Saturday, February 13, 2010

a bucketful of problems

while others played spin the bottle, Newton preferred spin the bucket

Canto: I think we should tackle the biggies, space and time, and such, since we've just seen a doco on time and whether it really did begin at the big bang.
Jacinta: We'll only be wading into the shallows, but hey we're here to educate ourselves as best we can, with whatever paltry capacities we have.
Canto: These are not only scientific questions but arguably metaphysical ones. Did space and time begin with the big bang, and if not, then do we go back infinitely somehow, with no first cause? Is the big bang a cause or an effect, or do we have to rethink our language?
Jacinta: The danger here, it seems to me, is to imagine you can come up with the right answer just by thinking about it. That way lies metaphysics, definitely, as well as theology.
Canto: Yes, it's all about basing your thinking on evidence, but in the field of cosmology - or in some areas of cosmology anyway - evidence is very hard to come by. A cosmologist or a string theorist spoke in the doco about his very firm conviction that time didn't begin with the big bang, that it was caused, I think by the clashing of two universe-planes which would in general circumstances remain unconnected, as parallel universes. Now what would constitute evidence for this? How can the theory be tested? As well as all the other theories floating around in cosmology?
Jacinta: It's not exactly metaphysics in the sense of dreamed-up noumenal worlds or the constructions in Plato's Timeaus, it's more mathematically based, and quite likely calculated to extreme degrees of precision, and maybe even testable in terms of some kind of internal consistency, and even coherence with theories already tested and accepted, and yet ...
Canto: So let's stick with the tested theories, and current understandings. What is space?
Jacinta: It's probably something that everyone has a 'common-sense view' about - for example, it's simply what separates discrete objects in the universe. Or it's everything that lies outside of the earth's atmosphere. In  The Fabric of the cosmos, by Brian Greene, the first three chapters - all I've read so far - look at this question, as well as the question of time, as it was wrestled with mainly by three thinkers; Newton, Mach and Einstein. It starts with a bucket experiment described by Newton. A bucket of water is tied by a rope which is twisted around and then let go, so that the bucket spins. The water in the bucket stays still and flat at first, but then, due to friction, the water starts to spin around too, and the surface becomes concave.
Canto: The water's being forced to the edge of the bucket, away from the centre, by the bucket's spinning motion. But how?
Jacinta: The water is being forced around the edge of the bucket, it can't move in a straight line because of the barrier of the bucket's edge. The spinning is the result of containment. The real issue, of course, is motion itself. When the bucket starts to spin, the water doesn't spin. The bucket is spinning relative to the water [and it's key to understand the relativity of all motion]. Then the water starts to spin relative to the bucket - the bucket's relative motion decreases. And the water's surface takes on its concave shape. Interestingly, though, when the bucket's rope untwists and starts twisting the other way, the bucket decelerates, while, for a time, the water continues to accelerate, increasing the relative motion between them once again. The surface of the water remains concave, more concave than ever.
Canto: So you're saying that the relative motion between water and bucket isn't itself responsible for the water's shape. Surely it's about force. The spinning bucket has imparted a force to the water, a force which continues to increase as the bucket accelerates. Even as the bucket slows down, it's still going in the same direction [it's responding to the force of the rope], imparting the same-wise force to the water. Only when the bucket has stopped does it cease to impart any force. The water carries on spinning - and that's where we have to introduce the concept of momentum?

