Archive for the ‘other life’ Category
is there life on enceladus?
a cool place – and note the tiger stripe
The Curiosity landing has been fabulously successful, and it’ll certainly be worth keeping tabs on the rover’s findings. I posted recently on the possibility of life on Mars, not a couple of billion years ago, as many Mars experts think probable, but right now. The Curiosity rover, as we know, will be investigating this possibility further, but meanwhile there are other possibilities of finding extra-terrestrial life in this solar system, and one of the best places to look, I’m reliably informed, is Enceladus, a tiny moon of Saturn.
Enceladus is only about 500 kilometres in diameter, but its surface has intrigued astronomers ever since Voyager 2revealed detailed features in the early eighties, indicating a wide range of terrains of varying ages. Data from the Cassini spacecraft that performed fly-bys in 2005 showed a geologically active surface, with the most spectacular feature being a large volume of material, mostly water vapour, issuing from the southern polar region. This indicated the existence of ice volcanoes, or cryovolcanoes, which have also been observed elsewhere, and were in fact first observed by Voyager 2 on Triton, Neptune’s largest moon. However, on Enceladus what we have are more like geysers spewing out material from an area known by observers as ‘the tiger stripes’, a series of prominent, geologically active ridges. This material is now known to account for much of the outermost E ring of Saturn, within which Enceladus has its orbit, though a certain amount falls back onto the moon as snow.
Finding water on any object in the solar system obviously excites the souls of astrobiologists. A report from a May 2011 conference on Enceladus stated that this moon “is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it”. However, there are plenty of sceptics, or I should say cautious questioners. First, the existence of water vapour spumes doesn’t necessarily entail liquid water below the surface – for, in spite of the thrill of detecting snow in large quantities on the surface, liquid water is generally regarded as essential to finding life. And even if we assume liquid water…
Some analysts argue that the spumes may be a result of sublimation – a change from a solid, icy state to a vapour, missing out on the liquid phase – or of the decomposition of clathrate deposits. A clathrate is a type of ice lattice that traps gas [methane clathrates are found at the polar regions of Earth]. However, the recent discovery of salt in these plumes has made these possibilities less plausible. Salt is more likely to be associated with liquid water, but hydrogen cyanide, also recently found, would have been expected to react with liquid water to form other compounds, not found as yet. In short, the jury is still out on the presence of liquid water.
And assuming there is liquid water, how could we test for life within it? With great difficulty, obviously. Analysts would be searching for biomarkers, ‘chemicals that appear to have biological rather than geophysical origins’ [Cosmos 44, p78]. Photosynthetic production wouldn’t be an option, so other systems are being hypothesised, including a methanogenic system in which methane is synthesised from carbon dioxide, or a system of metabolizing acetylene, which occurs on Earth. Traces of acetylene have been found on Enceladus. Other biomarkers include amino acids with the right chirality – that’s to say a strong chiral preference, one way [as found on Earth] or its opposite. Amino acids with no chiral preference are likely to be abiotic.
To test for such biomarkers would require new instrumentation and another visit to this intriguing moon. Something else to look forward to. What would we do without anticipation?
is there life on mars?
good question, Davie
Back in 1975, NASA sent two space probes to Mars. Their landers touched down on the Martian surface less than a year later. The Viking 1 lander remained operational for more than six years, Viking 2 for three and a half. During this time, biological experiments were conducted upon Martian soil. As far as the general public is concerned, the results of these tests were negative, though for those in the know, it wasn’t quite that simple. Not that there was any great conspiracy or cover-up; the consensus amongst the cognoscenti was that the evidence tilted much more towards no-life than towards life, for the minute samples examined.
It seems, though, that exobiologists have long been intrigued by some of the findings in a particular batch of experiments, known as the Labelled Release experiments. As this Wikipedia article describes, these experiments involved a soil sample being inoculated with a weak aqueous nutrient solution. The nutrients were of the type produced in the famous Miller-Urey experiments of the fifties. Evidence was sought for metabolisation of these nutrients by micro-organisms in the soil, if any, and the first trial of these experiments produced surprisingly positive results. In fact, both the Viking probes produced initially positive results from different soil samples, one with a sample of surface soil exposed to sunlight, the other with a sample from beneath a rock. However, when the tests were repeated later, they produced negative results. Many other different types of biological tests were carried out during this mission, all of them yielding negative results. So it was all very inconclusive and mysterious.
