Why ancient earth wasn't an iceball

One of the great science mysteries might finally have been solved - why wasn't ancient Earth covered in ice?

Back in the early days of our planet, it was mostly covered in seas. Since the Sun was warming much less back then, it has puzzled scientists why these seas were not frozen. Now Danish and US scientists offer an explanation.

Why Earth Wasn't One Big Ball of Ice 4 Billion Years Ago When Sun's Radiation Was Weaker

Scientists have solved one of the great mysteries of our geological past: Why Earth's surface was not one big lump of ice four billion years ago when Sun radiation was much weaker than today. Scientists have presumed that Earth's atmosphere back then consisted of 30 percent CO2 trapping heat like a greenhouse. However, new research shows that the reason for Earth not going into a deep freeze at the time was quite different.

[...]

Now, however, Professor Minik Rosing, from the Natural History Museum of Denmark, and Christian Bjerrum, from the Department of Geography and Geology at University of Copenhagen, together with American colleagues from Stanford University in California have discovered the reason for "the missing ice age" back then, thereby solving the Sun paradox, which has haunted scientific circles for more than 40 years.

Professor Minik Rosing explains: "What prevented an ice age back then was not high CO2 concentration in the atmosphere, but the fact that the cloud layer was much thinner than it is today. In addition to this, Earth's surface was covered by water. This meant that the Sun's rays could warm the oceans unobstructed, which in turn could layer the heat, thereby preventing Earth's watery surface from freezing into ice. The reason for the lack of clouds back in Earth's childhood can be explained by the process by which clouds form. This process requires chemical substances that are produced by algae and plants, which did not exist at the time. These chemical processes would have been able to form a dense layer of clouds, which in turn would have reflected the Sun's rays, throwing them back into the cosmos and thereby preventing the warming of Earth's oceans.

So, the lack of life, which in turns leads to less clouds, and the liquid surfaces, are the reasons why the water didn't freeze, even when the heat from the Sun were lower.

This is a much better explanation than the earlier proposed explanation (also mentioned in the ScienceDaily article) that the CO₂ levels were much higher back then. The new investigation which led to the new explanation demonstrates that the CO₂ levels back then were higher, but nowhere nearly as much higher as the old explanation would have required.

The actual study is behind a paywall at Nature, but if you have access, you can find it here.

Social anxiety among macaques (and humans?) explained

ScienceDaily reports this interesting story

Genetic Variation Cues Social Anxiety In Monkeys And Humans

A genetic variation involving the brain chemical serotonin has been found to shape the social behavior of rhesus macaque monkeys, which could provide researchers with a new model for studying autism, social anxiety and schizophrenia. Humans and macaques are the only members of the primate family to have this particular genetic trait.

The original study was published in PLoS One

Serotonin Transporter Genotype Modulates Social Reward and Punishment in Rhesus Macaques

Background

Serotonin signaling influences social behavior in both human and nonhuman primates. In humans, variation upstream of the promoter region of the serotonin transporter gene (5-HTTLPR) has recently been shown to influence both behavioral measures of social anxiety and amygdala response to social threats. Here we show that length polymorphisms in 5-HTTLPR predict social reward and punishment in rhesus macaques, a species in which 5-HTTLPR variation is analogous to that of humans.

Methodology/Principal Findings

In contrast to monkeys with two copies of the long allele (L/L), monkeys with one copy of the short allele of this gene (S/L) spent less time gazing at face than non-face images, less time looking in the eye region of faces, and had larger pupil diameters when gazing at photos of a high versus low status male macaques. Moreover, in a novel primed gambling task, presentation of photos of high status male macaques promoted risk-aversion in S/L monkeys but promoted risk-seeking in L/L monkeys. Finally, as measured by a “pay-per-view” task, S/L monkeys required juice payment to view photos of high status males, whereas L/L monkeys sacrificed fluid to see the same photos.

Conclusions/Significance

These data indicate that genetic variation in serotonin function contributes to social reward and punishment in rhesus macaques, and thus shapes social behavior in humans and rhesus macaques alike.

Since there are so big similarities between humans and macaques in this regard, they probably serve as a good animal model for human behavior, which makes this finding very interesting indeed.

One interesting thing about this, is that there are quite different frequencies of the different genetic variation among different human populations, which could help explaining different social behavior in different cultures.

PZ is getting slow

In the old days, PZ would not have let someone else scoop this story, but I guess he is getting slow now where he is king of the mountain.

ScienceDaily reports

Octopus Family Tree Traced Using New Molecular Evidence

Octopuses started migrating to new ocean basins more than 30 million years ago as Antarctica cooled and large ice-sheets grew.

I don't really have anything to add to this story, though I suggest people go read it. I just wanted to scoop PZ.

