Results 1 to 13 of 13

Thread: What We Learned About Human Evolution in 2012

  1. #1
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Lightbulb What We Learned About Human Evolution in 2012

    Charles Choi, LiveScience Contributor
    Date: 27 December 2012 Time: 10:03 AM ET



    Mysterious fossils of what may be a previously unknown human species were uncovered in caves in China. The hominins lived some time between 11,500 and 14,500 years ago, meaning they would have shared the landscape with modern humans when China's earliest farmer were first appearing. Discovered at what is called Red Deer Cave in southwest China, the hominins have been dubbed the Red Deer Cave People. A skull of the possibly new hominin, shown here.

    The controversial extinct human lineage known as "hobbits" gained a face this year, one of many projects that shed light in 2012 on the history of modern humans and their relatives. Other discoveries include the earliest known controlled use of fire and the possibility that Neanderthals or other extinct human lineages once sailed to the Mediterranean.


    Here's a look at what we learned about ourselves through our ancestors this year.


    We're not alone

    A trove of discoveries this year revealed a host of other extinct relatives of modern humans. For instance, researchers unearthed 3.4-million-year-old fossils of a hitherto unknown species that lived about the same time and place as Australopithecus afarensis, a leading candidate for the ancestor of the human lineage. In addition, fossils between 1.78 million and 1.95 million years old discovered in 2007 and 2009 in northern Kenya suggest that at least two extinct human species lived alongside Homo *****us, a direct ancestor of our species. Moreover, fossils only between 11,500 and 14,500 years old hint that a previously unknown type of human called the "Red Deer Cave People" once lived in China.

  2. #2
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    Bones were not all that scientists revealed about modern humans' extinct relatives in 2012. For instance, scientists finally put a face on the hobbit, a nickname for a controversial human lineage. Anthropologist Susan Hayes at the University of Wollongong in Australia reconstructed the appearance of the 3-foot (1-meter) tall, 30-year-old female member of the extinct humans officially known as Homo floresiensis, which were first discovered on the remote Indonesian island of Flores in 2003.


    The specimen, along with fossils of various animals, was unearthed in the Liang Bua cave on the island.


    Hobbit Skull
    Credit: Professor Peter Brown, University of New England
    To look into microencephaly, a team of scientists led by Dean Falk, a paleoneurologist at Florida State University, compared computer-generated three-dimensional reconstructions, called "endocasts," of brains from nine microcephalic modern humans with those of 10 normal modern-human brains. They found two ratios created using different skull measurements could accurately distinguish the normal humans (skull, right) from the microcephalics. When Falk's team applied this classification system to a virtual endocast the Hobbit's skull (left), they found its features more closely resembled that of a normal human than a microcephalic.



    In the Wrist

    Credit: Courtesy of William Jungers, Stony Brook University

    In 2007, work by Matthew Tocheri, an anthropologist at the National Museum of Natural History in Washington, D.C., and colleagues found the female Hobbit's wrist bones matched, in shape and orientation, those of non-human apes; they looked much different from the wrist bones of Neanderthals (Homo neanderthalensis) and modern humans, also pointing to a new species.

    Long Feet

    Credit: W. Jungers

    A detailed analysis of the feet of Homo floresiensis reveals the small-statured hominids, though bipedal, had feet that were so primitive their gait was not efficient; essentially, they couldn't hustle, suggests the 2009 study.


    Jawbone Added to 'Hobbit' Evidence

    Professor Chris Stringer, Head of Human Origins at London's Natural History Museum, holds a cast taken from a skull that is said to be that of a new species in the evolution of man named 'Homo Floresiensis', during a news conference in London, Wednesday Oct. 27, 2004.



    Eaten by Storks?

    Credit: Inge van Noortwijk.

    In the Liang Bua cave where the Hobbit remains were found, scientists also discovered a large number of bird fossils, including 20,000- to 50,000-year-old wing and leg bones from what appears to have been a stork that stood nearly 6 feet (1.8 meters) tall. The researchers speculated the extinct predatory stork may have fed on fishes, lizards and birds, and possibly in principle even small, juvenile hobbits, though they note no evidence for such hominid-munching.



