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For decades the origin and evolution of life was restricted to the fossil record that recorded hard-shelled life. We now know, through determination of absolute ages by radioactive decay, that this record only record the last 500 m.y. or so of life. Prior to that, life existed as soft-bodied organisms, or even earlier, as single cell bacteria (prokaryotes) or single-celled organisms with nuclei (eukaryotes). The oldest microfossils, composed of single-celled organisms that probably were similar to cyanobacteria, are 3.5 b.y. old, and are found in Western Australia (not the same locality where the very old zircon mineral grains were found). More convincing evidence for life in the Archean comes from fossil layered microbial communities called stromatolites. Although the 3.5 b.y. old microfossils are still debated, people pretty much agree that the fossil record for life is undisputable by about 3.0 b.y., and stromatolites are part of this evidence. Fossil bacteria are universally accepted for the Proterozoic, where the images (and chemical compositions) are much more clear than the fuzzy images for the 3.5 b.y. old microfossils. The Proterozoic microfossils are much more similar to the modern cyanobacteria. The occurrence of cyanobacteria early in earth's history is critical, since their metabolic "waste product" is oxygen, and it was essential to produce high levels of oxygen in the earth's atmosphere before more complex life (which requires different means of metabolism and energy storage) could evolve. In the latest part of the Proterozoic (~ 600 m.y. ago), multi-cellular, complex life is recorded in the fossil record. The figure shown above casts the origin and evolution of life into a 24 hour clock.
Permian Extinction 250 Millions years ago, which caused extinction of 95% of all living species in both animals & plants life. This extinctions was slow and took nearly 80000 years in 3 stages: 1- Increase in world temperature by 5 degrees Centigrade casued by super lengthy eruptions of Siberian Trapes 2-melting the frozen resoviours of Methan gas in the seabeds and releasing Carbon 12 (C12), which is a green house gas and raised sea temp by anothre 5 degrees, and that casued 3-world temp raised 10 degrees and that caused the mass extinctions it took Earth millions of years to recover and after 20 millions years from then Dinosaurs first appeared.
South African scientists claim to have uncovered the most complete skeleton yet of an ancient relative of man, hidden in a rock excavated from an archaeological site three years ago. The remains of a juvenile hominid skeleton, of the newly identified Australopithecus (southern ape) sediba species, are the most complete early human ancestor skeleton ever discovered. The skeleton is thought to be about 2 million years old. The upright-walking tree climber would have been aged between nine and 13 years when he or she died. It is not certain whether the species, which had long arms, a small brain and a thumb, was a direct ancestor of humans' genus, Homo, or simply a close relative.
Broadcast in 2010, NOVA Becoming Human examines the factors that caused us to split from the other great apes. The program explores the fossil of Selam, also known as Lucy's Child. Paleoanthropologist Zeray Alemseged spent five years carefully excavating the sandstone embedded fossil. NOVA's cameras are there to capture the unveiling of the face, spine, and shoulder blades of this 3.3 million year old fossil child. And NOVA takes viewers "inside the skull" to show how our ancestors' brains had begun to change from those of the apes. Why did leaps in human evolution take place? First Steps explores a provocative big idea that swings of climate were a key factor.
Nothing is more fascinating to us than, well, us. Where did we come from? What makes us human? NOVA's groundbreaking investigation explores how new discoveries are transforming views of our earliest ancestors. Featuring interviews with world renowned scientists, footage shot in the trenches as fossils were unearthed, and stunning computer generated animation, Becoming Human brings early hominids to life, examining how they lived and how we became the creative and adaptable modern humans of today. In the first episode, NOVA encounters Selam, the amazingly complete remains of a 3 million year old child, packed with clues to why we split from the apes, came down from the trees, and started walking upright. In gripping forensic detail, the second episode investigates the riddle of Turkana Boy a tantalizing fossil of Homo erectus, the first ancestor to leave Africa and colonize the globe. What led to this first great African exodus?
In the final episode, Becoming Human explores the origins of us where modern humans and our capacities for art, invention, and survival came from, and what happened when we encountered the mysterious Neanderthals. Crucial new evidence comes from the recent decoding of the Neanderthal genome. Did modern humans interbreed with Neanderthals? Exterminate them? Becoming Human examines why we survived while our other ancestral cousins including Indonesia's 3 foot high Hobbit died out and poses the question: are we still evolving today?
