Can you believe it? It’s more safe to ride a bicycle without a helmet. So says a man named Bill. And a judge. But what does the science say? We’ll get to that in a second. But first a rant.

The recent debate in Australia about the benefits of wearing helmets while bike riding is very similar to the Climate Change “debate”. After decades of research, hundreds of scientists and experts come to a very clear consensus: wearing a helmet can reduce your likelihood of getting a brain injury if you’re involved in an accident while riding a bike.

Helmets prevent injury through several avenues. Firstly, they share the load, distributing the impact of a forceful hit over a larger area than the head alone. Secondly, they absorb the impact, and finally, they provide a barrier for objects – like unlikely nails sticking up from the road. All clear right? Human induced Climate Change is real.

But then, one or two people come along and poo poo it for the rest of us. These people could be scientists, or not. And if they are scientists they’re not necessarily experts in the field they are tackling. So, these individuals take the decades of research, cherry pick the studies they like, forget inconvenient words like “not significant” results, fumble about with the statistics and viola! Climate change doesn’t exist. And you’re better off riding naked than wearing a helmet.

Enter Bill Curnow and the Cyclist Rights Action Group. Bill is not a neurologist, or accident prevention expert. But neither am I, so let’s leave that alone. According to Bill, the benefits of helmets “remain under question.” In a book chapter he wrote entitled, “Bicycle Helmets: A Scientific Evaluation” Bill says that helmets may increase the angle that your heat rotates if you’re in an accident, because it grips the road. He says, this rotational, or “angular acceleration” is to blame for most brain injuries on bikes – and research has shown it, therefore helmets can be harmful.

Problem 1: it’s not just angular acceleration that causes head injuries from bike accidents. M. Franklyn from the Monash University Accident Research Centre, Monash University, Australia says injuries from both your head rotating, and banging your head on the road lead to head injuries. And, helmets are very helpful in reducing injuries from the latter accident.

Problem 2: there’s not good evidence demonstrating that helmets “increase” the angular acceleration in real-life accidents. Rather, the evidence suggests helmets don’t help to reduce angular acceleration.

And even if Bill is right, and helmets somehow grip the road and increase angular acceleration, this would only be relevant to a particular kinds of accident. For example when you are contacting the road head first and your body is in a particular position. When trying to establish if helmets can prevent injury it’s much more accurate to get incident reports of real bike accidents and see the injuries presented when people wear helmets, and don’t. And this has been done. Many times.

Take McFadden of the Australian Transport Safety Bureau, who collated sixteen studies on helmets and injury published between 1980 and 1995 encompassing over 10,000 bicycle injuries (Accident Analysis and Prevention 33(2001) 345-352). The results? Helmets reduce the risk of head injury by at least 45%, they reduce the risk of brain injury by 33%, facial injury by 27% and fatal injury by 29%. “The associations are compelling,” says McFadden in the paper.

While some of those 16 studies did find that riders who wore helmets had larger injuries than non-helmeted riders, overall the results are clear. We can’t cherry pick our research, just because we want to wear a top hat and ride our bike to the races.

Other helmet nay sayers claim that people who wear helmets are more likely to risk-take when riding, so more likely to endanger themselves (but the research above doesn’t show that – because helmet-wearers have fewer injuries).

And then there’s the argument that wearing a helmet is such an inconvenience that it detracts riders, therefore doing more harm than good by having less environmentally friendly commuters on our roads. There is preliminary evidence that less people ride when there are compulsory helmet laws, such as in Australia. But the inconvenience is not so great, and certain activities in society have proven resilient to similar levelled laws inconvenience. There are many cars on the road despite seat belt laws, and people still go to pubs to drink, even though they’ll have to go outside to smoke.

Finally there is claim that we shouldn’t live in a grandmother state. “Hey, if I want to increase my risk of injury let me do it.” It’s funny, because rarely do these people say, “I love paying for my private health insurance.” If you want the state to fund your health care – then you’ve got to allow them to put in place sound measures to prevent risk of injury.

To make a long story short: Yes, you should wear a helmet when bike riding. Yes, Climate Change exists. And no, don’t trust every person using scientific sounding words. Except for me.

New Scientist Reports:

A new-and-improved successor to the troubled Japanese spacecraft Hayabusa – which finally returned a capsule to Earth earlier this year – could launch as soon as 2014. Hayabusa 2 would then be expected to return in 2020, bearing clues to the origin of life on Earth.

