Women's backs are built for pregancy (but still ache anyway)

A scientific comparison between of the lower backs of women and men has shown that women's backs are specially built for carrying the extra weight of pregnancy. Similar studies on our evolutionary ancestors bore the same result.

When human ancestors changed from walking on four legs to two, the bones and muscles of their spines had to evolve to accommodate the shift in weight. The lower spine curved, to shift the shoulders back, and keep our center of gravity over our two legs.

The term center of gravity refers to the mathematical average location of an object's weight. When your the center of gravity extends in front of the end of your feet, you fall over. You can experience this for yourself. Stand keeping the back of your feet and hips against a wall, and move your center of gravity forward by bending at the waist. If you do this, you'll know when your center of gravity is beyond the end of your toes.

Because of the extra weight of pregnancy, women's lower backs evolved differently than men's. The curve of a women's lower back spans three vertebrae; in men, it spans just two. The added vertebra helps distribute the pregnancy weight over a wider area. The joints located behind the spinal cord, called zygapophyseal joints, are 14 percent larger in women than in men, suggesting that the joints can bare more weight. These joints are also oriented at a slightly different angle in women, allowing them to better brace the vertebrae against slipping. link

Google thinks like you

PageRank, the computer program that is Google's search formula, works more like our own mind than previously thought.

In a study published in Psychological Science, people were asked to think of a word that begins with a particular letter, and their responses were recorded and ranked by popularity. The Google PageRank result for the letter turned out to be a good predictor of human responses.

When you get the PageRank search results for a search word, what you see is a list of websites associated with that word, ranked by PageRank's website popularity or importance. A web site's importance is determined by how many web pages are linked to the page, and how many web pages are linked to those pages, and so on. Using this method, a seemingly unimportant word can have great notoriety because of it's association with a popular word.

For example, think of the word myrrh. Nobody uses that word much through the year, but it maintains at least moderate importance because of it's link with Christmas, which has a lot of links. link

Clues to water on Mars lie here on Earth

Our everlasting Mars Rovers are still up there sniffing for evidence of Martian water. To better understand what evidence of Martian water looks like, researchers at the Byrd Polar Research Center at Ohio University are studing the McMurdo Dry Valleys in Antarctica.

Antartic and Martian dry valleys both experience sub-zero temperatures and both have iron-rich soil. Year round, salt water flows in the ground below the Antartic dry valleys. The topographical similarity between these two regions may be an indication of water under Martian soil; and if so, the prospect of present or past water on Mars looks pretty likely. link

Hurricane season wasn't as bad as expected

For the second year in a row, meteorologists expected a worse Atlantic hurricane season than the one we experienced, and meteorologists are beginning to be concerned that future predictions will not be taken seriously.

The conditions this year were ripe for intense hurricane activity. Seventeen named storms were predicted, but the season only produced 14. Only two of the 14 storms were were extremely intense: hurricanes Dean in August and Felix in September. These storms caused catastrophic damage in Mexico.

Meteorologists are still puzzling over the reason for the lower-than-predicted hurricane rate. It is likely that windblown dust from Africa blocked sunlight and keep water temperatures down near the surface of the Atlantic Ocean.

"We are in a time until about 2020 that hurricane threats will be more frequent and more intense on our coastlines. So instead of saying, Ha, ha, ha, there's nothing going on, people should be thankful that there's not as much going on," says Joe Bastardi, a meteorologist with the private weather forecasting service AccuWeather. link

Meanwhile, on Venus...

Lately, Earth and Mars seem to get all the press, but the NASA has ignored Venus since the NASA's Magellan mission used radar to map the planet in 1994 . Venus is Earth's neighbor, on the side closer to the Sun. The planet has roughly the same mass, size, and composition as Earth. Evidence shows that Venus was once partially covered by deep oceans of water. Today, Venus is unimaginably hot, with only a little water left on its surface. How could two planets that were once so essentially alike end up so different?