What may be the oldest fragments of the modern human genome found yet have now been revealed -- DNA from the 7,000-year-old bones of two cavemen unearthed in Spain, researchers say. These findings suggest the cavemen there were not the ancestors of the people found in the region today. The skeletons of two young adult males were discovered by chance in 2006 by cave explorers in a cavern high in the Cantabrian mountain range, whose main entrance is found at 4,920 feet (1,500 meters) altitude. Winters there are notably cold, which helped preserve the DNA in the bones. These bones date back to the Mesolithic period, before agriculture spread to the Iberian Peninsula with Neolithic settlers from the Middle East. These cavemen were hunter-gatherers, judging by the ornament that one was found with of red-deer canines embroidered onto a cloth. Scientists have recently sequenced the genomes of our closest extinct relatives, the Neanderthals and the Denisovans. When it came to our lineage, the oldest modern human genomes recovered yet came from Ötzi the Iceman, a 5,300-year-old mummy found in the Alps in 1991. Researchers have salvaged DNA from even older human cells, but this comes from the mitochondria that generate energy for our bodies, and not from the nucleus where our chromosomes are housed.
The Gregorian calendar is the one commonly used today. It was proposed by Aloysius Lilius, a physician from Naples, and adopted by Pope Gregory XIII (pictured above) in accordance with instructions from the Council of Trent (1545-1563) to correct for errors in the older Julian Calendar. It was decreed by Pope Gregory XIII in a papal bull on 24 February 1582. This bull is named “Inter Gravissimas” after its first two words. In the Gregorian calendar, the tropical year is approximated as 36597/400 days = 365.2425 days. Thus it takes approximately 3300 years for the tropical year to shift one day with respect to the Gregorian calendar. The approximation 36597/400 is achieved by having 97 leap years every 400 years. The papal bull of February 1582 decreed that 10 days should be dropped from October 1582 so that 15 October should follow immediately after 4 October, and from then on the reformed calendar should be used. This was observed in Italy, Poland, Portugal, and Spain. Other Catholic countries followed shortly after, but Protestant countries were reluctant to change, and the Greek orthodox countries didn’t change until the start of the 1900s. So in effect, every country changed at a different data, from late 1500s to early 1900s, being out of sync for a long time.
Select one of the times from the list on the left and travel through time and check out what the Earth looked liked in the far distant past or what it might look like far into the future. At each stop there is more information about the particular geological time period.
Humans and Neanderthals are close cousins. So close, in fact, that some researchers argue the two hominids might actually be members of the same species. But a few years ago, anthropologists discovered a mysterious new type of hominid that shook up the family tree. Known only from a finger fragment, a molar tooth and the DNA derived from both, the Denisovans lived in Asia and were contemporaries of Neanderthals and modern humans. And they might have been Neanderthals’ closest relatives. A recent study of virus “fossils” provides new evidence of this relationship. Hidden inside each, embedded in our DNA, are the genetic remnants of viral infections that afflicted our ancestors thousands, even millions of years ago. Most known virus fossils are retroviruses, the group that includes HIV. Consisting of a single strand of RNA, a retrovirus can’t reproduce on its own. After the retrovirus invades a host cell, an enzyme reads the RNA and builds a corresponding strand of DNA. The virus-derived DNA then implants itself into the host cell’s DNA. By modifying the host’s genetic blueprints, the virus tricks the host into making new copies of the retrovirus. These virus fossils have distinct genetic patterns that scientists can identify during DNA analyses. After the Human Genome Project was finished in 2003, researchers estimated that about 8 percent of human DNA is made up of virus DNA. A team led by Jack Lenz of the Albert Einstein College of Medicine in New York used virus fossils as a way to sort out the degree of relatedness among humans, Neanderthals and Denisovans. The researchers discovered that most of the ancient viruses found in Denisovans and Neanderthals are also present in humans, implying that all three inherited the viral genetic material from a common ancestor. However, the team also found one virus fossil present in Neanderthals and Denisovans that is missing in humans. This implies Denisovans are more closely related to Neanderthals than we are. Humans must have split off from the lineage leading to Neanderthals and Denisovans; then the infection occurred, and then Neanderthals and Denisovans split from each other.
It was thriving long before the dinosaurs ruled the Earth, and scientists thought it had died out more than 65 million years ago. But in 1938, fishermen on a South African trawler netted a massive, scaly, blue-gray fish, and suddenly the long-extinct creature from the depths was back, stunning scientists and capturing headlines across the world. In "Ancient Creature of the Deep," NOVA tells the story of the coelacanth, the most famous of all "living fossils."
