In experiments with butterflies, evolutionary biologists from Leiden University have demonstrated that natural selection is not always the only factor which determines the appearance of an organism. Constraints also appear to play a role at times in determining the progress and outcome of the evolutionary process.
This research from Leiden provides evidence for the hypothesis of Stephen Jay Gould and Richard Lewontin. In 1979, these two scientists stated that Darwin`s theory of natural selection is often incorrectly seen as the sole factor which determines the outcome of evolution. Constraints also play an important role.
For example, constraints play a role in not allowing the development of eyes in the back of the head. Although decidedly advantageous, the evolution of eyes at this location will occur in few animals. This is due to limitations during the development and growth or because no variation for this trait is present in the genetic material. Another form of constraints occurs if two traits are linked to each other. A person with long arms always has long legs.
Michel Philippens | alfa
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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