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Archive for the ‘evolution’ Category

What does NASA’s new life-form discovery mean?

In astronomy, evolution, extraterrestrial on December 3, 2010 at 4:37 pm

What does NASA’s new life-form discovery mean?

Scientists’ announcement of a new form of microbe raises questions about extraterrestrial life. An expert explains

By Christopher R. Walker

 

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What does NASA’s new lifeform discovery mean?

Jodi Switzer Blum/NASA

GFAJ-1 grown on arsenic, left, and the Mono Lake Research area

 

In a much anticipated press conference yesterday afternoon, NASA astrobiologists announced the discovery of an amazing new kind of microbes, which extend the boundaries of what we may rightly call life. According to the press release, “NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth.” Discovered in Mono Lake, an extremely salty and alkaline body of water near Yosemite National Park in California, the microorganism is the first known specimen to substitute arsenic for phosphorus in its cell components, and has raised questions about what the discovery means for extraterrestrial life.

 

To find out what it really means, we called Robert Shapiro, a professor of chemistry at New York University who has written extensively about life’s origins on earth and its potential existence in outer space.

What does this mean for the discovery of life in our solar system or universe?

Not much, except that people may need to broaden their perspectives, and that we should be less “Terracentric” as we seek out new forms of life. Mostly, this discovery adds a new extremophile [organism that lives in an extreme environment] to our inventory — it pushes the boundaries out a little farther. The grand prize would be to discover an independent origin of life: life with its very own chemistry. Such a discovery wouldn’t just say that evolution is robust, it would say that life is abundant. But this discovery doesn’t do that: These organisms are not completely different in their chemical makeup from what we already know.

 

From what I can tell, the microbes prefer to live “normally” but may insert arsenic as a substitute for phosphorus when conditions demand it — arsenic can play the same role that phosphorus would play under normal circumstances. This is a great novelty. Arsenic is bigger and heavier than phosphorus, and its compounds are less stable. These organisms would not have done this unless they didn’t have any other choice. Just like Dr. Gerald Joyce, who was quoted in the New York Times today, I feel sorry for these creatures. Their living conditions are horrible — their environment would be poisonous to most other life on Earth.

Are there any lessons about where to focus our search for extraterrestrial life?

 

Broader searches are better searches. I always marveled at how parochial the searches were that focused on existing genetic assumptions. Hopefully, these findings will shift attention at NASA from [Jupiter moon] Europa — where life may be more familiar, but trapped under a deep ice cap — to [Saturn moon] Titan — where surface life could exist, but conditions are most hostile to traditional life-forms.

That said, it does reinforce Paul Davies’ “Shadow Biosphere” theory that suggests we may be missing major strains of life right here on Earth — either in places traditionally deemed too hostile to life or maybe even right under our noses. An obvious question, then, would be to ask how alternate forms of life could have escaped our notice all this time. Some argue that carbon life may have evolved from mineral life with no carbon of its own, and one could imagine experiments to test this hypothesis. You could simply introduce a carbon-free broth to a carbon-free environment, for example, and see what grows. Or as some people suggest, there could be benefits to testing radioactive environments.

You mentioned that arsenic is poisonous. Are there any industrial applications of these critters that spring to mind?

 

No, there’s no obvious industrial applications. It just shakes up our thinking about what’s possible.

 

So what’s the takeaway, then?

 

It’s an exciting time for risky ideas. Let’s try them. If one in 10 or one in 100 work, wow!

 

Source: salon.com

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Has Life Spread Virally Through the Universe?

In astronomy, evolution, extraterrestrial on August 2, 2010 at 3:05 pm

Life originated in a nebular cloud, over 10 billion years ago, but may have had multiple origins in multiple locations, including in galaxies older than the Milky Way according to Rudolf Schild of Harvard-Smithsonian Center for Astrophysics and Rhawn Joseph of the Brain Research Laboratory. Multiple origins, they believe, could account for the different domains of life: archae, bacteria, eukaryotes.

The first steps toward life may have been achieved when self-replicating nano-particles initially comprised of a mixture of carbon, calcium, oxygen, hydrogen, phosphorus, sugars, and other elements and gasses were combined and radiated, forming a nucleus around which a lipid-like permeable membrane was established, and within which DNA-bases were laddered together with phosphates and sugars; a process which may have taken billions of years.

