The Origin of Walking

From New Scientist:

A lungfish that uses its fins for walking could help to unravel the steps our distant relations took in order to move from water to land.

The African lungfish (Protopterus annectens) has lobe-shaped fins similar to those seen in the ancestors of the first vertebrates to walk on land.

Anecdotal evidence suggested that the fish use these to walk along lake beds. Now Heather King of the University of Chicago in Illinois has filmed the lungfish in motion and found that they do indeed walk using their two pelvic fins.

This suggests fins were used for walking before they evolved into specialised limbs, says King.

New Scientist has a video of this but it’s rather brief. This is pretty cool – an idea of one step in the path species took from single-celled aquatic organisms to land animals.


Why Empty Space Isn’t Empty

New Scientist has a nice little video explaining that vacuums, empty space, aren’t really empty. You, my dear reader, already know that from reading about the big laser that will tear apart virtual particles, and the recent experiment that materialized virtual photons, but you should check this short video out if you’re interested (can’t embed the video here, sadly). 

They also link to a full-length article discussing how the theory of the vacuum has evolved over time, which it looks like you’ll have to register (for free) to read. I won’t go into all of it, but in essence it portrays a somewhat philosophical struggle over the millennia about how emptiness could be empty, which led to and away from the idea of a luminiferous aether filling everything, and finally to quantum mechanics.

Now we know that because of the quantum uncertainty involved at the smallest scales, there are always fluctuations of fields and particles in a vacuum, meaning that any vacuum does indeed have energy in it. There’s never nothing. Is that reassuring? I think a constantly fluctuating space is much more interesting than a giant, vast emptiness. 

“Lab-Grown Blood Given to Volunteer For the First Time”

From New Scientist:

RED blood cells generated in a lab have been successfully injected into a human volunteer for the first time. This is a vital step towards a future in which all the blood we need for transfusions can be made in the lab, so that blood donors are no longer essential.

Luc Douay at Pierre and Marie Curie University, Paris, and his colleagues extracted what are called hematopoetic stem cells from a volunteer’s bone marrow.

Hematopoietic stem cells are cells that can turn into any kind of blood cell. They’re a step in the path between embryonic stem cells, at the least differentiated extreme, and a specific type of blood cell, at the most differentiated extreme.

These cells were encouraged to grow into cultured red blood cells using a cocktail of growth factors. After labelling the cells so they could be traced, Douay’s team injected 10 billion – the equivalent of 2 millilitres of blood – back into the original donor to see how they survived…

“The results show promise that an unlimited blood reserve is within reach,” says Douay. That blood reserve is needed urgently. Although blood donations are increasing in many developed countries, blood banks struggle to keep up with the demands of ageing populations who need more operations – often involving blood transfusions. And a source of HIV-free blood is essential in countries with high rates of HIV infection…

Douay’s next challenge is to scale up production to a point where the cultured blood cells can be made quickly and cheaply in sufficient quantities for blood transfusions. The 10 billion cells his team made wouldn’t go very far – a transfusion typically requires 200 times that number. With his existing technology, Douay estimates that a single transfusion would require 400 litres of culture fluid, which is clearly impractical. “We are still a long way from the vision of dropping a couple of stem cells into the broth and making endless units of blood,” says John Hess of the University of Maryland in Baltimore.

Douay believes that it may take several years to scale up the technology. Another possibility is to use embryonic stem cells instead, as Lanza did in 2008. “We can generate up to 100 billion red blood cells from a single six-well plate of stem cells,” Lanza says. He also claims to have made red blood cells through yet another technique: generating “induced pluripotent” stem cells from skin samples and coaxing those stem cells into becoming blood cells.

This sounds like great news. Blood donations are always in need; supplementing those with lab-created blood should be a relief for patients in need of transfusions. New Scientist also gave us this handy-dandy timeline of the path to artificial blood, for your learning pleasure:

If you’re wondering what the “Rhesus blood group” it’s referring to above means, it’s a property of different blood types, part of which we’re familiar with by the positive/negative classification of our blood.

Creating a Supermouse

Getting rid of a particular protein in mice by knocking out the gene that codes for it resulted in mice that could run twice as far as regular mice. Wow.

