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.
Humans can evolve even when monogamy limits their potential to produce children, according to research published today (April 30) in Proceedings of the National Academy of Sciences. Using church records of the marriages, births, and deaths of nearly 6,000 people living in Finland in the 18th and 19th centuries, an international team of researchers showed that the population’s reproductive fitness varied enough for natural selection to act.
“This is a good confirming instance, with solid evidence” that humans still have the potential to evolve in modern times, said Stephen Stearns, an evolutionary biologist at Yale University, whose own work has suggested the potential for continuing human evolution beyond prehistoric times. Stearns, who did not participate in the current study, explained that the extremely strong data set, in which researchers could track each individual from birth through death, helped bolster the argument for evolution.
A sonic boom heard in California last week had an out-of-this world origin as ”a large meteoric event” according to NASA’s Meteoroid Environment Office. Scientists now estimate the blast measured in near 5 kilotons or roughly 1/3 the power of the atomic bomb dropped on Hiroshima, Japan during World War II.Bill Cooke of the Meteoroid Environment Office at NASA’s Marshall Space Flight Center, estimates the object was about the size of a minivan, weighed in at around 154,300 pounds.
“Most meteors you see in the night’s sky are the size of tiny stones or even grains of sand and their trail lasts all of a second or two,” said Don Yeomans of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “Fireballs you can see relatively easily in the daytime and are many times that size – anywhere from a baseball-sized object to something as big as a minivan.”
The meteor appears to be much more valuable than scientists first thought. Meteorite hunters found fragments of the rock, identified by the “fusion crust” that forms when it burns in the atmosphere. NASA and the SETI Institute in Mountain View, California, also mobilised a search team of about 30 scientists to search for the small black rocks.
Creating some of life’s building blocks in space may be a bit like making a sandwich – you can make them cold or hot, according to new NASA research. This evidence that there is more than one way to make crucial components of life increases the likelihood that life emerged elsewhere in the Universe, according to the research team, and gives support to the theory that a “kit” of ready-made parts created in space and delivered to Earth by impacts from meteorites and comets assisted the origin of life.
In the invisible, parallel world of Earth’s they kill half the bacteria in the ocean every day, and invade a microbe host 10 trillion times a second around the world. There are 10 billion trillion, trillion viruses inhabiting Planet Earth, which is more stars than are in the Universe — stacked end to end, they would reach out 100 million light years.
Over tens, hundreds and millions years, our ancestors have been picking up retroviruses (HIV is a retrovirus) that reproduce by taking their genetic material and inserting it into our own chromosomes. There are probably about 100,000 elements in the human genome that you can trace to a virus ancestor. They make up about 8 percent of our genome, and genes that encode proteins only make up 1.2 percent of our genome making us more virus than human.
Occasionally, a retrovirus will end up in a sperm cell or an egg and insert its genes there, which then may give rise to a new organism, a new animal, a new person where every cell in that body has got that virus.