    Hunting Pygmy Elephants

    Credit: National Geographic Society/ Peter Schouten

    Her stature combined with evidence from other fossils found at the site paint a picture of a diminutive bipedal individual who used stone tools and fire while hunting the island's pygmy elephants, Komodo dragons and giant rats.


    Revealing a Face

    Credit: University of Wollongong

    In more recent research, anthropologist Susan Hayes, a senior research fellow at University of Wollongong, New South Wales, fleshed out the face of the female Hobbit. To do so, Hayes uploaded information from 3D imaging scans of the skull into a computer graphic program and also looked at portraits by paleo-artists of the Hobbit, finding these earlier interpretations were skewed toward monkey features; her examination, meanwhile, suggested modern features were more accurate.


    Facial Features

    Credit: University of Wollongong

    "She's not what you'd call pretty, but she is definitely distinctive," Hayes said. The female doesn't have feminine-looking big eyes and she's lacking much of a forehead.
    Last edited by Ankhi_sena_mun; 28-12-2012 at 11:18 AM.

  3. #3
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    DNA extracted from a recently discovered extinct human lineage known as the Denisovans — close relatives of Neanderthals — also revealed new details about this group, which once interbred with modern humans. The Denisovan genome that was sequenced belonged to a little girl with dark skin, brown hair and brown eyes, and displayed about 100,000 recent changes in our genome that occurred after the split from the Denisovans. A number of these changes influenced genes linked with brain function and nervous system development, leading to speculation that we may think differently from the Denisovans.


    Scientists have just completed sequencing the entire genome of a species of archaic humans called Denisovans. The fossils, which consist of a finger bone and two molars, from this extinct lineage were discovered in Denisova Cave in southern Siberia in 2008. Scientists don't know the precise age of the material found, though they estimate it ranges anywhere from 30,000 to 80,000 years of age. Shown here, a distal molar of a Denisovan.
    CREDIT: Max Planck Institute for Evolutionary Anthropology

    The genome of a recently discovered branch of extinct humans known as the Denisovans that once interbred with us has been sequenced, scientists said today (Aug. 30).
    Genetic analysis of the fossil revealed it apparently belonged to a little girl with dark skin, brown hair and brown eyes, researchers said. All in all, the scientists discovered about 100,000 recent changes in our genome that occurred after the split from the Denisovans. A number of these changes influence genes linked with brain function and nervous system development, leading to speculation that we may think differently from the Denisovans. Other changes are linked with the skin, eyes and teeth.
    "This research will help [in] determining how it was that modern human populations came to expand dramatically in size as well as cultural complexity, while archaic humans eventually dwindled in numbers and became physically extinct," said researcher Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

    Future research may turn up other groups of extinct humans in Asia "in addition to Neanderthals and Denisovans," Pääbo told LiveScience.
    Although our species comprises the only humans left alive, our planet was once home to a variety of other human species. The Neanderthals were apparently our closest relatives, and the last of the other human lineages to vanish. [10 Mysteries of the First Humans]
    However, scientists recently revealed another group of extinct humans once lived at the same time as ours. DNA from fossils unearthed in Denisova Cave in southern Siberia in 2008 revealed a lineage unlike us and closely related to Neanderthals. The precise age of the Denisovan material remains uncertain — anywhere from 30,000 to 80,000 years of age.
    "The Denisovan genome is particularly close to my heart, because it was the first time that a new group of extinct humans was discovered and defined just from DNA sequence evidence and not from the morphology of bones," Pääbo said.
    Denisovan genes unzipped
    Now, based on only a tiny sample of genetic material from a finger bone, scientists have sequenced the complete genome of the Denisovans (pronounced deh-NEESE-so-vans), as they are now called.

