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.
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. This is the first time researchers have 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,” says 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.”
Paläontologen haben bislang fehlende Knochenteile des Frühmenschenjungen Karabo entdeckt. Der Fund könnte das Skelett zum vollständigsten Fossil eines unserer Vorfahren machen. Die Freilegung des Skeletts wollen die Wissenschaftler live im Internet übertragen.
Ridley Scott’s “Prometheus” Suggests DNA May Be a Constant in the Universe –Richard Dawkins and Other Scientists Agree
Mathematical analysis says that life as we know it is written into the laws of reality. The genetic code is the set of rules by which information encoded in genetic material –DNA or mRNA sequences– is translated into proteins (20 amino acid sequences) by living cells.The code defines how sequences of three nucleotides, called codons, specify which amino acid will be added next during protein synthesis. The first ten of those can create simple prebiotic life, and it seems that those ten are thermodynamically destined to occur wherever they can.
For those unfamiliar with thermodynamics, it’s the Big Brother of all energy equations and science itself. You can apply quantum mechanics at certain scales, and Newtonian mechanics work at the right speeds, but if Thermodynamics says something then everyone listens.
An energy analysis by Professors Pudritz and Higgs of McMaster University showed that the first ten amino acids are likely to form at relatively low temperatures and pressures, and the calculated odds of formation match the concentrations of these life-chemicals found in meteorite samples. They also match those in simulations of early Earth, and most critically, those simulations were performed by other people.
Schimpansen können auch harte Nüsse knacken – mit einer Baumwurzel als Amboss. Was die Tiere aber als Hammer benutzen, hängt offenbar davon ab, was ihre Gruppenmitglieder tun. Forscher sehen darin einen weiteren Beweis, dass die Menschenaffen kulturelle Eigenheiten pflegen.