Yep, kisses for all the creationists around :) Seriously, I think people underestimate the power of evolution as a scientific method and theory. Now, you can see some of its strengths. It's about 3 experiments that led to very exciting information.
First, the sexual evolutions got confirmed (or it looks like it)-which means that some traits of our physiology may not be biologically useful-those that are sexually useful, but in strong competition, they are passed to the generation. Second, an intermediate brink of the evolution from the oceans gives new ideas on how life changed to accommodate the new environment. And third, and very very awesome, a new experiment proves that life is not so hard to create from "dead" matter. Enjoy the articles, they are soooooo exciting.
Some flirtatious yeast cells have confirmed a part of Charles Darwin’s theory of evolution that was never tested as successfully as the rest of the theory, biologists say.
“Other half” of Darwin’s theory passes test
This somewhat special part of the theory is the concept of evolution through “sexual selection.”
In general, evolutionary theory holds that species gradually change because of certain mutations that spread through their populations. These mutations spread if, and only if, they’re beneficial—so that individuals possessing them survive longer, reproduce more or both. Thus the mutated trait appears increasingly often in succeeding generations.
Evolution has been observed in action numerous times, because in short-lived species, many forms of evolution occur fast enough for humans to watch the changes occur.
But one form of evolution has not been directly seen: evolution through sexual selection, notes a paper in the Oct. 7 online issue of the research journal Proceedings of the Royal Society B.
This variety of evolution is what biologists believe accounts for the appearance of sexual-advertising traits such as a peacock’s bright tail, or perhaps musical ability.
Such traits are believed to evolve for much the same reason as others: those who have a certain characteristic mate more, and thus spread the genes for that feature. The chief difference between this form of evolution and others is that with sexual selection, the driving factor in the process is sexual competition, rather than other exigencies of survival more generally.
Sexual selection is an intriguing aspect of evolution because it drives the evolution of traits that on their face, seem less than clearly beneficial, said Duncan Greig of University College in London, one of the paper’s authors.
“For example a peacock’s tail might be conspicuous to predators,” he noted in an email. Or for a human equivalent: “Ferrari drivers might be more likely to end up splatted against a tree than Buick drivers.” For both examples, “the simple explanation is that the cost is more than balanced by the benefit of extra mating.”
In the new paper, Greig, along with David W. Rogers of Imperial College in London, claim to have observed evolution through sexual selection for the first time. “Our yeast system is a powerful tool for investigating the genetics of sexual selection,” they wrote.
Yeast cells occur in two different mating types, somewhat akin to male and female. Each type signals to potential partners of the other type by producing an attractive chemical, called a pheromone. But cells vary widely in how strongly they can signal; the differences are genetic.
Rogers and Greig engineered one of the “sexes” of yeast cells, called MAT-alpha, to have either very high or very low signaling strength. They then mixed both types of cells with those of the opposite “sex” group, called MATa. This mixing was done in two different ways: in one, the MAT-alpha cells were few, and so faced little competition among each other; in the other, they were many, so that they faced tough competition for mating opportunities.
Only under the high-competition situation, the strong-signalling gene variant spread quickly through the population at the expense of the weak-signalling variant, Rogers and Greig found. This matched the predictions of sexual selection theory, they added. source
My comment: That is absolutely awesome! I mean they really have saw it! That's so unbelievable. And in such a simple way. Simply amazing. That's what science is about. Proving complicated things in elegant way.
Head skeleton sheds light on intermediate steps
October 15, 2008
New research has provided the first detailed look at the internal head skeleton of Tiktaalik roseae, the 375-million-year-old fossil animal that represents an important intermediate step in the evolutionary transition from fish to animals that walked on land.
Results of the study, published in this week's issue of the journal Nature, show that the transition from aquatic to terrestrial lifestyle involved complex changes not only to appendages (fins to limbs) but also to the internal head skeleton.
"Exquisite specimens of Tiktaalik roseae discovered several years ago continue to function as rosetta stones for understanding the emergence of quadripeds on land," said H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research.
A team co-led by scientist Ted Daeschler at the Academy of Natural Sciences in Philadelphia discovered Tiktaalik roseae (tik-TAHL-ik RO-zay) in 2004, in Devonian-age rock on Ellesmere Island in Canada, more than 700 miles above the Arctic Circle.
The creature was a large aquatic predator with a flattened head and body.
The body plan and nature of the deposits where the fossils were found suggest an animal that lived on the bottom in shallow water, and perhaps out of the water for short periods.
Tiktaalik roseae has features of the skull, neck, ribs and appendages that are shared with the earliest limbed animals (tetrapods), as well as fishlike features such as scales and fin rays. This mosaic of features makes it a textbook example of a transitional fossil, say paleontologists.
Jason Downs, a scientist at the Academy of Natural Sciences and lead author of this week's paper, said the examination of the internal head skeleton further demonstrates the intermediacy of Tiktaalik roseae.