The coelacanth story has more improbable twists than a crime thriller. The chance discovery in 1938 was topped by a bizarre stroke of fate in 1997, thousands of miles away from the original find. A marine biologist was casually strolling through a fish market in Indonesia when he spotted a new subspecies lying on a slab in a fish market. That find triggered a renewed hunt for the elusive creature in the wild. When a submersible finally revealed the fish's underwater lair, scientists were greeted with video images of coelacanths performing a bizarre "headstand" dance in the depths.
But having survived the theorized meteor strike that killed off the dinosaurs, will this hardy creature now withstand the attention from museums, aquariums, and media, all eager to acquire a specimen of their own?
The smudged red disk below the hand stencils is the oldest cave art yet dated, at 40,800 years old. Located in El Castillo cave in the Cantabria region of northern Spain, this image might have been created by Neanderthals.
Researchers agree that our immediate ancestors, the upright walking apes, arose in Africa. But the discovery of a new primate that lived about 37 million years ago in the ancient swamplands of Myanmar bolsters the idea that the deep primate family tree that gave rise to humans is rooted in Asia. If true, the discovery suggests that the ancestors of all monkeys, apes, and humans—known as the anthropoids—arose in Asia and made the arduous journey to the island continent of Africa almost 40 million years ago. Until 18 years ago, fossils of every suspected early anthropoid were found in Egypt and dated to about 30 million years ago. Then, starting in the 1990s, researchers began discovering the remains of petite primates that lived 37 million to 45 million years ago in China, Myanmar, and other Asian nations. This suggested that anthropoids may have actually arisen in Asia and then migrated to Africa a few million years later.
Spike in carbon-14 levels indicates a massive cosmic event — but supernovae and solar flares ruled out. Just over 1,200 years ago, the planet was hit by an extremely intense burst of high-energy radiation of unknown cause, scientists studying tree-ring data have found. The radiation burst, which seems to have hit between ad 774 and ad 775, was detected by looking at the amounts of the radioactive isotope carbon-14 in tree rings that formed during the ad 775 growing season in the Northern Hemisphere. The increase in 14C levels is so clear that the scientists, led by Fusa Miyake, a cosmic-ray physicist from Nagoya University in Japan, conclude that the atmospheric level of 14C must have jumped by 1.2% over the course of no longer than a year, about 20 times more than the normal rate of variation.
Researchers have identified what they say are the oldest-known musical instruments in the world. The flutes, made from bird bone and mammoth ivory, come from a cave in southern Germany which contains early evidence for the occupation of Europe by modern humans - Homo sapiens. Scientists used carbon dating to show that the flutes were between 42,000 and 43,000 years old.
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Browse the timeline of war and conflict across the globe. This database of global wars and conflicts is searchable through space and time. You can drag and click both the map and timeline to locate particular battles and wars, and then read more information about that conflict. This resource would be a great one to show students and let them explore to find what they see as interesting. This site is brimming with potential.
Via Seth Dixon, Martin Daumiller, Sakis Koukouvis
Sea levels may rise much higher than previously thought, according to scientists from The Australian National University, who have used fossil corals to understand how warmer temperatures in the past promoted dramatic melting of polar ice sheets. Dr. Andrea Dutton, formerly of the Research School of Earth Sciences (RSES) in the ANU College of Physical and Mathematical Sciences, teamed up with Professor Kurt Lambeck of the RSES to analyse fossil corals around the world from the last interglacial period, 125,000 years ago. They built an extensive database by compiling age and elevation data of fossil corals that live near the sea surface, and used a model to factor in the physics of how changing masses of ice sheets would affect regional sea level at the various fossil coral sites. They concluded that sea level during the last interglacial period peaked at 5.5 to 9 metres above present sea level.
North and South America were first populated by three waves of migrants from Siberia rather than just a single migration, say researchers who have studied the whole genomes of Native Americans in South America and Canada. Some scientists assert that the Americas were peopled in one large migration from Siberia that happened about 15,000 years ago, but the new genetic research shows that this central episode was followed by at least two smaller migrations from Siberia, one by people who became the ancestors of today’s Eskimos and Aleutians and another by people speaking Na-Dene, whose descendants are confined to North America.
Pottery fragments found in a south China cave have been confirmed to be 20,000 years old, making them the oldest known pottery in the world, archaeologists say. The findings add to recent efforts that have dated pottery piles in east Asia to more than 15,000 years ago, refuting conventional theories that the invention of pottery correlates to the period about 10,000 years ago when humans moved from being hunter-gathers to farmers. The research by a team of Chinese and American scientists also pushes the emergence of pottery back to the last ice age, which might provide new explanations for the creation of pottery,
Map of Europe: 1000 AD to present day....watch the march of history in just a few minutes.