Aggressive people might get pleasure from the pain of others

ScienceDaily reports on a new study that indicates that aggressive youth get a kick out of seeing other people in pain.

Bullies May Enjoy Seeing Others In Pain

Scans of the aggressive youth's brains showed that an area that is associated with rewards was highlighted when the youth watched a video clip of someone inflicting pain on another person. Youth without the unusually aggressive behavior did not have that response, the study showed.

The youth were picked because they had a record of aggressive behavior, while the control group didn't have such records.

The study is interesting because it indicates that aggressive people don't just lack empathy, they actually enjoy seeing other people in pain. In other words, they are sadists (though not necessarily with the sexual connotations that word sometimes contains).

There is more about the study at the website of the University of Chicago, which also links to a pdf version of the paper which is published in Biological Psychology.

So, what does this mean? Well, I guess it will be easier to determine whether aggressive behavior by someone is an one-time occurrence, or it might be symptoms of a general tendency towards aggression. In the later case, it might be important to work with the aggressive person, so they can try to behave in a socially acceptable manner. It cannot be stressed enough that just because someone get pleasure from something, it doesn't mean that they cannot avoid doing that thing. So, in other words, this knowledge must never become a tool for judging people, though it could perhaps be used as migrating circumstances in first-time juvenile cases.

BBC also writes of the study, and they bring up an important point.

Dr Michael Eslea, senior lecturer in psychology at the University of Central Lancashire said the research was interesting but needed to be repeated in a larger sample.

"A better understanding of the biological basis of these things is good to have but the danger is it causes people to leap to biological solutions - drugs - rather than other behavioural solutions."

Yes, just going for drugs is not a good long-term solution, but in some cases it could perhaps be a short-term solution.

When do people start learning from their mistakes?

Well, for some people, the answer to that question would be never, but generally it happens when children grow older. The question is of course, how old?

According to a new study, the answer to that question is after they've turned 12.

ScienceDaily reports the story.

Learning From Mistakes Only Works After Age 12, Study Suggests

Eight-year-old children have a radically different learning strategy from twelve-year-olds and adults. Eight-year-olds learn primarily from positive feedback ('Well done!'), whereas negative feedback ('Got it wrong this time') scarcely causes any alarm bells to ring. Twelve-year-olds are better able to process negative feedback, and use it to learn from their mistakes. Adults do the same, but more efficiently.

This would indicate that different teaching strategies are needed for different age-groups. Pre-teens should be taught through positive feedback, while teens and older should also have negative feedback mixed in.

The ScienceDaily article goes into more details, and is well worth reading. The original study by van Duijvenvoorde et al., Evaluating the Negative or Valuing the Positive? Neural Mechanisms Supporting Feedback-Based Learning across Development, can be found here at The Journal of Neuroscience, but is unfortunately behind a paywall.

Many new species found in the Great Barrier Reef

Yet again we see an example of new species getting found when scientists start looking through an area systematically.

ScienceDaily has the story

Explorers Find Hundreds Of Undescribed Corals, Other Species On Familiar Australian Reefs

Hundreds of new kinds of animal species surprised international researchers systematically exploring waters off two islands on the Great Barrier Reef and a reef off northwestern Australia -- waters long familiar to divers.

As the paragraph shows, my headline was a little misleading. It's not only the Great Barrier Reef which the scientists looked at, and found new species.

Interestingly enough, these species have been under our noses all the time, we just haven't looked properly.

The effort that lead to these discoveries are part of the Census of Coral Reefs

Lucky dinosaurs

ScienceDaily has an intriguing article titled Good Luck, Not Superiority, Gave Dinosaurs Their Edge, Study Of Crocodile Cousins Reveals

Back when dinosaurs first started to evolve to the types we have hear about (or have seen in Jurassic Park), there were several competing groups of animals that might evolve to the dominant species. Among those were the ancestors to the modern day crocodiles, the crurotarsan archosaurs, which together with dinosaurs formed the Archosauria group (which now consists of the crocodiles and the decedents of the dinosaurs - the birds).

It has been assumed that dinosaurs had some kind of edge over the other groups, including their cousins, the proto-crocodiles. The research mentioned in the ScienceDaily article, however shows otherwise.

The researchers examined the evolutionary pattern of dinosaurs and crurotarsans in the Late Triassic. Using a very large dataset of anatomical characters – nearly 500 features of the skeleton – and a new family tree of the entire archosaur group, they measured evolutionary rates and morphological disparity (a measurement of the range of different body plans and lifestyles that a group has).