Fast forward to April 2012, when a report was released by an international team of scientists suggesting that, after thorough analysis of the Labelled Release data, ‘extant microbial life on Mars’ may have been detected.
Researchers long ago abandoned the idea of multicellular life currently existing on Mars. Conditions for the maintenance of such life forms may have existed there billions of years ago – the Viking orbiters found evidence of erosion and the possible remains of river valleys – but those conditions have changed, though some have argued that the soil coloration and recent detection of silicate minerals indicates more recent signs of water, vegetation and microbial activity. All of this is highly contentious, but all good fun, and indicates that more research is required.
In 2008, a robotic spacecraft landed on Mars, in the polar region, and remained operational for about six months. The Phoenix lander had two principal objectives, to test for any history of water in the region, and to search for anything organic in the surrounding regolith [the surface layer of broken rock and soil affected by wind or water]. Preliminary data revealed perchlorate, an acid-derived salt, in the soil, which wasn’t a good sign. Perchlorate can act as an ‘anti-freeze’, lowering the freezing point of water. Generally, though, the pH levels of the tested soil, and its salinity, were benign from a biological perspective. CO2 and bound water were also detected.
We’ve only minutely scratched a few surface points of a huge beast, you might say. What we’ve found isn’t too promising, but it’s enough to keep us wanting to investigate further, just to make sure, or to know more. After all, there’s still plenty to learn about the surface of our own planet. Recently, for example, we learned how perchlorates can be formed from soils with highly concentrated salts, in the presence of UV and sun light. Chloride is converted to perchlorate in the process, which has been reproduced in the lab. Only in 2010, soils with high concentrations of perchlorate were discovered over a large section of Antarctica.
Between August 6 and August 20, that’s to say in two or three weeks time, the Mars Science Laboratory [MSL, also known as ‘Curiosity’] will land on Mars and look for further signs, past or present, of biological activity. It’s likely that whatever is discovered, not just in terms of life itself, but in terms of conditions for life, will be hotly debated. This Wikipedia article, covering the whole life-on-Mars search and debate, includes this intriguing para:
The best life detection experiment proposed is the examination on Earth of a soil sample from Mars. However, the difficulty of providing and maintaining life support over the months of transit from Mars to Earth remains to be solved. Providing for still unknown environmental and nutritional requirements is daunting. Should dead organisms be found in a sample, it would be difficult to conclude that those organisms were alive when obtained.
True enough, but even if dead, what a revelation it would be. Extra-terrestrial death means extra-terrestrial life, and so very very close to home in the great vastness of the universe. Another blow to our uniqueness, what terrible fun.
animals r us
I felt a bit disheartened a while back when a teenage lass I know and love declared to me that she ‘hated animals’. Worse, one of her aunties chimed in enthusiastically with, ‘yeah, I hate them too’. I wasn’t sure about taking these assertions seriously, especially the fifteen-year-old’s, but my suppressed response, apart from WTF???, might’ve been, uhh but you do know that you’re animals, right?
In fact I didn’t respond at all, being too taken aback, but I’m sure they knew they were animals, and yet…
Us and them thinking is commonplace. It’s a feature of any species of living thing that they’re concerned with other members of their species, both positively and negatively. We compete with members of our own species for resources, and we also share resources with our own species. We mate, and fight, with our own species. We try to impress our own, either by our scariness or our attractiveness, depending on circumstances. Other species just don’t matter so much to us, except insofar as we need them, or need to avoid them, for our survival.
I’m speaking for species in general here, but humans have learned something about other species that should make a big difference to us, and that is that all species are more or less related. We even have techniques which can tell us just how related we are. We know that we’re a bit more closely related to chimps than we are to gorillas, and that we’re a bit more related to gorillas than we are to gibbons, and that we share a much more common ancestor with tree shrews than we do with lungfish, but the important point is that we know that we’re related to every other organism in the biosphere, without which not, as they say. So to hate animals, if you really mean it, is to be self-defeating in a big way.
And hatred, or dismissiveness, towards other animals, surely comes from an unthinking us-and-them position, a position that needs to be continually questioned and challenged.