Via Daniel House
An unexpectedly warm period about 15 million years ago temporarily thawed Antarctica, turning the continent green around its edges, a new study says. Antarctica developed its ice sheets about 34 million years ago. But during the more recent warm period, the interior landscape would've resembled tundra found in parts of modern-day Chile and New Zealand, and the coasts would've been lined with beeches and a type of conifer. The surprising evidence comes from "abundant" remains of leaf waxes in sediment cores taken from deep beneath Antarctica's Ross Ice Shelf, said study leader Sarah Feakins, a biogeochemist at the University of Southern California. The sediments had blown off Antarctic soils into the ocean during the Miocene, a mild period in Earth's history between about 15 and 20 million years ago. The Arctic even went through ice-free periods of extreme warmth over the past 2.8 million years, based on a new analysis of deep sediment in Russia. The team led by Martin Melles of the University of Cologne, Germany, drilled into an iced-over lake formed by a meteorite impact on the Chukchi Peninsula in Siberia for the longest sediment core ever collected in the terrestrial Arctic. Since the meteorite struck an area of Lake El'gygytgyn that was not eroded by glaciers, the sediment record reaches back nearly 30 times further in time than ice cores from Greenland that cover the past 110,000 years. The sediment reveals periods of extreme warmth that show the polar regions are much more vulnerable to change than previously thought, and are difficult to explain by greenhouse gases alone, according to the study in the journal Science. Read also: http://www.abc.net.au/science/articles/2012/06/22/3531167.htm
Join a small group of ancient Europeans as they teeter on the brink of annihilation, struggling with the most extreme living conditions anyone has ever faced, from encroaching sheets of ice that swallowed every bit of fertile land to a climate that was, on average, 70 degrees colder than it is today. For these humans, survival meant more than simply keeping warm; it meant abandoning their hunting and gathering lifestyle and finding a whole new way of living - a way of living that endures to this day. Go back in time 24,000 years to the last Ice Age and watch in awe as Ice World brings this amazing stuggle to life. Through computer graphics and reconstructions, you'll see how the earth's climate shifted over time, eventually covering much of North America and Europe with two-mile-thick ice sheets.
The Tasmanian tiger, also known as the thylacine, was hunted to extinction in the early 1900s; the last one died in a Tasmanian zoo in 1936. Even if humans hadn't hunted the Tasmanian tiger to extinction, its low genetic diversity may have naturally doomed the curious marsupial, researchers have found.
Biological and Geologic Timeline of the Earth. The origin of the Earth and the Moon. The evolution of life on Earth.
An 18-member international team of researchers that includes James Kennett, professor of earth science at UC Santa Barbara, has discovered melt-glass material in a thin layer of sedimentary rock in Pennsylvania, South Carolina, and Syria. According to the researchers, the material -- which dates back nearly 13,000 years -- was formed at temperatures of 1,700 to 2,200 degrees Celsius (3,100 to 3,600 degrees Fahrenheit), and is the result of a cosmic body impacting Earth. These new data are the latest to strongly support the controversial Younger Dryas Boundary (YDB) hypothesis, which proposes that a cosmic impact occurred 12,900 years ago at the onset of an unusual cold climatic period called the Younger Dryas. This episode occurred at or close to the time of major extinction of the North American megafauna, including mammoths and giant ground sloths; and the disappearance of the prehistoric and widely distributed Clovis culture.
Giant insects ruled the prehistoric skies during periods when Earth's atmosphere was rich in oxygen. Then came the birds. After the evolution of birds about 150 million years ago, insects got smaller despite rising oxygen levels.
It took some 10 million years for Earth to recover from the greatest mass extinction of all time, latest research has revealed. Life was nearly wiped out 250 million years ago, with only 10 per cent of plants and animals surviving. It is currently much debated how life recovered from this cataclysm, whether quickly or slowly. There were apparently two reasons for the delay, the sheer intensity of the crisis, and continuing grim conditions on Earth after the first wave of extinction. The end-Permian crisis, by far the most dramatic biological crisis to affect life on Earth, was triggered by a number of physical environmental shocks -- global warming, acid rain, ocean acidification and ocean anoxia. These were enough to kill off 90 per cent of living things on land and in the sea.
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