April 28, 2008 at 5:40 AM EDT
Scientists have found a direct link between the frozen remains of a man found in a glacier in northern B.C. and 17 people living in B.C., Yukon and Alaska.
The news came at a symposium in Victoria this past weekend, focusing on Kwaday Dan Ts'inchi', an aboriginal man whose remains were found in 1999 by hunters in Tatshenshini-Alsek Park, which is in the traditional territory of the Champagne and Aishihik First Nations.
"The connection to the people," said Al Mackie, an archaeologist on the project, "how they know his clan, how they know who his relatives are, that's amazing. You just don't get that in archaeology. It never happens."
Kwaday Dan Ts'inchi' means Long Ago Person Found, and he's believed to have died some time between the years 1670 and 1850. His remains were revealed after a glacier started to recede.
Since the discovery, scientists have been studying all facets of the man, including his clothes, tools, migratory patterns, even the contents of his stomach. But it's the DNA link to living people that has created the biggest stir.
"It's just thrilling," said Pearl Callaghan, a member of the Teslin-Tlingit First Nation. "The knowledge is so new to us; we're still in a state of amazement."
Her sister, Sheila Clark, said she was happy to be part of something special, but added, "it's overwhelming in a way."
"The significance is huge," said Chief Diane Stand of the Champagne and Aishihik First Nations. "A lot of people are really happy and really excited."
Chief Strand said it proves that there is not only a link between people, but also between cultures as well. Long Ago Person Found is believed to have spent time both in the Interior and on the coast.
"The Champagne and Aishihik First Nations have a huge number of people that live in Alaska ... and this discovery has made those ties even stronger."
"We never stuck to our villages," said Art Johns, of the Carcross-Tagish First Nation. Mr. Johns, also a DNA-linked descendant, said it was common for aboriginal people to be nomadic.
Chief Strand said the findings are important for her people, especially the youth, who seem captivated by learning about their people's past. "Their eyes got big and they got so excited."
Chief Strand applauded the news of the DNA link, but she expressed some frustration over the scientific community's attitude toward cultural issues. Chief Stand said that for years, she and others have tried to contribute to the investigative process by telling ancestral stories, but they were discounted or not taken seriously. She said the discovery lends greater credibility to first nations' traditions.
"This reaffirms the integrity of our oral history," Chief Strand said. "Our oral history needs to have a place in your scientific world."
At the symposium in Victoria, many praised the collaborative effort in investigating the iceman and the role it played in the research.
While the work on the human DNA project has opened new doors and work will continue on establishing a fuller family tree, Long Ago Person Found's descendants said they finally have the opportunity to give their ancestor a proper burial. Because his lineage had never been established, no memorial potlatch could be held. Of the 17 people linked through DNA, 15 self-identify with the Wolf Clan, meaning the young man was most likely Wolf as well.
"We needed to know who he is so we can treat him properly," said Chief Strand, "with the respect and dignity he deserves."
Wednesday, April 30, 2008
Eight of the World's Most Unusual Plants
Weird is relative. What seems weird to me might not seem weird to you. In the plant kingdom, however, there are definitely some species that most people would acknowledge are highly unusual. In the wack spirit of Halloween, some of my findings follow.
1. Rafflesia arnoldii: this parasitic plant develops the world's largest bloom that can grow over three feet across. The flower is a fleshy color, with spots that make it look like a teenager's acne-ridden skin. It smells bad and has a hole in the center that holds six or seven quarts of water. The plant has no leaves, stems, or roots.
. Hydnora africana, an unusual flesh-colored, parasitic flower that attacks the nearby roots of shrubby in arid deserts of South Africa. The putrid-smelling blossom attracts herds of carrion beetles.
3. Dracunculus vulgaris: smells like rotting flesh, and has a burgundy-colored, leaf-like flower that projects a slender, black appendage.
4. Amorphophallus: means, literally, "shapeless penis." The name comes from the shape of the erect black spadix.
5. Wollemia nobilis: This bizarre-looking tree was known only from 120 million-year-old fossil leaves before 1994; fewer than one hundred exist in the wild. They have strange bark that looks like bubbles of chocolate, multiple trunks, and ferny-looking leaves growing in spirals. They can grow up to 125 feet tall.
6. Welwitschia mirabilis consists of only two leaves and a stem with roots. Its two leaves continue to grow until they resemble an alien life form. The stem gets thicker rather than higher, although this plant can grow to be almost six feet high and twenty-four feet wide. Its estimated lifespan is 400 to 1500 years. Mirabilis grows in Namibia, and is thought to be a relic of the Jurassic period.
7. Drakaea glyptodon: an orchid. It is the color of, and smells like, raw meat. Pollinated by male wasps.
8. Wolffia angusta: the world's smallest flower. A dozen plants would easily fit on the head of a pin and two plants in full bloom will fit inside a small printed letter "o."
Did Dinosaurs Die Because They Weren't Fat Enough?
Birds, unlike mammals, lack a tissue that is specialized to generate heat. A
team of researchers at New York Medical College writes that the same lack of
heat-generating tissue may have contributed to the extinction of ...
dinosaurs.
Humans, like all mammals, have two kinds of adipose tissue, white fat and
brown fat. White fat is used for storing energy-rich fuels, while brown fat
generates heat. Hibernating bears have a lot of brown fat, as do human
infants, who have much more than adults, relative to their body size.
Infants' brown fat protects them from hypothermia. Clinicians would like to
find ways of making adult white fat behave more like brown fat so that we
could burn, rather than store, energy.
While most mammals have a key gene called UCP1, which is responsible for the
heat-generation function of brown fat, birds do not. The researchers found
they could induce a specific type of stem cell in chicken embryos to produce
differentiated cells that are structured and behave like brown fat. These
chicken cells can even activate a UCP1 gene if presented with one from a
mouse.
The ability to produce brown fat evolved in a common ancestor of birds and
mammals, but the ability to generate heat was lost in the group that gave
rise to birds and lizards after it separated from the mammalian lineage (the
researchers found the lizard genome similarly lacks a UCP1 gene). This
strongly implies that dinosaurs, which diverged from birds even later than
lizards, also lacked brown fat.
Article: "The brown adipocyte differentiation pathway in birds: an
evolutionary road not taken," by Stuart A. Newman, Ph.D., professor of cell
biology and anatomy, Nadejda Mezentseva, a Ph.D. candidate at New York
Medical College, and Jaliya Kumaratilake, Ph.D., University of Adelaide,
Australia. BMC
team of researchers at New York Medical College writes that the same lack of
heat-generating tissue may have contributed to the extinction of ...
dinosaurs.
Humans, like all mammals, have two kinds of adipose tissue, white fat and
brown fat. White fat is used for storing energy-rich fuels, while brown fat
generates heat. Hibernating bears have a lot of brown fat, as do human
infants, who have much more than adults, relative to their body size.
Infants' brown fat protects them from hypothermia. Clinicians would like to
find ways of making adult white fat behave more like brown fat so that we
could burn, rather than store, energy.
While most mammals have a key gene called UCP1, which is responsible for the
heat-generation function of brown fat, birds do not. The researchers found
they could induce a specific type of stem cell in chicken embryos to produce
differentiated cells that are structured and behave like brown fat. These
chicken cells can even activate a UCP1 gene if presented with one from a
mouse.
The ability to produce brown fat evolved in a common ancestor of birds and
mammals, but the ability to generate heat was lost in the group that gave
rise to birds and lizards after it separated from the mammalian lineage (the
researchers found the lizard genome similarly lacks a UCP1 gene). This
strongly implies that dinosaurs, which diverged from birds even later than
lizards, also lacked brown fat.
Article: "The brown adipocyte differentiation pathway in birds: an
evolutionary road not taken," by Stuart A. Newman, Ph.D., professor of cell
biology and anatomy, Nadejda Mezentseva, a Ph.D. candidate at New York
Medical College, and Jaliya Kumaratilake, Ph.D., University of Adelaide,
Australia. BMC
A Fantastic Pony
Meet Molly. She's a gray speckled pony who was abandoned by her owners when Katrina hit southern Louisiana, USA . She spent weeks on her own before finally being rescued and taken to a farm where abandoned animals were stockpiled. While there, she was attacked by a pit bull terrier, and almost died. Her gnawed right front leg became infected and her vet went to LSU for help. But LSU was overwhelmed, and this pony was a welfare case. You know how that goes.But after surgeon Rustin Moore met Molly, he changed his mind. He saw how the pony was careful to lie down on different sides so she didn't seem to get sores, and how she allowed people to handle her. She protected her injured leg. She constantly shifted her weight, and didn't overload her good leg. She was a smart pony with a serious survival ethic.
