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Atlas of the Human Journey - The Genographic Project

Atlas of the Human Journey - The Genographic Project
When humans first ventured out of Africa some 60,000 years ago, they left genetic footprints still visible today. By mapping the appearance and frequency of genetic markers in modern peoples, we create a picture of when and where ancient humans moved around the world. These great migrations eventually led the descendants of a small group of Africans to occupy even the farthest reaches of the Earth. Our species is an African one: Africa is where we first evolved, and where we have spent the majority of our time on Earth. According to the genetic and paleontological record, we only started to leave Africa between 60,000 and 70,000 years ago. Once the climate started to improve, after 70,000 years ago, we came back from this near-extinction event. Slightly later, a little after 50,000 years ago, a second group appears to have set out on an inland trek, leaving behind the certainties of life in the tropics to head out into the Middle East and southern Central Asia. Related:  lawryieTimelineHumanitat

Bacteria make major evolutionary shift in the lab - life - 09 June 2008 A major evolutionary innovation has unfurled right in front of researchers' eyes. It's the first time evolution has been caught in the act of making such a rare and complex new trait. And because the species in question is a bacterium, scientists have been able to replay history to show how this evolutionary novelty grew from the accumulation of unpredictable, chance events. Twenty years ago, evolutionary biologist Richard Lenski of Michigan State University in East Lansing, US, took a single Escherichia coli bacterium and used its descendants to found 12 laboratory populations. The 12 have been growing ever since, gradually accumulating mutations and evolving for more than 44,000 generations, while Lenski watches what happens. Profound change Mostly, the patterns Lenski saw were similar in each separate population. Indeed, the inability to use citrate is one of the traits by which bacteriologists distinguish E. coli from other species. Rare mutation? Evidence of evolution Promoted Stories

Permis gratuit - conduire, boire, se marier... Earth - Your life on earth Explore BBC Earth's unique interactive, personalised just to you. Find out how, since the date of your birth, your life has progressed; including how many times your heart has beaten, and how far you have travelled through space. Investigate how the world around you has changed since you've been alive; from the amount the sea has risen, and the tectonic plates have moved, to the number of earthquakes and volcanoes that have erupted. Grasp the impact we've had on the planet in your lifetime; from how much fuel and food we've used to the species we've discovered and endangered. And see how the BBC was there with you, capturing some of the most amazing wonders of the natural world. Explore, enjoy, and share with your friends either the whole page, or your favourite insights. This is your story, the story of your life on earth. BBC Earth's Your life on earth is based on the following sources. Lead photo credit: John Kellerman / Alamy.

La genètica de les migracions humanes - Revista Mètode L’estudi d’aquestes variants genètiques del nostre genoma ha demostrat que les poblacions africanes actuals presenten més variants i, per tant, més diversitat genètica que la resta de poblacions humanes. A més, gran part de la diversitat en poblacions no africanes és un subconjunt de les variants que trobem al continent africà. Aquests resultats abonen l’anomenada teoria de la sortida d’Àfrica (Out-of-Africa), protagonitzada pels humans, que representa la primera gran migració. Un dels grans reptes que encara afrontem des de la genètica de poblacions humanes és esbrinar quins processos demogràfics van patir les poblacions africanes des del seu origen fins a aquesta primera sortida d’Àfrica. D’altra banda, la menor diversitat genètica en poblacions fora d’Àfrica s’explica com a resultat d’un efecte fundador: un petit grup portador d’un subconjunt de variants africanes va sortir del continent i va ocupar la resta de territoris del planeta (figura 1).

How did life originate? How did life originate? Living things (even ancient organisms like bacteria) are enormously complex. However, all this complexity did not leap fully-formed from the primordial soup. Instead life almost certainly originated in a series of small steps, each building upon the complexity that evolved previously: Simple organic molecules were formed. Simple organic molecules, similar to the nucleotide shown below, are the building blocks of life and must have been involved in its origin. Multicellularity evolved.

Looking Back: NASA's "Mono Lake Discovery" --What Did They Really Find? (A 2011 Most Popular) Dec. 2, 2010: NASA-supported researchers announced that they had discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. The microorganism, which lives in 740,000 year old California's Mono Lake, substitutes arsenic for phosphorus in the backbone of its DNA and other cellular components. "The definition of life has just expanded," said Ed Weiler, NASA's associate administrator for the Science Mission Directorate at the agency's Headquarters in Washington. This finding of an alternative biochemistry makeup will alter biology textbooks and expand the scope of the search for life beyond Earth, NASA suggested. "Biological dependence on the six major nutrient elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus is complemented by a selected array of other elements, usually metal(loid)s present in trace quantities that serve critical cellular functions, such as enzyme co-factors.

Welcome to Adopt-A-Native-Elder The Origin of Humans Is Surprisingly Complicated HUMAN FAMILY TREE used to be a scraggly thing. With relatively few fossils to work from, scientists' best guess was that they could all be assigned to just two lineages, one of which went extinct and the other of which ultimately gave rise to us. Discoveries made over the past few decades have revealed a far more luxuriant tree, however—one abounding with branches and twigs that eventually petered out. This newfound diversity paints a much more interesting picture of our origins but makes sorting our ancestors from the evolutionary dead ends all the more challenging, as paleoanthropologist Bernard Wood explains in the pages that follow. More on this topic: The Latest Fossil Finds Make the Puzzle of Human Evolution Harder Than Ever to Solve New Evidence Shows How Human Evolution Was Shaped by Climate New Twist Added to the Role of Culture in Human Evolution

The Origin of Us Who are we? Where did we come from? Why are we here? The age-old question of our origin has been baffling mankind for centuries. For most of our history, it was widely accepted that man had been created by an omnipresent, omnipotent, God or Gods. One of the most hotly debated issues in paleoanthropology (the study of human origins) focuses on the origins of modern humans, Homo sapiens.9,10,3,6,13,15,14 Roughly 100,000 years ago, the Old World was occupied by a morphologically diverse group of hominids. Understanding the issue Multiregional theory: homo erectus left Africa 2 mya to become homo sapiens in different parts of the world. To understand this controversy, the anatomical, archaeological, and genetic evidence needs to be evaluated. Anatomical evidence Sometime prior to 1 million years ago early hominids, sometimes referred to as Homo ergaster, exited Africa and dispersed into other parts of the Old World.

Twist in the tail of eukaryotic origins - life - 19 December 2011 Complex life may have had parasitic origins. New evidence suggests that the relatives of the mitochondria within our cells once had a tail, like many parasitic bacteria. Life on Earth is packaged into three domains: the simple bacteria, the archaea, and the complex eukaryotes that make up most of the life we see with the naked eye. The first eukaryotes appeared around 2 billion years ago. Different picture Nathan Lo at the University of Sydney in Australia and Claudio Bandi at the University of Milan, Italy, and colleagues think it is time to view this serendipitous encounter in a different light. That suggests that the bacteria might once have been mobile, like many parasitic bacteria. The team focused on Midichloria mitochondrii, a relatively little-known member of the Rickettsiales. Open relationships Bacteria take an open approach to sharing genetic information, so it's possible that Midichloria picked up the genes from a distant relative that does carry a flagellum. Promoted Stories

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