This week, the European Space Agency (ESA) released eight papers in Nature magazine documenting the findings of the Venus Express mission, their unmanned probe launched in 2005. The ESA has been building their understanding of Venusian weather, which to Earthlings is astounding: above the planet's 460-degree-C surface, the Sun’s energy blasts thick sulphuric acid clouds through an atmosphere that is about 95 percent carbon dioxide.

On Earth, a small amount of atmospheric carbon dioxide warms the surface, which is tempered by vast oceans. On Venus, the thin spots of surface water are vaporizing into space under intense heat. With an atmosphere composed mainly of carbon dioxide, no oceans to cool lava that flows to its surface, and a closer proximity to the sun, Venus experiences an extreme greenhouse effect.

Venus' inhospitable conditions ruins our chances of finding any remaining record of past life there, and makes the possibility of landing an astronaut there a pipe dream. link

Beer fridges are widening our carbon footprints

According to a researcher at the University of Alberta, the secondary refrigerators found in many Canadian households are significant contributors to greenhouse gas emissions.

In Canada, one in three households have a second refrigerator, and most of these second refrigerators are used to keep beverages cold. Beer fridges tend to be older and less energy efficient, 65 percent are more than 10 years old. According to a Canadian researcher, secondary refrigerators in Canada consumed at least as much electricity as 100,000 US homes.

Although the study did not include the US, it's fair to assume that US households contributing to greenhouse emissions in a similar way. The According to the National Resources Defense Council, 98 to 99 percent of US homes have at least one refrigerator, and 18 percent of those have two or more refrigerators. link

Emryonic stem cells - without the embryos

Embryonic stem cells are pluripotent-- they have an almost magical ability to grow into any kind of cell and perform any function. There is a good possibility that some day we may use cells like this to heal injuries and deceases. Until recently, the only way to get these cells was to remove them from the cells of a embryo, a process that is fatal to the embryo and controversial to many.

It was reported on November 20 that a method was developed for making pluripotent stem cells from ordinary skin cells, with no need for an embryo. Two different scientific teams developed the method independently, using specialized viruses to deliver four genes to the skin cell's genetic code. Adding four genes is all it takes to make a embryonic-like stem cell from a skin cell.

Anytime genes are added to normal cells, there is a risk that the cells can grow cancerous. But, researchers are confident that they will soon find a way to switch the cell's genes instead of adding to them, removing the cancer risk.

Having a method for making pluripotent stem cells without using embryos will extinguish the controversy that beleaguers stem cell research. "People working on ethics will have to find something new to worry about," says stem cell researcher Jose Cibelli of Michigan State University. link

Why do the trees change color in the fall?

It seems a fairly obvious question for this time of year. My daughter asked me this question last week, and I was embarrassed that I didn't know what to tell her.

According to News@nature.com, color change in leaves is not very well understood. The predominant theory is that leaves change their color in order to recycle the last bit of nutrients from their leaves before they are lost. Thus, trees grown in areas with less soil nutrients will produce more brilliant leaf colors.

As the weather turns colder, the trees switch to winter hibernation mode. The green chlorophyll in the leaves breaks down and disappears, revealing the yellow carotinoids that have been lurking among the chlorophyll all summer. The brilliant red color that people admire comes from a pigment called anthocyanin, which trees produce in autumn. Why trees expend their precious energy producing anthocyanin is still a matter of study and debate. It is believed that anthocyanin acts as a sunscreen, protecting leaves which are more vulnerable to sun damage after the chlorophyll is gone. The protected leaves can stay on the trees longer, allowing leaf nutrients to be absorbed into the other parts of the tree. link

Gravity victorious in rocket competition

NASA held their 2007 X Prize Cup rocket expo this past weekend near Alamogordo, New Mexico. The weekend's big event was the Northrop Grumman Lunar Lander Challenge, offering 1.35-million dollars in prize money to the company that can demonstrate a new space vehicle capable of landing humans on the moon.