DNA-based life, they propose, may be a “cosmic imperative” such that life can only achieve life upon acquiring a DNA genome. Alternatively, the “Universal Genetic Code” may have won out over inferior codes through natural selection. When the first microbe evolved, it immediately began multiplying and spreading throughout the cosmos via panspermia carried by solar winds, Bolide impact, comets, ejection of living planets prior to supernova which are then captured by a newly forming solar system, galactic collisions and following the exchange of stars between galaxies.

Bacteria, archae, and viruses, act as intergalactic genetic messengers, acquiring genes from and transferring genes to life forms dwelling on other planets. Viruses also serve as gene depositories, storing vast numbers of genes which may be transferred to archae and bacteria depending on cellular needs. The acquisition of these genes from the denizens of other worlds, enables prokaryotes and viruses to immediately adapt to the most extreme environments, including those that might be encountered on other planets.

OrionStarFormation

Whether the universe was created by a Big Bang Universe or an Eternal Infinite Universe, once life was established it began to evolve. Archae, bacteria, and viruses may have combined and mixed genes, fashioning the first multi-cellular eukaryote which continued to evolve. Initially, evolution on Earth-like planets was random and dictated by natural selection. Over time, increasingly complex and intelligent species evolved through natural selection whereas inferior competitors became extinct. However, their genes were copied by archae, bacteria, and viruses. If the first steps toward life in this galaxy began 13.6 billion years ago, then using Earth as an example, intelligent life might have evolved within this galaxy by 9 billion years ago. As life continued to spread throughout the cosmos, and as microbes and viruses were cast from world to world, genes continued to be exchanged via horizontal gene transfer and copies of genes coding for advanced and complex characteristics were acquired from and transferred to eukaryotes and highly evolved intelligent life.

Eventually descendants of these microbes, viruses, and their vast genetic libraries, fell to the new born Earth. The innumerable genes stored and maintained in the genomes of these viruses, coupled with prokaryote genes and those transferred to eurkaryotes, made it possible to biologically modify and terraform new Earth, and in so doing, some of these genes, now within the eurkaryote genome, were activated and expressed, replicating various species which had evolved on other worlds. Genes act on genes, and genes act on the environment and the altered environment activates and inhibits gene expression, thereby directly influencing the evolution of species.

On Earth, Schild and Joseph conclude, “the progression from simple cell to sentient intelligent being is due to the activation of viral, archae, and bacteria genes acquired from extra-terrestrial life and inserted into the Earthly eukaryote genome. What has been described as a random evolution is in fact the metamorphosis and replication of living creatures which long ago lived on other planets.”

Jason McManus via Journal of Cosmology

Ability to tolerate enemies influences coevolution

In evolution on March 19, 2010 at 5:43 pm

Stay and fight, or flee? These are usually the alternatives facing a victim when it is attacked by an enemy. Two researchers from Lund University have now collected and discussed various examples from the animal world where the victim makes use of another possibility.


“The victim can allow the enemy to remain and instead try to live with the consequences”, explains Erik Svensson, Professor of Animal Ecology at Lund University, Sweden.

There are many examples of ‘coevolution’, i.e. where the enemy and the victim influence each other’s development in close interaction. In several plant studies it is for instance  a  between a parasite (the enemy) and its  (the victim). Erik Svensson and his colleague Lars Rľberg have recently published an article in the journal Trends in Ecology & Evolution, in which they discuss the evolution of enemy-victim relations in animals.

The cuckoo’s brood parasitism is a classic example. The great spotted cuckoo lays its  in the nest of the European magpie and lets the magpie pair raise its young. The magpie can in turn respond by trying to recognise alien eggs and reject them; this is a form of resistance. However, there is a risk that the magpie may accidently reject one of its own eggs. In addition, the magpies that reject cuckoos’ eggs run a higher risk of having their nests destroyed by adult cuckoos. There is evidence that magpies that live in close proximity to great spotted cuckoos actually compensate for this by laying more eggs than magpies that breed in areas where cuckoos are not present. One reason for this could be that it is a way to compensate for the eggs that risk being destroyed. This defence tactic is classified as tolerance, rather than resisistance. It means that the victim tries to live with the presence of the enemy instead of resisting.