I recently read the excellent Shadows of forgotten ancestors by Carl Sagan and Ann Druyan. Much of it, especially the second half, is devoted to demolishing claims to human specialness, our separateness from ‘animals’. They do so mainly by examining the lives and behaviour of other primates. Much of the following will derive from their book. I will start with the most general claim, and then look at some specific ones
Humans are different from all other animals, not just in degree, but in kind.
This ultimate us-versus-them claim is questionable in many respects. It usually comes with particular examples: we are the only ones who have x, or can do x, therefore…
But are we the only ones with property x, and if we are, where does this property come from? Humans, we know, are primates. We share a common ancestor with chimps and bonobos going back six million years. Are we different in kind from that common ancestor? If, for argument’s sake, we say that we are, at what point did that qualitative, rather than quantitative, difference emerge? We are still unable to clearly trace our descent back to that common ancestor, but we have plenty of example of earlier hominids to chose from – this site offers some 20 distinct species that might have been along the line of descent. Which one, if any, represented a qualitative transformation? Or do incremental quantitative changes somehow amount to a qualitative transformation? If so, how many changes, and, again, when exactly did the quantitative become qualitative? I don’t think these are fruitful questions, and the more we learn about other species, the more these questions dissolve away.
We share the properties of other animals in many ways, but I’ll pick on sex as one of the clearer examples. Humans long ago realized that the castrating of war captives rendered them less aggressive – though they would’ve had little idea why. They did of course know why such a practise rendered then incapable of producing offspring, another signal benefit. The removal of the testes, whether in humans, cats, dogs, sparrows or quails, has much the same effect; aggression is reduced, as are various other male traits governing behaviour towards females and towards other males. The reason is that the testicles produce most of the androgens – that’s to say the steroids or sex hormones, such as testosterone. The action of testosterone and other sex hormones is strikingly similar across all animal species. Experimenters have added or removed the hormones with increasingly predictable results, not only in mammals and birds, but lizards and fish as well. This isn’t to say, though, that the males of all these species, when their sex hormones aren’t interfered with, are always the more aggressive or dominant gender, for that depends on how much, and what types, of the sex hormones are naturally produced or released. Male and female wolves, gibbons and tree squirrels are about equally aggressive. Species have, over time, developed the ‘right’ hormone levels for their kind – that’s to say, the most adaptive. Give certain birds too much sex hormone, and the males sometimes end up killing each other, and overall numbers fall. In all of this humans are no different.
Of course patterns of sexual behaviour vary among mammals. Most mammals only mate when the female is ‘in heat’, during a particular phase of the estrous cycle, the estrus phase, which precedes ovulation. Menstruating females, though – the menstrual cycle is a subset of the estrous cycle, in which endometrial material is shed during menstruation – including a number of primate species, are not confined in their sexual activity to a particular period [so, no, we’re not the only ones with that ‘freedom’]. Interestingly, though, human societies often have prohibitions against sex during the menstrual period, whereas in other primates, sexual activity actually increases at this time. One of the wonders of human culture.
Humans are the only creatures that make tools
We only need one solid counter-example to demolish these general claims, and in this case we have several to choose from, but I’ll opt here for a very well-attested one; the use of reeds, straws or vine branches by chimps to catch termites. Not all chimps are able to do this, and few are able to do it really well (we tend to forget, with other species, apart from the domestic ones we deal with every day, that they have their bright sparks and their half-wits just as humans do), but it’s a highly developed skill which human researchers haven’t been able to develop. What’s more, it’s a skill that takes years to develop, and older chimps teach it to the young. What chimps have to do is find just the right kind of tool for the job – that is, to be manipulated down a termite hole and retrieved from the hole with as many termites clinging to it as possible, to serve as a dish worthy of the effort and expertise. This requires matching the tool to the termite burrow, which means knowing the characteristics of the various mounds in the neighbourhood, and then having the dexterity, not only to get the tool into the hole with the minimum of disturbance to the termites but, more importantly, to be able to twist it and move it to attract termites to the ‘intruder’, and then withdraw it without knocking all the termites off. If chimps can’t find the right shape and size of tool, they can and do modify it to suit the job, which is no different in kind from early humans modifying stones for cutting and for use as weapons. Such stones are our first well-attested tools, though only, of course, because stone outlasts other materials. This activity is far from simply opportunistic. It requires planning and foresight, and it’s certainly not the only example of tool use in chimps or in other animals, including birds.