Thursday, January 14, 2010

grief, trauma, revenge

Canto: I'd like to bring up a subject not directly related to anything we've been talking about here, but generally related to other life forms, especially the more complex creatures we share the planet with. The intelligence and emotional depth of two such creatures, chimps and elephants, have been brought home to me recently, first [the chimps] by the photo shown above, first sighted by me in The Advertiser back in November, and widely available on the net, and second [the elephants], by a powerful documentary I've just seen on the ABC [The Revengeful Elephant]. Both the image and the documentary highlight the phenomenon of grief, and the acknowledgement of death - features of the lives of other species that our species has, in general, been reluctant to recognize in the past.
Jacinta: Yes, it's a photo to ponder over. We're moving away from the old strictures against anthropomorphizing in ethology it seems, simply because we're coming across so much more evidence of actions and interactions, in the more complex of other species, that we once imagined only ourselves to be capable of. 
Canto: Well let me talk of the elephant documentary, while it's fresh in my mind. In two separate places in Africa, elephants were behaving with unwonted aggression - in national parks in Kenya and in South Africa. In Kenya they were attacking and killing the cattle of the Masai, whereas in South Africa, it was the endangered rhinos. Elephants are herbivores, and these attacks seemed on the surface to lack rhyme or reason. It took years to get to the bottom of it all, but when they did, the findings about elephant behaviour proved revelatory.
Jacinta: I know they’re highly intelligent animals.
Canto: Highly emotional, too, and highly social. This is the key. The ‘bad’ behaviour of the elephants was all about social disruption and trauma. To take the Kenyan situation first, it was found that the elephants doing the killing were females, who had suffered at the hands of the Masai in the past. The Masai had been moved off their land some years before, to make way for the park. Out of resentment, and to highlight their plight, the Masai had attacked and killed a number of baby elephants. In the South African situation, on the other hand, the rhino killers were young bull elephants who had come into musth earlier than usual.
Jacinta: Musth? What’s that?
Canto: Musth is an incompletely understood phase, usually occurring in winter, in which bull elephants secrete a thick substance called temporin from their temporal ducts on each side of the head. During this phase, their testosterone levels can be as much as 60 times higher than normal, and they’re very aggressive, to humans, to other elephants, everyone. The point here is that bull elephants normally only enter the musth phase when they’re quite mature, but these South African bulls were an exception. The final diagnosis was that these ‘teenagers’ were traumatized. In the late seventies, as babies, they’d been transported to the South African park from elsewhere, because in those days only very young elephants could be transported, they didn’t have the technology to ship larger ones. But not only were the baby elephants thus separated from parents and families, in fact their parents were mostly exterminated before their eyes in an elephant cull. They had no role models, and of course they were never treated for post-traumatic stress disorder.
Jacinta: So what did they do then, treat them?
Canto: They brought in older elephants [this was in the early nineties, when transportation technology had improved] who effectively bonded with the younger ones and calmed them down. I don’t know how or if they solved the Kenyan situation.
Jacinta: Revenge killings. That must’ve been a controversial finding.
Canto: Well, possibly not so much of a surprise among these who’ve worked closely with elephants. The old saying that an elephant never forgets must’ve been based on observation. I mean they must have behaved in ways that showed they remembered, and were affected by, events in the past. It makes you feel real empathy with their suffering. You know the two must powerfully affecting moments in the doco for me were these. First, a baby elephant was described as trumpeting in its sleep. It was having a nightmare. Elephants generally only trumpet when there is danger about – it’s a kind of high-adrenalin response. What’s more, baby elephants never trumpet. It’s an adult thing. The second was footage showing an elephant gently and respectfully touching with its trunk the skull of one of its dead fellows. The doco reported extensive evidence of this behaviour as regular and almost ritualized, a behaviour very rare amongst other mammals.
Jacinta: So we seem to be coming to a new anthropomorphism, as we recognize the depth of mourning of chimps and elephants, an anthropomorphism based on a deeper understanding, rather than the old sentimentality.
Canto: Well, I wouldn’t dismiss the old sentimentality too off-handedly. I read Ernest Thompson Seton’s Biography of a Grizzly as a lad, and I was an emotional wreck afterwards. It affected me more than any other book of my childhood, by far, and though it probably was sentimental in parts, it taught me a lot about animals, and especially about respect for them. It would be a good starting point for any budding ethologist. But the new understanding works both ways – it teaches us not only how like us they are, but how like them we are. That we too are mammals, and our social behaviour and morality are no less mammalian than those of many other creatures. It’s exciting and moving and vaguely humbling.

Thursday, January 7, 2010

human origins and cladistics

Homo erectus?