Last week, the Japan Aerospace Exploration Agency (JAXA) got the go-ahead from the government to begin development of Hayabusa 2, which will cost an estimated 164 billion yen ($2 billion).

To find out more check out newscientist.com.

New Scientist reports

The giant horned turtles of the Pacific became extinct later than we thought – and we were to blame.

The half-tonne meiolaniid turtles were thought to have died out 30 to 40,000 years ago. With no signs of human interference, climate change was blamed.

Now butchered turtle remains have been found in the South Pacific island nation of Vanuatu. Carbon dating shows that the most recent bones are between 2890 and 2760 years old. Humans arrived 3000 years ago: “Within 200 years, the turtles were gone,” says Trevor Worthy of the University of New South Wales in Sydney, Australia, who identified the bones.

I’ve always figured that all animals – big, small, ugly – could feel pain. It made sense that every creature should be able to detect some horrible stimuli in order to quickly move away from it. Whilst this feeling of “pain” may not be as complex as the human experience, it’s still pain – isn’t it?

Well, it’s very difficult to objectively study pain in humans – let alone cows, mice or fish. The best evidence we have is looking at how animals react to potentially painful stimuli – like heat and bee venom – and seeing if their reaction is similar to how humans behave. These days we can also look at the neurons firing in animal’s brains to see how it responds to this stimuli, and again comparing it to human neuron firing patterns.

From observations of cows headed to the abattoir, mice exposed to searing heat, and even pet dogs who hurt themselves – western society seems pretty comfortable with the idea that mammals can feel pain on a similar level to humans. Studies of “pain sensitive” regions of rat brains, and mice genetically engineered not have genes that transmit pain, also supported this conclusion. But, more controversial is whether fish fell pain.

In 2003 researchers from the Roslin Institute in Scotland found that when lips of rainbow trout are injected with bee venom or acid they behave similar to how humans would. For example, they started “breathing heavily” i.e. their rate of gill breathing was similar to a fish swimming fast. And took 90 minutes longer to start feeding, when compared with saline injection

The fish didn’t act like this when their lips were injected with harmless saline. They also rocked from side to side, a repetitive behaviour seen in unhealthy zoo animals. And, when injected with acid, the fish rubbed their lips on the side and bottom of the tank, just like humans might to reduce the pain from a burn. The Scottish researchers say this sort of behaviour isn’t just a reflex response – they are feeling some discomfort and attempting to alleviate it.

The fish’s neurons did funny things too. When injected with the venom or acid around 20 neurons in the trout fired in a similar pattern to that seen when humans feel pain. This didn’t happen when the trout were injected with saline.

Does this mean the fish feel pain?

Not necessarily. While the fish might be behaving as if they feel pain and some extra neurons are firing, it’s still very possible they just don’t have emotional capacity to percieve the stimuli as “pain” per se. That’s what fish neurobiologist James Rose at the University of Wyoming thinks. Those extra neurons could just be firing as a response to new and unexpected substances.

Considering fish are renown for their short memory span they might just be thinking – “What’s that?” “What’s that?” rather than the complex emotion of “OUUUUUCHHH.”

Until the fish in Walt Disney’s Finding Nemo start translating, I guess, we’ll never know for sure if fish feel pain. But, the more we learn about animal behaviour, the more we realise how similar humans are to the rest of the animal kingdom.

Notions that humans, or even mammals, are the only creatures to feel pain seems to hark back to theology – that we two legged, (mostly) hairless creatures, are somehow special and different. Pain is such an innate feeling, all creatures must feel it on some level, right? On the other hand, the human brain is pretty special, so it’s likely we can do and feel a whole lot more than a trout, maybe feeling pain is one of those things.

The world’s marsupials – including Australia’s iconic kangaroos, wallabies, Tasmanian devils – all originated in what was once South America.

So says Maria Nilsson at the University of Munster in Germany in a paper published this week in PLoS Biology.

By comparing unique genes called retroposons in the genome of 22 marsupials, Nilsson concluded that ancient South American marsupials migrated to Australia more than 80 million years ago – when the continents were part of a supercontinent, called Gondwana.

Not surprisingly, some Australians aren’t impressed.

“Hands off our marsupials!” screams Sydney’s the Daily Telegraph. “Roo must be joking!” roars Melbourne’s Herald Sun.

More seriously, Mike Archer, an evolutionary biologist of the University of New South Wales, Australia takes issue with the findings. He told the Australian Broadcasting Corporation Online “They just assume Australia is the arse-end of the world and gets everyone else’s leftovers.” So where did Skippy come from?

