Come gather round one and all. Science talk is here. New discoveries, new takes on old knowledge, and other bits of news are all available for the perusing in today's information world. Over the fold are selections from the past week from a few of the many excellent science news sites around the world. Today's tidbits include Earth's temperature in the past, hydrogen peroxide found in space, being small has its advantages if you are a leaf, thank parasites for sex as we know it, holes in fossil bones reveal dinosaur activity, and ancestry of polar bears traced to Ireland. Gather yourselves around. Pull up that comfy chair and bask in the sunshine. There is plenty of room for everyone. Get ready for one more session of Dr. Possum's science education and entertainment.
Featured Stories
In an ongoing effort to study the potential effects of climate change in our future scientists continue to explore the Earth's temperature in past times.
Previous studies have suggested that the polar regions (high-latitude areas) during the Eocene were very hot—greater than 30 degrees centigrade (86 degrees Fahrenheit). However, because the sun’s rays are strongest at the Earth’s equator, tropical and subtropical areas (lower latitude) will always be at least as warm as polar areas, if not hotter. Until now, temperature data for subtropical regions were limited.
The SU (Syracuse University) and Yale research team found that average Eocene water temperature along the subtropical U.S. Gulf Coast hovered around 27 degrees centigrade (80 degrees Fahrenheit), slightly cooler than earlier studies predicted. Modern temperatures in the study area average 75 degrees Fahrenheit. Additionally, the scientists discovered that, during the Eocene, temperatures in the study area did not change more than 3 to 5 degrees centigrade across seasons, whereas today, the area’s seasonal temperatures fluctuate by 12 degrees centigrade. The new results indicate that the polar and sub-polar regions, while still very warm, could not have been quite as hot as previously suggested.
The findings are based on a chemical analysis of the growth rings of the shells of fossilized bivalve mollusks and on the organic materials trapped in the sediment packed inside the shells, which was conducted by Keating-Bitonti and her colleagues. Ivany collected the fossils from sediment layers exposed along the Tombigbee River in Alabama. The mollusks lived in a near-shore marine environment during a time when the sea level was higher and the ocean flooded much of southern Alabama. The sediments that accumulated there contain one of the richest and best-preserved fossil records in the country.
A team of astronomers observing the Rho Ophiuchi clouds have found the chemical signature of hydrogen peroxide.
Hydrogen peroxide (H2O2) is a key molecule for both astronomers and chemists. Its formation is closely linked to two other familiar molecules, oxygen and water, which are critical for life. Because much of the water on our planet is thought to have originally formed in space, scientists are keen to understand how it is created [1].
Hydrogen peroxide is thought to form in space on the surfaces of cosmic dust grains — very fine particles similar to sand and soot — when hydrogen (H) is added to oxygen molecules (O2). A further reaction of the hydrogen peroxide with more hydrogen is one way to produce water (H2O). This new detection of hydrogen peroxide will therefore help astronomers better understand the formation of water in the Universe.
In many species the larger the better but for leaves being small may offer some distinct advantages.
They found that small leaves' major veins — those you can see with the naked eye — are spaced more closely together and are of greater length, relative to the leaf's size, than those of larger leaves.
This redundancy of major veins, the researchers say, protects the leaves from the effects of embolism — bubbles that form in their "water pipes" during drought — because it provides alternate routes for water to flow around vein blockages.
Sexual reproduction through the mating of two parents may have arisen to allow better resistance to parasites.
By combining the DNA of two parents, sex allows parents to produce offspring that are genetically diverse and different from their parents. Parasites that have adapted to infect one generation may have difficulty infecting the next generation. However, offspring produced through self-fertilization inherit the DNA of their single parent, thus any parasites adapted to infect the parent should also be capable of infecting the offspring.
(snip...in laboratory study)
In host populations where either sex or self-fertilization were possible, the evolutionary state of the parasite determined the most effective reproductive strategy. When the parasite did not coevolve, self-fertilization evolved as the dominant form of host reproduction. However, when the parasite was allowed to coevolve with the hosts, then sex became the favored reproductive strategy.