Jacinta: When Tudge described Cro-Magnons as 'the first fully modern humans' I think he was referring to their cultural development, or evolution. My guess is that he was referring to fossil remains, in Europe, that were accompanied by other materials tools, perhaps ornamentations and such artifacts.
Canto: You mean there was no sign that these Cro-Magnons had evolved anatomically or physiologically from the Homo sapiens that they've managed to date back 500,000 years? By the way, can you give some more detail about this dating reference?
Jacinta: Tudge is a little vague on this. Here's the main quote:
The very first people who were more or less like ourselves – who would not have attracted too many stares on today's public transportation – date from about 500,000 years ago.
Canto: Oh so he doesn't specifically call them Homo sapiens. Or does he?
Jacinta: Well that's what I mean, he's a bit cagey. In fact one of the main take-home messages from this book is that we shouldn't get hung up on the 'Homo sapiens' moniker. As you know, there's been something of a shake-up in taxonomy over the past few decades, with clades and grades what they call cladistics being the preferred categories, with a lot of slippage and bushiness and imprecision in categorisation. Tudge doesn't give us a lot of detail on the fossils he's talking about from that era how much material has been found, for example - but he calls them 'archaic', or rather that's what the palaeontologists call them, but though they might be a little different from your modern Cro-Magnon type, they might not be different enough to prevent interbreeding. One definition of a separate species is that it breeds separately, though that definition is disputed, as is everything in taxonomy these days, it seems.
Canto: So we might be talking about the Neanderthals for example.
Jacinta: Yes, and there's another archaic type which has been given a separate species identity, Homo heidelbergensis, but Tudge doesn't provide any further information, whether it's based on half a skeleton or some jaw, or some teeth. Looks like I might have to read another book to get the dirt on that.
Canto: Or do some basic internet research.
Jacinta: We'll get on it soon.
Canto: So tell us a bit more about cladistics, if you can. I know we've talked about this before.
 Jacinta: Well, we're offline at present, because of stupid Optus downloading constraints, so my information will come from two books, The Link, by Colin Tudge, and Galileo's finger, by Peter Atkins. A clade is defined simply by Tudge as a group of creatures that shares a common ancestor. Clades exist within clades which exist within clades, but the key feature of a clade is this, to quote Tudge:
A clade is not a true clade unless it contains all the descendants of any particular ancestor plus the ancestor itself; and it must not contain any other creatures that are not part of the lineage.
This is clearly a tighter definition than what we have for a species, a definition that has changed over time and that has different emphases. For example, Atkins cites biological species, in which breeding pools are the significant factor, but also ecological species, recognition species and phylogenetic species, as well as the earliest understanding of species based on broad similarities. With the tighter approach of cladistics, we can create cladograms [a family tree or bush] which branch off whenever some significantly unique trait emerges. For example the loss of the opposable thumb on the foot occurred sometime after the chimps branched off from us some seven million years ago. That's a missing link, of sorts.

the missing bone

canines have them

Canto: We'll give the global warming crisis a break for a while, and maybe return to the origins of life, or the origins of the universe, or the origins of Homo sapiens whatever you'd like to focus on.
Jacinta: Thanks for the choice Canto. I'm currently reading The Link, by Colin Tudge, so if we're talking origins, it'll have to be Homo sapiens. It's a great book, it has taught me so much. Frankly, I'm woefully ignorant when it comes to palaeontology, so this has been like an introduction for me, in spite of reading a few Stephen Jay Gould essays.
 Canto: So what specifically have you learned from The Link?
Jacinta: A lot of confusing stuff. That Homo sapiens is maybe 500,000 years old, but that Cro Magnon woman, someone as recognisable as ourselves, is maybe only 40,000 years old.
 Canto: That is confusing. So there's a Homo sapiens that isn't Cro-Magnon? I thought Cro-Magnon and Homo sapiens were interchangeable, that they had found fossils more than 40,000 years old though that were just like us, and so they named them Cro-Magnon, presumably after some location...
 Jacinta: We'll try to clarify all that later, but so many other things I've learned, such as that we're the only primate without an os penis that's a bone in the penis. Every other male primate has one. And most mammals too. And there at least 250 species of living primates, by the way.
Canto: You mean, we human-type blokes have boners without having bones?
Jacinta: Correctamundo.
Canto: And chimps and bonobos, our nearest living relatives, have penis bones?
Jacinta: That's what I've read.
Canto: So when did it drop off, and why?
 Jacinta: Qui sait? The fossil record with regard to our hominid ancestors is extremely patchy bits of skull, jawbones, teeth. Nothing like the near-perfectly preserved fossil of Ida, the subject of The Link. Not too many penis bones either, not attached anyway. There are speculations as to why humans are penis-boneless though. Here's how Tudge summarises it:
For animals without an os penis, the only way to achieve a convincing erection is by hydrostatic pressure – which only a vigorous animal can generate. An erection achieved without obvious support may not tell a potential mate all she might want to know about her suitor's health, but it does tell her that he is not actually ill, at least in one important respect.
Canto: Yes, the only respect that counts for some women, eh Jass?
Jacinta: Eh?
 Canto: So maybe as we got smarter, we got to convince our females that being sexy was more about thinking sexy, especially when she was around, than about the size of bone in our boner.
Jacinta: Something like that. You could call it the romantic turn.
 Canto: You know, I'm pretty sure that cats don't have an os penis. Have you seen a cat's dick? It's pretty teeny.
Jacinta: I'd have to look more closely at that one.
Canto: Don't excite yourself. Take my word for it. Let's get back to the Cro-Magnon issue, if you please.