They found no difference in the rates at which dinosaurs and crurotarsans were evolving. This was surprising as, if dinosaurs were truly 'superior' or 'out-competing' crurotarsans in the Triassic, they should be expected to evolve faster. Instead, crurotarsans were keeping pace.

The results for the second measure, morphological disparity, were even more remarkable. Crurotarsans had a much higher disparity than dinosaurs in the Triassic. In other words, crurotarsans were exploring a larger range of body types, diets, and lifestyles. This greatly contrasts with the classic image of dinosaur superiority since their greatest competitors, the crurotarsans, were doing so much more.

To these surprising results can be added two other, previously known, findings: crurotarsans were more abundant (more individuals, more fossils, more species) than dinosaurs in many Triassic ecosystems, and crurotarsans were in some cases more diverse (greater number of species). Putting all this together, it is very difficult to argue that dinosaurs were 'superior' to crurotarsans, or that they were out-competing crurotarsans.

So, it's debatable if dinosaurs actually were the dominant species when looking at the period as a whole. Why then the impression that they were? Well, first of all, it's not easy to tell fossils from the two subgroups apart, so in the past many crurotarsan fossils were considered dinosaur fossils. Second of all, dinosaurs won out in the end, continuing after the crurotarsans died in great numbers. This is also explained in the ScienceDaily article

Steve Brusatte, who conducted the research while an MSc student in Bristol University's Department of Earth Sciences, said: "If we were standing in the Late Triassic, 210 million years ago or so, and had to bet on which group would eventually dominate ecosystems, all reasonable gamblers would go with the crurotarsans. There was no sign that dinosaurs were eventually going to succeed so why did they? The answer is two mass extinction events: the dinosaurs not only got lucky, but they got lucky twice.

"They first weathered the storm during the Carnian-Norian event 228 million years ago, but so did the crurotarsans. In contrast, many other potential competitor groups went extinct. Then dinosaurs weathered a second, much bigger, storm 200 million years ago. This was the end Triassic extinction event, which was a sudden and catastrophic extinction caused by rapid climate change, possibly facilitated by an asteroid impact. Strangely, and suddenly, all crurotarsans except for a few lineages of crocodiles went extinct. On the other hand, the dinosaurs did not. They survived and then radiated in the Early Jurassic, and very quickly established themselves as the dominant vertebrate group on land across the world.

"Why did crurotarsans go extinct and not dinosaurs? We don't know the answer to that, but we suspect that it was nothing more than luck, plain and simple."

When we talk about randomness in evolution, this is the sort of things we mean. It's a typical case of a major impact occurrence which for some reason affected the one group of animals more than the other.

The Science article by Brusatte et al is behind a paywall, but can be found here: Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs

Invasive species implicated in killing prehistoric animals

New findings show that it's likely that an invasive species killed off large marsupial species in prehistoric Australia.

What invasive species would that be? Home sapient, the most invasive around.

ScienceDaily has the story.

Humans Implicated In Prehistoric Animal Extinctions With New Evidence

Research led by UK and Australian scientists sheds new light on the role that our ancestors played in the extinction of Australia's prehistoric animals. The new study provides the first evidence that Tasmania's giant kangaroos and marsupial 'rhinos' and 'leopards' were still roaming the island when humans first arrived.

The findings suggest that the mass extinction of Tasmania's large prehistoric animals was the result of human hunting, and not climate change as previously believed.

While the ScienceDaily article makes it sound like this is amazing news, but the idea of a human cause of the megafauna's extinction is hardly a novel idea, and it has certainly been investigated before. PNAS had a good overview article on it back in 2002 Explaining the Pleistocene megafaunal extinctions: Models, chronologies, and assumptions by Brook and Bowman.

The focus of these investigations have mostly focused on whether there were an overlap of human and megafauna inhabitation of Australia, but other studies have shown that even if there were, the extinction might still be at least partly caused by climate changes - see e.g Prolonged coexistence of humans and megafauna in Pleistocene Australia (.pdf) by Trueman et al.

According to the ScienceDaily article, new findings puts humans as the culprits.

Previous research by Professor Flannery and Professor Bert Roberts of the University of Wollongong, Australia, has shown that 90 per cent of mainland Australia's megafauna disappeared about 46,000 years ago, soon after humans first settled the continent. But humans did not reach Tasmania until a few thousand years later, when the island became connected to the mainland by a land bridge as sea levels fell during the last glaciation. "The Tasmanian results echo those on mainland Australia, putting humans squarely back in the frame as the driving force behind megafaunal extinction", said Professor Roberts.

It should perhaps be pointed out that human driven extinction could be cause indirectly, e.g. through changes to the living habitats by the burning of forests etc. or by animals brought along by the humans (e.g. dingos).