Moore agreed to remove her leg below the knee and a temporary artificial limb was built. Molly walked out of the clinic and her story really begins there.
"This was the right horse and the right owner," Moore insists.
Molly happened to be a one-in-a-million patient. She's tough as nails, but sweet, and she was willing to cope with pain. She made it obvious she understood (that) she was in trouble. The other important factor, according to Moore , is having a truly committed and compliant owner who is dedicated to providing the daily care required over the lifetime of the horse.
Molly's story turns into a parable for life in post-Katrina Louisiana . The little pony gained weight, her mane felt a comb. A human prosthesis designer built her a leg.
The prosthetic has given Molly a whole new life, Allison Barca DVM, Molly's regular vet, reports.
And she asks for it! She will put her little limb out, and come to you and let you know that she wants you to put it on. Sometimes she wants you to take it off too." And sometimes, Molly gets away from Barca. "It can be pretty bad when you can't catch a three-legged horse", she laughs.
Most important of all, Molly has a job now. Kay, the rescue farm owner, started taking Molly to shelters, hospitals, nursing homes, rehabilitation centers. Anywhere she thought that people needed hope. Wherever Molly went, she showed people her pluck. She inspired people. And she had a good time doing it.
"It's obvious to me that Molly had a bigger role to play in life", Moore said, "She survived the hurricane, she survived a horrible injury, and now she is giving hope to others."
"She's not back to normal," Barca concluded, "but she's going to be better. To me, she could be a symbol for New Orleans itself."
Friday, April 25, 2008
Cloud Of Bees Swarming In 'Tornado Pattern' Chases Diners From Restaurant
DeLAND, Fla. -- A giant cloud of thousands of bees mysteriously appeared and began to swirl in a "tornado pattern" around a Central Florida Mexican restaurant.
Customers at Oxie's restaurant located near Highway 17-92 and Plymouth Avenue in DeLand said they noticed a cloud in the sky and thought it was raining. They then realized, the cloud was a swarm of bees.
"A lot of people said it was bees and ran to their cars," restaurant owner Oxie Ochiana said. "It was scary. I was panicking. I didn't know what to do."
Witnesses said the bees began to swirl like a tornado and menace customers Thursday.
"I looked and it was like a tornado of bees just all around our parking lot, swarming," said restaurant worker Marie Olson.
A crowd formed at a distance to watch the cloud of bees.
"It was crazy," Olson said. "I was shocked. I was surprised to see it. I don't know where they came from, so it was amazing to actually see them like that. It was awesome."
State bee experts said the bees, which were moving from tree to tree, are now resting because they have formed two huge cone-shaped swarms in a tree.
Experts said the bees would likely move out about 24 hours after forming the cones.
However, Ochiana called beekeepers to remove the cones from nearby trees Thursday night.
Thursday, April 24, 2008
Out-of-This-World Fishing
What lurked in the depths, will now haunt your boat.
Be careful what you hook up. Aside from picking some vicious industrial garbage, you can bring to the surface some strange and unmentionable things. Most fishermen will happily brag about an extraordinary big fish (and we'll show plenty of those in this article). But sometimes the catch is so bizarre, that they'd rather forget it over a drink or two.
Tuesday, April 22, 2008
Lizards Rapidly Evolve After Introduction to Island
Italian wall lizards introduced to a tiny island off the coast of Croatia are evolving in ways that would normally take millions of years to play out, new research shows.
In just a few decades the 5-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say.
In 1971, scientists transplanted five adult pairs of the reptiles from their original island home in Pod Kopiste to the tiny neighboring island of Pod Mrcaru, both in the south Adriatic Sea.
Genetic testing on the Pod Mrcaru lizards confirmed that the modern population of more than 5,000 Italian wall lizards are all descendants of the original ten lizards left behind in the 1970s.
Lizard Swarm
While the experiment was more than 30 years in the making, it was not by design, according to Duncan Irschick, a study author and biology professor at the University of Massachusetts, Amherst.
After scientists transplanted the reptiles, the Croatian War of Independence erupted, ending in the mid-1990s. The researchers couldn't get back to island because of the war, Irschick said.
In 2004, however, tourism began to open back up, allowing researchers access to the island laboratory.
"We didn't know if we would find a lizard there. We had no idea if the original introductions were successful," Irschick said.
What they found, however, was shocking.
"The island was swarming with lizards," he said.
The findings were published in March in the journal Proceedings of the National Academy of Sciences.
Fast-Track Evolution
The new habitat once had its own healthy population of lizards, which were less aggressive than the new implants, Irschick said.
The new species wiped out the indigenous lizard populations, although how it happened is unknown, he said.
The transplanted lizards adapted to their new environment in ways that expedited their evolution physically, Irschick explained.
Pod Mrcaru, for example, had an abundance of plants for the primarily insect-eating lizards to munch on. Physically, however, the lizards were not built to digest a vegetarian diet.
Researchers found that the lizards developed cecal valves—muscles between the large and small intestine—that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation's cellulose into volatile fatty acids.
"They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. "This was a brand-new structure."
Along with the ability to digest plants came the ability to bite harder, powered by a head that had grown longer and wider.
The rapid physical evolution also sparked changes in the lizard's social and behavioral structure, he said. For one, the plentiful food sources allowed for easier reproduction and a denser population.
The lizard also dropped some of its territorial defenses, the authors concluded.
Such physical transformation in just 30 lizard generations takes evolution to a whole new level, Irschick said.
It would be akin to humans evolving and growing a new appendix in several hundred years, he said.
"That's unparalleled. What's most important is how fast this is," he said.
While researchers do know the invader's impact on its reptile brethren, they do not know how the species impacts local vegetation or insects, a subject of future study, Irschick said.
Dramatic Changes
The study demonstrates that a lot of change happens in island environments, said Andrew Hendry, a biology professor at Montreal's McGill University.
What could be debated, however, is how those changes are interpreted—whether or not they had a genetic basis and not a "plastic response to the environment," said Hendry, who was not associated with the study.
There's no dispute that major changes to the lizards' digestive tract occurred. "That kind of change is really dramatic," he added.
"All of this might be evolution," Hendry said. "The logical next step would be to confirm the genetic basis for these changes."
Monday, April 21, 2008
Three-Headed Frog
Frog born with three heads. All of the heads and legs function properly.
See more funny videos at CollegeHumor
Friday, April 18, 2008
Adorable... bird killers
These are tarsiers found in Bohol, Philippines.Their eyes are connected ("wired") to their brain in a unique way, different from all other primates.
They catch insects by jumping at them, and apparently can even catch a bird in motion while jumping from tree to tree.
The Color of Plants on Other Worlds
The Color of Plants on Other Worlds
On other worlds, plants could be red, blue, even black
By Nancy Y. Kiang
The prospect of finding extraterrestrial life is no longer the domain of science fiction or UFO hunters. Rather than waiting for aliens to come to us, we are looking for them. We may not find technologically advanced civilizations, but we can look for the physical and chemical signs of fundamental life processes: “biosignatures.” Beyond the solar system, astronomers have discovered more than 200 worlds orbiting other stars, so-called extrasolar planets. Although we have not been able to tell whether these planets harbor life, it is only a matter of time now. Last July astronomers confirmed the presence of water vapor on an extrasolar planet by observing the passage of starlight through the planet’s atmosphere. The world’s space agencies are now developing telescopes that will search for signs of life on Earth-size planets by observing the planets’ light spectra.
Photosynthesis, in particular, could produce very conspicuous biosignatures. How plausible is it for photosynthesis to arise on another planet? Very. On Earth, the process is so successful that it is the foundation for nearly all life. Although some organisms live off the heat and methane of oceanic hydrothermal vents, the rich ecosystems on the planet’s surface all depend on sunlight.
Photosynthetic biosignatures could be of two kinds: biologically generated atmospheric gases such as oxygen and its product, ozone; and surface colors that indicate the presence of specialized pigments such as green chlorophyll. The idea of looking for such pigments has a long history. A century ago astronomers sought to attribute the seasonal darkening of Mars to the growth of vegetation. They studied the spectrum of light reflected off the surface for signs of green plants. One difficulty with this strategy was evident to writer H. G. Wells, who imagined a different scenario in The War of the Worlds: “The vegetable kingdom in Mars, instead of having green for a dominant colour, is of a vivid blood-red tint.” Although we now know that Mars has no surface vegetation (the darkening is caused by dust storms), Wells was prescient in speculating that photosynthetic organisms on another planet might not be green.