Skippys with sombreros

Marsupials, mammals that carry their young in front pouch, are Australia’s pride and joy, but there are seven existing Marsupial orders, three from the Americas and four from Australia.

According Matt Phillips an evolutionary biologist at the Australian National University in Canberra, who was not involved in the work,“there’s not much debate” about the fact that marsupials originated from South America.

The real debate, he says, is whether some marsupials once in Australia crossed Gondwana once more, returning to South America.

It’s been difficult to decipher early migration patterns of marsupials because ancient fossil records for marsupials are limited. So, Nilsson and her team, tackled the issue by analysing retroposons. These “jumping genes” copy and paste themselves from one location to another within an animal’s genome.

Since the insertion sites of retroposons are effectively random, finding them in similar places in different species suggests a common ancestor.

To begin their search for marsupial retroposons the German team analysed the genome sequences of the South American opossum (Monodelphis domestica) and the Australian tammar wallaby (Macropus eugenii).

Los Angeles Times reports

“The scientists found 53 similar retroposons in the opossum and wallaby, verifying their common ancestry.

The team then compared the wallaby and opossum data to the DNA of 20 other marsupial species, including the wallaroo, the common wombat, and the marsupial mole, to find out which marsupial lineages are more closely related and which split off first.

They found that all of the species had common retroposons, and thus a common ancestor. Closer analysis revealed that the South American opossum order, Didelphimorphia, was the oldest living marsupial order, indicating that all marsupials originated in South America.”

Super two- way highway

But, Archer told the ABC that the study doesn’t give credence to evidence that Gondwanan migration was a “not just a one-way highway, it was a super two-way highway.”

In 2008, Archer and colleagues found fossils demonstrating that ancestors of the little mountain monkey Dromiciops gliroides, now found in the rainforests of Chile and Argentina lived in Australia 55 million years ago.

Phillips says while Nilsson’s paper correctly identifies which marsupial species diverged first, but without fossil evidence, “it’s difficult to interpret locations.”

Photo by cleopold73

New Scientist reports:

Male fetuses ignore their mothers’ response to stress – unlike females, which are very sensitive to it. The finding could lead to better treatments for male fetuses at risk of premature birth.

It is known that when a pregnant woman produces the stress hormone cortisol, it can cross the placenta. But it has been unclear how this affects fetal development, and whether female and male fetuses respond differently to the hormone.

During an asthma attack, high levels of cortisol are released. So Vicki Clifton and colleagues at the University of Adelaide in South Australia investigated the effect of cortisol on fetuses by following 123 asthmatic women and 51 healthy women during their pregnancies, recording the severity of each woman’s asthma and her medication at 12, 18 and 30 weeks of pregnancy.

Forty-five minutes after the women gave birth, Clifton and her team measured the cortisol in their umbilical cord blood and analysed the placenta for the expression of genes related to stress response. She also recorded the newborn’s sex and birth weight.
Stressful information

Baby girls born to women with moderate to severe asthma had higher levels of cortisol in their cord blood – an average of 245 millimoles per litre – compared with girls born to controls and mildly asthmatic women, who averaged 202 and 209 millimoles per litre respectively.

However, no difference in cortisol levels was observed in baby boys born to either group.

To find out more check out New Scientist.

It was a beautiful day – blue sky, sun shining – but I wasn’t fooled. It was Melbourne in the Spring, and I knew there would be an icy breeze. I put on a jumper, coat and scarf, and headed out to meet a friend. When I reached the cafe, I saw her basking in the sunlight, wearing only a T-shirt. Huh? “Aren’t you freezing?” “No,” she replied smugly, eyeing my woollen layers. “I’m black, I absorb more heat than you.” Huh? That can’t be right.

Do black people really absorb more heat than whites?

Pop this question into Google, and you’ll be insulted. But, aside from responders wincing at the derogatory descriptions of “black and white” skin tones, it’s a reasonable question. After all, when you wear a black coat or sit in a black car you get hotter than doing the same activity in white. So why would skin be any different? Well, unsurprisingly, it’s complicated.

Oft sited – amongst grandfathers and milk-bar ladies – as evidence that darker skin absorbs more light and therefore heat, than lighter skin is this anecdote: In places with hotter climates, such as Nigeria, you see darker skin compared to people from colder climates, such as the pale Britons. But, if darker skin did absorb more heat, wouldn’t it be better to have dark skin in Britain, so your skin could grasp what tiny light is left? Hm.

