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Team finds Earth's 'oldest rocks'
By James Morgan
Science reporter, BBC News
Nuvvuagittuq greenstone
The rocks contain structures which might indicate life was present
Earth's most ancient rocks, with an age of 4.28 billion years, have been found on the shore of Hudson Bay, Canada.
Writing in Science journal, a team reports finding that a sample of Nuvvuagittuq greenstone is 250 million years older than any rocks known.
It may even hold evidence of activity by ancient life forms.
If so, it would be the earliest evidence of life on Earth - but co-author Don Francis cautioned that this had not been established.
"The rocks contain a very special chemical signature - one that can only be found in rocks which are very, very old," he said.
The professor of geology, who is based at McGill University in Montreal, added: "Nobody has found that signal any place else on the Earth."
"Originally, we thought the rocks were maybe 3.8 billion years old.
The exciting thing is that we've seen a chemical signature that's never been seen before
Prof Don Francis, McGill University
"Now we have pushed the Earth's crust back by hundreds of millions of years. That's why everyone is so excited."
Ancient rocks act as a time capsule - offering chemical clues to help geologists solve longstanding riddles of how the Earth formed and how life arose on it.
But the majority of our planet's early crust has already been mashed and recycled into Earth's interior several times over by plate tectonics.
Before this study, the oldest whole rocks were from a 4.03 billion-year-old body known as the Acasta Gneiss, in Canada's Northwest Territories.
The only things known to be older are mineral grains called zircons from Western Australia, which date back 4.36 billion years.
Date range
Professor Francis was looking for clues to the nature of the Earth's mantle 3.8 billion years ago.
He and colleague Jonathan O'Neil, from McGill University, travelled to remote tundra on the eastern shore of Hudson Bay, in northern Quebec, to examine an outcrop of the Nuvvuagittuq greenstone belt.
Geologists
The rocks turned out to be far older than first thought
They sent samples for chemical analysis to scientists at the Carnegie Institution of Washington, who dated the rocks by measuring isotopes of the rare earth elements neodymium and samarium, which decay over time at a known rate.
The oldest rocks, termed "faux amphibolite", were dated within the range from 3.8 to 4.28 billion years old.
"4.28 billion is the figure I favour," says Francis.
"It could be that the rock was formed 4.3 billion years ago, but then it was re-worked into another rock form 3.8bn years ago. That's a hard distinction to draw."
The same unit of rock contains geological structures which might only have been formed if early life forms were present on the planet, Professor Francis suggested.
Early habitat?
The material displays a banded iron formation - fine ribbon-like bands of alternating magnetite and quartz.
This feature is typical of rock precipitated in deep sea hydrothermal vents - which have been touted as potential habitats for early life on Earth.
"These ribbons could imply that 4.3 billion years ago, Earth had an ocean, with hydrothermal circulation," said Francis.
"Now, some people believe that to make precipitation work, you also need bacteria.
"If that were true, then this would be the oldest evidence of life.
"But if I were to say that, people would yell and scream and say that there is no hard evidence."
Fortunately, geologists have already begun looking for such evidence, in similar rocks found in Greenland, dated 3.8 billion years.
"The great thing about our find, is it will bring in people here to Lake Hudson to carry out specialised studies and see whether there was life here or not," says Francis.
"Regardless of that, or the exact date of the rocks, the exciting thing is that we've seen a chemical signature that's never been seen before. That alone makes this an exciting discovery."
//////////////////////////////“Always do what you are afraid to do.”
////////////////A Switch to Turn Off Autism?
Researchers have found a way to slow overactive brain cells that may be triggering neurological disorders
By Susannah F. Locke
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neuron inhibitory brain autism schizophrenia
THE BRAIN'S BRAKES: Scientists have fingered a gene that calms brain cells down when they get too excited.
© ISTOCKPHOTO/KIYOSHI TAKAHASE
Scientists say they have pinpointed a gene in the brain that can calm nerve cells that become too jumpy, potentially paving the way for new therapies to treat autism and other neurological disorders.
"It's exciting because it opens the field up," says Michael Greenberg, a neurobiologist at Harvard Medical School. "Nobody has [found] a gene that controls the process in quite that way before."
The brain is continually trying to strike a balance between too much and too little nerve cell activity. Neurologists believe that when the balance tips, disorders such as autism and schizophrenia may occur. They are not sure why neurons (nerve cells) go berserk. But Greenberg says he and his colleagues located a gene in mice and rats that helps keep neural activity in check—and may one day be manipulated to prevent or reverse neurological problems.