Even Earth has a diversity of photosynthetic organisms besides green plants. Some land plants have red leaves, and underwater algae and photosynthetic bacteria come in a rainbow of colors. Purple bacteria soak up solar infrared radiation as well as visible light. So what will dominate on another planet? And how will we know when we see it? The answers depend on the details of how alien photosynthesis adapts to light from a parent star of a different type than our sun, filtered through an atmosphere that may not have the same composition as Earth’s.
Harvesting Light
In trying to figure out how photosynthesis might operate on other planets, the first step is to explain it on Earth. The energy spectrum of sunlight at Earth’s surface peaks in the blue-green, so scientists have long scratched their heads about why plants reflect green, thereby wasting what appears to be the best available light. The answer is that photosynthesis does not depend on the total amount of light energy but on the energy per photon and the number of photons that make up the light.
Whereas blue photons carry more energy than red ones, the sun emits more of the red kind. Plants use blue photons for their quality and red photons for their quantity. The green photons that lie in between have neither the energy nor the numbers, so plants have adapted to absorb fewer of them.
The basic photosynthetic process, which fixes one carbon atom (obtained from carbon dioxide, CO2) into a simple sugar molecule, requires a minimum of eight photons. It takes one photon to split an oxygen-hydrogen bond in water (H2O) and thereby to obtain an electron for biochemical reactions. A total of four such bonds must be broken to create an oxygen molecule (O2). Each of those photons is matched by at least one additional photon for a second type of reaction to form the sugar. Each photon must have a minimum amount of energy to drive the reactions.
The way plants harvest sunlight is a marvel of nature. Photosynthetic pigments such as chlorophyll are not isolated molecules. They operate in a network like an array of antennas, each tuned to pick out photons of particular wavelengths. Chlorophyll preferentially absorbs red and blue light, and carotenoid pigments (which produce the vibrant reds and yellows of fall foliage) pick up a slightly different shade of blue. All this energy gets funneled to a special chlorophyll molecule at a chemical reaction center, which splits water and releases oxygen.
The funneling process is the key to which colors the pigments select. The complex of molecules at the reaction center can perform chemical reactions only if it receives a red photon or the equivalent amount of energy in some other form. To take advantage of blue photons, the antenna pigments work in concert to convert the high energy (from blue photons) to a lower energy (redder), like a series of step-down transformers that reduces the 100,000 volts of electric power lines to the 120 or 240 volts of a wall outlet. The process begins when a blue photon hits a blue-absorbing pigment and energizes one of the electrons in the molecule. When that electron drops back down to its original state, it releases this energy—but because of energy losses to heat and vibrations, it releases less energy than it absorbed.
The pigment molecule releases its energy not in the form of another photon but in the form of an electrical interaction with another pigment molecule that is able to absorb energy at that lower level. This pigment, in turn, releases an even lower amount of energy, and so the process continues until the original blue photon energy has been downgraded to red. The array of pigments can also convert cyan, green or yellow to red. The reaction center, as the receiving end of the cascade, adapts to absorb the lowest-energy available photons. On our planet’s surface, red photons are both the most abundant and the lowest energy within the visible spectrum.
For underwater photosynthesizers, red photons are not necessarily the most abundant. Light niches change with depth because of filtering of light by water, by dissolved substances and by overlying organisms themselves. The result is a clear stratification of life-forms according to their mix of pigments. Organisms in lower water layers have pigments adapted to absorb the light colors left over by the layers above. For instance, algae and cyanobacteria have pigments known as phycobilins that harvest green and yellow photons. Nonoxygen-producing (anoxygenic) bacteria have bacteriochlorophylls that absorb far-red and near-infrared light, which is all that penetrates to the murky depths.
Organisms adapted to low-light conditions tend to be slower-growing, because they have to put more effort into harvesting whatever light is available to them. At the planet’s surface, where light is abundant, it would be disadvantageous for plants to manufacture extra pigments, so they are selective in their use of color. The same evolutionary principles would operate on other worlds.
Just as aquatic creatures have adapted to light filtered by water, land dwellers have adapted to light filtered by atmospheric gases. At the top of Earth’s atmosphere, yellow photons (at wavelengths of 560 to 590 nanometers) are the most abundant kind. The number of photons drops off gradually with longer wavelength and steeply with shorter wavelength. As sunlight passes through the upper atmosphere, water vapor absorbs the infrared light in several wavelength bands beyond 700 nm. Oxygen produces absorption lines—narrow ranges of wavelengths that the gas blocks—at 687 and 761 nm. We all know that ozone (O3) in the stratosphere strongly absorbs the ultraviolet (UV). Less well known is that it also absorbs weakly across the visible range.
Putting it all together, our atmosphere demarcates windows through which radiation can make it to the planet’s surface. The visible radiation window is defined at its blue edge by the drop-off in the intensity of short-wavelength photons emitted by the sun and by ozone absorption of UV. The red edge is defined by oxygen absorption lines. The peak in photon abundance is shifted from yellow to red (about 685 nm) by ozone’s broad absorbance across the visible.
Plants are adapted to this spectrum, which is determined largely by oxygen—yet plants are what put the oxygen into the atmosphere to begin with. When early photosynthetic organisms first appeared on Earth, the atmosphere lacked oxygen, so they must have used different pigments from chlorophyll. Only over time, as photosynthesis altered the atmospheric composition, did chlorophyll emerge as optimal.
The firm fossil evidence for photosynthesis dates to about 3.4 billion years ago (Ga), but earlier fossils exhibit signs of what could have been photosynthesis. Early photosynthesizers had to start out underwater, in part because water is a good solvent for biochemical reactions and in part because it provides protection against solar UV radiation—shielding that was essential in the absence of an atmospheric ozone layer. These earliest photosynthesizers were underwater bacteria that absorbed infrared photons. Their chemical reactions involved hydrogen, hydrogen sulfide or iron rather than water, so they did not produce oxygen gas. Oxygen-generating (oxygenic) photosynthesis by cyanobacteria in the oceans started 2.7 Ga. Oxygen levels and the ozone layer slowly built up, allowing red and brown algae to emerge. As shallower water became safe from UV, green algae evolved. They lacked phycobilins and were better adapted to the bright light in surface waters. Finally, plants descended from green algae emerged onto land—two billion years after oxygen had begun accumulating in the atmosphere.
And then the complexity of plant life exploded, from mosses and liverworts on the ground to vascular plants with tall canopies that capture more light and have special adaptations to particular climates. Conifer trees have conical crowns that capture light efficiently at high latitudes with low sun angles; shade-adapted plants have anthocyanin as a sunscreen against too much light. Green chlorophyll not only is well suited to the present composition of the atmosphere but also helps to sustain that composition—a virtuous cycle that keeps our planet green. It may be that another step of evolution will favor an organism that takes advantage of the shade underneath tree canopies, using the phycobilins that absorb green and yellow light. But the organisms on top are still likely to stay green.
Painting the World Red
To look for photosynthetic pigments on another planet in another solar system, astronomers must be prepared to see the planet at any of the possible stages in its evolution. For instance, they may catch sight of a planet that looks like our Earth two billion years ago. They must also allow that extrasolar photosynthesizers may have evolved capabilities that their counterparts here have not, such as splitting water using longer-wavelength photons.
The longest wavelength yet observed in photosynthesis on Earth is about 1,015 nm (in the infrared), in purple anoxygenic bacteria. The longest wavelength observed for oxygenic photosynthesis is about 720 nm, in a marine cyanobacterium. But the laws of physics set no strict upper limit. A large number of long-wavelength photons could achieve the same purpose as a few short-wavelength ones.
The limiting factor is not the feasibility of novel pigments but the light spectrum available at a planet’s surface, which depends mainly on the star type. Astronomers classify stars based on color, which relates to temperature, size and longevity. Only certain types are long-lived enough to allow for complex life to evolve. These are, in order from hottest to coolest, F, G, K and M stars. Our sun is a G star. F stars are larger, burn brighter and bluer, and take a couple of billion years to use up their fuel. K and M stars are smaller, dimmer, redder and longer-lived.
Around each of these stars is a habitable zone, a range of orbits where planets can maintain a temperature that allows for liquid water. In our solar system, the habitable zone is a ring encompassing Earth’s and Mars’s orbits. For an F star, the habitable zone for an Earth-size planet is farther out; for a K or M star, closer in. A planet in the habitable zone of an F or K star receives about as much visible radiation as Earth does. Such a planet could easily support oxygenic photosynthesis like that on Earth. The pigment color may simply be shifted within the visible band.