"The braincase, palate and gill arches of Tiktaalik help reveal the pattern of evolutionary change in this part of the skeleton," said Downs. "We see that cranial features once associated with land-living animals were in fact the first adaptations for life in shallow water."
"The gradual evolutionary transition from fish to tetrapod, and the transition from aquatic to terrestrial lifestyles required much more than the evolution of limbs," said Daeschler. "The head of these animals was becoming more solidly constructed and, at the same time, more mobile with respect to the body across this transition."
Trends in head shape include a flattening of the skull and a lengthening of the snout.
Using several well-preserved specimens of Tiktaalik roseae, the research helps document the relative timing of the particular skeletal changes associated with changes in head shape.
"We used to think of this transition of the neck and skull as a rapid event, largely because we lacked information about the intermediate animals," said Neil Shubin of the University of Chicago, who co-led the team that discovered Tiktaalik roseae. "Tiktaalik neatly fills this morphological gap, and helps to resolve the timing of this complex transition."
During this transition, interactions among the different parts of the head skeleton also were changing.
"Fish in deep water move and feed in three-dimensional space, and can easily orient their bodies in the direction of their prey," said Farish Jenkins, Jr., an evolutionary biologist at Harvard University and co-author of the paper. "A mobile neck is advantageous in settings where the body is relatively fixed, as is the case in shallow water and on land." source
My comment: Nice, nice, nice. I wonder what would a undersea human would look like. They claim fixed head is ok in 3D, but after all, it depends on the environment, more precisely the predators they have to evade. It's not so simple I guess. And if the "thing" has to live in water and on the Earth, then it gets even more complicated. But it's so nice to see they found that intermediate level. And that evolution still get some attention.
Vials holding the results of a famous chemistry experiment conducted 55 years ago have been discovered in dusty cardboard boxes, and a new analysis of their contents has revealed fresh insights into a big question: the origin of life on earth. In 1953, chemist Stanley Miller tried to duplicate the conditions present on the primordial earth in laboratory flasks, and while some of his results were published to great acclaim, other results were packed away and forgotten–until now.
Miller’s classic experiment involved putting atmospheric components thought to reflect those of the early Earth (ammonia, hydrogen, methane, and water) in a closed system and stimulating that mixture with an electric current to mimic the effects of lightning storms. He generated a small number of biochemically significant compounds, including amino acids, hydroxy acids, and urea, showing that conditions of primitive earth can create the building blocks of life [Ars Technica]. These results generated considerable excitement, but later researchers argued that Miller was wrong about the composition of the young earth’s atmosphere, and the experiment was written off as a novelty.
In the new study, published in Science , researchers analyzed vials of material that were produced by a slightly different process that Miller had viewed as a flop; in that process, the gases were also mixed with a jet of steam to replicate conditions around an erupting volcano. Using modern methods to analyze the samples, researchers found they contained a total of 22 amino acids (including some that Miller had never identified in any of his experiments), the most complex mix yet produced by Miller’s method.
Study coauthor Jeffrey Bada, who was a graduate student of Miller’s, says the findings suggest that life could have originated on earth in the fiery and turbulent regions around volcanoes. “The model is that you have these small pockets, volcanic hot spots,” explains Bada, in which a volatile reducing atmosphere, one in which chemicals are more likely to react with one another, may have produced amino acids. The team’s reanalysis makes it plausible that a shallow tide pool tucked into the side of a volcano and a fortuitous bolt of lightning could have led to an abundance of amino acids [Science News].
However, theories on the origin of life have moved on since the days of Miller’s original experiments, and have taken decidedly new directions. The discovery of amino acids in meteorites suggested that the building blocks of life came from space, eliminating the need for finding chemical processes that could produce them on Earth. Some scientists have since suggested places like the ocean bottom as most likely to be where the building blocks first came together as a living organism…. “My take on this is you want to consider everything,” Dr. Bada said. source
My comment:And my opinion is that life is obviously much more common than we think. If we can produce its building blocks with 2 different processes, how many more we're missing? And that's even without the clear understanding what life is.The comment I left on the site:
If you can recreate building blocks of life with two different experiments, imagine how much Nature can do. On every planet, on all the different situations-volcano, particles emissions on the poles, earthquakes, lightnings- you name it.
For me, this experiment proves that life is much more common than we think. And probably that the whole theory that something brought "it" is wrong, because maybe it wasn't a single lucky even, but a multiplicity of events-from above, from below, from everywhere, that sparkled and spread over, some died away, some evolved and in the end-we had so much life, it simply flourished.
Why it doesn''t happen everywhere? Two possible reasons: A) it requires some basic elements and you can find it where they are present-unlikely since on Earth there are bacteria like everywhere. B) it is all around, we just can't see it so easily, because it's based on different building blocks or is on different scale-too big or too small.
In any case, Mars exploration is going on, Europa is also a good candidate for life, so sooner or later, we'll find out how common life in space is.