Of the nine companies that registered for the event, only Armadillo Aerospace of Mesquite, Texas was ready to go on launch day. Armadillo is headed by John Carmack, the creator of the video game Doom. Their entry, Module 1, failed the test the first two times and exploded on the third. Interestingly, Armadillo was the only entry to show up for the 2006 competition, and its entry crashed that year, too.

Why is it that a team can't meet the challenge? It's not exactly rocket science. link

Some Neanderthals were redheads

The journal Science reports that at least 1 percent of Neanderthals were fair-skinned redheads. This adaption likely helped the Neanderthals of the high latitudes synthesize vitamin D with less sunlight.

Separate teams isolated a version of a gene called mc1r from the fossils of two different Neanderthals, one 43,000-year-old fossil from Spain, and another 50,000-year-old fossil from Italy. The Neanderthal version of the mc1r gene is similar to a gene found in humans that have fair skin and red hair.

The Neanderthal version of mc1r is not found in humans, which confirms that the gene samples were not mistakenly taken from a human. This also strengthens the currently-accepted theory that humans did not evolve from Neanderthals. link

Engineered virus shrinks tumors

Viruses have been known to shrink tumors. A reduction in tumor size can be observed after vaccinating a cancer patient, because vaccinating introduces a small amount of virus. The challenge has been to get enough virus cells to target the tumor without damaging healthy cells.

By genetically modifying the pox virus, David Kirn at Jennerex Biotherapeutics in San Francisco has engineered a special virus to seek and destroy tumors. Kirn's genetically-modified virus spreads more easily within tumors thanks to a tail composed of a protein called actin. Kirn has also modified the virus so that it is unable to produce an enzyme called thymidine kinase, without which the virus is unable to replicate and damage healthy tissue. Since cancerous cells contain an abundance of thymidine kinase, it is easy for the modified virus to multiply within tumors, and once the virus enters a cancer cell, it replicates itself until the cancer cell bursts. The third modification to the pox virus makes it produce a signalling molecule called cytokine, which attracts the body's immune cells towards tumors.

Clinical trials on the virus treatment was conducted with 13 patients with advanced liver cancer. The patients were so advanced that all previous therapies had failed, and they had a life expectancy of only three to four months. Beginning in July 2006, researchers started treating by administering the engineered virus directly into the participants' tumors every three weeks.

Seven of the participants survived for more than eight months, and three are still alive today, over 15 months later. The virus shrank the tumors of 10 of the 13 participants, including five whose tumors were reduced more than 50 percent. The only notable side effect experienced by the participants was temporary flu-like symptoms. link

Predicting global climate change: mission impossible

In the current issue of Science magazine, two University of Washington scientists suggest that we "call off the quest" for predicting global temperature changes, and that political decisions should not be made based on climate models.

For 20 years now, scientists have been working on predicting how much the average global temperature will increase when carbon dioxide levels reach double the pre-industrial levels. For all the effort, the predictions are not getting any more accurate -- current estimates range between 2.0 and 8.0 degrees C.

The article states that even the best computer models have too much uncertainty; this uncertainty comes from feedbacks in the system that change the way the system changes. For example, the sun is melting the polar ice caps. As they melt, they reflect less of the suns energy, changing the balance. These types of feedbacks cause uncertainty.

The article does not dispute that global temperatures will continue to rise; but nonetheless, the article will likely fuel the critics of the the climate change movement. link

Carbon dioxide emissions are still climbing

The greenhouse gas problem is nothing new, and you might think we've begun to at least slow our increasing carbon dioxide emissions. However, a paper published in the Proceedings of the National Academy of Sciences discloses more inconvenient truth.