Humans are the only self-aware animals
We have to be careful, of course, not to define ‘self-awareness’ and other related concepts in such a way that they can only apply to humans. Similarly, I can think of ways of defining the term which would make it inclusive of a great many species. Because of the great difficulty of accurate definition here, it’s quite useful, as a first approximation, to use a crude, behaviourist approach to the problem, such as the well-known mirror test – first applied, though in a non-rigorous way, by Charles Darwin. All of the great apes can pass this test, as can elephants, some cetaceans, and, probably most surprisingly, European magpies. They all fail the mirror test initially, but soon learn that they’re looking at their own reflection. Humans don’t pass the mirror test before the age of eighteen months, on average – though there are some problems with the reliability of that measure because of possible flaws with the classic mirror test which I won’t go into here. Suffice to say that learning to use mirrors for grooming, etc, is pretty solid evidence of self-awareness in other species.
Humans are the only species able to conceptualize
‘It would be senseless to attribute to an animal a memory that distinguished the order of events in the past, and it would be senseless to attribute to it an expectation of an order of events in the future. It does not have the concepts of order, or any concepts at all.’ [Stuart Hampshire, philosopher]
The above sort of observation, though it wasn’t actually an observation, was commonplace in philosophy well into the 20th century, but research into ‘comparative cognition’ has largely blown this bias away, as you might expect, with a bit of thought. After all where does conceptualisation come from if it isn’t an evolutionary development over time and species? Of course the concept of concepts is a bit murky, but researchers have been able to distinguish three types of concept learning – perceptual, associative and relational – and a more sophisticated type of concept-formation called analogical reasoning. A 2008 survey of the research found that many non-human species were capable of the first three types, with only the higher primates showing evidence of the fourth.
Humans are the only species with language
‘Language is our Rubicon, and no brute will dare to cross it.’ [Max Muller, 19th century linguist]
There has long been a great debate about this one, and much research and effort put in to trying to teach the rudiments of language to chimps and bonobos. Sagan & Druyan dwell at length on this work, though well-known linguists such as Charles Hockett and Steven Pinker suggest that there is a bigger divide than sometimes admitted between other primates and humans in this area. Again, this depends on how tight, loose or technical your definition of language is. Still, no matter how language is defined to exclude non-humans – such as arbitrariness between sound and meaning, and discreteness in the construction of terms – researchers manage to find evidence of it in other creatures. Nobody denies that language has reached a pinnacle of sophistication with humans, but again there are many traces of complex communication in many other species, and it’s of no value to us to try to reduce their import. The Muller quote above indicates how our preoccupation with our own superiority can lead to a hostile attitude to any knowledge that dares to threaten it.
Humans are the only creatures who know they will die.
We know from an early age that we will die largely because of our sophisticated communications. We learn of the history of our culture, peopled with dead contributors, we see monuments to the dead everywhere, the disappearance of aged pets and relatives is patiently explained to us. Other animals, without these communications, may still feel it in their bones as the time approaches. There’s certainly evidence for mourning in elephants, chimps and many other animals.
Humans are the only ethical animals.
Ethics and social living are an almost essential pairing. The Biblical commandments that still make sense to us are all about making society more predictable and therefore more bearable to us as individuals, which is why they’re common to most religions and cultures. Whilst it may be argued that humans are more consciously and explicitly ethical than other social animals, some recent research has cast doubt on our freedom to choose our ethics. We appear to be driven, genetically, to preserve ourselves and our own, and to rationalise an ethical system around that drive. Other creatures have evolved the same drives and act in similar ways to ourselves.
Humans are the only animals that possess culture
If you think of culture as a process, rather than working back from cultural products, it would be hard to deny that this process exists in many other species. I’ve already pointed out that simple tool-making is passed down from adult chimps to children. This is cultural transmission, and is a basic factor in all culture. Basic tool-making and teaching were presumably the first forms of cultural transmission in humans.