From New Scientist:

Auwerx and his colleagues used a targeted virus to knock out the gene that makes a protein called nuclear receptor corepressor 1 (NCoR1) in the muscle of mice. Without NCoR1, mitochondria, which power cells, keep working at full speed. “Effectively, the mice go further, faster, on the same amount of gas,” says Auwerx.

“The treated mice ran an average of 1600 metres in 2 hours, compared with 800 metres for untreated mice,” he says…

Auwerx warns athletes not to try to grow their muscles and stamina illicitly by somehow targeting the NCoR1 protein, however.

“We only know what happens if it’s knocked out either in fat or muscle, and it could have serious side effects on other organs,” he says. Also, he points out that without NCoR1, all fetuses perish, so it plays a vital but undiscovered role in fetal development.

Maybe I’m just naive, but this seems like a bit of a bombshell to drop without further details. What happened to the health of the mice in the long run? I can’t imagine it would be improved, but it’d be interesting to know exactly what the side effects were. 

The protein they mention, NCoR1, is responsible for down-regulating particular genes, preventing the cell from reading and using them, which is why it’s called a repressor. This raises a mountain of new questions – what do the genes it regulates code for? How are the mitochondria affected, specifically? I must know! 

This sounds like the kind of finding that can lead to the production of dangerous, illegal performance-enhancers in the future – let’s hope it works out for the best. 

What We Do and Don’t Know About Climate Change

As I said in the last post, the science behind climate change has been in the news recently, which brings the side benefit of having New Scientist publish a series of articles on climate change for our education. You may not be able to access the articles without registering with them (for free), but they’re very short in any case and I’ll summarize them here. Because they’re very short though, be warned that they’re probably slight-to-gross oversimplifications, so don’t take any of this as whole, perfect truths. 

This ended up being super duper long – feel free to just skim over the titles and read more only if you’re interested. I think the important thing to note is that we don’t know everything – and we likely never will. That applies to every field of science though, as the final article eloquently explains. Climate change science has been brutally politicized, but that shouldn’t distract people from the facts.

Climate known: Greenhouse gasses are warming the planet

From melting glaciers and earlier springs to advancing treelines and changing animal ranges, many lines of evidence back up what thermometers tell us – Earth is getting warmer. Over the 20th century, the average global temperature rose by 0.8 °C

Studies of Earth’s past climate tell us that whenever CO2 levels have risen, the planet has warmed. Since the beginning of the industrial age in the 19th century, CO2 levels in the atmosphere have increased from 280 parts per million to 380 ppm. Satellite measurements now show both that less infrared of the specific frequencies absorbed by CO2 and other greenhouses gases is escaping the planet and that more infrared of the same frequencies is being reflected back to Earth’s surface. While many factors affect our planet’s climate, there is overwhelming evidence that CO2 is the prime cause of its recent warming.

Climate unknown: How much greenhouse gas to expect

The biggest uncertainty is human… Our current emissions trajectory is close to the worst-case scenario of the Intergovernmental Panel on Climate Change (IPCC). If we continue on this path, CO2 levels could hit 1000 ppmby 2100 – or perhaps even higher.

The second uncertainty is Earth’s response… Currently, rising CO2 levels are driving global warming, but in the past CO2 levels have naturally risen in response to rising temperatures. We do not know why exactly, but the reduced solubility of CO2 in warm water and changes in biological activity have been suggested as reasons. If such mechanisms kick in, even bigger cuts in emissions will be needed to limit warming.

There are also vast quantities of greenhouse gases locked away in permafrost, in peat bogs and undersea methane hydrate deposits. We don’t know how big these stores are. Nor do we know how much permafrost will melt, or how much peat will dry out and decay, or whether the seas will get warm enough to trigger the release of methane – an even more potent greenhouse gas than CO2 – from the hydrates.

Climate known: Other pollutants are cooling the planet

We pump all kinds of substances into the atmosphere. Nitrous oxide and CFCs warm the planet as CO2 does. Black carbon – soot – warms things up overall by soaking up heat, but cools Earth’s surface by shading it. But other pollutants reflect the sun’s heat back into space and so cool things down…

Burning sulphurous fossil fuels has been adding huge amounts of SO2 to the atmosphere. Between the 1940s and 1970s, this pollution was so high that it balanced out warming from CO2. But as western countries limited sulphur emissions to tackle acid rain, the masking effect was lost and global warming resumed.