In 2006, global carbon dioxide emissions resulted in a release of 9.9-billion tons of carbon into the atmosphere; 35-percent higher than the 1990 carbon emissions. In the atmosphere, carbon concentrations are now increasing at a rate of 1.93 parts per million (ppm) each year. This is the highest rate of increase since carbon monitoring activities began in 1959. The current rate of annual increase is considerably higher than the 1.58-ppm average for the 1980s and the 1.49 ppm for the 1990s.

Dr. Pep Canadell, the study's lead author and the Executive Director of the Global Carbon Project, explains that emission rates have likely risen as a result of the increase in global population and wealth. We have yet to find a way to increase increase global wealth without increasing carbon emissions rates. In addition, there has been a slowing of the effectiveness of global carbon-absorbing systems, such as rainforests and oceans. link

Flu spreads faster in cold weather

We can tell our grandmas they were right. New research from the Journal of the American Medical Association shows that the flu virus spreads easier in cold and dry weather. We used to explain that the increase in indoor activity in the colder months makes the flu season a cold-weather event. But, that's not the whole story.

The flu virus is exhaled from the body attached to aerosol water droplets. In as series of medical studies, the flu was spread through a population of guinea pigs. Since guinea pigs were in separate cages and do not sneeze or cough, the virus was spread only through breathing. Results showed that the flu spread much faster in colder air and in drier air.

When the air is dry, water aerosols and viruses move efficiently. But in damp air, the virus can't stay airborne; the aerosols containing the virus tend to combine with other water aersols and settle out of the air. Warm air can hold more moisture than cold air, so cold air tends to be drier and is better at spreading the flu.

After further study of the ginea pigs, researchers concluded that the spread of flu is also affected by the health of the mucus layers that line the nose and throat. In warm conditions, the mucus layer traps viruses and carries them from the body. Cold air damages the mucus layer, making the it more viscus and hindering the ability of the mucus to rid the infection.

So grandmas, bring on the chicken soup. link

A step closer Alzheimer's detection

More than 5-million North Americans are diagnosed with Alzheimer's decease, and a quarter of a million more are estimated to be living undiagnosed. Currently, doctors diagnose Alzheimer's by the patients' behavior and by eliminating other possible deceases. The only fool-proof way to diagnose the decease is after it's too late - through autopsy of the brain.

Researchers at the Stanford School of Medicine studied concentrations of communicode proteins the blood of living patients. The communicode is a set of 120 proteins that human cells use to communicate with each other. It is thought that the decease damages the communicode proteins in the brain and that these damaged proteins circulate throughout the bloodstream. Doctors diagnosed 20 patients with or without Alzheimer's. The blood test and the doctors' diagnoses agreed in 18 of 20 patients.

Unfortunately, even if diagnosed early, there is no current treatment for the decease. link

Mars orbiter snaps new high-resolution color images

Searching for the next Mars landing sights, the Mars Reconnaissance Orbiter captured 143 high-resolution color images of the planet's surface. The pictures are the first color images from the High Resolution Imaging Science Experiment (HiRISE) camera aboard the orbiter. The images are quite striking; they illustrate the unique geological history and chemical make-up of the planet's surface.

The next landing of a Mars rover will be in 2009. The unmanned rover, called the Mars Science Laboratory, will carry the next generation of instrumentation, searching for conditions that can or had once supported life on Mars.

Meanwhile, Opportunity and Spirit, the first two Mars Rovers, are still sending back data after more than three years of service. Not bad, considering the missions were expected to last three months. The aging rovers are beginning to fatigue due to the daily temperature swings of 200 degrees F. link

Memory shuts off just before sleep

What can we remember from surgery? What do we remember while dropping off - but not quite - asleep? Anesthesiology researchers say that we don't remember much.

Anesthetized patients were played a recording of words and sounds just before they went under. The patients brains were monitored through the whole process using functional magnetic resonance imaging. Although researchers observed brain activity in the part of the brain that recognizes language, the part of the brain that has to untangle language and meaning did not function well. After recovering, patients had difficulty identifying the last things they heard.