Humans are the only creatures who explore their own origins, and the origins of all else
This may well be the last bastion, but again it doesn’t represent a difference in kind – even supposing that such explorations don’t occur to non-human minds. These types of explorations are the culmination of increasingly sophisticated concept-formation, meme-transmission and theoretical and technological development. With all this, knowledge, ideas and speculations are converging on us at an ever-increasing pace. It’s no surprise, therefore, that the idea of a ‘singularity’ has captured our imagination, tenuous though the idea might be. Interestingly, the idea of the singularity is another instance of quantity building up to a sudden ‘flip’, a qualitative transformation. Another self-serving and self-congratulatory idea perhaps?
We humans are quite fascinating, the more so the more we examine ourselves, but we are learning that what we’re made up of is the same stuff that other life forms are made of, and the similarities are every bit as instructive as the differences. We’re a distinct species, no doubt, but it is counter-productive to think of ourselves as a species apart.
bonobo genome sequenced, but nothing jumps out
I’ve long had an interest in bonobos, and now I read [via 3QD] that they’ve had their DNA sequenced, and researchers are trying to find clues in their genome as to their relatively placid and highly sexual behaviours. So we can now compare what the sequencing tells us with what has been learned in the field.
I’ve dealt a little with bonobos before in one of my experiments with podcasting here, where I told the story of how they were separated from chimps physically by the Congo River, maybe a couple of million years ago. The sequencing shows that this separation was radical and permanent, with modern bonobos showing no closer genetic affinity with their chimp neighbours across the river than with chimp populations much further away. It looks like it’s going to take some time, though, to identify in genetic terms the particular changes that have occurred since the split. In fact, it appears easier to identify environmental factors to explain bonobos’ more relaxed and non-aggressive behaviour when compared to chimps. North of the river the chimps compete for territory and food with gorillas, whereas south of the river the bonobos face relatively little competition.
The sequencing of one particular, possibly ‘atypical’ bonobo doesn’t necessarily provide all the answers, any more than it does with humans or any other species. In this case the specimen was an 18-year-old-female, Ulindi, who displayed quite a bit of aggression to one of the research team. In any case, there’s a lot of variation in bonobo behaviour, and to pick out one individual as ‘typical’ for sampling is as questionable as assuming that any one human is typical. The bonobo is the last of the ‘great apes’ to have its genome sequenced, following the chimp, the gorilla and the orang-outang, but some if not all of these species have sub-species, and there’s enough genetic variation within species to make it vital that we sequence more than one, and even more than a few, individuals of each species. As it is, preliminary findings from Ulindi’s genome indicate that we have a long way to go:
As a start, Prüfer’s team identified regions of the bonobo genome that differ from those of chimps and that may have evolved in bonobos since the split. Many of these regions contain no genes, while the genomic region that seems to have evolved the fastest in bonobos encodes a microRNA molecule that probably regulates the activity of as-yet unidentified genes.
So the story is complex and will take time and a lot more research to tease out. Some 1.6% of our genome is more closely related to that of bonobos than to that of chimps. The significance of this connection will also take time to establish. Mapping our genome to our closest relatives in this way will help us to determine how exactly we are different, to home in on that subsection of our genome that is unique to us. We’re still not clear on that, and then we have to try to work out what emerges from that subsection, in terms of physiology, behaviour and so forth.
returning to cephalopods
A while back I wrote about the extraordinary spawning grounds of the Giant Australian Cuttlefish in Spencer Gulf, not so far from here. Though I’d heard of this habitat a while ago, courtesy of the controversy around the placement of a desalination plant nearby, it took a fascinating TV doco to really spur my interest. Another recent documentary on the intelligence of octopuses, together with some bad news about those spawning grounds, has prompted me to return to the subject of this fascinating class of molluscs.
I’m particularly interested in the sub-class of cephalopods which includes cuttlefish, squid and octopuses [fisherfolk cluster them together as inkfish, for obvious reasons], a sub-class which, it seems to me, has become flavour of the month, or year, or decade, for marine biologists of late.
