this Dec. 7, 2006 file photo, tourists visit the Hualapai Indian Reservation along the western end of the Grand Canyon. A new study published in the journal Science Thursday, Nov. 29, 2012, suggests the western Grand Canyon formed 70 million years ago. Some scientists disagree and believe the canyon was mainly carved by the Colorado River in the past 5 to 6 million years.Jake Bacon/The Associated Press
A roundup of some of the week's science headlines:
Tourist attraction for dinosaurs too?
The awe-inspiring Grand Canyon was probably carved about 70 million years ago, much earlier than thought, a provocative new study suggests – so early that dinosaurs might have roamed near this natural wonder. Using a new dating tool, a team of scientists came up with a different age for the western section of the gorge in the U.S. southwest, challenging conventional wisdom that much of the canyon was scoured by the mighty Colorado River in the last 5 million to 6 million years.
They focused on the western end of the Grand Canyon occupied today by the Hualapai Reservation, which owns the Skywalk attraction, a horseshoe-shaped glass bridge that extends from the canyon's edge. To come up with the age, the team crushed rocks collected from the bottom of the canyon to analyze a rare type of mineral called apatite. The mineral contains traces of radioactive elements that release helium during decay, allowing researchers to calculate the passage of time since the canyon eroded.
Not everyone is convinced with the latest viewpoint, published online Thursday in the journal Science. Critics contend the study ignores a mountain of evidence pointing to a geologically young landscape and they have doubts about the technique used to date it. Though the exposed rocks are ancient, most scientists believe the Grand Canyon itself was forged in the recent geologic past, created when tectonic forces uplifted the land that the Colorado River later carved through. – The Associated Press
Home is where the brine is
Home sweet home for one community of bacteria is cold, dark – and could point to how life survives in hostile environments. Researchers from Nevada's Desert Research Institute and the University of Illinois at Chicago examined the brine of Lake Vida, an oxygen-free, mostly frozen Antarctic lake that has the highest levels of nitrous oxide than any other natural body of water. (Previous studies show the brine – which is six times saltier than seawater – hasn't been touched by outside substances for more than 3,000 years.) This new analysis suggests chemical reactions between the brine and the lake's sediment may generate what's needed to provide energy for the lake's microbial dwellers, the scientists said in a news release. Other icy environments beyond Earth could provide similar supports for life. The research was published Monday in the early edition of the Proceedings of the National Academy of Science. – Aleysha Haniff
Fall and rise
The melting of the Antarctic and Greenland ice sheets has raised sea levels by 11.1 millimetres since 1992 , a fifth of the total rise which threatens low-lying regions around the globe, a new study published on Thursday said.
The results of the study involving 47 researchers from 26 laboratories which was supported by the European Space Agency and the National Aeronautics and Space Administration give the most accurate measurements of ice loss to date, they said in the journal Science. Two thirds of the ice loss was in Greenland, which is losing five times as much ice as in the 1990s, and the remainder was in Antarctica.
Together, the two receding ice sheets are now adding 0.95 millimetres to sea levels a year compared to 0.27 millinetres per year in the 1990s, the study said. – Reuters
Staying alive and then some
A newly discovered gene that keeps embryos alive appears to control the immune system and determine how it battles chronic diseases such as HIV and autoimmune diseases such as sepsis. Author Marc Pellegrini at the Walter and Eliza Hall Institute of Medical Research in Australia said the gene Arih2 appears to act like a switch, flipping the immune system on and off.
"Arih2 is responsible for the most fundamental and important decision that the immune system has to make – whether the immune response should be initiated and progressed or whether it should be switched off to avoid the development of chronic inflammation or autoimmunity," Dr. Pellegrini said in a news release. "If the wrong decision is made, the organism will either succumb to the infection, or succumb to autoimmunity."
Targeting Arih2 and learning how it can manipulate the immune system – by promoting or suppressing the body's immune response, depending on the disease – could one day lead to new drug treatments. The next stage of research involves examining the effects of briefly switching off the gene. The paper was published Nov. 25 in the journal Nature Immunology. – Aleysha Haniff/Reuters