This finally proves what I've been telling you for 8 years about dozing off in class. link

Al Gore wins Nobel Peace Prize for work on climate change

Congratulations to Al Gore and the Intergovernmental Panel on Climate Change (IPCC) for claiming the Nobel Peace Prize. Gore has been a widely-visible spokesman for the climate change cause. The IPCC is a central repository for climate change research that collects and organizes the results of all climate change research, and then compiles plain-language summaries for the World's governments. Although the work of Gore and the IPCC is largely scientific, the work was viewed as an act of peace based on its intergovernmental nature. link

There are persuasive arguments to debunk Gore's film An Inconvenient Truth. The film may contain some partial and convenient facts (link), but the science of the matter is conclusive. The Earth is getting warmer and we are the cause. link

The appendix is good for something afterall

Back in my teaching days, I occasionally gave a lesson on useless body parts. The list would include discussions on the wisdom teeth, the sinuses, the coccyx, and male nipples. Students were surprised to learn that we still have muscles specifically for hanging from trees or walking on all fours, and that women have sperm ducts in their ovaries.

Until recently, the appendix was a regular on the useless list. This 4-inch-long sac at the juncture of the small and large intestines is known mostly for getting infected and bursting. Recently, researchers at the Duke University Medical Center have concluded that the appendix has a back-up role in the digestive process. The appendix stores a variety of good bacteria, the kind that healthy intestines use to break down nutrients. These bacteria can be deployed to repopulate the intestines after a catastrophic decease and diarrhea clears the contents of the intestines.

Now, what about those male nipples? link

Chilli powder: a cure for pain

The thing that makes the dentist's drill bearable is local anaesthetics. Local anaesthetics work rather haphazardly; they block not only pain channels but all the message channels in your nerve cells. The result is a loss of all sensation and temporary paralysis in the affected area; thus, the drooling.

But there are more serious problems with local anaesthetics. Take, for example, the epidural, a common childbirth procedure in which an anaesthetic is injected directly into the mother's spine. The process ameliorates the pain of childbirth, but leaves the mother's body unable to push out the baby.

It was reported in Nature that capsaicin, the active ingredient in chili peppers, has the ability to specifically activate pain channels in nerve cells and leave all other channels alone. When capsaicin is injected along with a local anaesthetic, pain channels can be targeted by the capsaicin and closed by the anaesthetic, allowing pain sensation to be blocked without loss of other sensations and without paralysis. Since the anaesthetic and capsaicin are already approved for the drug market, use of capsaicin in pain therapy is expected to be available soon. link

Sputnik turns 50

Fifty years ago today, the USSR successfully launched the first ever man-made Earth satellite. The orbiter was nothing more than a beachball-sized metal sphere that contained a radio and batteries to emit a beeping signal. The beeping little orbiter, named Sputnik, carried on for about two days before it faded into oblivion. Many Americans recall the eerie bleeping that was received by radio operators and replayed on radio and TV newscasts.

Those of us who were not around back then may be surprised to learn the emotional toll that Sputnik caused on most Americans. The Sputnik program was held completely secret to the public. It as only until after the launch that Americans (and even the Russian populace) heard the shocking news. In the height of the cold war, the thought that communist Russia had technologically surpassed the US was distasteful to most Americans, not to mention scary. If communists can put a radio beacon in orbit that can fly over America every 90 minutes, many Americans worried about what would come next - a spy satellite, or worse a warhead.

It was a real wake-up call to the US space program. President Kennedy announced the goal of landing on the moon within 3 years. The space race was on, thanks to that beachball in orbit. link

Radio burst puzzles astronomers

The Parkes radio telescope in Australia picked up a single, quick blast of radio waves that contained as much energy in its mere 5-millisecond duration as the sun puts out in a month. The signal was by far the strongest short signal radio astronomers have ever observed, and no previously-detected cosmic radio burst has the same set of frequency characteristics. After analysis, it was estimated that the radio burst came from 3-billion light-years away.