This season, the numbers of cuttlefish coming in to breed and spawn at Point Lowly in Spencer Gulf have been disastrously low. Those that have come are generally smaller than usual. They normally congregate in mid to late June. No clear cut reason for this drop is on offer [the desal plant is still at the proposal stage – maybe they heard about it on the seagrape vine?], and we’ll have to wait and see if they return next year. Of course we also don’t know if they’ve relocated, or if this would be a normal thing to do – for example we don’t know for how long they’ve been breeding at Point Lowly. It appears that nobody is responsible for monitoring cuttlefish numbers, and presumably nobody is responsible for monitoring temperature, salinity and other variables there either. The comments on the news article linked to above present various conspiracy theories, not too seriously I hope. BHP did it, to get rid of the cuttlefish as an environmental issue. The Greens did it, to highlight the sensitivity of cuttlefish to even rumours of environmental degradation. Others are arguing that the environment there has already been massively degraded recently, but they offer no suggestions as to what caused this, if it’s true. Hopefully some serious investigations can be made.
Meanwhile, research continues into the intelligence and learning abilities of octopuses. The documentary ‘Aliens of the Deep Sea’, which I saw a couple of nights ago, provided exciting proof of these abilities in a few simple but effective experiments. The most exciting of these involved a newly captured octopus being placed in a tank, where it tended to hide in a corner behind some rocks. A transparent container containing a crab, and with a hole on one side just large enough for the octopus to enter [octopuses are able to squeeze through the narrowest of openings, through distortions of their invertebrate bodies] was placed inside the tank. The octopus didn’t respond to the unfamiliar container. Then another tank was placed alongside it, containing an octopus of the same species. This octopus had been in captivity for some time, and had learned or been taught how to enter the opening to get at the tasty crab. So the experiment was repeated with the experienced octopus, and the inexperienced octopus literally rushed to the edge of its tank to get a ringside view of how the experienced octopus did it. I don’t know if there was any tricksy editing in this scene, but I do know that the sight of this eager spectating had me almost falling off the edge of my seat. And sure enough, when the experiment with the crab was repeated with the inexperienced octopus, it got the idea straight away, and was able to find the hole and get at the crab in no time at all. A number of similar experiments were shown [including the opening of a screw cap], and it became clear that the learning capabilities of these creatures were truly outstanding. It doesn’t seem to matter which species are chosen for these experiments, so it seems evident that such intelligence exists over the range of octopus species [there are presently around 300 recognized species], though more research might have to be done to confirm this.
All this raises tantalizing questions. How do they learn? Octopuses have short lifetimes [some as little as six months] and they learn virtually nothing from their parents, with whom they have almost no contact [females live only long enough to see their eggs hatch, and males die shortly after mating]. Also, how long have they been behaving in such an ‘evolved’ way? Cephalopoda date back some 500 million years, and a rare example of a fossilized octopus has been found, dating back 95 million years. This fossil appears to be remarkably similar to modern species – it appears that little evolving has taken place in the interim. So this kind of cleverness existed on the planet long before homo sapiens arrived on the scene. Indeed the first primates appeared only about 60 million years ago, according to current evidence. What we have here is a fascinating example of how highly intelligent life forms can evolve along completely different pathways from ourselves. Some researchers and atheists are keen to find extra-terrestrial life, especially of a highly evolved type, to demolish any notion that we are special, the uniquely privileged end-game of a supernatural designer. Yet we don’t have to look elsewhere for intelligence, it has been right under our noses throughout the lifetime of our species. We’ve just been too blind, too arrogantly bound up in our ‘specialness’, to really notice.
cool naturalism stuff in South Australia
It looks like there’s a bit of a focus on South Australia science-wise right now, which is fun.
Ed Yong, writing from Britain, reports on some findings from the Uni of Adelaide, just down the road from me – don’t you just love the internet – about bone holes in dinosaurs and what they tell us about dinosaur activity [not to mention the activity of other land-dwelling mammals]. More specifically, the femurs of all dinosaurs, as well as all humans, all birds, all reptiles, every creature that actually has a femur, have holes in them called ‘nutrient foramina’. The hole allows an artery to pass through, supplying the bone with blood and oxygen. Roger Seymour, the principal scientist in the study, found [after looking at about a hundred animals] that the bigger the femur, the bigger the hole, but that mammals had holes about twice the size of similarly-sized reptiles. This has to do with metabolism, which has to do with activity – the lifestyle of the particular creature. Mammals are generally much more active than reptiles. However, monitor lizards, which chase down and kill prey, are an exception. Their foramina are on a par with mammals of similar size.