Researchers report in Nature that they discovered a gene called Npas4 churns out a protein that keeps neurons from becoming overexcited when they fire (communicate with one another through connections known as synapses). When scientists blocked the protein, the nerve cells fired or sent out more signals than normal; when they beefed up production, the neurons quieted down.
//////////////////////Is Morality Natural?
Science is tracing the biological roots of our intuitive sense of what is right and what is wrong.
Marc D. Hauser, Ph.D.
NEWSWEEK
From the magazine issue dated Sep 22, 2008
On Jan. 2, 2007, a large woman entered the Cango caves of South Africa and wedged herself into the only exit, trapping 22 tourists behind her. Digging her out appeared not to be an option, which left a terrible moral dilemma: take the woman's life to free the 22, or leave her to die along with her fellow tourists? It is a dilemma because it pushes us to decide between saving many and using someone else's life as a means to this end.
A new science of morality is beginning to uncover how people in different cultures judge such dilemmas, identifying the factors that influence judgment and the actions that follow. These studies suggest that nature provides a universal moral grammar, designed to generate fast, intuitive and universally held judgments of right and wrong.
Consider yourself a subject in an experiment on the Moral Sense Test (moral .wjh.harvard.edu), a site presenting dilemmas such as these: Would you drive your boat faster to save the lives of five drowning people knowing that a person in your boat will fall off and drown? Would you fail to give a drug to a terminally ill patient knowing that he will die without it but his organs could be used to save three other patients? Would you suffocate your screaming baby if it would prevent enemy soldiers from finding and killing you both, along with the eight others hiding out with you?
These are moral dilemmas because there are no clear-cut answers that obligate duty to one party over the other. What is remarkable is that people with different backgrounds, including atheists and those of faith, respond in the same way. Moreover, when asked why they make their decisions, most people are clueless, but confident in their choices. In these cases, most people say that it is acceptable to speed up the boat, but iffy to omit care to the patient. Although many people initially respond that it is unthinkable to suffocate the baby, they later often say that it is permissible in that situation.
Why these patterns? Cases 1 and 3 require actions, case 2 the omission of an action. All three cases result in a clear win in terms of lives saved: five, three and nine over one death. In cases 1 and 2, one person is made worse off, whereas in case 3, the baby dies no matter what choice is made. In case 1, the harm to the one arises as a side effect. The goal is to save five, not drop off and drown the one. In case 2, the goal is to end the life of the patient, as he is the means to saving three others.
Surprisingly, our emotions do not appear to have much effect on our judgments about right and wrong in these moral dilemmas. A study of individuals with damage to an area of the brain that links decision-making and emotion found that when faced with a series of moral dilemmas, these patients generally made the same moral judgments as most people. This suggests that emotions are not necessary for such judgments.
Our emotions do, however, have a great impact on our actions. How we judge what is right or wrong may well be different from what we chose to do in a situation. For example, we may all agree that it is morally permissible to kill one person in order to save the lives of many. When it comes to actually taking someone's life, however, most of us would turn limp.
Another example of the role that emotions have on our actions comes from recent studies of psychopaths. Take the villains portrayed by Heath Ledger and Javier Bardem, respectively, in "The Dark Knight" and "No Country for Old Men." Do such psychopathic killers know right from wrong? New, preliminary studies suggest that clinically diagnosed psychopaths do recognize right from wrong, as evidenced by their responses to moral dilemmas. What is different is their behavior. While all of us can become angry and have violent thoughts, our emotions typically restrain our violent tendencies. In contrast, psychopaths are free of such emotional restraints. They act violently even though they know it is wrong because they are without remorse, guilt or shame.
These studies suggest that nature handed us a moral grammar that fuels our intuitive judgments of right and wrong. Emotions play their strongest role in influencing our actions—reinforcing acts of virtue and punishing acts of vice. We generally do not commit wrong acts because we recognize that they are wrong and because we do not want to pay the emotional price of doing something we perceive as wrong.
So, would you have killed the large woman stuck in the cave or allowed her to die with the others? If you are like other subjects taking the moral sense test, you would say that it is permissible to take her life because you don't make her worse off. But could you really do it? Fortunately, there was a simpler solution: she was popped out with paraffin after 10 hours.
Hauser is a professor of psychology and human evolutionary biology at Harvard, and author of “Moral Minds” (Ecco/HarperPerennial).
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