Unfortunately it appears that the study the ScienceDaily article refers to haven't appeared online yet - it should be published in the Proceedings of the National Academy of Sciences of the USA (PNAS), so I expect it to be only a matter of time before it's available (though probably behind a paywall).

While looking after the article, however, I did come across to one that's seems somewhat related:
Species invasions and extinction: The future of native
biodiversity on islands (.pdf) by Sax and Gaines. It does address the role of humans in the recent extinction of species.

Weakness in virus gives hope for cancer cure

ScienceDaily has the news.

Serious Weakness Found In Virus Responsible For Most Cervical Cancer

The virus responsible for most cases of cervical cancer has a serious weakness which may provide hope for new treatments for the disease.

Human Papillomavirus (HPV), a virus which causes several types of cancer but is particularly associated with cervical cancer, has developed clever ways of hiding in the body, but researchers at the University of Leeds have found that its ability to trick the body's first line of defence leaves it vulnerable to attack from a second defence system.

This sounds like a promising line, and hopefully the new knowledge can lead to a treatment for this virus, before it causes cancer.

Evolution is not random

We all know that a lot of people misunderstand the concept of evolution, and believes it to be random ("pure chance"), but this is not what the theory states at all.

Now, a new international study shows that the theory is right, and evolution is not random.

Via ScienceDaily:
New Findings Confirm Darwin's Theory: Evolution Not Random

According to Darwin’s theory of evolution, individuals in a species pass successful traits onto their offspring through a process called “deterministic inheritance.” Over multiple generations, advantageous developmental trends – such as the lengthening of the giraffe’s neck – occur.

An opposing theory says evolution takes place through randomly inherited and not necessarily advantageous changes. Using the giraffe example, there would not be a common neck-lengthening trend; some would develop long necks, while others would develop short ones.

Now, the findings of an international team of biologists demonstrate that evolution is not a random process, but rather occurs through the natural selection of successful traits. The collaborative study by researchers at the Technion-Israel Institute of Technology in Israel, the U.S, France and Germany is published in the November 2007 issue of Current Biology (vol. 17, pp. 1925-1937).

To settle the question about whether evolution is deterministic or random, the researchers used various tools – including DNA strand analysis and electronic microscopy – to study female sexual organ development in 51 species of nematode, a type of worm commonly used to better understand evolutionary processes.

The findings showed similar development in the species, which falsifies the idea that the development is random.

The Current Biology article about the study, can be found here:
Trends, Stasis, and Drift in the Evolution of Nematode Vulva Development. It's quite technical, and much of it went over my head. Still, it's worth taking a look at.

New knowledge about glacier behavior

I wasn't aware that the behavior of outlet glaciers was still clouded in mystery, but from what I can understand from this ScienceDaily article, there have been some unexplained behavior.

Alaska Glacier Speed-up Tied To Internal Plumbing Issues, Says Study

A University of Colorado at Boulder study indicates meltwater periodically overwhelms the interior drainpipes of Alaska's Kennicott Glacier and causes it to lurch forward, similar to processes that may help explain the acceleration of glaciers observed recently on the Greenland ice sheet that are contributing to global sea rise.

Basically, glaciers have some paths through which water can travel, but occasionally, those paths might not be enough, and the whole glacier moves. This has probably started to happen more frequently because of the increased amount of melting that happens because of the increased temperatures.

The study was published in a new monthly scientific journal, Nature Geoscience. To my surprise, it's possible to access the full paper: Response of glacier basal motion to transient water storage

I think this will be great news for people working under deadlines

Via ScienceDaily, I see that researchers reverse effects of sleep deprivation

Researchers at Wake Forest University School of Medicine have shown that the effects of sleep deprivation on cognitive performance can be reversed when the naturally occurring brain peptide, orexin-A, is administered in monkeys.

This is a very interesting finding, since earlier research has shown that it's possible to reach a state where it's no longer possible to catch up on sleep when sleep deprived. See Youngsoo Kim et al (link takes you to the abstract, but if you click on the pdf link in the right side, you can get to the full article).

This is obviously more Coturnix's field of expertise, but I would guess that it will need more research into the long term harmful effects of 'catching up' with this peptide has been investigated. It might be that it's 'cost free' so to speak, but before used on humans, we have to be certain about this (or at least know the costs).

The research was published in the Journal of Neuroscience, and the abstract can be found here. The full article is unfortunately hidden behind a pay wall.

Invasive fish in Australia

As most people are probably well aware, Australia has a lot of trouble with invasive species. Of course, people tend to think of rabbits and maybe rats, foxes, and Cane Toads. There is, however, another widespread one - the European, or Common, Carp. This particular invasive species is also widespread in the US and Canada, causing problems for the native fish.

