a little Scientific interlude....

[irishgrl]

http://www.latimes.com/news/opinion/...mment-opinions

Evolution's case evolves
By Ann Gibbons
ANN GIBBONS is the author of "The First Human: The Race to Discover Our Earliest Ancestors," and a contributing correspondent for Science.

April 22, 2006

IT'S BEEN A TOUGH month for creationists. (all together now: AWWWWWWW!)On April 6, evolutionary biologists announced the discovery of a fossil of Tiktaalik roseae, a giant fish whose fins were evolving into limbs when it died 375 million years ago. This scaly creature of the sea was in transition to becoming a land animal, the discoverers wrote in Nature.

A day later, molecular biologists reported in Science that they had traced the origin of a key stress hormone, found in humans and all vertebrates, back 450 million years to a primitive gene that arose before animals emerged from oceans onto land.

Both teams of scientists stressed that their findings contradicted creationists — and demonstrated how small, incremental steps over millions of years could indeed produce complex life, ranging from the intricate mechanisms of a hormone molecule to the assembly of limbs from fins.

But even as they were touting their results as yet another validation of Charles Darwin's theory of evolution, biochemist Michael Behe, a leading advocate of "intelligent design," dismissed the hormone discovery as "piddling."

As if in response to Behe's challenge, paleoanthropologists raised the stakes last week with yet another example of evolution unfolding in our own lineage. In the journal Nature, a team of researchers from UC Berkeley and Ethiopia found an "intermediate" member of the human family that they say unambiguously fills the gap in the fossil record between two early types of human ancestors. Australopithecus anamensis was a creature the size of an orangutan that walked upright in the Rift Valley of eastern Africa about 4 million years ago, more than 2 million years after the human lineage split from the ancestor we share with chimpanzees

The team found the species in a mile-deep stack of sediment in northeastern Ethiopia, which has become the Comstock Lode of human evolution. Across 11 separate layers, researchers unearthed several types of early human ancestors, with the anamensis bones sandwiched between layers containing two other species — Australopithecus afarensis, the species whose most famous member was the diminutive skeleton Lucy that lived 3.2 million years ago; and the 4.4-million-year-old Ardipithecus ramidus. (They also found the oldest known member of our species, Homo sapiens, in a layer dating back 155,000 years.) When researchers compared the teeth and bones of these various human ancestors, they saw a clear path from primitive to modern.

But lest you assume that the transition inevitably yields "intelligent" design, just think about the more problematic aspects of our own anatomy: How about arthritic backs and knees? Or the size of the birth canal in modern humans. Lucy's species had an easier time 3.2 million years ago delivering babies who would grow up to have brains the size of a large orange, compared with modern mothers whose infants grow brains four times larger. We did evolve wider pelvises, but these also mean that more force is put on the sides of our knees, which any soccer player can tell you is not optimal design.

The point is that all these changes evolved over time in response to specific environments. The competing demands of an expanding brain and upright walking, for example, had to be balanced and accommodated in a basic body plan that persisted for millions of years in apes that spent most of their time hanging out in trees.

From what they have seen so far, the discoverers of these fossils think that the evolution from Ardipithecus to A. anamensis was a rapid affair. It took only 200,000 years, if they are right, for natural selection to refit one early hominid body into a new model. In the realm of deep time, that may seem like a blink of the eye. But in human terms, that would allow for at least 13,000 generations — enough time for genetic mutations to change the shape and size of teeth, and for individuals to learn how to use them. More of their offspring would survive as a result, and the trait would become fixed in later populations.

Although there are still gaps in the fossil record, many dots have already been connected on the branches of the human family tree, connecting Lucy to our own genus Homo, to our Neanderthal cousins and maybe even to a dwarf-like species that lived on an Indonesian island just 18,000 years ago. Together these species of human ancestors reveal different ways to become a human. You can see evolution's work in the fins of the ancient Tiktaalik or the stress hormones of the venerable lamprey fish. You can also look in the mirror.

[irishgrl]

http://news.yahoo.com/s/space/200606...E0BHNlYwN0bWE-

Bursting Ice Dam Flooded the Ancient Ocean

Ker Than
LiveScience Staff Writer
LiveScience.comThu Jun 29, 8:00 PM ET

Near the end of the last Ice Age 8,000 years ago, an ice dam on North America's east coast broke, releasing a torrent of fresh water seven times more voluminous than all the Great Lakes combined. It all rushed into the Atlantic Ocean over the course of only a few months.

At around the same time, ocean circulation worldwide slowed to a crawl, plunging Europe into a second ice age that lasted centuries.

Scientists have long suspected the two events were linked, and now they have the evidence from sediment core samples to prove it.

The finding, detailed in the June 30 issue of the journal Science, provides the first clear evidence that the so-called North American "lake burst" was the trigger that slowed ocean circulation and cooled the climate about 8,200 years ago.

Shell chemistry

The researchers studied a sediment core taken from the North Atlantic seabed south of Iceland. By analyzing the chemistry of shells belonging to microscopic sea creatures called foraminifera which were embedded in the core, they estimated the salinity of the seawater at different time points.

Also, by analyzing the size of sediment grains, the researchers were able to estimate the speed of deep ocean currents along the ocean bottom. More large particles there means that ocean currents were moving faster when the sediment layer was formed.

