Forscher haben einen riesigen Stammbaum mit allen bekannten Lebensformen der Erde aufgestellt. Das Mammutprojekt umfasst 2,3 Millionen Tiere, Pflanzen, Pilze und Mikroben. Der „Baum des Lebens“ ist frei im Internet abrufbar.
In einer Höhle in Südafrika haben Forscher Tausende Knochen einer bislang unbekannten Menschenart entdeckt. Das grazile Wesen war offenbar gut zu Fuß. Es pflegte wie der moderne Mensch einen Bestattungsritus.
Seit etwa 2.000 Jahren verdummt die Menschheit von Generation zu Generation. Grund dafür ist die fehlende natürliche Selektion, denn früher konnten sich nur intelligente Menschen erfolgreich Fortpflanzen. Diese These stellt der US-Entwicklungsbiologe Gerald Crabtree in Folge seiner Studien auf.
Astrophysiker schreibt brutale Erwiderung auf den WSJ Artikel der behauptete die Wissenschaft hätte die Existenz Gottes bewiesen
Kürzlich – tatsächlich an Weihnachten – hat das Wall Street Journal einen Artikel eines Streiters für das Christentum veröffentlicht, der kühn erklärte, dass die Wissenschaft Jahr für Jahr zunehmend Gott bestätige.
Eric Metaxas, ein bekannter Biograph, wird (in konservativen Kreisen) auch für seine Arbeiten gefeiert, die die Pro-Life-Bewegung unterstützen und radikale haarsträubende Schlüsse zur Existenz Gottes schlussfolgern. Diese basieren auf allem was gerade als Beleg zur Hand ist. Wenn die radikalen haarsträubenden Schlüsse das „tägliche Brot“ bei Metaxas sind, dann ist der Artikel im Wall Street Journal sein Opus Magnum. Es ist ein Prachtexemplar.
Nach dem Untertitel seiner Arbeit „Die Chancen für die Existenz von Leben auf anderen Planeten werden immer geringer. Intelligent Design?“, folgte eine mäandernde Reise in die Gedankenwelt eines Kreationisten, der mit wissenschaftlicher Belesenheit spielte – aber nur, wenn sie zu seinen vorgefassten Schlüssen passte.
Why does life exist?
Popular hypotheses credit a primordial soup, a bolt of lightning, and a colossal stroke of luck.
But if a provocative new theory is correct, luck may have little to do with it. Instead, according to the physicist proposing the idea, the origin and subsequent evolution of life follow from the fundamental laws of nature and “should be as unsurprising as rocks rolling downhill.”
From the standpoint of physics, there is one essential difference between living things and inanimate clumps of carbon atoms: The former tend to be much better at capturing energy from their environment and dissipating that energy as heat.
Jeremy England, a 31-year-old assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity. The formula, based on established physics, indicates that when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life.
In einem 45.000 Jahre alten menschlichen Knochen haben Leipziger Forscher Neandertaler-Gene entdeckt. Ihre Analyse erlaubt neue Einblicke in die Ursprünge der Menschwerdung.
Ist die Konkurrenz groß genug, kann die Evolution richtig schnell gehen – das haben Forscher an einer Echsenart jetzt eindrucksvoll belegt. Die Tiere entwickelten in nur 15 Jahren Riesenfüße mit Klebesohle, um Gegnern davonzuklettern.
In 2010, scientists discovered that simple peptides can organize into bi-layer membranes. The finding suggests a “missing link” between the pre-biotic Earth’s chemical inventory and the organizational scaffolding essential to life. Many groups studying the origins of life have focused on RNA, which is believed to have pre-dated living cells. But RNA is a much more complicated molecule than a peptide. The 2010 studies showed that, if you just add water, simple peptides access both the physical properties and the long-range molecular order that is critical to the origins of chemical evolution.
“This is a boon to our understanding of large, structural assemblies of molecules,” said Emory Chemistry Chair David Lynn, who helped lead the effort, which were collaborations of the departments of chemistry, biology and physics. “We’ve proved that peptides can organize as bi-layers, and we’ve generated the first, real-time imaging of the self-assembly process. We can actually watch in real-time as these nano-machines make themselves.”
For billions of years, simple creatures like plankton, bacteria, and algae ruled the earth. Then, suddenly, life got very complicated. Recent discoveries from Canada’s Burgess Shale Deposits, Greenland, China, Siberia, and Namibia document clearly that a period of biological creativity known as the Cambrian Explosion occurred in a „geological instant“ over 500 million years ago virtually all around the globe -an explosion of life that continues to puzzle evolutionists.
During the Cambrian explosion animals as diverse as arthropods, molluscs, jellyfish, and primitive vertebrates all appear within a time span of only 5-10 million years with no ancestors and no intermediates.Recent discoveries have narrowed the time frame from over 70 million years to less than 10 million years. The same basic body plans that arose in the Cambrian remain surprisingly constant ever since. Apparently, the most significant biological changes in the history of the earth occurred in less than ten million years, and for 500 million years afterward, this level of change never happened again.
Harvard’s Stephen Jay Gould once said, „Fast is now a lot faster than we thought, and that is extraordinarily interesting.“
Wann begannen sich die Wege von Mensch und Affe zu trennen? Bisher gab es nur Indizien und Vermutungen über die Frühphase unserer Entwicklung. Zwei neue Funde füllen nun klaffende Lücken im Primatenstammbaum – und bestätigen die Richtigkeit von auf Genen basierenden Hochrechnungen.
The widespread disappearance of stromatolites, the earliest visible manifestation of life on Earth, may have been driven by single-celled organisms called foraminifera. Stromatolites (“layered rocks”) are structures made of calcium carbonate and shaped by the actions of photosynthetic cyanobacteria and other microbes that trapped and bound grains of coastal sediment into fine layers. They showed up in great abundance along shorelines all over the world about 3.5 billion years ago.