The really interesting point of this study, though, is that it may be possible to infer much about a particular mammal or reptile’s lifestyle from the size of these holes. Especially in the case of extinct creatures whose behaviour we can’t observe directly. Seymour’s team examined the foramina of ten dinosaurs, and found that they were even larger for their size than those of mammals – suggesting a highly active lifestyle, fast growth, and a correspondingly hefty appetite. It’s an intriguing finding, because the lifestyles of these beasts, their diet and range, and whether or not they were warm-blooded, has long been a subject of debate. Seymour’s approach provides a way forward. His sample was quite small and localised, but there will probably be a lot of dinosaur-thigh-bone-hole-hunting on a world-wide scale in the near future.
I first came across another development out of South Australia in, of all places, the Murdoch-owned Adelaide Advertiser. I later came across it on the Panda’s Thumb blog, written up by P Z Myers. He refers us to a more detailed description at Why Evolution is True. It’s all about a discovery of a number of preserved complex eyes, dating back 515 million years, and found at the Emu Shale in Kangaroo Island, only a couple of hours’ drive [and a bit of a swim] from here. Matthew Cobb reckons this shale compares pretty well with Canada’s Burgess Shale and Chenjiang in China.
The dating puts these small compound eyes [about 7 millimetres long, with around 3000 individual lenses, called ommatidia] into the early Cambrian period, the first eyes of this type found before the Ordovician. Trilobites from the early Cambrian had highly developed eyes, but these eyes, believed to belong to an arthropod, possibly a bivalve arthropod species of Tuzoia, contain more ommatidia and are in other ways more complex. In fact, they bear comparison to modern complex eyes, as indicated by the photo of a modern species of fly, above. Apparently this has aerated the usual bunch of creationists who imagine that the existence of ‘fully-formed’ complex eyes in the Cambrian [aha! irreducible complexity!] is some kind of evidence against what they insist on calling Darwinism. This is just the usual cherry-picking of evidence. It’s hard to credit that these people trawl through the scientific research for anything that might confirm their fixation with fixity, while ignoring the masses of disconfirming evidence, but that’s just what they do. The point is that if a species evolves an effectively adapted visual apparatus, which it can do comparatively quickly, it seems, then that particular aspect of its evolution may not find an improvement, in that species or any other, for a long time. Natural selection still operates, but only in the negative sense, weeding out the maladaptive variants. Anyway, it’s an exciting story, from Kangaroo Island to the world.
The third story isn’t about any new discovery, but it’s about a nearby underwater world that I only became vaguely aware of a few years ago, when the South Australian government was considering building a desal plant at the top of Spencer Gulf. There was much talk of possible/probable disturbance to the unique breeding grounds of the Australian Giant Cuttlefish, Sepia apama, at Point Lowly, just north of Whyalla. Naturally I knew little about all this, but a recent documentary, about cuttlefish generally but with much focus on the particular species, the world’s largest, has certainly sparked my interest.
These creatures are truly amazing. Up to a quarter of a million of them come to Point Lowly to breed and spawn, after which they quickly die off. The doco showed them sort of giving up the ghost, a particularly eerie and moving sight. They only live for about two years, though they’re complex and highly intelligent creatures. They have three hearts [which for all I know may be standard stuff for cephalopods] and they use chromatophore cells to put on amazing light displays, for various purposes such as camouflage, impressing potential mates and ‘hypnotising’ prey. Here’s an excellent vid of a cuttlefish camouflaging itself. The recent doco showed the cuttlefish briefly putting on its ‘flicker show’, a kind of strobe lighting effect, when a fake lobster was placed in its territory, but it soon realised it was being duped and switched off. Researchers such as Roger Hanlon have found that cuttlefish only have three different ‘camouflage templates’, which they’re able to manipulate to blend into just about any underwater environment. Obviously there’s still a lot to learn about these particular beasties. They can also change shape to look like rocks or to look like females [which are smaller and more non-descript looking than the males]. The males grow to around one metre, including tentacles. So if you’re a cuttlefish lover, this ain’t a bad place to be.
I also note that there’s a cuttlefish fan club, based apparently in Singapore.