Tuesday, January 5, 2010

a touch of acid

Jacinta: Let's talk today about ocean acidification, or at least let's start off talking about it. Who knows where it will lead.
Canto: There's been a decrease in overall surface ocean pH over the past couple of hundred years, attributed to the uptake of carbon dioxide in the atmosphere, the high levels of which are attributed to human activity. As you might expect, the process of acidification, and its consequences, are complex, but it has much to do with the carbon cycle, particularly the cycle of inorganic carbon. Seawater temperature, along with alkalinity, affects the ratio of carbon dioxide dissolution. This is chemistry stuff - a reaction occurs with the water to form a balance of ionic and non-ionic forms, including 'dissolved free carbon dioxide', carbonic acid, bicarbonate and carbonate. Overall this increases the hydrogen ion content and decreases the pH. It's called acidification, but another way of looking at it is a reduction in alkalinity. The sea is still alkaline.
Jacinta: Yes, the pH of water is 7, that's neutral. They reckon the pH of the surface ocean has come down from a little under 8.2 in the 1700s to a little over 8.1 currently, but that the acidification is accelerating and the  future is looking increasingly grim depending on which expert you consult. And the effects on marine life?
Canto: Shellfish produce calcium carbonate. It's a process called calcification, and it's essential to many marine organisms. I won't go into the chemistry here but unless the surrounding seawater is saturated with carbonate ions, the structures built out of calcification will simply dissolve. It's more complicated than this [for example, it depends on which calcium carbonate structure the organism relies on for calcification - there are two, aragonite and calcite, with varying degrees of solubility], but the saturation state of seawater, which varies with temperature and carbon dioxide levels, is vital to the health of the organisms inhabiting it.
Jacinta: So what organisms are we talking about here?
Canto: A very wide range indeed. Think of corals of course, but also molluscs and crustaceans. And perhaps most importantly, the very abundant single-celled micro-organisms with little calcium carbonate plates, called  coccolithophores. However there's a lot of disagreement, both about the current extent of acidification, and about its long-term, and even short-term impacts. It may not all be doom and gloom, and we should remember the human tendency, generally a positive one, to motivate ourselves into action through these negative projections.
Jacinta: More research is required! More more more!
Canto: That’s right – all scientists want is the opportunity, and the funding, to get to the bottom of all these bottomless issues, to keep on with their research – and who can blame them.
Jacinta: And there are always new crises coming up to concern ourselves with. Have you heard about the methane clathrates under the ocean? They have the potential, apparently, to release such volumes of methane as to send global temperatures skyrocketing, just as might have happened at the time of the Paleocene-Eocene Thermal maximum. Watch this space!