Astronomers know of only two possible sources of the burst: either the merger of two neutron stars or the final gasp of a dying black hole. Whatever the source, "it's bound to be exciting," says radio astronomer Lawrence Rudnick of the University of Minnesota, Minneapolis. The source is likely to "push us into exciting new realms of physics." Astronomers are searching archives for similar phenomena. Meanwhile, we'll stay tuned for more. link

Thinking like a human, a computer program falls for similar illusions

If you designed a computer program to make decisions like a human, wouldn't you expect it to make human mistakes?

At the University College in London, researchers made a computer program that acquired knowledge the same way humans do, from experience, trial and error. The computer studied a series of gray-scale images. Its job was to judge the lightness of the shade at the center of each image. As the computer made its choices, it changed its decision technique depending on whether its previous decision was right or wrong.

Not surprisingly, when looking at certain gray-scale contrasts, the computer program fell for the same optical illusions that trick most of us. For example, when it studied a light object on a darker background, it predicted that the shade of object was lighter than it really was. Dark objects on lighter backgrounds similarly fooled the program. The computer also fell for 'White's Illusion', a pattern in which the same shade of gray is usually predicted by humans to be two different shades (see link for illustration).

The program points out the difference between hard-wired, computer-coded decision making and the more human process of making judgements based on experience. Human minds are not wired for accuracy, they're wired to find what's useful. link

Birds likely see magnetic fields

Imagine if your eyes could see the Earth's magnetic field around you. It's likely that migratory birds can do just that.

We've known that migratory birds use the Earth's magnetic field to navigate during their migrations. In order to sense magnetic fields, birds use their eyes and the part of the brain that processes vision.

Recently, scientists observed the jumping behavior of garden warblers under different colors of light. It was observed that only certain colors of light threw off the birds' navigation system. This hinted that vision played a role. In further studies, brain activity was monitored while the birds where in migratory mode. The neuron pathways for sensing vision and magnetism were found to be one in the same. link audio

It's a comet - it's an asteroid - it's both

It used to be an asteroid was an asteroid and a comet was a comet. Now, astronomers realize, the line's getting blurry.

In 1999, the Heliospheric Observatory (SOHO) spacecraft spotted an object (later dubbed 'P/2007 R5') passing close to the Sun. The object was assumed to be a comet, because it was passing the sun, and that's what comets are known to do. What puzzled some scientists was that P/2007 R5 did not have classic comet features such as a tail and a coma – the cloud of gas and dust that surrounds a comet's body, or nucleus. The tail and coma are created when the Sun's heat vaporizes frozen water and carbon dioxide on the comet, and blasts a brightly illuminated cloud of dust off the comet's surface. Without these features, P/2007 R5 would be better classified as an asteroid. Asteroids traditionally do not contain high enough quantities of solid carbon dioxide and water ice to make such a display.

When SOHO spotted P/2007 R5 swinging by the Sun again in 2003, scientists officially designated it as a short-period comet.

Pesky little P/2007 R5 appeared near the Sun again in September 2007. It still didn't have the classic comet features, but on this passage near the Sun, when it was just 15% of Mercury's distance from the star, it brightened by a factor of a million and faded again. These brilliant flashes are common for comets, but not for asteroids.

Based on its orbit, P/2007 R5 is likely a comet from the Kuiper belt, a reservoir of icy comets and asteroids that orbit the Sun way out beyond the orbit of Neptune. Most of P/2007 R5's surface ice was probably baked off during previous passes near the Sun, so that it now shows little to no tail or comma when it feels the Sun's heat.

So, is it a comet or is it an asteroid? Scott Sheppard of the Carnegie Institution of Washington in DC says, "There's probably not a sharp cutoff. Comets probably have a lot of rock in them and asteroids probably have a lot of ice in them as well." link

Bacteria cultured in space are more deadly

It turns out that a few bacteria can really ruin your space flight. That's why NASA quarantines astronauts several days before their launch.