From Australia, there is now evidence that the current drought that New South Wales is experiencing, is reducing the spreading of the carp. While the drought obviously have some bad consequences on a number of things, it might make it possible to get rid of these unwanted fish, who makes up 80-90% of all fish in inland NSW.

Even if the fish are not removed, the drought has led to new knowledge about their breeding habits, allowing for more efficient combating of the fish.

Better understanding of mammalian hearing

I had the impression that the hows and whys of hearing was pretty much known, at least when it came to mammals, but a new discovery shows that I was wrong about that.

ScienceDaily reports on it.

New Hearing Mechanism Discovered

MIT researchers have discovered a hearing mechanism that fundamentally changes the current understanding of inner ear function. This new mechanism could help explain the ear's remarkable ability to sense and discriminate sounds. Its discovery could eventually lead to improved systems for restoring hearing.

MIT Professor Dennis M. Freeman, working with graduate student Roozbeh Ghaffari and research scientist Alexander J. Aranyosi, found that the tectorial membrane, a gelatinous structure inside the cochlea of the ear, is much more important to hearing than previously thought. It can selectively pick up and transmit energy to different parts of the cochlea via a kind of wave that is different from that commonly associated with hearing.

The article explains in some detail how this discovery differentiates from our former knowledge.

It has been known for over half a century that inside the cochlea sound waves are translated into up-and-down waves that travel along a structure called the basilar membrane. But the team has now found that a different kind of wave, a traveling wave that moves from side to side, can also carry sound energy. This wave moves along the tectorial membrane, which is situated directly above the sensory hair cells that transmit sounds to the brain. This second wave mechanism is poised to play a crucial role in delivering sound signals to these hair cells.

In short, the ear can mechanically translate sounds into two different kinds of wave motion at once. These waves can interact to excite the hair cells and enhance their sensitivity, "which may help explain how we hear sounds as quiet as whispers," says Aranyosi. The interactions between these two wave mechanisms may be a key part of how we are able to hear with such fidelity - for example, knowing when a single instrument in an orchestra is out of tune.

It's always fascinating when scientists expand on our knowledge, especially so when it's on our knowledge of how the body functions.

The research has been published in Proceedings of the National Academy of Sciences (with the graduate student as the first-name author), and it's a featured article, so it's available for free.

Longitudinally propagating traveling waves of the mammalian tectorial membrane

Altruism in wasps tied to maternal behavior

ScienceDaily reports on an interesting study of wasps, where to researchers took a look at the genes of the different types of wasps, and saw if there was any connection to their genes.

Altruism Evolved From Maternal Behavior, Wasp Genetics Study Suggests

Researchers at the University of Illinois have used an innovative approach to reveal the molecular basis of altruistic behavior in wasps. The research team focused on the expression of behavior-related genes in Polistes metricus paper wasps, a species for which little genetic data was available when the study was begun.

Like honey bee workers, wasp workers give up their reproductive capabilities and focus entirely on nurturing their larval siblings, a practice that seems to defy the Darwinian prediction that a successful organism strives, above all else, to reproduce itself. Such behaviors are indicative of a eusocial society, in which some individuals lose, or sacrifice, their reproductive functions and instead work to benefit the larger group.

I don't get the use of 'Darwinian' unless it refers to some predictions made by Darwin. Even if it does, the reference to the prediction seems a bit weird, as it has long been known that evolution works on the species level, so it's not important if one particular individual reproduces, but rather that the species on the whole, reproduces in the most efficient way possible. For some species that apparently involves "a eusocial society" (an expression I've never heard before).

The researchers found that the pattern of behavior-related genes expressed in the brains of worker wasps was most similar to that seen in foundresses, the female wasps who alone build new colonies and devote much of their early lives to maternal tasks.

"These wasps start out as single moms," said postdoctoral researcher Amy Toth. "They don't have any workers to help them, so they're responsible for laying all the eggs and provisioning the developing larvae which then turn into workers."

The researchers selected this species because it appears to represent an evolutionary transition. Once a foundress has raised a first generation of workers, she turns over the task of nurturing the larvae to the workers and devotes herself entirely to her "queenly" reproductive function.

At this point, the researchers discovered, behavioral gene expression in her brain changes, becoming distinct from that seen during her maternal period.

Toth noted that the P. metricus wasps represent a kind of intermediate stage in the evolution of eusocial behavior. The honey bee colony, in which queens never perform maternal tasks, is considered a more developed form of eusociality.

So, queens have a different behavioral gene expression than foundresses, who are more similar to workers in their expression than queens and gynes (future queens in existing colonies). So, in other words, worker wasps (bees, etc.) are more maternal even though they are unable to sexually reproduce.

That's quite interesting.