The ongoing debate about whether dinosaurs were cold-blooded and sluggish or warm-blooded and active had new fuel added in recent days.
Human thigh bones have tiny holes - known as the 'nutrient foramen' - on the shaft that supply blood to living bone cells inside. New research has shown that the size of those holes is related to the maximum rate that a person can be active during aerobic exercise.
(snip)
"On a relative comparison to eliminate the differences in body size, all of the dinosaurs had holes in their thigh bones larger than those of mammals," (researcher) Professor Seymour says.
"The dinosaurs appeared to be even more active than the mammals. We certainly didn't expect to see that. These results provide additional weight to theories that dinosaurs were warm-blooded and highly active creatures, rather than cold-blooded and sluggish."
According to scientists the mother of all polar bears was a brown bear that lived in the vicinity of present-day Britain and Ireland just prior to the peak of the last ice age, 20,000 to 50,000 years ago.
Although previous researchers had suggested that the ancient female ancestor of modern polar bears lived on the ABC Islands -- the Alaskan islands of Admiralty, Baranof, and Chichagof -- only 14,000 years ago, Shapiro's team found evidence of a much earlier hybridization event. Because of this event, the modern polar bear's mitochondrial DNA probably underwent fixation -- a drastic reduction in genetic variation and a transition to a state in which the entire gene pool includes only one form of a particular gene. After performing genetic analyses of 242 brown-bear and polar-bear mitochondrial lineages sampled throughout the last 120,000 years and across multiple geographic ranges, (researcher) Shapiro's team found that the fixation of the mitochondrial genome likely occurred during or just before the peak of the last ice age, possibly as early as 50,000 years ago, near present-day Ireland. Shapiro noted that the specific population of brown bears that shared its maternal DNA with polar bears has been extinct for roughly 9,000 years. However, her data offer clear genetic evidence that the two species were in contact long before the brown bear's disappearance from the British Isles.
Other Worthy Stories of the Week
How horseshoe blood saves lives
Weevil has nuts and bolts in its legs
Scientists sequence genome of cancer resistant rat
Lens-free pinhead camera developed
Climate change forces early spring
Cassini captures images and sounds of Saturn storm
Termites digestive system could act as biofuel refinery
Fisher decline documented in California
Warmer weather is officially the new normal
Atlantis blasts off on end-of-era spaceflight
Herschel helps solve mystery of cosmic dust origins
Indoor air pollution is linked to cardiovascular risk
Ocean's carbon dioxide uptake reduced by climate change
For even more science news:
General Science Collectors:
Alpha-Galileo
BBC News Science and Environment
Eureka Science News
LiveScience
New Scientist
PhysOrg.com
SciDev.net
Science/AAAS
Science Alert
Science Centric
Science Daily
Scientific American
Space Daily
Blogs:
A Few Things Ill Considered Techie and Science News
Cantauri Dreams space exploration
Coctail Party Physics Physics with a twist.
Deep Sea News marine biology
Laelaps more vertebrate paleontology
List of Geoscience Blogs
ScienceBlogs
Space Review
Techonology Review
Tetrapod Zoologyvertebrate paleontology
Science Insider
Scientific Blogging.
Space.com
Wired News
Science RSS Feed: Medworm
The Skeptics Guide to the Universe--a combination of hard science and debunking crap
At Daily Kos:
This Week in Science by DarkSyde
Overnight News Digest:Science Saturday by Neon Vincent. OND tech Thursday by rfall.
Pique the Geek by Translator Sunday evenings about 9 Eastern time
All diaries with the DK GreenRoots Tag.
All diaries with the eKos Tag
A More Ancient World by matching mole
Astro Kos
SciTech at Dkos.
Sunday Science Videos by palantir
NASA picture of the day. For more see the NASA image gallery or the Astronomy Picture of the Day Archive.
The final Space Shuttle liftoff, NASA, Public Domain