Sulphur emissions began rising again in 2000, largely as China built more coal-fired power stations. Now China is installing sulphur-scrubbing equipmentin those power stations. If SO2 emissions fall, global warming could accelerate…

Climate unknown: How great our cooling effects are

Pollutants that form minute aerosol droplets in the atmosphere have horrendously complex effects. How much radiation is reflected by sulphur dioxide aerosols varies according to the size of the droplets, their height in the atmosphere, whether it is night or day, what season it is and several other factors…

But if aerosol cooling is larger than generally assumed, the planet will warm more rapidly than predicted as soon as aerosol levels fall.

Climate known: The planet is going to get a lot hotter

Take water. Water vapour is a powerful greenhouse gas. When an atmosphere warms, it holds more of the stuff. As soon as more CO2 enters a watery planet’s atmosphere, its warming effect is rapidly amplified.

This is not the only such “positive feedback” effect. Any warming also leads to the rapid loss of snow cover and sea ice, both of which reflect sunlight back into space. The result is that more heat is absorbed and warming escalates. Longer timescales bring changes in vegetation that also affect heat absorption, and the possibility that land and oceans begin to release CO2 rather than absorb it. Over hundreds or thousands of years, vast ice sheets can melt away, further decreasing the planet’s reflectivity. Barring some unexpected catastrophe such as a megavolcano eruption, then, the planet is going to warm considerably.

Climate unknown: Just how much hotter things will get

The bulk of the evidence still points to a short-term climate sensitivity of around 3 °C, as the IPCC’s models suggest. But while a figure much lower than that is unlikely, there is a significant probability of higher sensitivities (see diagram)…

Climate unknown: How things will change in each region

Even with an average global temperature rise of just 2 °C, there will be some pretty dramatic changes. Which regions are going to turn into tropical paradises? Which into unbearably humid hellholes? Which into deserts? For planning purposes it would be useful to know.

Unfortunately, we don’t. The broad picture is that the tropics will expand and get a bit wetter. The dry zones either side of the tropics will get dryer and move towards the poles. High latitudes will get much warmer and wetter.

When it comes to the finer details, though, there is not much agreement…

Climate known: Sea level is going to rise many metres

Studies of sea level and temperatures over the past million years suggest that each 1°C rise in the global mean temperature eventually leads to a 20-metre rise in sea level.

That makes the effects of a rise of at least 2°C rather alarming. How alarming depends on how quickly the great ice sheets melt in response to warming – and that is another big unknown.

Climate unknown: How quickly sea level will rise

We have little clue how much room we have for manoeuvre. Past melting episodes provide little help. Melting can be rapid: as the last ice age ended, the disappearance of the ice sheet covering North America increased sea level by more than a metre per century at times. It is unclear if Greenland’s ice will melt as rapidly.

To predict exactly how quickly sea level will rise, we would first need to know how much hotter the planet is going to get. As we have seen, we don’t.

Climate unknown: How serious the threat to life is

Many species will have to move to stay within a tolerable temperature range. Animals will also have to change their time of hatching or migration to stay in sync with food sources. Many won’t make it: theoretical studies based on relatively conservative warming scenarios have come up with dire estimates of a third or more terrestrial species going extinct. Real-world studies of the effects of warming so far have backed these conclusions.

Climate known: There will be more floods and droughts

Warm air holds more moisture: about 5 per cent more for each 1°C temperature increase. This means more rain or snow overall, and more intense rain or snowfall on average.This trend is already evident, and is stronger than models predict.

More intense precipitation means more floods…

Although most of the world will get more rainfall on average, dry periods will still occur from time to time. When they do, soils will dry out faster because of the higher temperatures. Once soils dry out, the sun’s heat goes into warming the land rather than evaporating water, triggering or exacerbating heatwaves.

Climate unknown: Will there be more hurricanes?