    The genetic analysis of the fossil finger (a replica shown here with a U.S. penny) revealed it apparently belonged to a little girl with dark skin, brown hair and brown eyes, researchers noted.
    CREDIT: Max Planck Institute for Evolutionary Anthropology
    View full size image



    To make the most of what little genetic material they had, the researchers developed a technique that unzipped the double strands of DNA in the bone, doubling the amount of DNA they could analyze. This enabled them to sequence each position in the genome about 30 times over, generating an extremely thorough genome sequence. [See Photos of Denisovan Fossils]
    "We have very few errors in the sequences, even less errors than we often have when you sequence a person today," Pääbo said. "With just a few technical reservations, there is actually today then no difference in what we can learn genetically about a person that lived 50,000 years ago and from a person today, provided that we have well-enough preserved bones."
    Comparing the Denisovan genome with ours confirmed past research suggesting the extinct lineage once interbred with ours and lived in a vast range from Siberia to Southeast Asia. The Denisovans share more genes with people from Papua New Guinea than any other modern population studied.
    In addition, more Denisovan genetic variants were found in Asia and South America than in European populations. However, this likely reflects interbreeding between modern humans and the Denisovans' close relatives, the Neanderthals, rather than direct interbreeding with the Denisovans, researchers said.
    Denisovans began to diverge from modern humans in terms of DNA sequences about 800,000 years ago. Among the genetic differences between Denisovans and modern humans are likely changes that "are essential for what made modern human history possible, the very rapid development of human technology and culture that allowed our species to become so numerous, spread around the whole world, and actually dominate large parts of the biosphere," Pääbo said.
    Eight of these genetic changes have to do with brain function and brain development, "theconnectivity in the brain of synapses between nerve cells function, and some of them have to do with genes that, for example, can cause autism when these genes are mutated," Pääbo added.
    What makes humans special?
    It makes a lot of sense to speculate that what makes us special in the world relative to the Denisovans and Neanderthals "is about connectivity in the brain," Pääbo said. "Neanderthals had just as large brains as modern humans had — relative to body size, they even had a bit larger brains. Yet there is, of course, something special in my mind that happens with modern humans. It's sort of this extremely rapid technological cultural development that comes, large societal systems, and so on. So it makes sense that, well, what pops up is sort of connectivity in the brain."

    Another view of the excavation of Denisova Cave.
    CREDIT: Max Planck Institute for Evolutionary Anthropology
    View full size image



    The fact that differences are seen between modern humans and Denisovans in terms of autism-linked genes is especially interesting, because whole books have been written "suggesting that autism may affect sort of a trait in human cognition that is also crucial for modern humans, for how we put ourselves in the shoes of others, manipulate others, lie, develop politics and big societies and so on," Pääbo said.
    The genetic diversity suggested by this Denisovan sample was apparently quite low. This was probably not due to inbreeding, the researchers say — rather, their vast range suggests their population was initially quite small but grew quickly, without time for genetic diversity to increase as well.
    "If future research of the Neanderthal genome shows that their population size changed over time in similar ways, it may well be that a single population expanding out of Africa gave rise to both the Denisovans and the Neanderthals," Pääbo said.
    Intriguingly, comparing the X chromosome, which is passed down by females, to the rest of the genome, which is passed down equally in males and females, revealed "there is substantially less Denisovan genetic material in New Guinea on the X chromosome than there is on the rest of the genome,"researcher David Reich at Harvard Medical School in Boston told LiveScience.

  4. #4
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    One possible explanation "is that the Denisovan gene flow into modern humans was mediated primarily by male Denisovans mixing with female modern humans," Reich said. "Another possible explanation is that actually there was natural selection to remove genetic material on the X chromosome that came from Denisovans once that entered the modern human population, perhaps because it caused problems for the people who carried it."
    These current Denisovan findings have allowed the researchers to re-evaluate past analysis of the Neanderthal genome. They discovered modern humans in the eastern parts of Eurasia and Native Americans actually carry more Neanderthal genetic material than people in Europe, "even though the Neanderthals mostly lived in Europe, which is really, really interesting," Reich said.
    The researchers would now like to upgrade the Neanderthal genome to the quality seen with the Denisovan genome. The genetic techniques they used could also be employed in forensic investigations, and in analyzing other fossil DNA, said researcher Matthias Meyer, also at the Max Planck Institute for Evolutionary Anthropology.
    The scientists detailed their findings online today in the journal Science.


  5. #5
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    The Real Question: Who Didn't Have Sex with Neanderthals?