Erik Svensson conducts research on damselflies. He has shown that enemy-victim relationships can also occur within the same species. When damselflies mate, the male clasps the female’s thorax. Immediately after fertilisation, the female begins laying eggs. Yet females are constantly subject to mating attempts and harassment from other males, which incur costs in the form of a reduced number of eggs. However, some females have developed a higher tolerance to this mating harassment, which means that they are able to partly buffer the negative effects of mating harassment on their egg laying.

Lars Rľberg has studied tolerance in mice. He has performed an experiment in which he infected different mouse strains with malaria. It was apparent that the different mice did not become ill to the same extent, despite the fact that they had the same number of  in their bodies. Thus tolerance can also reflect itself in how sensitive a victim is to an enemy.

“This is a new way of viewing the evolution of enemy-victim interactions in animals. The role of tolerance in suchinteractions have previously been discussed primarily in the context of the plant world. We believe that tolerance could be at least as important as resistance in animal co-evolution between enemies and their victims”, says Erik Svensson.

Intelligent people have ‘unnatural’ preferences and values that are novel in human evolution

In brain, evolution on March 1, 2010 at 10:18 am

More intelligent people are significantly more likely to exhibit social values and religious and political preferences that are novel to the human species in evolutionary history. Specifically, liberalism and atheism, and for men (but not women), preference for sexual exclusivity correlate with higher intelligence, a new study finds.

The study, published in the March 2010 issue of the peer-reviewed scientific journal  Quarterly, advances a new theory to explain why people form particular preferences and values. The theory suggests that more intelligent people are more likely than less intelligent people to adopt evolutionarily novel preferences and values, but intelligence does not correlate with preferences and values that are old enough to have been shaped by evolution over millions of years.”

“Evolutionarily novel” preferences and values are those that humans are not biologically designed to have and our  probably did not possess. In contrast, those that our ancestors had for millions of years are “evolutionarily familiar.”

“General intelligence, the ability to think and reason, endowed our ancestors with advantages in solving evolutionarily novel problems for which they did not have innate solutions,” says Satoshi Kanazawa, an evolutionary psychologist at the London School of Economics and Political Science. “As a result, more intelligent people are more likely to recognize and understand such novel entities and situations than less intelligent people, and some of these entities and situations are preferences, values, and lifestyles.”

An earlier study by Kanazawa found that more intelligent individuals were more nocturnal, waking up and staying up later than less intelligent individuals. Because our ancestors lacked artificial light, they tended to wake up shortly before dawn and go to sleep shortly after dusk. Being nocturnal is evolutionarily novel.

In the current study, Kanazawa argues that humans are evolutionarily designed to be conservative, caring mostly about their family and friends, and being liberal, caring about an indefinite number of genetically unrelated strangers they never meet or interact with, is evolutionarily novel. So more intelligent children may be more likely to grow up to be liberals.

Data from the National Longitudinal Study of Adolescent Health (Add Health) support Kanazawa’s hypothesis. Young adults who subjectively identify themselves as “very liberal” have an average IQ of 106 during adolescence while those who identify themselves as “very conservative” have an average IQ of 95 during adolescence.

Similarly, religion is a byproduct of humans’ tendency to perceive agency and intention as causes of events, to see “the hands of God” at work behind otherwise natural phenomena. “Humans are evolutionarily designed to be paranoid, and they believe in God because they are paranoid,” says Kanazawa. This innate bias toward paranoia served humans well when self-preservation and protection of their families and clans depended on extreme vigilance to all potential dangers. “So, more intelligent children are more likely to grow up to go against their natural evolutionary tendency to believe in God, and they become atheists.”

Young adults who identify themselves as “not at all religious” have an average IQ of 103 during adolescence, while those who identify themselves as “very religious” have an average IQ of 97 during adolescence.

In addition, humans have always been mildly polygynous in . Men in polygynous marriages were not expected to be sexually exclusive to one mate, whereas men in monogamous marriages were. In sharp contrast, whether they are in a monogamous or polygynous marriage, women were always expected to be sexually exclusive to one mate. So being sexually exclusive is evolutionarily novel for men, but not for women. And the theory predicts that more intelligent men are more likely to value sexual exclusivity than less intelligent men, but general intelligence makes no difference for women’s value on sexual exclusivity. Kanazawa’s analysis of Add Health data supports these sex-specific predictions as well.

One intriguing but theoretically predicted finding of the study is that more intelligent people are no more or no less likely to value such evolutionarily familiar entities as marriage, family, children, and friends.