As the lower atmosphere gets warmer and wetter over the coming decades, there will be more fuel available to power extreme storms. But how often will this fuel ignite? Hurricanes are relatively rare because they form only when conditions are just right. While higher sea-surface temperatures will favour their formation, stronger high-level winds may rip them apart. The result could be fewer hurricanes overall, but with greater strength when they do occur. As the destructive power of hurricanes rises exponentially with increasing wind speed, a few intense storms could wreak more havoc than many weak ones.

At temperate northern latitudes, the news might be better. There winter storms are powered largely by the temperature differences between cold air from the poles and warmer air masses from the tropics. Such storms may become less common as rapid warming in the Arctic reduces the temperature differences.

Climate unknown: If and when tipping points will come

If the Arctic suddenly cooled, sea ice would recover within a few years. If the great ice sheets of Greenland and Antarctica lose enough ice to raise sea level a metre or more, though, it would take thousands of years for snowfall to build up the ice sheets again. The risk is real: we know that the West Antarctic ice sheet has collapsed many times in the past, raising sea levels at least 3 metres.

We can identify many other such dangerous “tipping points“. The Amazon could flip from being rainforest to grassland, just as the Sahara suddenly dried up 8000 years ago. Massive amounts of methane could be released from undersea methane hydrates.

I really like the concluding article. Here it is (most of it anyway) in its sciency glory:

The biggest climate change uncertainty of all

WOULD you jump off a skyscraper? What if someone told you that physicists still don’t fully understand gravity: would you risk it then?

We still have a lot to learn about gravity, but that doesn’t make jumping off a skyscraper a good idea. Similarly, we still have a lot to learn about the climate but that doesn’t make pumping ever more greenhouse gases into the atmosphere a good idea.

Uncertainty is one of the defining features of science. Absolute proof exists only in mathematics. In the real world, it is impossible to prove that scientific theories are right in every circumstance; we can only prove that they are wrong. This provisionality can cause people to lose faith in the conclusions of science, but it shouldn’t. The recent history of science is not one of well-established theories being proven wrong. Rather, it is of theories being gradually refined. Newton’s laws of gravity may have been superseded, but they are still accurate enough to be used for many purposes…

In fact, perhaps the biggest source of uncertainty is not to do with the science at all, or the global climate system, but with us.

Will we burn every last drop of fossil fuel? Or will some amazing technological advance make the switch to renewable energy a no-brainer? Will we keep building cities in places vulnerable to sea-level rise, like Shanghai?

Even politicians who back action to curb global warming are not delivering on their promises. Many of the countries that signed up to the Kyoto protocol have failed to achieve their very modest targets. Meanwhile, some countries in Europe are signing up to more ambitious goals for reducing emissions by 2030, while still commissioning coal-fired power stations.

By the time the need for drastic action becomes blindingly obvious, the best opportunity to curb harmful change will have been squandered. Yet if draconian action is taken today, any success in limiting warming will be greeted with scepticism that drastic measures were ever worthwhile or even necessary. Perhaps the greatest unknown, then, is how to persuade people to act today to help protect their long-term future, not to mention future generations.

One more thing is certain: only science can reveal how our planet can provide a decent home for billions of people without toppling over the precipice.

I love it. Succinct, honest and forthright. 

The World’s First Commercial Spaceport

Spaceport America opened on Tuesday with a snazzy dedication. Its sole tenant at the moment is Virgin Galactic, which has already sold hundreds of future trips to the edge of space for $200,000 a pop. It’s unclear when they’ll actually be in a position to start sending up customers, but it seems that it will be within the next couple of years. I think I’ll hold off until the price comes down a bit though…

From New Scientist:

 Over 100 of those in attendance for Virgin’s “dedication” of the hangar have already put deposits down to fly on Virgin’s SpaceShipTwoMovie Camera. They watch in awe at a test flight of WhiteKnightTwo, the plane that will help the spaceship on its way. Slung between WhiteKnightTwo’s two fuselages, SpaceShipTwo will be transported to 15 kilometres above Earth, before it breaks away and fires its engine to reach the edge of space. Six passengers and two pilots will then experience a few minutes of weightlessness on flights that will last a couple of hours.