M stars, also known as red dwarfs, are of special interest because they are the most abundant type in our galaxy. They emit much less visible radiation than our sun; their output peaks in the near-infrared. John Raven, a biologist at the University of Dundee in Scotland, and Ray Wolstencroft, an astronomer at the Royal Observatory, Edinburgh, have proposed that oxygenic photosynthesis is theoretically possible with near-infrared photons. An organism would have to use three or four near-infrared photons to split H2O, rather than the two that suffice for Earth’s plants. The photons work together like stages of a rocket to provide the necessary energy to an electron as it performs the chemical reactions.
M stars pose an extra challenge to life: when young, they emit strong UV flares. Organisms could avoid the damaging UV radiation deep underwater, but would they then be starved for light? If so, photosynthesis might not arise. As M stars age, though, they cease producing flares, at which point they give off even less UV radiation than our sun does. Organisms would not need a UV-absorbing ozone layer to protect them; they could thrive on land even if they did not produce oxygen.
In sum, astronomers must consider four scenarios depending on the age and type of star:
* Anaerobic, ocean life. The parent star is a young star of any type. Organisms do not necessarily produce oxygen; the atmosphere may be mostly other gases such as methane.
* Aerobic, ocean life. The parent star is an older star of any type. Enough time has elapsed for oxygenic photosynthesis to evolve and begin to build up atmospheric oxygen.
* Aerobic, land life. The parent star is a mature star of any type. Plants cover the land. Life on Earth is now at this stage.
* Anaerobic, land life. The star is a quiescent M star, so the UV radiation is negligible. Plants cover the land but may not produce oxygen.
Photosynthetic biosignatures for these different cases would clearly not be the same. From experience with satellite imagery of Earth, astronomers expect that any life in the ocean would be too sparsely distributed for telescopes to see. So the first two scenarios would not produce strong pigment biosignatures; life would reveal itself to us only by the atmospheric gases it produced. Therefore, researchers studying alien plant colors focus on land plants, either on planets around F, G and K stars with oxygenic photosynthesis or on planets around M stars with any type of photosynthesis.
Black Is the New Green
Regardless of the specific situation, photosynthetic pigments must still satisfy the same rules as on Earth: pigments tend to absorb photons that are either the most abundant, the shortest available wavelength (most energetic) or the longest available wavelength (where the reaction center absorbs). To tackle the question of how star type determines plant color, it took researchers from many disciplines to put together all the stellar, planetary and biological pieces.
Martin Cohen, a stellar astronomer at the University of California, Berkeley, collected data for an F star (sigma Bootis), a K star (epsilon Eridani), an actively flaring M star (AD Leo), and a hypothetical quiescent M star with a temperature of 3,100 kelvins. Antígona Segura, an astronomer at the National Autonomous University of Mexico, ran computer simulations of Earth-like planets in the habitable zone of these stars. Using models developed by Alexander Pavlov, now at the University of Arizona, and James Kasting of Pennsylvania State University, Segura studied the interaction between the stellar radiation and the atmosphere’s likely constituents (assuming that volcanoes on these worlds emit the same gases they do on Earth) to deduce the planets’ atmospheric chemistry, both for negligible oxygen and for Earth-like oxygen levels.
Using Segura’s results, Giovanna Tinetti, a physicist at University College London, calculated the filtering of radiation by applying a model developed by David Crisp of the Jet Propulsion Laboratory in Pasadena, Calif. (This is one of the models enlisted to calculate how much light reaches the solar panels of the Mars rovers.) Interpreting these calculations required the combined knowledge of five of us: microbial biologist Janet Siefert of Rice University, biochemists Robert Blankenship of Washington University in St. Louis and Govindjee of the University of Illinois at Urbana-Champaign, planetary scientist Victoria Meadows of the University of Washington, and me, a biometeorologist at the NASA Goddard Institute for Space Studies.
We found that the photons reaching the surface of planets around F stars tend to be blue, with the greatest abundance at 451 nm. Around K stars, the peak is in the red at 667 nm, nearly the same as on Earth. Ozone plays a strong role, making the F starlight bluer than it otherwise would be and the K starlight redder. The useful radiation for photosynthesis would be in the visible range, as on Earth.
Thus, plants on both F- and K-star planets could have colors just like those on Earth but with subtle variations. For F stars, the flood of energetic blue photons is so intense that plants might need to reflect it using a screening pigment similar to anthocyanin, giving them a blue tint. Alternatively, plants might need to harvest only the blue, discarding the lower-quality green through red light. That would produce a distinctive blue edge in the spectrum of reflected light, which would stand out to telescope observers.
The range of M-star temperatures makes possible a very wide variation in alien plant colors. A planet around a quiescent M star would receive about half the energy that Earth receives from our sun. Although that is plenty for living things to harvest—about 60 times more than the minimum needed for shade-adapted Earth plants—most of the photons are near-infrared. Evolution might favor a greater variety of photosynthetic pigments to pick out the full range of visible and infrared light. With little light reflected, plants might even look black to our eyes.
Pale Purple Dot
The experience of life on Earth indicates that early ocean photosynthesizers on planets around F, G and K stars could survive the initial oxygen-free atmosphere and develop the oxygenic photosynthesis that would lead ultimately to land plants. For M stars, the situation is trickier. We calculated a “sweet spot” about nine meters underwater where early photosynthesizers could both survive UV flares and still have enough light to be productive. Although we might not see them through telescopes, these organisms could set the stage for life at the planet’s surface. On worlds around M stars, land plants that exploited a wider range of colors would be nearly as productive as plants on Earth.
For all star types, an important question will be whether a planet’s land area is large enough for upcoming space telescopes to see. The first generation of these telescopes will see the planet as a single dot; they will lack the resolution to make maps of the surface. All scientists will have is a globally averaged spectrum. Tinetti calculates that for land plants to show up in this spectrum, at least 20 percent of the surface must be land that is both covered in vegetation and free from clouds. On the other hand, oceanic photosynthesis releases more oxygen to the atmosphere. Therefore, the more prominent the pigment biosignature, the weaker the oxygen biosignature, and vice versa. Astronomers might see one or the other, but not both.
If a space telescope sees a dark band in a planet’s reflected light spectrum at one of the predicted colors, then someone monitoring the observations from a computer may be the first person to see signs of life on another world. Other false interpretations have to be ruled out, of course, such as whether minerals could have the same signature. Right now we can identify a plausible palette of colors that indicate plant life on another planet; for instance, we predict another Earth to have green, yellow or orange plants. But it is currently hard to make finer predictions. On Earth, we have been able to determine that the signature of chlorophyll is unique to plants, which is why we can detect plants and ocean phytoplankton with satellites. We will have to figure out unique signatures of vegetation for other planets.
Finding life on other planets—abundant life, not just fossils or microbes eking out a meager living under extreme conditions—is a fast-approaching reality. Which stars shall we target, given there are so many out there? Will we be able to measure the spectra of M-star planets, which tend to be very close to their stars? What wavelength range and resolution do the new telescopes need? Our understanding of photosynthesis will be key to designing these missions and interpreting their data. Such questions drive a synthesis of the sciences in a way that is only beginning. Our very ability to search for life elsewhere in the universe ultimately requires our deepest understanding of life here on Earth.
On other worlds, plants could be red, blue, even black
By Nancy Y. Kiang
The prospect of finding extraterrestrial life is no longer the domain of science fiction or UFO hunters. Rather than waiting for aliens to come to us, we are looking for them. We may not find technologically advanced civilizations, but we can look for the physical and chemical signs of fundamental life processes: “biosignatures.” Beyond the solar system, astronomers have discovered more than 200 worlds orbiting other stars, so-called extrasolar planets. Although we have not been able to tell whether these planets harbor life, it is only a matter of time now. Last July astronomers confirmed the presence of water vapor on an extrasolar planet by observing the passage of starlight through the planet’s atmosphere. The world’s space agencies are now developing telescopes that will search for signs of life on Earth-size planets by observing the planets’ light spectra.
Photosynthesis, in particular, could produce very conspicuous biosignatures. How plausible is it for photosynthesis to arise on another planet? Very. On Earth, the process is so successful that it is the foundation for nearly all life. Although some organisms live off the heat and methane of oceanic hydrothermal vents, the rich ecosystems on the planet’s surface all depend on sunlight.