These two pieces of evidence showed that as ocean salinity decreased, ocean currents slowed. Normally, ocean currents function like a global conveyer belt, ferrying warm, buoyant water from the southern hemisphere into the far north, where it loses its heat and sinks to the bottom because cold water is denser than warm water. The cold water is then ferried back towards the southern hemisphere along ocean currents on the bottom of the seafloor and the entire cycle repeats.

When the lake bursts occurred, the rapid influx of freshwater diluted the seas. Freshwater is more buoyant than seawater and does not sink as quickly. As the ocean became less salty, chilled water in the northern hemisphere took longer to sink, and the entire ocean circulation slowed down.

"It didn't switch it off completely; it just made it less intense," explained study team member Mark Chapman, also of the University of East Anglia.

For reasons that are still unclear, ocean salinity and circulation returned to normal after about two hundred years.

Future Implications

The ancient lake bursts event could also have implications for future climate change, scientists say.

"The impact of large-scale pulsed inputs of freshwater on ocean circulation and climate during the time of the last Ice Age are well documented, but our results clearly demonstrate that these sorts of abrupt reorganizations also can occur during periods of warm climate," said study leader Ian Hall of Cardiff University.

In the movie "An Inconvenient Truth," Al Gore mentions the North American lake bursts event and the stalling of the ocean currents. If large parts of Greenland and Antarctica were to melt as some global warming models predict, a similar stalling of the world's ocean currents could occur, Gore said.

But Chapman says that caution is needed when using past events to predict future climate changes.

"I think you have to be a little bit careful. It's not just the volume of water; it's how quickly they enter the system," Chapman told LiveScience.

In their study, Chapman and his colleagues estimated that the lake bursts released the equivalent of seven times the volume of all the Great Lakes combined into the ocean within about six months to a year.

"We don't really know what will happen if we have that same amount of water and, instead of having it released over a matter of months or a year or so, it was released over decades or a century" as global warming scenarios predict for the melting of Greenland, Chapman said.

[irishgrl]

http://news.yahoo.com/s/ap/20060630/...0BHNlYwN0bWE-.

Calif. smog rules may be used nationwide

By ERICA WERNER, Associated Press WriterThu Jun 29, 8:16 PM ET

The federal government may use California's strict pollution rules for lawnmowers and other small-engine machines as a national standard, a top Environmental Protection Agency official said Thursday.

While environmentalists and air quality regulators would welcome the development, it would be bad news for much of the small engine industry. California aims to cut smog emissions from the highly polluting engines by about 35 percent.

Margo Oge, director of EPA's office of transportation and air quality, said implementing California's standard nationally could work well, though no final decision has been made.

"We believe harmonizing with California will be cost-effective, good for the environment, good for the industry, good for all the stakeholders," Oge said after a hearing Thursday on California's request for an EPA waiver so it can implement the rules.

"We are concerned that as other sources are being controlled, this source is going to continue to be a bigger source for air pollution, so we are pretty interested in finishing our work and putting forth cost-effective standards for the country," she said. "... A strong option that we're considering is harmonizing with California."

EPA is considering California's waiver request even as it works to write the national small-engine rules. Both decisions are expected by year's end, after lengthy delays because of opposition from Sen. Christopher "Kit" Bond, R-Mo.

Missouri is home to two factories owned by Briggs & Stratton Corp., the nation's largest small engine maker. Briggs & Stratton has resisted California's approach, which would require adding catalytic converters to the small engines that power lawn mowers, leaf blowers, chain saws and other devices.

The company says adding catalytic converters would be so costly that jobs would have to be sent overseas, and also has contended there could be fire safety risks. An EPA study mandated by Bond rejected any safety risk when it was released in March, but Bond and the small-engine industry have criticized that finding, and the industry is funding its own, separate safety study.

No one from Briggs & Stratton testified Thursday, and officials from Honda and Kohler said they supported California's rules.

But Bill Guerry of the Outdoor Power Equipment Institute said the results of California's rules would be less availability of power equipment in the state. He said the industry has decided not to try to block California from implementing its rules, but that many in the industry don't want to see those regulations apply nationally.

"A lot of my members are very concerned," Guerry said after the hearing. "What they're going to do to comply in California is eliminate half of their product line."

California officials testified that the rules were necessary so the state could meet federally mandated clean air attainment goals. Environmentalists and regulators from other states also testified in favor of giving the state a waiver to implement its rules and pave the way for national standards.

"I consider this regulation of major importance in our efforts to achieve clean air," said Robert Sawyer, chairman of the California Air Resources Board.

Without new rules, pollution from small engines is expected to account for 15 percent of mobile source pollution nationally by 2020. California contains more areas with high air pollution than any other state.

[David]

For your July reading, irishgirl, I recommend the following new book:

"Intelligent Thought" (Vintage), assembled by John Brockman: A set of 16 essays, each responding to the anti-evolution Intelligent Design Movement (IDM)

The contributors include Richard Dawkins, a noted evolutionary biologist; Jerry Coyne; Neil Shubin; Leonard Susskind, a theoretical physicist; Lee Smolin; the philosopher-cognitive scientist Daniel Dennett; paleontologists Tim White and Scott Sampson; psychologists Steven Pinker, Nicholas Humphrey, & Marc Hauser; physicists Seth Lloyd and Lisa Randall; mathematical biologist Stuart Kauffman; anthropologist Scott Atran; & the science historian and behaviorist Frank Sulloway.

[irishgrl]

Sounds Good! if Im flush and Im going by Barnes and Noble, you can bet it'll be in my hot little hands