“I think the first moment when I see the curvature of the Earth will be the really exciting part,” says David Whitcomb, co-founder of Revolutionary Tennis Innovations, who was the 186th person to sign up for the trips. “Even if the first one crashes, I’m still going.”

There are still technical hurdles to overcome before commercial trips begin. So far, Virgin Galactic has only tested SpaceShipTwo without rocket power. The rocket motor has been undergoing separate tests, and the firm hopes powered flights will begin next year.

The spaceport’s construction is funded by taxpayers in New Mexico. Promised that it will bring 2000 jobs to the area in the next five years, they have paid $209 million, via bonds. “We think it will help New Mexico,” says Judy Wallin, a local cattle rancher. After December 2013, these bonds expire and rent from Virgin Galactic is expected to pay for operations.

Christine Anderson, executive director of the New Mexico Spaceport Authority, says New Mexico is the ideal place for a spaceport. As it is at an altitude of about 1400 metres, rockets need less fuel to take off than if they were starting out at sea level. The 330 clear days per year also help, as does the area’s sparse population, which means there is less chance that a crash would endanger large numbers of people.

Perhaps best of all is its location next to the 890,000 hectare White Sands Missile Range – the site of the first space flight by a rocket launched on US soil. This means the spaceport’s airspace is restricted, so no commercial aircraft fly overhead.

I find it interesting that New Mexico paid for the spaceport – that’s a big investment into a very novel and expensive industry. I can’t help but feel that $200,000 a flight is just too expensive to attract a large base of people, but if there is interest then I trust that competition and innovation will emerge to drive that cost down. In the meantime I’ll keep my eyes peeled for the first YouTube video from a Virgin Galactic flight.

If you’d like more info, here’s another article on the opening of Spaceport America: I didn’t think either article was great, so maybe in combination they suffice. 

“Oldest Artist’s Workshop in the World Discovered”

Archaeologists have discovered materials for mixing paint from 100,000 years ago, in a cave in South Africa. Keep in mind that homo sapiens only originated as an anatomically distinct species 200,000 years ago; this means that roughly halfway between the first homo sapiens and the present day, there were already painters. That’s pretty crazy.

From New Scientist:

The purpose of the paint is unknown, but the researchers who discovered the workshop at the Blombos cave on South Africa’s southern coast (see photo) think it was most likely applied to skin for decoration or ritual, or perhaps even as an insect repellent.

Inside the cave, Christopher Henshilwood of the University of the Witwatersrand in Johannesburg, South Africa, and his team found tools and two abalone shells (see photos) that were used for mixing and storing the paint. Alongside one of them were quartzite stones used to hammer and grind ochre to a powder, and animal bones used to stir the powder with other materials, which included bone, charcoal, quartz fragments and other stones.

They also discovered evidence that some of the bones had been heated, probably to melt fat from the marrow that would have then bound the minerals. “There were also quartzite fragments to cement it, mixed with a liquid, probably urine,” says Henshilwood.

The whole lot survived together in one place because after the cave was abandoned it filled with wind-blown sand, sealing the cache as a “time capsule”, says Henshilwood.

Whatever our ancestors did with their paint, the simple fact that they were mixing minerals to prepare it 100,000 years ago is in itself a major discovery, and tells us something about our ancestors’ cognitive abilities at the time.

For instance, Henshilwood points out that this is the first known use of containers from that time. What’s more, the artists would have had to collect ochre and other materials with the specific purpose of making paint in mind – a sign that they were planners – and needed a “basic knowledge of chemistry”.

The nearest known source of ochre, he says, is at least 20 kilometres away from the cave, so the find demonstrates that Homo sapiens was capable of this high degree of organisation and planning only 50,000 to 100,000 years after the species emerged.

It’s pretty interesting to think of very ancient humans doing things that we think of as quintessentially human. If they could find evidence of painting from before the emergence of homo sapiens, that could be quite a shock to people who consider art a defining characteristic of our species (not that “art” or “species” are well defined anyway). 

I wish I had the knowledge to actually evaluate findings like this. On its surface it looks like a whole lot of conjecture, but I’m sure they have their ways of backing it up. 

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