galaxy news: Evolution

‏إظهار الرسائل ذات التسميات Evolution. إظهار كافة الرسائل

الجمعة، 7 سبتمبر 2012

Image of the Day: 14-Billion-Year Evolution of the Universe (VIDEO)

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الثلاثاء، 28 أغسطس 2012

Is the Biological, Darwinian Phase of Human Evolution Over? Hawking Says "Yes" (Today's Most Popular)

But what distinguishes us from our cave man ancestors is the knowledge that we have accumulated over the last ten thousand years, and particularly, Hawking points out, over the last three hundred.

"I think it is legitimate to take a broader view, and include externally transmitted information, as well as DNA, in the evolution of the human race," Hawking said.

In the last ten thousand years the human species has been in what Hawking calls, "an external transmission phase," where the internal record of information, handed down to succeeding generations in DNA, has not changed significantly. "But the external record, in books, and other long lasting forms of storage," Hawking says, "has grown enormously. Some people would use the term, evolution, only for the internally transmitted genetic material, and would object to it being applied to information handed down externally. But I think that is too narrow a view. We are more than just our genes."

The time scale for evolution, in the external transmission period, has collapsed to about 50 years, or less.

Meanwhile, Hawking observes, our human brains "with which we process this information have evolved only on the Darwinian time scale, of hundreds of thousands of years. This is beginning to cause problems. In the 18th century, there was said to be a man who had read every book written. But nowadays, if you read one book a day, it would take you about 15,000 years to read through the books in a national Library. By which time, many more books would have been written."

But we are now entering a new phase, of what Hawking calls "self designed evolution," in which we will be able to change and improve our DNA. "At first," he continues "these changes will be confined to the repair of genetic defects, like cystic fibrosis, and muscular dystrophy. These are controlled by single genes, and so are fairly easy to identify, and correct. Other qualities, such as intelligence, are probably controlled by a large number of genes. It will be much more difficult to find them, and work out the relations between them. Nevertheless, I am sure that during the next century, people will discover how to modify both intelligence, and instincts like aggression."

If the human race manages to redesign itself, to reduce or eliminate the risk of self-destruction, we will probably reach out to the stars and colonize other planets. But this will be done, Hawking believes, with intelligent machines based on mechanical and electronic components, rather than macromolecules, which could eventually replace DNA based life, just as DNA may have replaced an earlier form of life.

The Daily Galaxy via http://www.centauri-dreams.org/

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السبت، 4 أغسطس 2012

Astrobiologists Resurrect a 500-Million-Year-Old Gene --New Insights into Evolution

Astrobiologists Resurrect a 500-Million-Year-Old Gene --New Insights into Evolution
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July 31, 2012 Astrobiologists Resurrect a 500-Million-Year-Old Gene --New Insights into Evolution

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Using a process called paleo-experimental evolution, Georgia Tech researchers have resurrected a 500-million-year-old gene from bacteria and inserted it into modern-day Escherichia coli (E. coli) bacteria. This bacterium has now been growing for more than 1,000 generations, giving the scientists a front row seat to observe evolution in action.

“We think that this process will allow us to address several long standing questions in evolutionary and molecular biology,” said Betül Kacar, a NASA astrobiology postdoctoral fellow in Georgia Tech’s NASA Center for Ribosomal Origins and Evolution. “Among them, we want to know if an organism’s history limits its future and if evolution always leads to a single, defined point or whether evolution has multiple solutions to a given problem.”

“This is as close as we can get to rewinding and replaying the molecular tape of life,” said Kacar.“The ability to observe an ancient gene in a modern organism as it evolves within a modern cell allows us to see whether the evolutionary trajectory once taken will repeat itself or whether a life will adapt following a different path.”

In 2008, Kacar’s postdoctoral advisor, Associate Professor of Biology Eric Gaucher, successfully determined the ancient genetic sequence of Elongation Factor-Tu (EF-Tu), an essential protein in E. coli. EFs are one of the most abundant proteins in bacteria, found in all known cellular life and required for bacteria to survive. That vital role made it a perfect protein for the scientists to answer questions about evolution.

After achieving the difficult task of placing the ancient EF-Tu gene in the correct chromosomal order and position in place of the modern gene within E. coli, Kacar produced eight identical bacterial strains and allowed “ancient life” to re-evolve.

This chimeric bacteria composed of both modern and ancient genes survived, but grew about two times slower than its counterpart composed of only modern genes.* “The altered organism wasn’t as healthy or fit as its modern-day version, at least initially,” said Gaucher, “and this created a perfect scenario that would allow the altered organism to adapt and become more fit as it accumulated mutations with each passing day.”

The growth rate eventually increased and, after the first 500 generations, the scientists sequenced the genomes of all eight lineages to determine how the bacteria adapted.

Not only did the fitness levels increase to nearly modern-day levels, but also some of the altered lineages actually became healthier than their modern counterpart.

When the researchers looked closer, they noticed that every EF-Tu gene did not accumulate mutations. Instead, the modern proteins that interact with the ancient EF-Tu inside of the bacteria had mutated and these mutations were responsible for the rapid adaptation that increased the bacteria’s fitness. In short, the ancient gene has not yet mutated to become more similar to its modern form, but rather, the bacteria found a new evolutionary trajectory to adapt.

These results were presented at the recent NASA International Astrobiology Science Conference. The scientists will continue to study new generations, waiting to see if the protein will follow its historical path or whether it will adopt via a novel path altogether.

Sources: Betül Kaçar, Eric A. Gaucher, Towards the Recapitulation of Ancient History in the Laboratory: Combining Synthetic Biology with Experimental Evolution, Proceedings of the Thirteenth International Conference on the Simulation and Synthesis of Living Systems, 2012, DOI: 10.7551/978-0-262-31050-5-ch002 (open access).

The Daily Galaxy via Georgia Institute of Technology and http://www.kurzweilai.net

Posted at 08:45 AM | Permalink

Comments

One thing to do to see if it follows its historical path or adapt another one is to put it in different situations. Such as hotter weather. Different conditions at different times througout its evolution. Watery situations, hot and cold, different bacteria even maybe to see if it adapts or changes sequences. Just an idea.

Posted by:Justin |July 31, 2012 at 08:42 PM