Monday, January 4, 2010

surviving doom and gloom

Jacinta: The 'little ice age' is a complex and controversial event, with the IPCC describing it as a series of more or less connected regional effects rather than a 'globally synchronous increased glaciation'. And since there's just no agreement on the timing and duration of this soi-disant little ice age, it's almost impossible to come to a determination of causes. Possibilities include the usual suspects - low solar radiation, volcanism, natural climate variability, ocean current activity - and some new human factors, which I'm none too convinced about. The fact is, though, that the reasons for the warming between the end of the little ice age, whenever that was, and around 1950, remain unclear. What is quite clear to the vast majority of climatologists is that the warming since 1950 has been largely due to human fossil fuel burning and land clearing.
Canto: From my cursory reading, I gather that Dr Barry Brook is of the view that human effect on greenhouse gas levels and global warming, previous to 1950, and even 1850, has been considerably underestimated. But what I also notice from this cursory reading is how head-spinningly complex this multi-factorial issue actually is. Endless difficulties in measurement, in interpretation, in extrapolation and prediction. It's hardly surprising that nonscientific but naturally sceptical types like myself can be so thoroughly discombobulated, what with radiative forcings, radiosonde data, solar-cycle lengths, carbon sink capacities, tropical hotspots, biomes, urban heat islands, and more and more.
Jacinta: A pleasant puddle of dummy spit there, Canto, but I think it's best if we keep our eye on the big picture, while gradually trying to educate ourselves on these undoubtedly significant details. And the big picture is that there is an apparently accelerating rise in global temperatures, the effects of which are currently being felt especially in the northern hemisphere. The large-scale burning of fossil fuels and the continuing clearing of forest areas that act as carbon sinks, and various other large-scale human practices, seem to be having an effect upon the climate. Certainly this is the consensus view of the experts in the field, and though there may be assessment flaws here and there, and exaggerations on the fringes, we would surely be unwise not to act on this general consensus.
Canto: But what will be the effects of this global warming, and what should we do about it? I mean, given that the Eocene warming led first to extinctions then to speciations, what with the hot and steamy atmosphere just right for reproduction, the future surely doesn't look all bad? Maybe there'll be a collapse of the human population, and after a period the warming will level out, and the cooling trend will start again. That's a reasonable scenario isn't it? And all of this will have a transformative impact on the biosphere, like many previous transformative impacts.
Jacinta: Yes but I think the area of really unfamiliar territory is the speed of this temperature rise. If it continues like this for, say, a century, it might well be more catastrophic than anything that has gone before. I agree though that some species will thrive. Mass extinctions may not have a negative impact on the whole biomass, but it's generally top of the food chain species that are most vulnerable, paradoxically.
Canto: You mean us? I'm not sure if we're talking out of our arses, but it's kind of exciting stuff. I wonder if we somehow require doom and gloom scenarios to get us motivated.

Sunday, January 3, 2010

global warming controversies

Canto: Before we go on to look at the causes of modern global warming, how can it be that some aren't convinced that global warming is actually happening? Some are even saying that the globe is cooling.
Jacinta: Well you know that, at least since the Eocene, and probably overall since the beginning of the planet, earth has been cooling, with many fluctuations such as this one. Claims about cooling since 1998 are dealt with here, and on many other sites. The 1998 spike was likely due to a strong El Nino effect, and the 2005 year was also quite warm, but a couple of years of relative coolness since then doesn't buck the overall trend. It's a matter of being patient with data - a year or two's figures aren't enough to reveal an underlying trend.
Canto: And didn't they just release figures for - 2008 was it? Which suggested it was the warmest year on record?
Jacinta: No, 2008 is down at only around equal eighth place, according to the USA's National Oceanic and Atmospheric Administration, and from what I can gather 2009 was warmer, but the decade was the warmest on record - that is, for a mere 150 years or so.
Canto: And even a million years is a mere blip in planetary time.
Jacinta: But we won't get complacent. We want realism, not complacency. This is possibly the fastest upward spike in planetary history, and it may already be out of control.
Canto: So what proof is there that this warming trend is due to human activity?
Jacinta: Here's where we move into difficult waters because of the complexity of the subject. I'm not a scientist, and so I have to defer to the scientists, especially the climatologists of the IPCC who have reached a general consensus on the issue. The February 2007 summary of the IPCC's fourth assessment report stated that there was a ninety percent likelihood that the global warming being experienced was anthropogenic and primarily related to the burning of fossil fuels. This, along with land clearing and other agricultural practices, has increased the level of carbon dioxide and methane in the atmosphere.
Canto: Yet there's a vociferous crowd who argue that this a natural cycle, and that our contribution to the greenhouse gases in the atmosphere is negligible, and even if there is some warming there's no need for all the alarmism. And many of these guys, such as Edward Townes and Joanne Nova and Australia's endless Andrew Bolt, are very tenacious indeed.
Jacinta: And so were the flat-earthers, remember. It's evidence that counts, not tenacity.
Canto: So let's look at the evidence. Joanne Nova presents, on her blog [actually it's guest post by a Dr David Evans], 'a simple proof that global warming is not man-made'. Evans presents graphs and data showing that the vast bulk of emissions occurred after the second world war, with post-war reconstruction and industrialism. In fact, he claims that half of all human emissions [presumably throughout human history] occurred from the seventies on. However, he claims, global warming began after the 'little ice age', approximately from 1700, and has been trending up ever since. He argues that, if it was all to do with anthropogenic emissions, this would be better represented in the figures, with little or no warming before 1945. So what do you say to that?
Jacinta: Next time.