Photosynthetic biosignatures could be of two kinds: biologically generated atmospheric gases such as oxygen and its product, ozone; and surface colors that indicate the presence of specialized pigments such as green chlorophyll. The idea of looking for such pigments has a long history. A century ago astronomers sought to attribute the seasonal darkening of Mars to the growth of vegetation. They studied the spectrum of light reflected off the surface for signs of green plants. One difficulty with this strategy was evident to writer H. G. Wells, who imagined a different scenario in The War of the Worlds: “The vegetable kingdom in Mars, instead of having green for a dominant colour, is of a vivid blood-red tint.” Although we now know that Mars has no surface vegetation (the darkening is caused by dust storms), Wells was prescient in speculating that photosynthetic organisms on another planet might not be green.
Even Earth has a diversity of photosynthetic organisms besides green plants. Some land plants have red leaves, and underwater algae and photosynthetic bacteria come in a rainbow of colors. Purple bacteria soak up solar infrared radiation as well as visible light. So what will dominate on another planet? And how will we know when we see it? The answers depend on the details of how alien photosynthesis adapts to light from a parent star of a different type than our sun, filtered through an atmosphere that may not have the same composition as Earth’s.
Harvesting Light
In trying to figure out how photosynthesis might operate on other planets, the first step is to explain it on Earth. The energy spectrum of sunlight at Earth’s surface peaks in the blue-green, so scientists have long scratched their heads about why plants reflect green, thereby wasting what appears to be the best available light. The answer is that photosynthesis does not depend on the total amount of light energy but on the energy per photon and the number of photons that make up the light.
Whereas blue photons carry more energy than red ones, the sun emits more of the red kind. Plants use blue photons for their quality and red photons for their quantity. The green photons that lie in between have neither the energy nor the numbers, so plants have adapted to absorb fewer of them.
The basic photosynthetic process, which fixes one carbon atom (obtained from carbon dioxide, CO2) into a simple sugar molecule, requires a minimum of eight photons. It takes one photon to split an oxygen-hydrogen bond in water (H2O) and thereby to obtain an electron for biochemical reactions. A total of four such bonds must be broken to create an oxygen molecule (O2). Each of those photons is matched by at least one additional photon for a second type of reaction to form the sugar. Each photon must have a minimum amount of energy to drive the reactions.
The way plants harvest sunlight is a marvel of nature. Photosynthetic pigments such as chlorophyll are not isolated molecules. They operate in a network like an array of antennas, each tuned to pick out photons of particular wavelengths. Chlorophyll preferentially absorbs red and blue light, and carotenoid pigments (which produce the vibrant reds and yellows of fall foliage) pick up a slightly different shade of blue. All this energy gets funneled to a special chlorophyll molecule at a chemical reaction center, which splits water and releases oxygen.
The funneling process is the key to which colors the pigments select. The complex of molecules at the reaction center can perform chemical reactions only if it receives a red photon or the equivalent amount of energy in some other form. To take advantage of blue photons, the antenna pigments work in concert to convert the high energy (from blue photons) to a lower energy (redder), like a series of step-down transformers that reduces the 100,000 volts of electric power lines to the 120 or 240 volts of a wall outlet. The process begins when a blue photon hits a blue-absorbing pigment and energizes one of the electrons in the molecule. When that electron drops back down to its original state, it releases this energy—but because of energy losses to heat and vibrations, it releases less energy than it absorbed.
The pigment molecule releases its energy not in the form of another photon but in the form of an electrical interaction with another pigment molecule that is able to absorb energy at that lower level. This pigment, in turn, releases an even lower amount of energy, and so the process continues until the original blue photon energy has been downgraded to red. The array of pigments can also convert cyan, green or yellow to red. The reaction center, as the receiving end of the cascade, adapts to absorb the lowest-energy available photons. On our planet’s surface, red photons are both the most abundant and the lowest energy within the visible spectrum.
For underwater photosynthesizers, red photons are not necessarily the most abundant. Light niches change with depth because of filtering of light by water, by dissolved substances and by overlying organisms themselves. The result is a clear stratification of life-forms according to their mix of pigments. Organisms in lower water layers have pigments adapted to absorb the light colors left over by the layers above. For instance, algae and cyanobacteria have pigments known as phycobilins that harvest green and yellow photons. Nonoxygen-producing (anoxygenic) bacteria have bacteriochlorophylls that absorb far-red and near-infrared light, which is all that penetrates to the murky depths.
Organisms adapted to low-light conditions tend to be slower-growing, because they have to put more effort into harvesting whatever light is available to them. At the planet’s surface, where light is abundant, it would be disadvantageous for plants to manufacture extra pigments, so they are selective in their use of color. The same evolutionary principles would operate on other worlds.
Just as aquatic creatures have adapted to light filtered by water, land dwellers have adapted to light filtered by atmospheric gases. At the top of Earth’s atmosphere, yellow photons (at wavelengths of 560 to 590 nanometers) are the most abundant kind. The number of photons drops off gradually with longer wavelength and steeply with shorter wavelength. As sunlight passes through the upper atmosphere, water vapor absorbs the infrared light in several wavelength bands beyond 700 nm. Oxygen produces absorption lines—narrow ranges of wavelengths that the gas blocks—at 687 and 761 nm. We all know that ozone (O3) in the stratosphere strongly absorbs the ultraviolet (UV). Less well known is that it also absorbs weakly across the visible range.
Putting it all together, our atmosphere demarcates windows through which radiation can make it to the planet’s surface. The visible radiation window is defined at its blue edge by the drop-off in the intensity of short-wavelength photons emitted by the sun and by ozone absorption of UV. The red edge is defined by oxygen absorption lines. The peak in photon abundance is shifted from yellow to red (about 685 nm) by ozone’s broad absorbance across the visible.
Plants are adapted to this spectrum, which is determined largely by oxygen—yet plants are what put the oxygen into the atmosphere to begin with. When early photosynthetic organisms first appeared on Earth, the atmosphere lacked oxygen, so they must have used different pigments from chlorophyll. Only over time, as photosynthesis altered the atmospheric composition, did chlorophyll emerge as optimal.
The firm fossil evidence for photosynthesis dates to about 3.4 billion years ago (Ga), but earlier fossils exhibit signs of what could have been photosynthesis. Early photosynthesizers had to start out underwater, in part because water is a good solvent for biochemical reactions and in part because it provides protection against solar UV radiation—shielding that was essential in the absence of an atmospheric ozone layer. These earliest photosynthesizers were underwater bacteria that absorbed infrared photons. Their chemical reactions involved hydrogen, hydrogen sulfide or iron rather than water, so they did not produce oxygen gas. Oxygen-generating (oxygenic) photosynthesis by cyanobacteria in the oceans started 2.7 Ga. Oxygen levels and the ozone layer slowly built up, allowing red and brown algae to emerge. As shallower water became safe from UV, green algae evolved. They lacked phycobilins and were better adapted to the bright light in surface waters. Finally, plants descended from green algae emerged onto land—two billion years after oxygen had begun accumulating in the atmosphere.
And then the complexity of plant life exploded, from mosses and liverworts on the ground to vascular plants with tall canopies that capture more light and have special adaptations to particular climates. Conifer trees have conical crowns that capture light efficiently at high latitudes with low sun angles; shade-adapted plants have anthocyanin as a sunscreen against too much light. Green chlorophyll not only is well suited to the present composition of the atmosphere but also helps to sustain that composition—a virtuous cycle that keeps our planet green. It may be that another step of evolution will favor an organism that takes advantage of the shade underneath tree canopies, using the phycobilins that absorb green and yellow light. But the organisms on top are still likely to stay green.
Painting the World Red
To look for photosynthetic pigments on another planet in another solar system, astronomers must be prepared to see the planet at any of the possible stages in its evolution. For instance, they may catch sight of a planet that looks like our Earth two billion years ago. They must also allow that extrasolar photosynthesizers may have evolved capabilities that their counterparts here have not, such as splitting water using longer-wavelength photons.
The longest wavelength yet observed in photosynthesis on Earth is about 1,015 nm (in the infrared), in purple anoxygenic bacteria. The longest wavelength observed for oxygenic photosynthesis is about 720 nm, in a marine cyanobacterium. But the laws of physics set no strict upper limit. A large number of long-wavelength photons could achieve the same purpose as a few short-wavelength ones.
The limiting factor is not the feasibility of novel pigments but the light spectrum available at a planet’s surface, which depends mainly on the star type. Astronomers classify stars based on color, which relates to temperature, size and longevity. Only certain types are long-lived enough to allow for complex life to evolve. These are, in order from hottest to coolest, F, G, K and M stars. Our sun is a G star. F stars are larger, burn brighter and bluer, and take a couple of billion years to use up their fuel. K and M stars are smaller, dimmer, redder and longer-lived.