It does not follow that all observed altruistic behavior have roots in maternal (or paternal) behaviour, but it would follow from what we generally know about evolution.

The study can be found here (behind a paywall)

This might revolutionize cancer treatment

One of the big issues with cancer treatment is finding the cancer in time to do something about it. At ScienceDaily there is some news which might help in this regard.

New Technology For Cancer Screening Listens For The Signs Of Cancer

Cancer-sensing devices built as cheaply and efficiently as wristwatches -- using many of the same operating principles -- could change the way clinicians detect, treat and monitor cancer in patients.

A device which can be mass-produced cheaply sounds like good news indeed. This would mean that it could be widely distributed to family doctors (presuming it's easy to use), and save people hospital visits for a diagnosis.

Researchers from the Georgia Institute of Technology have created an acoustic sensor that can report the presence of small amounts of mesothelin, a molecule associated with a number of cancers including mesothelioma, as they attach to the sensor's surface.

I am sure this will result in a number of false positives, but I'd rather have false positives, than diagnoses that come to late to do anything about it.

Of course, it's important to note that not all types of cancers would be possible to detect this way.

According to the researchers, the study is a proof of principle, demonstrating a technique that might work for the detection of nearly any biomarker -- a collective term for a molecular signal that denotes the presence of disease.

"It is one thing to be able to identify biomarkers for a disease, but it is another to be able to find them in blood quickly and easily at very low concentrations," said Anthony Dickherber, a graduate student in the School of Electrical and Computer Engineering at Georgia Tech. "We envision that, one day, doctors can use an array of our sensors as a sort of laboratory in their office, where they could use a quick blood sample to detect or monitor the signs of cancer."

I hope that the proof of principle can be reproduced, and that this device will become available as fast as possible. If they are right, I can't see any downside to the device. However, it would require the device to be at least as reliable in detecting cancers than current methods (though more false positives would be acceptable) for it to become a reliable first step of diagnosis.

A good example of a field, engineering, bringing its expertise to another field, medicine, to help solve a problem. Hopefully it will fulfill its potential.

New NASA computer model predicts more severe storms

Via ScienceDaily I became aware of this NASA press release:

NASA Study Predicts More Severe Storms With Global Warming

NASA scientists have developed a new climate model that indicates that the most violent severe storms and tornadoes may become more common as Earth’s climate warms.

This is quite on par with what we already presume. As a matter of fact, I'm pretty sure that it's the premise of Chris Mooney's newest book.

Previous climate model studies have shown that heavy rainstorms will be more common in a warmer climate, but few global models have attempted to simulate the strength of updrafts in these storms. The model developed at NASA’s Goddard Institute for Space Studies by researchers Tony Del Genio, Mao-Sung Yao, and Jeff Jonas is the first to successfully simulate the observed difference in strength between land and ocean storms and is the first to estimate how the strength will change in a warming climate, including “severe thunderstorms” that also occur with significant wind shear and produce damaging winds at the ground. This information can be derived from the temperatures and humidities predicted by a climate computer model, according to the new study published on August 17 in the American Geophysical Union’s Geophysical Research Letters. It predicts that in a warmer climate, stronger and more severe storms can be expected, but with fewer storms overall.

Interesting. I knew that it was presumed that there would be more strong storms, and that the strength of the strongest ones would be worse, but I didn't know that tehre would be an overall decline in the number of storms.

As the NASA story tells, the models has been applied to know conditions, and was correct, so it would seem that we should take its predictions seriously. Given that those predicitions are quite uncomfortable, it again shows us the bad consequences of global warming.

Go read the rest of the story

Physical and mathematical modelling gives new knowledge about the feeding habits of pterosaurs

ScienceDaily has an interesting piece about how new research shows that our theories about some pterosaurs' feeding habits have to be re-evaluated.

Feeding Habits Of Flying Reptiles Uncovered

Using new physical and mathematical modelling, Dr Stuart Humphries from the University of Sheffield, along with scientists from the Universities of Portsmouth and Reading, has shown that suggestions that extinct pterosaurs gathered their food by 'skimming' the surface of the ocean with their beaks are inaccurate.

Previous studies have suggested that some pterosaurs may have fed like modern-day 'skimmers', a rare group of shorebirds, belonging to the Rynchops group. These sea-birds fly along the surface of lakes and estuaries scooping up small fish and crustaceans with their submerged lower jaw. Inferred structural similarities between pterosaur and Rynchops jaws had previously been used to suggest that some pterosaur were anatomically suited for skimming.

However, new evidence provided by the researchers suggests that the fossilised jaws of suggested pterosaur skimmers mean that these creatures may have found it impossible to feed in this way.

