In my continuing diatribe about photography, about how some pictures are merely shots of what is already beautiful, like my picture of the |Mona Lisa, which, as a photograph, is not at all artistic, since the art is already there. In this picture I get a feeling of loneliness and very exact solitude, but the building's architects probably were not after any such effect. It is the photographer that has seen something in his or her view finder and recorded it. It is, for me, art.
In a striking revelation, scientists have discovered that all plants live and die by a precise and simple rule. Scientists have found for the first time that plants can self-regulate their populations to maintain stability and optimize their lives, and that the lengths of their lives are precisely related to their mass. Even more incredible, a single scaling power for lifespan holds true across the entire spectrum of plants, from minute single-celled phototrophs to the massively majestic redwoods.
Scientists previously understood that animals’ lifespans are somewhat scaled to the species’ body size, with elephants living much longer than mice. Plant biologists have predicted a similar connection in plants, but a full study had never been conducted until recently.
Researchers Núria Marbà, Carlos Duarte and Susana Agustí at the Mediterranan Institute for Advanced Studies—a joint institute between the CSIC (Spanish Council for Scientific Research) and the University of the Balearic Islands in Esporles, Spain examined more than 1,000 reports of plant birth and mortality rates across a wide spectrum of species, discovering that the connection holds with extreme precision.
The researchers found that both population mortality rates and population birth rates of all plant species scale as the –1/4 power of plant mass. In other words, the smaller a plant, the higher its mortality and birth rates, meaning the shorter its lifespan. Hence, plant lifespan scales as almost exactly the 1/4 power of plant mass.
“The functioning of biological systems depends to a large extent on their metabolism, i.e., on how they process energy and materials, such as light, water, and nutrients,” Marbà explained to PhysOrg.com. “Small plants require fewer resources per unit of time than large ones, and, therefore, they are able to turn over the individuals of their populations faster than large plants. As plant size increases, more resources and time are needed to produce a fully grown individual, and thus their lifespan increases, resulting in small plants having shorter life spans than larger ones.”
One very interesting aspect of these relationships is that mortality and birth rates is nearly identical within a species, keeping the population stable. Nature has clever reasons for this perfect cycle, which include stabilizing carbon cycling, optimizing plant life histories, and stabilizing the ecosystems the plants inhabit. The scientists suggest that, to achieve this balance, plant mortality rates have evolved to match the birth rates.
Although they have found the delicate balance between mortality and birth rates, the actual mechanisms governing plant life and death are still unknown. Controls probably include an assortment of metabolic processes interacting at all levels, from molecular on up, which would include respiration, reproduction, cellular damage, and structural imbalances. Plants retain their reproductive capacity throughout their lives, unlike animals. Therefore, evolution might put greater selective pressure on plants’ lifespans. Similar studies are bring planned to continue the effort to unlock the many mysteries of the green kingdom.
The dusty disk of the Milky Way contains billions of stars, including, of course our Sun which orbits the galaxy every 200-250 million years traveling at a velocity of about 155 miles per second (250 km/sec). It is extremely difficult to define the age of the Milky Way but the age of the oldest star in the Galaxy yet discovered, HE 1523-0901, is estimated to be about 13.2 billion years, nearly as old as the Universe itself.
Since our solar system is inside this arc, the band appears to encircle the Earth. The bright spot just below the band is the planet Jupiter. In the foreground lies the moonlit caldera of the volcano Haleakala, located on the island of Maui in Hawaii, USA. A close look near the horizon will reveal light clouds and the dark but enormous Mauna Kea volcano on the Big Island of Hawaii.
Recent work at Cardiff University suggests that our solar system's orbit through the Milky Way encounters regular speedbumps - and by "speedbumps" we mean "potentially extinction-causing asteroids".
Professor William Napier and Dr Janaki Wickramasinghe have completed computer simulations of the motion of the Sun in our outer spiral-arm location in the Milky Way (image left of spiral arms).
These models reveal a regular oscillation through the central galactic plane, where the surrounding dust clouds are the densest. The solar system is a non-trivial object, so its gravitational effects set off a far-reaching planetoid-pinball machine which often ends with comets hurled into the intruding system.
The sun is about 26,000 light-years from the center of the Milky Way Galaxy, which is about 80,000 to 120,000 light-years across (and less than 7,000 light-years thick). We are located on on one of its spiral arms, out towards the edge.
Many of the ricocheted rocks collide with planets on their way through our system, including Earth. Impact craters recorded worldwide show correlations with the ~37 million year-cycle of these journeys through the galactic plane - including the vast impact craters thought to have put an end to the dinosaurs two cycles ago.
Almost exactly two cycles ago, in fact. The figures show that we're very close to another danger zone, when the odds of asteroid impact on Earth go up by a factor of ten. Ten times a tiny chance might not seem like much, but when "Risk of Extinction" is on the table that single order of magnitude can look much more imposing. Worse, Bruce Willis will only be available to save us for another fifty years at most. But you have to remember that ten times a very small number is still a very small number - and Earth has been struck by thousands of asteroids without any exciting extinction events. A rock doesn't just have to hit us, it has to be large enough to survive the truly fearsome forces that cause most to burn up on re-entry.
Professors Medvedev and Melott of the University of Kansas have a different theory based on the same regular motion. As the Sun ventures out "above" the galactic plane, it becomes increasingly exposed to the cosmic ray generating shock front that the Milky Way creates as it ploughs through space. As we get closer to this point of maximum exposure, leaving the shielding of the thick galactic disk behind, the Kansas researchers hold that the increasing radiation destroys many higher species, forcing another evolutionary epoch. This theory also matches in time with the dinosaur extinction - and it's nice to see theories for that from Kansas not based on "an angry bearded man in the sky did it".
Either way, don't go letting your VISA bill run up just yet. "Very close" in astronomical terms is very, very different to "close" in shaved-monkey time.
Posted by Luke McKinney and Casey Kazan. Image Credit & Copyright: Wally Pacholka (TWAN)
These two posts are from The Daily Galaxy. I get ten news feeds a day. Look them up on Google, if you find this sort of article intriguing.