“Stromatolites were one of the earliest examples of the intimate connection between biology—living things—and geology—the structure of the Earth itself,” said Woods Hole Oceanographic Institution (WHOI) geobiologist Joan Bernhard, lead author of the study.
The growing bacterial community secreted sticky compounds that bound the sediment grains around themselves, creating a mineral “microfabric” that accumulated to become massive formations. Stromatolites dominated the scene for more than two billion years, until late in the Proterozoic Eon.
“Then, around 1 billion years ago, their diversity and their fossil abundance begin to take a nosedive,” said Bernhard. All over the globe, over a period of millions of years, the layered formations that had been so abundant and diverse began to disappear. To paleontologists, their loss was almost as dramatic as the extinction of the dinosaurs millions of years later, although not as complete: Living stromatolites can still be found today, in limited and widely scattered locales, as if a few velociraptors still roamed in remote valleys.
DNA sequencing of 36 complete Y chromosomes has uncovered a previously unknown population explosion that occurred 40 to 50 thousand years ago, between the first expansion of modern humans out of Africa 60 to 70 thousand years ago and the Neolithic expansions of people in several parts of the world starting 10 thousand years ago. Research completed in fall of 2012 used the information from large-scale DNA sequencing to create an accurate family tree of the Y chromosome, from which the inferences about human population history could be made.
„We have always considered the expansion of humans out of Africa as being the largest population expansion of modern humans, but our research questions this theory,“ said Ms Wei Wei, first author from the Wellcome Trust Sanger Institute and the West China University of Medical Sciences. „The out-of-Africa expansion, which happened approximately 60,000 years ago, was extremely large in geographical terms with humans spreading around the globe. Now we’ve found a second wave of expansion that is much larger in terms of human population growth and occurred over a very short period, somewhere between 40,000 to 50,000 years ago.“
Understanding how and why diversification occurs is important for understanding why there are so many species on Earth. In a new study published on 19 February in the open access journal PLOS Biology, researchers show that similar—or even identical—mutations can occur during diversification in completely separate populations of E. coli evolving in different environments over more than 1000 generations. Evolution, therefore, can be surprisingly predictable.
The experiment, conducted by Matthew Herron, research assistant professor at the University of Montana, and Professor Michael Doebeli of the University of British Columbia, involved 3 different populations of bacteria. At the start of the experiment, each population consisted of generalists competing for two different sources of dietary carbon (glucose and acetate), but after 1200 generations they had evolved into two coexisting types each with a specialized physiology adapted to one of the carbon sources. Herron and Doebeli were able to sequence the genomes of populations of bacteria frozen at 16 different points during their evolution, and discovered a surprising amount of similarity in their evolution.
„In all three populations it seems to be more or less the same core set of genes that are causing the two phenotypes that we see,“ Herron said. „In a few cases, it’s even the exact same genetic change.“
Recent discoveries in vast interstellar dust clouds permeating the universe and in nebula have revealed hints of organic matter that could be created naturally by stars, according to researchers in a 2011 study at the University of Hong Kong. The discovery team observed stars at different evolutionary phases and found that they are able to produce complex organic compounds and eject them into space, filling the voids between stars.
The compounds are so complex that their chemical structures resemble the makeup of coal and petroleum, the study’s lead author, Sun Kwok of the University of Hong Kong, said. Kwok and his colleague Yong Zhang, also of the University of Hong Kong, studied a set of well-known but mysterious infrared emissions found in stars, interstellar space and galaxies. These phenomena, which are collectively called Unidentified Infrared Emission (UIE) features, have been known for 30 years, but the exact source of the emissions has not been identified, and remains a broad assumption.
Such chemical complexity was thought to arise only from living organisms, but the results of the new study show that these organic compounds can be created in space even when no life forms are present. In fact, such complex organics could be produced naturally by stars, and at an extremely rapid pace.
A radical new approach to the question of life’s origin has been proposed by two Arizona State University scientists that attempts to dramatically redefine the problem. The researchers – Paul Davies, an ASU Regents‘ Professor and director of the Beyond Center for Fundamental Concepts in Science, and Sara Walker, a NASA post-doctoral fellow at the Beyond Center. „We propose that the transition from non-life to life is unique and definable,“ added Davies. „We suggest that life may be characterized by its distinctive and active use of information, thus providing a roadmap to identify rigorous criteria for the emergence of life. This is in sharp contrast to a century of thought in which the transition to life has been cast as a problem of chemistry, with the goal of identifying a plausible reaction pathway from chemical mixtures to a living entity.“
In a nutshell, the authors shift attention from the „hardware“ – the chemical basis of life – to the „software“ – its information content. To use a computer analogy, chemistry explains the material substance of the machine, but it won’t function without a program and data. Davies and Walker suggest that the crucial distinction between non-life and life is the way that living organisms manage the information flowing through the system.
Researchers have identified the moment in history 500 million years ago that provided our ability to learn complex skills, analyze situations and have flexibility in the way in which we think. According to Professor Seth Grant of the University of Edinburgh, who led the new research, intelligence in humans developed as the result of an increase in the number of brain genes in our evolutionary ancestors: a simple invertebrate animal living in the sea 500 million years ago experienced a “genetic accident,” which resulted in extra copies of these genes being made.
The research team studied the mental abilities of mice and humans, using comparative tasks that involved identifying objects on touch-screen computers. They then combined results of these behavioral tests with information from the genetic codes of various species to work out when different behaviors evolved and discovered that higher mental functions in humans and mice were controlled by the same genes.