According to the research, the thicker jaws of pterosaurs would make it difficult for them to deflect water the way the extraordinarily slim bills of Rynchops do. By combining experiments using life-size models of pterosaur and skimmer jaws with hydrodynamic and aerodynamic modelling, the researchers demonstrated that skimming requires more energy than the giant reptilian fliers were likely able to supply.

In other words, what we assumed about the feeding habits of these prehistoric creatures is almost certainly wrong, and other ideas have to be tested. Due to the simple fact that these creatures cannot be observed while feeding, we can never be entirely certain about how they feed, but we can at least remove some possibilities, and make a case for the most likely way.

The findings are also interesting because they show that we can't assume anything from just the shape and form and form of the fossils. Something the article also states.

Discovering the ecological traits of these reptiles though is far more complicated. One way scientists currently gain an insight into ecological traits of extinct animals is by comparing fossilized morphological (shape and form) features to those of living animals.

However, as this new research shows, these records do not provide direct evidence of behaviour and ecology. Dr Humphries, from the Department of Animal and Plant Sciences, said: "Our results illustrate the pitfalls involved in using morphological data to study the ecology of extinct animals, including dinosaurs and pterodactyles."

This shows the importance of re-evaluating and testing our ideas frequently. In this case, it probably makes little difference that our assumptions were wrong, but in other cases, those assumptions could be the basis of other assumptions, which would have to be re-evaluated, or maybe even discarded, as an result of the first assumptions being wrong.

Annoyingly, the ScienceDaily article didn't state where the study was published, but I managed to locate it at PLoS Biology
Did Pterosaurs Feed by Skimming? Physical Modelling and Anatomical Evaluation of an Unusual Feeding Method

Author Summary

Just because a component of an extinct animal resembles that of a living one does not necessarily imply that both were used for the same task. The lifestyles of pterosaurs, long-extinct flying reptiles that soared ancient skies above the dinosaurs, have long been the subject of debate among palaeontologists. Similarities between the skulls of living birds (black skimmers) that feed by skimming the water surface with their lower bill to catch small fish, and those of some pterosaurs have been used to argue that these ancient reptiles also fed in this way. We have addressed this question by measuring the drag experienced by model bird bills and pterosaur jaws and estimating how the energetic cost of feeding in this way would affect their ability to fly. Interestingly, we found that the costs of flight while feeding are considerably higher for black skimmers than previously thought, and that feeding in this way would be excessively costly for the majority of pterosaurs. We also examined pterosaur skulls for specialised skimming adaptations like those seen in modern skimmers, but found that pterosaurs have few suitable adaptations for this lifestyle. Our results counter the idea that some pterosaurs commonly used skimming as a foraging method and illustrate the pitfalls involved in extrapolating from living to extinct forms using only their morphology.

Are older drivers more likely to cause accidents?

ScienceDaily has an article about some new RAND research that shows the usual RAND quality in their papers - i.e. next to none.

Drivers 65 and older are just one-third as likely as drivers 15 to 24 to cause auto accidents, and not much more likely than drivers 25 to 64 to cause accidents, according to a new RAND Corporation study.

Does that RAND study show that? Well, RAND and the authors of the studies says so, but when reading the RAND paper about the study, it becomes clear that this is a highly doubtful claim.

The paper can be found Regulating Older Drivers - Are New Policies Needed? by David S. Loughran, Seth A. Seabury, and Laura Zakaras (.pdf)

In the introduction, the authors write

Although it has been scientifically established that physical and cognitive degeneration at older ages compromises driving ability, it is not clear just how much riskier older drivers are than other drivers. Most published research shows that accidents per mile driven increase when drivers are in their fifties and, by the time they reach their eighties, accidents per mile driven are almost as high as they are for the youngest drivers (see, for example, Li, Braver, and Chen, 2003). As we describe later, however, this measure of risk can be misleading.

Our research departs from previous studies that rely on this measure. Instead, we use an innovative statistical method to estimate the likelihood that older drivers will cause an accident relative to the likelihood that other drivers will cause an accident, controlling for vehicle miles driven. We will refer to this statistic throughout this paper as the relative riskiness of older drivers. Levitt and Porter (2001) first devised and employed our statistical method in their study of the relative riskiness of drunk drivers. Based on our findings, we make a number of policy recommendations aimed at stemming the rise in traffic-related injuries and deaths that are expected as the average age of the driving population increases.

I am probably not alone in thinking that a study using "an innovative statistical method", that reaches a different conclusion from all studies, raises some major warning signs.

The traditional method of looking at accidents per mile driven takes into account that older people drive less than other people, and looks at the relative risk created by the older drivers.