Around each of these stars is a habitable zone, a range of orbits where planets can maintain a temperature that allows for liquid water. In our solar system, the habitable zone is a ring encompassing Earth’s and Mars’s orbits. For an F star, the habitable zone for an Earth-size planet is farther out; for a K or M star, closer in. A planet in the habitable zone of an F or K star receives about as much visible radiation as Earth does. Such a planet could easily support oxygenic photosynthesis like that on Earth. The pigment color may simply be shifted within the visible band.
M stars, also known as red dwarfs, are of special interest because they are the most abundant type in our galaxy. They emit much less visible radiation than our sun; their output peaks in the near-infrared. John Raven, a biologist at the University of Dundee in Scotland, and Ray Wolstencroft, an astronomer at the Royal Observatory, Edinburgh, have proposed that oxygenic photosynthesis is theoretically possible with near-infrared photons. An organism would have to use three or four near-infrared photons to split H2O, rather than the two that suffice for Earth’s plants. The photons work together like stages of a rocket to provide the necessary energy to an electron as it performs the chemical reactions.
M stars pose an extra challenge to life: when young, they emit strong UV flares. Organisms could avoid the damaging UV radiation deep underwater, but would they then be starved for light? If so, photosynthesis might not arise. As M stars age, though, they cease producing flares, at which point they give off even less UV radiation than our sun does. Organisms would not need a UV-absorbing ozone layer to protect them; they could thrive on land even if they did not produce oxygen.
In sum, astronomers must consider four scenarios depending on the age and type of star:
* Anaerobic, ocean life. The parent star is a young star of any type. Organisms do not necessarily produce oxygen; the atmosphere may be mostly other gases such as methane.
* Aerobic, ocean life. The parent star is an older star of any type. Enough time has elapsed for oxygenic photosynthesis to evolve and begin to build up atmospheric oxygen.
* Aerobic, land life. The parent star is a mature star of any type. Plants cover the land. Life on Earth is now at this stage.
* Anaerobic, land life. The star is a quiescent M star, so the UV radiation is negligible. Plants cover the land but may not produce oxygen.
Photosynthetic biosignatures for these different cases would clearly not be the same. From experience with satellite imagery of Earth, astronomers expect that any life in the ocean would be too sparsely distributed for telescopes to see. So the first two scenarios would not produce strong pigment biosignatures; life would reveal itself to us only by the atmospheric gases it produced. Therefore, researchers studying alien plant colors focus on land plants, either on planets around F, G and K stars with oxygenic photosynthesis or on planets around M stars with any type of photosynthesis.
Black Is the New Green
Regardless of the specific situation, photosynthetic pigments must still satisfy the same rules as on Earth: pigments tend to absorb photons that are either the most abundant, the shortest available wavelength (most energetic) or the longest available wavelength (where the reaction center absorbs). To tackle the question of how star type determines plant color, it took researchers from many disciplines to put together all the stellar, planetary and biological pieces.
Martin Cohen, a stellar astronomer at the University of California, Berkeley, collected data for an F star (sigma Bootis), a K star (epsilon Eridani), an actively flaring M star (AD Leo), and a hypothetical quiescent M star with a temperature of 3,100 kelvins. Antígona Segura, an astronomer at the National Autonomous University of Mexico, ran computer simulations of Earth-like planets in the habitable zone of these stars. Using models developed by Alexander Pavlov, now at the University of Arizona, and James Kasting of Pennsylvania State University, Segura studied the interaction between the stellar radiation and the atmosphere’s likely constituents (assuming that volcanoes on these worlds emit the same gases they do on Earth) to deduce the planets’ atmospheric chemistry, both for negligible oxygen and for Earth-like oxygen levels.
Using Segura’s results, Giovanna Tinetti, a physicist at University College London, calculated the filtering of radiation by applying a model developed by David Crisp of the Jet Propulsion Laboratory in Pasadena, Calif. (This is one of the models enlisted to calculate how much light reaches the solar panels of the Mars rovers.) Interpreting these calculations required the combined knowledge of five of us: microbial biologist Janet Siefert of Rice University, biochemists Robert Blankenship of Washington University in St. Louis and Govindjee of the University of Illinois at Urbana-Champaign, planetary scientist Victoria Meadows of the University of Washington, and me, a biometeorologist at the NASA Goddard Institute for Space Studies.
We found that the photons reaching the surface of planets around F stars tend to be blue, with the greatest abundance at 451 nm. Around K stars, the peak is in the red at 667 nm, nearly the same as on Earth. Ozone plays a strong role, making the F starlight bluer than it otherwise would be and the K starlight redder. The useful radiation for photosynthesis would be in the visible range, as on Earth.
Thus, plants on both F- and K-star planets could have colors just like those on Earth but with subtle variations. For F stars, the flood of energetic blue photons is so intense that plants might need to reflect it using a screening pigment similar to anthocyanin, giving them a blue tint. Alternatively, plants might need to harvest only the blue, discarding the lower-quality green through red light. That would produce a distinctive blue edge in the spectrum of reflected light, which would stand out to telescope observers.
The range of M-star temperatures makes possible a very wide variation in alien plant colors. A planet around a quiescent M star would receive about half the energy that Earth receives from our sun. Although that is plenty for living things to harvest—about 60 times more than the minimum needed for shade-adapted Earth plants—most of the photons are near-infrared. Evolution might favor a greater variety of photosynthetic pigments to pick out the full range of visible and infrared light. With little light reflected, plants might even look black to our eyes.
Pale Purple Dot
The experience of life on Earth indicates that early ocean photosynthesizers on planets around F, G and K stars could survive the initial oxygen-free atmosphere and develop the oxygenic photosynthesis that would lead ultimately to land plants. For M stars, the situation is trickier. We calculated a “sweet spot” about nine meters underwater where early photosynthesizers could both survive UV flares and still have enough light to be productive. Although we might not see them through telescopes, these organisms could set the stage for life at the planet’s surface. On worlds around M stars, land plants that exploited a wider range of colors would be nearly as productive as plants on Earth.
For all star types, an important question will be whether a planet’s land area is large enough for upcoming space telescopes to see. The first generation of these telescopes will see the planet as a single dot; they will lack the resolution to make maps of the surface. All scientists will have is a globally averaged spectrum. Tinetti calculates that for land plants to show up in this spectrum, at least 20 percent of the surface must be land that is both covered in vegetation and free from clouds. On the other hand, oceanic photosynthesis releases more oxygen to the atmosphere. Therefore, the more prominent the pigment biosignature, the weaker the oxygen biosignature, and vice versa. Astronomers might see one or the other, but not both.
If a space telescope sees a dark band in a planet’s reflected light spectrum at one of the predicted colors, then someone monitoring the observations from a computer may be the first person to see signs of life on another world. Other false interpretations have to be ruled out, of course, such as whether minerals could have the same signature. Right now we can identify a plausible palette of colors that indicate plant life on another planet; for instance, we predict another Earth to have green, yellow or orange plants. But it is currently hard to make finer predictions. On Earth, we have been able to determine that the signature of chlorophyll is unique to plants, which is why we can detect plants and ocean phytoplankton with satellites. We will have to figure out unique signatures of vegetation for other planets.
Finding life on other planets—abundant life, not just fossils or microbes eking out a meager living under extreme conditions—is a fast-approaching reality. Which stars shall we target, given there are so many out there? Will we be able to measure the spectra of M-star planets, which tend to be very close to their stars? What wavelength range and resolution do the new telescopes need? Our understanding of photosynthesis will be key to designing these missions and interpreting their data. Such questions drive a synthesis of the sciences in a way that is only beginning. Our very ability to search for life elsewhere in the universe ultimately requires our deepest understanding of life here on Earth.
Wednesday, April 16, 2008
Oldest Living Tree
A Norway spruce growing in Sweden has a root system that has been growing for 9,550 years! The tree is only about 13 feet tall, but the trunk is not the first first one grown from the roots. Leif Kullman, professor at Umeå University led the team that discovered the tree’s age.
The spruce’s stems or trunks have a lifespan of around 600 years, “but as soon as a stem dies, a new one emerges from the same root stock,” Kullman explained. “So the tree has a very long life expectancy.”
The age of the root system was determined by radiocarbon dating.
Trees much older than 9,550 years would be impossible in Sweden, because ice sheets covered the country until the end of the last Ice Age around 11,000 years ago, Kullman noted.
Baby Fire Ants Play Dead When Attacked
Opossums aren’t the only animals that play dead - turns out that fire ants do it too:
When threatened by danger, the young insects will play dead to fake out an attacker.
"No one has ever reported this before, and it was a big shock to me," said Deby Cassill, an evolutionary biologist at the University of South Florida St. Petersburg. "Ants from an attacking colony will come up to inspect them, and they’ll be curled up just like a dead ant. Then moments later they uncurl and walk away."
