react to a hypothetical colony planet, with g=0.68? or 1.3? or 0.17 (if we’re talking about a Moon colony)?

I’ll be clear about one thing; at the moment, we don’t know for an absolute fact. But there is some evidence to suggest that there could be tears before bedtime…

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Gravity, Pt. 1

Posted in Science, Speculation with tags , , , on March 29, 2011 by davidnm2009

We’ve already talked – a bit – about the possible role air pressure might play in planetary colonisation. I didn’t do much more than dip my toe into what is by any standards a vast topic. You could loosely summarise it as ‘human beings function best at 1 standard atmosphere’ – surprise, surprise! However, there is also some flexibility – presumably, our pre-human ancestors did encounter big hills and mountains often enough for evolution to factor it in. Human settlements can and do exist at altitudes as high as ~5000 metres.

Gravity, however, is potentially a very different problem. It’s something that will be a fundamental property of any planet. It’s also something that isn’t amenable to human influence, short of some kind of completely-incomprehensible, borderline-magic type technology. But, irritatingly, it’s something that will have major health implications for any putative human society. So it can’t be ignored. One can imagine taking supplements to deal with chemical deficiencies in the local soil, one can imagine pressurised houses to deal with air pressure differences, one can imagine vaccines or perhaps genetic engineering to cope with local diseases – but you can’t really do anything about the surface gravity! (By the way, if you think I’m being absurdly glib in dismissing the other issues, you’re dead right! All of these would be major undertakings just by themselves…)

Now, a note before we go any further. Most of this series of articles will be me commiting the physicist’s cardinal error – speculating outside one’s own field! So, any errors you see in the medicine and the biology are most definitely not my sources’ fault, they are a consequence of my own faulty comprehension. (Incidentally, if we do have any biologists or doctors in the audience, I would be very interested in their views on this topic.)

First off, let’s start with a brief – and it will be brief! – overview of what gravity is from a physics perspective.

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Air Pressure

Posted in SF, Space, Speculation with tags , on February 12, 2011 by davidnm2009

Feeling the pressure…

Recently, I’ve been attempting to re-read a book. I first read it back in ’90s, and didn’t get that much from it. I thought I might enjoy it more now – unfortunately, though, I’m actually liking it even less. Without naming the guilty, it’s sort-of a space colonisation story. You could sum the plot up as Rugged Libertarian Authority Figure(tm) is forced to Take Control and show a bunch of useless strawman liberals what’s good for them. (The authors do not appear to notice the inherent irony of a libertarian authority figure, either.) Few of the characters are at all sympathetic – the only one who is has severe brain damage and thus the IQ of a 10-year old. Also, we’re repeatedly assured that the colonists are a special elite, selected for their inherent genetic superior-ness to ordinary, scummy, untermensch humans. (That is, you and me. Just so we’re clear on this.)

Given my current politics, I found all of this utterly irritating.

I don’t think I’ll bother to finish the book. But there’s actually worse, though. You see, it’s supposedly hard SF. Now, I like hard SF. But what I don’t like is schoolboy research errors. (For instance, in this book, the authors seem to think that Tau Ceti is an F-class star – it’s really, really not). Also, the book is supposedly about the impact of an alien environment on the colonists. (I say ‘suppposedly’ what it actually seems to be about is an excuse for their uber-manly Heinleinian poster-boy to flex his manly Marty Stuish pecs at the readers.) However, the environment makes a surprisingly small impact on the characters. In particular, two critical world-building factors are entirely ignored.

These are surface gravity and air pressure.

I’ll deal with gravity some other time, but let’s talk about air pressure.

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Posted in Science with tags , , on September 26, 2010 by davidnm2009

Okay, I’ve talked about food security a couple of times before, and let’s face it, I’ve been pretty pessimistic in the past. However, potentially at least, the genome of wheat business could be good news. Improved crop yields, resistance to disease, resistance to water shortages and climate changes … all of these could be very important, given our current global circumstances.

However, before we all get maniacally excited and decide the world is saved and there will be no more problems, nevah EVAR!, a couple of notes of caution:

  • 1. Sequencing the genome is the start, not the end. For instance, the human genome has been sequenced for a decade or so, but genetic medicine remains something of a pipe dream. We still don’t have a clear idea what all of those 30,000 or so genes do, let alone how they interact with each other. And this is the case of the most well-studied organism on Earth, as well.
  • 2. What about the proteome? I can’t help but notice no mention of the wheat proteome. And presumably, umm, if the plan is to use genetic engineering to make super-wheat, then the enzymes and so on are going to become important, right?
  • 3. The social-political dimension. Look at what happened with GM food. And, umm, that’s what super-wheat will be, basically. If there’s no market for it, then the research risks remaining an academic curiosity. And I’m afraid this isn’t one those things where we can turn around at the last minute and pull a super-food out of our backsides at the last minute … I’ll agree that the NIMBYs might change their minds about GM when the dieback begins and they get a bit hungry, but it’ll be far too late by then. There is a widespread, and growing, distrust of new ideas and technologies, partly fueled by things like the ghost-writing scandal, and partly by dodgy politics, and this is a major barrier.

Now, I should stress that I’m not trying to belittle the research in question. Quite the contrary. I think it’s interesting, I think it’s an important beginning and I think it could be very significant. As I said earlier, this could be very good news. However, I got annoyed with the breathless and giddy tone of some of the reporting in parts of the media.

Admittedly, I shouldn’t be surprised by idiot journalists either failing to understand or just plain mis-representing what they’d been told, but critical thinking is a key part of any scientific endeavour. (It’d be interesting if journalists had to cite a bibliography to support their assertions…) And to make this go somewhere useful, a lot of critical thinking will be needed.