What makes skin darker?

Human skin colour is largely determined by a pigment called melanin, which is made by tiny melanin factories called melanosomes, that sit inside skin cells – called melanocytes. Melansomes make more melanin when they are larger and not clumped together. And overall, the more melanin they produce, the darker the skin.

But other pigments also affect skin colour – such as carotene, which makes our skin orange coloured. And hemoglobin, which transports oxygen throughout the body, can turn our skin reddish or blueish depending on whether there is oxygen in our blood.

How does skin absorb light?

Light moves in waves, which can be short and powerful, like X-rays, or long waves, such as microwaves. Today, we aren’t too concerned with just any light waves – we want the ones that make us feel hot, and these are infrared lightwaves. According to NASA, they are about the size of a pin head. And when they reach our skin, or the pavement or just about anything, they get absorbed – and the energy from the light is transformed into heat.

In general, darker objects absorb more infrared light than lighter objects, and become hotter because they are transforming more light into heat.

Does darker pigmented skin absorb more light than whiter skin?

According to anthropologist Nina Jablonski, “there is essentially no difference in absorption of infrared light between dark and light skin” (Annu. Rev. Anthropol. 2004: 33:585-623). Funny thing is – I’m not sure I believe her. The two papers she cited didn’t directly measure the amount of infrared light being absorbed on the skin (which these days can be measured using an instrument called a reflectance spetrophotometry). And from first principles I can’t see why darker pigments would be any different to darker coats or cars – in terms of the light wave absorption.

Perhaps, what Jablonski meant to say, is that if there is a difference in the light being absorbed in the skin, it’s not directly translating into extra body heat. Humans of all shades and sizes have the same core body temperature – 37 degrees Celsius. Through exercise and seasonal changes, this body temperature doesn’t change because humans can release heat by increasing blood flow and sweating. Studies have shown that the heart rate and sweat rate of African Americans and Europeans, matched for height and weight, is the same when they exercise. So if darker skin is absorbing more heat where is it going?

Possibly into the melanocytes. There is anecdotal evidence, along with medical records from the Korean War that darker individuals, with heavily pigmented skin, are more susceptible to frostbite than lighter individuals. Animal studies show that melanocytes are killed by freezing than other skin cells. So, it’s possible that while more light is being absorbed, the larger melanocytes are somehow using the heat, so it’s not getting transferred to the rest of the body – but this is a lot of speculation on my behalf.

So, darker skin might absorb more light waves than light skin– we don’t really know, but going from first principles, they probably do. However, this doesn’t mean these lucky individuals are hotter in the sun because the energy from absorbed the light waves isn’t converting into body heat. Where it is going – I’m not sure. But it does seem that this is no black and white issue.

If it’s not about heat, why is some skin darker than others?

There is a strong link between pigmentation and locations that receive high doses of UV radiation. The more UV radiation hitting an area, the darker the skin.

UV radiation – which is another form of light wave, that is shorter and more powerful than infrared – can penetrate the skin, causing sunburn, DNA damage, and skin cancer. Melanin acts as a natural barrier to UV radiation by absorbing the UV radiation, but then very effectively scatters them – so they don’t harm the DNA of skin cells below. Some academics believe that darker skin naturally confers a sun protection factor (SPF) of 10 – 15.

And why bother with whiter skin then?

It’s still up for debate. The most popular reason for why lighter skin is that it allows Vitamin D production. Vitamin D is needed to absorb calcium absorption and a deficiency can lead to weak bones and impaired locomotion. The production of this handy vitamin is triggered by UVB radiation. So, when people live in areas that have low doses of UV radiation, the last thing they need is melanin scattering it.

New Scientist reports: AGAINST all the odds, a number of shape-shifting islands in the middle of the Pacific Ocean are standing up to the effects of climate change.

For years, people have warned that the smallest nations on the planet – island states that barely rise out of the ocean – face being wiped off the map by rising sea levels. Now the first analysis of the data broadly suggests the opposite: most have remained stable over the last 60 years, while some have even grown.

Paul Kench at the University of Auckland in New Zealand and Arthur Webb at the South Pacific Applied Geoscience Commission in Fiji used historical aerial photos and high-resolution satellite images to study changes in the land surface of 27 Pacific islands over the last 60 years.

To find out more checkout New Scientist.