Cassill and her students also noticed that as the ants age — some live six months to a year — they grow out of the curious behavior. Middle-aged ants tend to flee, while the eldest are aggressive and attack furiously.
"All worker ants are sterile females, so it’s the cranky old ladies who are the ones fighting to the death," Cassill said.
We all should know better than messing with cranky old ladies: Link (photo: Scott Bauer)
When threatened by danger, the young insects will play dead to fake out an attacker.
"No one has ever reported this before, and it was a big shock to me," said Deby Cassill, an evolutionary biologist at the University of South Florida St. Petersburg. "Ants from an attacking colony will come up to inspect them, and they’ll be curled up just like a dead ant. Then moments later they uncurl and walk away."
Cassill and her students also noticed that as the ants age — some live six months to a year — they grow out of the curious behavior. Middle-aged ants tend to flee, while the eldest are aggressive and attack furiously.
"All worker ants are sterile females, so it’s the cranky old ladies who are the ones fighting to the death," Cassill said.
We all should know better than messing with cranky old ladies: Link (photo: Scott Bauer)
Tuesday, April 15, 2008
Heavy snow breaking plows in Yellowstone
Heavy snow breaking plows in Yellowstone
By Cory Hatch, Jackson Hole, Wyo.
Date: April 12, 2008
Yellowstone officials say heavy snow has resulted in the breakdown of two bulldozers as road crews attempt to remove snow from park roads before they open for spring.
The park has since rented two machines in an attempt to clear roads from Mammoth to the West Entrance and south to Old Faithful by opening day March 2.
Yellowstone spokesman Al Nash said this winter stands out as the snowiest in recent memory. “This is the most significant winter in terms of snowfall in years,” he said. “It could be the most snowfall we’ve seen in seven to ten years. For a change we’ve had a normal winter.”
Though cumulative snowfall amounts park-wide weren’t available, Nash said that, during the month of March alone, the park’s South Entrance received 101 inches.
According to Nash, the snow is so deep in some places that the bulldozer operators have to push the snow off the roadway in layers to feed it to rotary plows that then blow it off the road surface.
The south and east areas of the park typically see the most snow, especially the road between the South Entrance and West Thumb, Dunraven Pass, the Beartooth Highway and Sylvan Pass. Even during poor snow years, snowbanks along Sylvan Pass can reach 30 feet high, Nash said.
Nash said he expects that the park’s East Entrance will open May 2 and the South Entrance on May 9. Dunraven Pass and the Beartooth Highway aren’t scheduled to open until Memorial Day.
By Cory Hatch, Jackson Hole, Wyo.
Date: April 12, 2008
Yellowstone officials say heavy snow has resulted in the breakdown of two bulldozers as road crews attempt to remove snow from park roads before they open for spring.
The park has since rented two machines in an attempt to clear roads from Mammoth to the West Entrance and south to Old Faithful by opening day March 2.
Yellowstone spokesman Al Nash said this winter stands out as the snowiest in recent memory. “This is the most significant winter in terms of snowfall in years,” he said. “It could be the most snowfall we’ve seen in seven to ten years. For a change we’ve had a normal winter.”
Though cumulative snowfall amounts park-wide weren’t available, Nash said that, during the month of March alone, the park’s South Entrance received 101 inches.
According to Nash, the snow is so deep in some places that the bulldozer operators have to push the snow off the roadway in layers to feed it to rotary plows that then blow it off the road surface.
The south and east areas of the park typically see the most snow, especially the road between the South Entrance and West Thumb, Dunraven Pass, the Beartooth Highway and Sylvan Pass. Even during poor snow years, snowbanks along Sylvan Pass can reach 30 feet high, Nash said.
Nash said he expects that the park’s East Entrance will open May 2 and the South Entrance on May 9. Dunraven Pass and the Beartooth Highway aren’t scheduled to open until Memorial Day.
Saturday, April 12, 2008
Gator Blood May Be New Source of Antibiotics
Call it a case of gator aid. New research suggests that alligator blood could serve as the basis for new antibiotics targeting infections caused by ulcers, burns and even drug-resistant "superbugs."
The research is in its early stages -- extracts of alligator blood have only been tested in the laboratory -- and there's no guarantee that it will work in humans. Still, the findings are promising, researchers said.
"We need new antibiotics. Anything like this is a step forward," said Dr. Stuart Levy, a professor of medicine at Tufts University School of Medicine, who's an expert in antibiotic-resistant infections and is familiar with the new study. "But there are hurdles that this kind of antibiotic poses that others might not."
The study authors, from McNeese State University and Louisiana State University, said their research is the first to take an in-depth look at alligator blood's prospects as an antibiotic source. According to the researchers, alligators can automatically fight germs such as bacteria and viruses without having been exposed to them before launching a defense.
For the study, the researchers extracted proteins known as peptides from white cells in alligator blood. As in humans, white cells are part of the alligator's immune system. The researchers then exposed various types of bacteria to the protein extracts and watched to see what happened.
In laboratory tests, tiny amounts of these protein extracts killed a so-called "superbug" called methicillin-resistant Staphylococcus aureus, or MRSA. The bacteria has made headlines in recent years because of its killing power in hospitals and its spread among athletes and others outside of hospitals.
The extracts also killed six of eight strains of a fungus known as Candida albicans, which causes a condition known as thrush, and other diseases that can kill people with weakened immune systems.
The researchers, who presented their findings April6 at the national meeting of the American Chemical Society in New Orleans, said the blood extract could be used to develop an antibiotic in a topical cream form. They suggest that it could be called "alligacin."
Levy said the human body might reject alligator proteins, thinking they're foreign invaders. "Our bodies love to make antibodies to proteins," he said. "After you get the first dose, the body sees it as foreign, and the next dose gets scooped up by the immune system, and it's done."
But study lead author Lancia Darville, a doctoral student at Louisiana State University in Baton Rouge, La., said scientists might be able to create drugs that copy the blood proteins once they figure out their structure. The idea would be to make a chemical that the body doesn't think is a protein. Even so, Darville said, "it is not easy to mimic any antimicrobial peptide for clinical use."
Levy noted that many pharmaceutical companies have stopped investigating new antibiotics, because other areas of medicine are more profitable. The gap "has to be filled by more discovery," said Levy, who's also president of the Alliance for the Prudent Use of Antibiotics.
The study authors said alligator blood could become a drug source for humans within a decade.
Still, Emily Ackiss, a clinical epidemiologist at Scripps Mercy Hospital in Chula Vista, Calif., who's familiar with the study findings, said, "The research discussed in this article is basic research. More extensive research and experimentation are needed before drug development could be expected."
The research is in its early stages -- extracts of alligator blood have only been tested in the laboratory -- and there's no guarantee that it will work in humans. Still, the findings are promising, researchers said.
"We need new antibiotics. Anything like this is a step forward," said Dr. Stuart Levy, a professor of medicine at Tufts University School of Medicine, who's an expert in antibiotic-resistant infections and is familiar with the new study. "But there are hurdles that this kind of antibiotic poses that others might not."
The study authors, from McNeese State University and Louisiana State University, said their research is the first to take an in-depth look at alligator blood's prospects as an antibiotic source. According to the researchers, alligators can automatically fight germs such as bacteria and viruses without having been exposed to them before launching a defense.
For the study, the researchers extracted proteins known as peptides from white cells in alligator blood. As in humans, white cells are part of the alligator's immune system. The researchers then exposed various types of bacteria to the protein extracts and watched to see what happened.
In laboratory tests, tiny amounts of these protein extracts killed a so-called "superbug" called methicillin-resistant Staphylococcus aureus, or MRSA. The bacteria has made headlines in recent years because of its killing power in hospitals and its spread among athletes and others outside of hospitals.
The extracts also killed six of eight strains of a fungus known as Candida albicans, which causes a condition known as thrush, and other diseases that can kill people with weakened immune systems.
The researchers, who presented their findings April6 at the national meeting of the American Chemical Society in New Orleans, said the blood extract could be used to develop an antibiotic in a topical cream form. They suggest that it could be called "alligacin."
Levy said the human body might reject alligator proteins, thinking they're foreign invaders. "Our bodies love to make antibodies to proteins," he said. "After you get the first dose, the body sees it as foreign, and the next dose gets scooped up by the immune system, and it's done."
But study lead author Lancia Darville, a doctoral student at Louisiana State University in Baton Rouge, La., said scientists might be able to create drugs that copy the blood proteins once they figure out their structure. The idea would be to make a chemical that the body doesn't think is a protein. Even so, Darville said, "it is not easy to mimic any antimicrobial peptide for clinical use."