The National Academy of Sciences reported that bacteria exposed to the microgravity of space are considerably more deadly than their earthbound relatives. During last year's space shuttle Atlantis mission, astronauts brought aboard (on purpose) infectious Salmonella bacteria to see how they are affected by microgravity. When the space-tourist bacteria returned to Earth, they were injected into mice. Mice exposed to space bacteria were three times more likely to die from the Salmonella infection than the control mice, which were injected with earthbound Salmonella.

The most likely explanation for this dwells along the outer cell walls of the bacteria. It is thought that microgravity reduces fluid shear - the movement of liquid around the bacterium cells. Low fluid shear conditions are what the cells experience when they are in the human body. It was also observed that the low fluid shear stimulated the expression of the gene Hfq, which scientists are now fingering as the key to Salmonella's increased strength.

Couple microgravity's affect on bacteria with the fact that microgravity is also known to weaken the human immune system, and it creates a perfect storm for bacteria to attack space travelers. link

Blurring the line between algorithm and judgment

A NYTimes science columnist has eloquently mused on the input-feedback dynamic between cyberspace and its users. "As you sit with your eHarmony spouse watching the movies Netflix prescribes, you might as well be an avatar in Second Life. You have been absorbed into the operating system." link
(If you don't want to register for NYT free content, go to http://www.bugmenot.com/)

Why our cells regenerate the hard way

We lose billions of cells from our body everyday. It's natural to lose them, and luckily, we can naturally replace them. But when our cells regenerate, but they don't do it the easy way. The easy way would be for similar cells in the location to divide and replicate themselves to fill in for their lost neighbors. That would be a very fast and energy-efficient way of regenerating. But that's not the way it works, as summarized in a new report in Nature.

When dead cells are replaced, they are replaced from scratch. Each kind of cell in the body has its own dedicatied set of stem cells. To keep up with the need for replacement cells, stem cells act as the seeds from which new cells for that part of the body are sprung. By dividing, the stem cells initiate a series of cell generations, each new generation more speciallized than the one before it, until the just the right replacement cell is produced. This process takes a lot more energy and time than a single cell division.

Building replacement cells from scratch is safer for the body; it guarentees that replacement cells will not have the mutations of the cells from which they divided. Why is this safer? If the dividing cell was deceased, or if it were a cancer cell, then deceased cells would divide and quickly multiply beyond the organism's control.

Futhermore, if our cells were to regenerate by a single cell division, single organisms would evolve as they aged. For example, consider a frog genetically built for a cool, wet environment that moves to a hot, dry environment. As the cells of this frog are naturally replaced over time, the cells that are better suited for dry heat will out-complete the others. And with each generation of new cells, the whole frog would evolve towards the hot, dry environment. Within its single lifespan, this organism would do what is not possible: evolve into a very different one. A species cannot evolve in one generation; it must evolve over a long series of generations.

So, for an organism to make a replacement cell, it must be built from scratch from stem cells; it cannot make cheap copies of ready-made cells.

Interestingly, there is an exception to this rule, found in cells of the immune system. The cells of an organism's immune system must evolve within the organism's lifespan. Take our frog for example: when the frog's immune system encounters a decease it has never handled before, immune cells capable of fighting the decease can directly divide themselves to increase their numbers. It does the frog no good if the frog's descendants' evolve to fight the decease. The frog's immune cells must evolve during the frog's lifetime, or the frog won't stand a chance against the new decease. Does this mean that cells of the immune system are more vulnerable to decease, given that deceased immune cells are can divide and spread themselves? Yes. This is why deceases that attack the immune system are so deadly. link