The authors of the paper argue that older drivers tend to be more risk adverse in their driving (avoiding high speed zones, driving in the dark etc.), so they feel that a look of the dangers imposed by giving older driver easy access to renew their driver's license should reflect this.

This sounds somewhat reasonable, until one realizes that even with the risk adverse behaviour, people aged above 75 is more dangerous when they are on the road than any other group of people, except people aged below 25 (see figure 2.1 in the paper), who certainly are not risk adverse. In other words, the old people who renew their diver's license impose a disproportional number of the accidents. Making it harder for older people to renew their driver's license would have a disproportional positive influence on the number of road accidents (as would making it harder for people under 25).

There are also some other problems with the study, since it only looks at the age of drivers involved in accidents resulting in fatalities. This is certainly one parameter of risk, but there are also the accidents resulting in non-fatal injuries (something the authors acknowledge), accidents with only material damage, and accidents caused by other peoples' risky behaviour.

Once the authors have looked at the age of people involved in fatal accidents, they find that more accidents are caused by younger people than older people (two groups that are not precisely defined in the study).

In summary, we find that older drivers are only slightly likelier than other drivers to cause an accident but are considerably likelier to be killed in one. Younger drivers, on the other hand, are considerably likelier than other drivers to cause a crash, drive much more frequently than older drivers, and are less susceptible to fatal injuries than older drivers are. These findings do not mean that driving skills do not, in fact, deteriorate with age as a result of worsening mental
and physical impairments. Instead, our evidence suggests that older drivers adjust their behavior in light of these worsening impairments. Many older drivers cease to drive altogether; many others reduce the miles they drive and avoid the most dangerous driving conditions. Because they are aware of their own limitations and adjust their driving patterns in response, older drivers pose only a slightly increased risk to other drivers. The main danger they pose on the road is not to others but to themselves.

Again this sounds reasonable until you think a little harder about it. Yes, we know that younger people causes more accidents than older people (here I define younger people as below 25), but that's because of very different reasons. Younger people are usually involved in accidents because of inexperience and/or risky behaviour (like drunk driving), something that cannot be tested for when renewing a driver's license. Old people on the other hand, are involved in more accidents due to having their driving ability impaired. Something that could easily be tested for when renewing a driver's license.
In other words, just because a different group of drivers are more risky, doesn't mean that the problem of old people driving past their ability shouldn't be addressed. And the fact that they are more at risk to themselves doesn't mean that they are not unqualified for renewing their driver's licenses. The driver's license is a license to drive a potentially deadly vehicle, and should only be given to people who are actually able to drive it without posing a danger to themselves or others.

I agree with the study that the relative risk caused by younger people should certainly be addressed, but this is not a zero-sum game. Making it harder to get a driver's license for younger people (or easier to loose it) doesn't mean that the states can't at the same time reduce the risks caused by older people driving. Both things could (and should) be done to reduce the number of accidents.

RAND probably publishes some well-researched papers some times, but I have yet to come across any. I am quite disappointed at ScienceDaily for just passing on such bad stuff.

Understanding anaesthetics better

One of my friends is an anaesthetic doctor, who works in hospitals all over Europe. My friendship with him has resulted in at least two pieces of worrysome knowledge. One is, how bad certain countries' hospital systems really are. The other one is how dangerous anaesthetics really is (don't worry, in modern hospitals, it's pretty risk-free).

One of the reasons why anaesthetics are so dangerous is because of the lack of knowledge about how they works on humans. We know that a certain amount will knock someone out, but individual reactions are very varied - that's why people are observed pretty closed while under anaesthetia. This is generally done with hi-tech equipment these days, which is why it's pretty much risk-free in modern hospitals - not so in countries/hopsitals with less than state of the art equipment.

In ScienceDaily there is some good news related to this.

Scientists A Step Closer To Understanding How Anaesthetics Work In The Brain

An important clue to how anaesthetics work on the human body has been provided by the discovery of a molecular feature common to both the human brain and the great pond snail nervous system, scientists now report. Researchers hope that the discovery of what makes a particular protein in the brain sensitive to anaesthetics could lead to the development of new anaesthetics with fewer side effects.

This is great news, as the article makes clear.

This kind of research, explains Professor Franks, is important because understanding exactly how anaesthetics work may pave the way for the development of a new generation of anaesthetics which solely affect specific anaesthetic targets, which could potentially reduce the risks and side effects associated with current anaesthetics.

"At the moment, anaesthetics have many unwanted side-effects on the human body such as nausea and effects on the heart. This is because our current drugs are relatively non-selective and bind to several different targets in the body. A better understanding of how anaesthetics exert their desirable effects could lead to much more specific, targeted alternatives being developed, which could greatly reduce these problems," he said.

Hopefully this will create the desired break-through in the development of anaesthetics.