Levy noted that many pharmaceutical companies have stopped investigating new antibiotics, because other areas of medicine are more profitable. The gap "has to be filled by more discovery," said Levy, who's also president of the Alliance for the Prudent Use of Antibiotics.
The study authors said alligator blood could become a drug source for humans within a decade.
Still, Emily Ackiss, a clinical epidemiologist at Scripps Mercy Hospital in Chula Vista, Calif., who's familiar with the study findings, said, "The research discussed in this article is basic research. More extensive research and experimentation are needed before drug development could be expected."
Swarm of Earthquakes Detected Off Oregon
GRANTS PASS, Ore. (AP) - Scientists listening to underwater microphones have detected an unusual swarm of earthquakes off the central Oregon Coast.
Scientists don't know what the earthquakes mean, but they could be the result of magma rumbling underneath the Juan de Fuca Plate - away from the recognized earthquake faults off Oregon, said geophysicist Robert Dziak of the National Oceanic and Atmospheric Administration and Oregon State University's Hatfield Marine Science Center in Newport, Ore.
They hope to send out the OSU research ship, Wecoma, to take water samples, looking for evidence that sediment on the ocean bottom has been stirred up and chemicals in the water that would indicate magma is moving up through the crust, Dziak said.
There have been more than 600 quakes over the past 10 days in a basin 150 miles southwest of Newport. The biggest was magnitude 5.4 and two others were more than magnitude 5.0, OSU reported. They have not followed the typical pattern of a major shock followed by a series of diminishing aftershocks, and few have been strong enough to be felt on shore.
It looks like what happens before a volcanic eruption, except there are no volcanoes in the area, Dziak said.
The Earth's crust is made up of plates that rest on molten rock, which are rubbing together side to side and up and down. When the molten rock, or magma, erupts through the crust it creates volcanoes. That can happen in the middle of a plate. When the plates lurch against each other, they create earthquakes along the edges of the plates.
In this case, the Juan de Fuca Plate is a small piece of crust being crushed between the Pacific Plate and North America, Dziak said.
On the hydrophones, the quakes sound like low rumbling thunder and are unlike anything scientists have heard in 17 years of listening, Dziak said. Some of the quakes have also been detected by earthquake instruments on land.
The hydrophones are leftover from a network the Navy used to listen for submarines during the Cold War. They routinely detect passing ships, earthquakes on the ocean bottom and whales calling to each other.
Scientists don't know what the earthquakes mean, but they could be the result of magma rumbling underneath the Juan de Fuca Plate - away from the recognized earthquake faults off Oregon, said geophysicist Robert Dziak of the National Oceanic and Atmospheric Administration and Oregon State University's Hatfield Marine Science Center in Newport, Ore.
They hope to send out the OSU research ship, Wecoma, to take water samples, looking for evidence that sediment on the ocean bottom has been stirred up and chemicals in the water that would indicate magma is moving up through the crust, Dziak said.
There have been more than 600 quakes over the past 10 days in a basin 150 miles southwest of Newport. The biggest was magnitude 5.4 and two others were more than magnitude 5.0, OSU reported. They have not followed the typical pattern of a major shock followed by a series of diminishing aftershocks, and few have been strong enough to be felt on shore.
It looks like what happens before a volcanic eruption, except there are no volcanoes in the area, Dziak said.
The Earth's crust is made up of plates that rest on molten rock, which are rubbing together side to side and up and down. When the molten rock, or magma, erupts through the crust it creates volcanoes. That can happen in the middle of a plate. When the plates lurch against each other, they create earthquakes along the edges of the plates.
In this case, the Juan de Fuca Plate is a small piece of crust being crushed between the Pacific Plate and North America, Dziak said.
On the hydrophones, the quakes sound like low rumbling thunder and are unlike anything scientists have heard in 17 years of listening, Dziak said. Some of the quakes have also been detected by earthquake instruments on land.
The hydrophones are leftover from a network the Navy used to listen for submarines during the Cold War. They routinely detect passing ships, earthquakes on the ocean bottom and whales calling to each other.
Friday, April 11, 2008
Frog Without Lungs Found in Indonesia
BANGKOK, Thailand (AP) - A frog has been found in a remote part of Indonesia that has no lungs and breathes through its skin, a discovery that researchers said Thursday could provide insight into what drives evolution in certain species.
The aquatic frog Barbourula kalimantanensis was found in a remote part of Indonesia's Kalimantan province on Borneo island during an expedition in August 2007, said David Bickford, an evolutionary biologist at the National University of Singapore. Bickford was part of the trip and co-authored a paper on the find that appeared in this week's edition of the peer-reviewed journal Current Biology.
Bickford said the species is the first frog known to science without lungs and joins a short list of amphibians with this unusual trait, including a few species of salamanders and a wormlike creature known as a caecilian.
"These are about the most ancient and bizarre frogs you can get on the planet," Bickford said of the brown amphibian with bulging eyes and a tendency to flatten itself as it glides across the water.
"They are like a squished version of Jabba the Hutt," he said, referring to the character from Star Wars. "They are flat and have eyes that float above the water. They have skin flaps coming off their arms and legs."
Bickford's Indonesian colleague, Djoko Iskandar, first came across the frog 30 years ago and has been searching for it ever since. He didn't know the frog was lungless until they cut eight of the specimens open in the lab.
Graeme Gillespie, director of conservation and science at Zoos Victoria in Australia, called the frog "evolutionarily unique." He said the eight specimens examined in the lab showed the lunglessness was consistent with the species and not "a freak of nature." Gillespie was not a member of the expedition or the research team.
Bickford surmised that the frog had evolved to adapt to its difficult surroundings, in which it has to navigate cold, rapidly moving streams that are rich in oxygen.
"It's an extreme adaptation that was probably brought about by these fast-moving streams," Bickford said, adding that it probably needed to reduce its buoyancy in order to keep from being swept down the mountainous rivers.
He said the frog could help scientists understand the environmental factors that contribute to "extreme evolutionary change" since its closest relative in the Philippines and other frogs have lungs.
Bickford and Gillespie said the frog's discovery adds urgency to the need to protect its river habitat, which in recent years has become polluted due to widespread illegal logging and gold mining. Once- pristine waters are now brown and clogged with silt, they said.
"The gold mining is completely illegal and small scale. But when there are thousands of them on the river, it really has a huge impact," Bickford said. "Pretty soon the frogs will run out of the river."
The aquatic frog Barbourula kalimantanensis was found in a remote part of Indonesia's Kalimantan province on Borneo island during an expedition in August 2007, said David Bickford, an evolutionary biologist at the National University of Singapore. Bickford was part of the trip and co-authored a paper on the find that appeared in this week's edition of the peer-reviewed journal Current Biology.
Bickford said the species is the first frog known to science without lungs and joins a short list of amphibians with this unusual trait, including a few species of salamanders and a wormlike creature known as a caecilian.
"These are about the most ancient and bizarre frogs you can get on the planet," Bickford said of the brown amphibian with bulging eyes and a tendency to flatten itself as it glides across the water.
"They are like a squished version of Jabba the Hutt," he said, referring to the character from Star Wars. "They are flat and have eyes that float above the water. They have skin flaps coming off their arms and legs."
Bickford's Indonesian colleague, Djoko Iskandar, first came across the frog 30 years ago and has been searching for it ever since. He didn't know the frog was lungless until they cut eight of the specimens open in the lab.
Graeme Gillespie, director of conservation and science at Zoos Victoria in Australia, called the frog "evolutionarily unique." He said the eight specimens examined in the lab showed the lunglessness was consistent with the species and not "a freak of nature." Gillespie was not a member of the expedition or the research team.
Bickford surmised that the frog had evolved to adapt to its difficult surroundings, in which it has to navigate cold, rapidly moving streams that are rich in oxygen.
"It's an extreme adaptation that was probably brought about by these fast-moving streams," Bickford said, adding that it probably needed to reduce its buoyancy in order to keep from being swept down the mountainous rivers.
He said the frog could help scientists understand the environmental factors that contribute to "extreme evolutionary change" since its closest relative in the Philippines and other frogs have lungs.
Bickford and Gillespie said the frog's discovery adds urgency to the need to protect its river habitat, which in recent years has become polluted due to widespread illegal logging and gold mining. Once- pristine waters are now brown and clogged with silt, they said.
"The gold mining is completely illegal and small scale. But when there are thousands of them on the river, it really has a huge impact," Bickford said. "Pretty soon the frogs will run out of the river."
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