Martian surface water: none to be found

Finding liquid water on Mars has been a frustrating endeavor. We know that the poles are covered with ice, but several satellite missions have failed to find water flowing on the surface of the red planet. This month's journal Science describes the latest information from the first 100 days of the mission of the Mars Reconnaissance Orbiter (MRO). Hoping that the orbiter would identify waterfront landing sites for future rovers, scientists were disappointed to find that the virtually all of the Mars surface is dry. The formations once thought to be carved out by flowing water have been formed by lava flows. Dry areas thought to be riverbeds and former ocean floors are covered with volcanic rock. link

Things could always be worse

Think the environment in your area is bad? Yesterday, National Geographic reported the 10 most polluted places in the word, as named by the Blacksmith Institute. No sites in the US made the list, which includes several mining towns and Chernobyl. link

A rose is not a rose

The old saying goes, "a rose is a rose is a rose." Scientists, however know otherwise. Two humans can describe and react to the same smell quite differently. In a recent study at Rockefeller University in NY, some human subjects found the compound androstenone to be appealing and sweet, others found it to be foul and offensive, and others could not smell it at all. Going on a hunch, the scientists examined each subjects' genetic code, and found that how the subjects perceived androstenone depended on a single gene. This is one step in unravelling the links between our genetic code and our senses. link audio link

Waking a sleeping red giant

Better get your stuff done. Time's running out. Five-billion years from now, our sun will live out it's current stage of life. Having turned all the hydrogen in it's core into helium, it's outer layers of hydrogen will collapse into the center. The sun will become a red giant. In the process, it's core will heat and expand, it's radius will grow to 100 times it's size, and anything in the way, including Mercury and Venus, will be obliterated. But, according to a group of Italian astronomers, the Earth will be spared. The astronomers report that a nearby star called V 391 Pegasi has a planet orbiting it at about the same distance as we are to our sun. Remarkably, this planet has survived V 391 Pegasi's transformation to a red giant, so there's hope for Earth. Unfortunately, even though the Earth will survive, we will not. When the sun becomes a red giant, the intense heat and proximity of the sun will scorch the Earth and boil off the oceans. Perhaps within five-billion years, humans will have evolved into higher, purely spiritual beings, and we'll have no need for a planet anyway. link

Japanese head for the moon

Given all we know about distant planets and their moons, it is surprising that we still haven't got a definitive theory about where the moon came from. This morning, the Japan Aerospace Exploration Agency (JAXA) launched their Selenological and Engineering Explorer (SELENE) satellite. The satellite will orbit the earth a couple of times, and then head for the moon. After reaching the moon's orbit, it will launch two support satellites, and over the next year the satellite system will send back lunar topography and gravity data in unrivalled detail . This data is expected to firm up the 'giant impact' theory. According to this theory, a planetary body slammed into Earth 4.5-billion years ago, and the resulting debris eventually gathered to form the moon. link

The healing power of embryonic stem cells

Embryonic stem cells are formed so early in an organism's development that they have an almost magical ability to grow into any kind of cell and perform any function. For some time now, researchers have sought ways to recruit these adaptable cells to replace others that have been damaged by diseases like cancer and Alzheimer's. But recently, it was seen that embryonic stem don't just replace damaged cells, they also release chemical signals that prompt the defective cells to reboot and start developing properly. After examining tissue that was repaired by the injection of embryonic stem cells, it was determined that only one in five of the repaired cells were actually descendants of the injected embryonic stem cells. The rest repaired themselves after receiving signals from the injected stem cells. link

Neanderthals not the victim of climate change

What happened to the Neanderthals? They lived in Europe until about 30,000 years ago. After comparing the most likely dates of their extinction to climate data, scientists have concluded that their extinction was not caused by climate change. Their extinction was most likely due to their inability to complete with a more intelligent species: humans. link

Wow is an understatement

A year and a half ago, I stopped blogging. It seemed like I was shouting into an anthill, and I lost interest. I looked at my blog today. I haven't looked at it for a long time. I actually had comments, and I missed them while I was on hiatus. Thank you, much too late, for your comments. I'm back.