Provided by American Sociological Association

Source: http://www.physorg.com/print186236813.html

Scientists reveal driving force behind evolution

In evolution, science on February 25, 2010 at 4:11 pm

Scientists at the University of Liverpool have provided the first experimental evidence that shows that evolution is driven most powerfully by interactions between species, rather than adaptation to the environment.

The team observed viruses as they evolved over hundreds of generations to infect bacteria. They found that when the bacteria could evolve defences, the viruses evolved at a quicker rate and generated greater diversity, compared to situations where the bacteria were unable to adapt to the viral infection.

The study shows, for the first time, that the American Leigh Van Valen was correct in his ‘Red Queen Hypothesis’. The theory, first put forward in the 1970s, was named after a passage in Lewis Carroll’s Through the Looking Glass in which the Red Queen tells Alice, ‘It takes all the running you can do to keep in the same place’. This suggested that species were in a constant race for survival and have to continue to evolve new ways of defending themselves throughout time.

Dr Steve Paterson, from the University’s School of Biosciences, explains: “Historically, it was assumed that most  was driven by a need to adapt to the environment or habitat. The Red Queen Hypothesis challenged this by pointing out that actually most  will arise from co-evolutionary interactions with other species, not from interactions with the environment.

“This suggested that  was created by ‘tit-for-tat’ adaptations by species in constant combat. This theory is widely accepted in the science community, but this is the first time we have been able to show evidence of it in an experiment with living things.”

Dr Michael Brockhurst said: “We used fast-evolving viruses so that we could observe hundreds of generations of evolution. We found that for every viral strategy of attack, the bacteria would adapt to defend itself, which triggered an endless cycle of co-evolutionary change. We compared this with evolution against a fixed target, by disabling the bacteria’s ability to adapt to the virus.

“These experiments showed us that co-evolutionary interactions between species result in more genetically diverse populations, compared to instances where the host was not able to adapt to the parasite. The virus was also able to evolve twice as quickly when the  were allowed to evolve alongside it.”

The team used high-throughput DNA sequencing technology at the Centre for Genomic Research to sequence thousands of virus genomes. The next stage of the research is to understand how co-evolution differs when interacting species help, rather than harm, one another.

The research is published in journal Nature.

Πηγή: http://www.physorg.com/news186311100.html

New Research Pinpoints Regions of Human Brain Responsible for Intelligence

In evolution, science on February 25, 2010 at 11:25 am
Caltechneuro
“One of the main findings that really struck us was that there was a distributed system here. Several brain regions, and the connections between them, were what was most important to general intelligence.”
Jan Gläscher, postdoctoral fellow at California Institute for Technology

The brain regions important for general intelligence are found in several specific places (orange regions shown on the brain on the left). Looking inside the brain reveals the connections between these regions, which are particularly important to general intelligence. In the image on the right, the brain has been made partly transparent. The big orange regions in the right image are connections (like cables) that connect the specific brain regions in the image on the left. Credit:

The research team included and Ralph Adolphs, the Bren Professor of Psychology and Neuroscience and professor of biology. The Caltech scientists teamed up with researchers at the University of Iowa and USC to examine a uniquely large data set of 241 brain-lesion patients who all had taken IQ tests. The researchers mapped the location of each patient’s lesion in their brains, and correlated that with each patient’s IQ score to produce a map of the brain regions that influence intelligence.

“General intelligence, often referred to as Spearman’s g-factor, has been a highly contentious concept,” says Adolphs. “But the basic idea underlying it is undisputed: on average, people’s scores across many different kinds of tests are correlated. Some people just get generally high scores, whereas others get generally low scores. So it is an obvious next question to ask whether such a general ability might depend on specific brain regions.”

The researchers found that, rather than residing in a single structure, general intelligence is determined by a network of regions across both sides of the brain.

“It might have turned out that general intelligence doesn’t depend on specific brain areas at all, and just has to do with how the whole brain functions,” adds Adolphs. “But that’s not what we found. In fact, the particular regions and connections we found are quite in line with an existing theory about intelligence called the ‘parieto-frontal integration theory.’ It says that general intelligence depends on the brain’s ability to integrate—to pull together—several different kinds of processing, such as working memory.”

The researchers say the findings will open the door to further investigations about how the brain, intelligence, and environment all interact.

Casey Kazan via  California Institute of Technology