    Charles Choi, LiveScience Contributor
    Date: 01 November 2012 Time: 08:55 AM ET


    Modern North Africans carry genetic traces from Neanderthals, suggesting their ancestors, too, interbred with humanity's closest known extinct relatives, report scientists online Oct. 17, 2012, in the journal PLoS One.
    CREDIT: NASA/JPL-Caltech

    The only modern humans whose ancestors did not interbreed with Neanderthals are apparently sub-Saharan Africans, researchers say.
    New findings suggest modern North Africans carry genetic traces from Neanderthals, modern humanity's closest known extinct relatives.
    Although modern humans are the only surviving members of the human lineage, others once roamed the Earth, including theNeanderthals. Genetic analysis of these extinct lineages’ fossils has revealed they once interbred with our ancestors, with recent estimates suggesting that Neanderthal DNA made up 1 percent to 4 percent of modern Eurasian genomes. Although this sex apparently only rarely produced offspring, this mixing was enough to endow some people with the robust immune systemsthey enjoy today.

    The Neanderthal genome revealed that people outside Africa share more genetic mutations with Neanderthalsthan Africans do. One possible explanation is that modern humans interbred with Neanderthals mostly after the modern lineage began appearing outside Africa at least 100,000 years ago. Another, more complex scenario is that an African group ancestral to both Neanderthals and certain modern human populations genetically split from other Africans beginning about 230,000 years ago. This group then stayed genetically distinct until it eventually left Africa.
    To shed light on why Neanderthals appear most closely related to people outside Africa, scientists analyzed North Africans. Some researchers had suggested these groups were the sources of the out-of-Africa migrations that ultimately spread humans around the globe.
    The researchers focused on 780,000 genetic variants in 125 people representing seven different North African locations. They found North Africans had dramatically more genetic variants linked with Neanderthals than sub-Saharan Africans did. The level of genetic variants that North Africans share with Neanderthals is on par with that seen in modern Eurasians.
    The scientists also found this Neanderthal genetic signal was higher in North African populations whose ancestors had relatively little recent interbreeding with modern Near Eastern or European peoples. That suggests the signal came directly from ancient mixing with Neanderthals, and not recent interbreeding with other modern humans whose ancestors might have interbred with Neanderthals. [10 Mysteries of the First Humans]
    "The only modern populations without Neanderthal admixture are the sub-Saharan groups," said researcher Carles Lalueza-Fox, a paleogeneticist at the Institute of Evolutionary Biology at Barcelona, Spain.
    The researchers say their findings do not suggest that Neanderthals entered Africa and made intimate contact with ancient North Africans. Rather, "what we are saying is that the contact took place outside Africa, likely in the Near East, and that there was a back migration into Africa of some groups that peopled North Africa, likely replacing or assimilating some ancestral populations," Lalueza-Fox told LiveScience.
    This research also suggests that North African groups were not the source of the out-of-Africa migrations. Rather, other groups, perhaps out of East Africa, might have led this diaspora.
    The scientists detailed their findings Oct. 17 in the journal PLoS ONE.

  6. #6
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    Ancient artifacts revealed this year also have shown how tool use has helped humanity reshape the world — and perhaps inadvertently reshape humanity as well.


    Micrograph of burned bone on a paleosurface at Wonderwerk Cave in South Africa.
    CREDIT: Image courtesy of P. Goldberg.



    For instance, ash and charred bone, the earliest known evidence of controlled use of fire, reveal that human ancestors may have used fire 1 million years ago, 300,000 years earlier than thought, suggesting that human ancestors as early as Homo *****us may have begun using fire as part of their way of life. Controlled fires and cooked meat may have influenced human brain evolution, allowing our ancestors to evolve to have larger, more calorie-hungry brains and bodies.

    The stone used to produce these blades, known as silcrete — quartz grains cemented by silica — was carefully treated with heat to make it easier to shape.
    CREDIT: Simen Oestmo

    Discoveries involving ancient weapons also revealed that humans learned to make and use these tools far earlier than scientists thought. For instance, what may be ancient stone arrowheads or lethal tools for hurling spearssuggest humans innovated relatively advanced weapons about 70,000 years ago, while a University of Toronto-led team of anthropologists found evidence that humans in South Africa used stone-tipped weapons for hunting 500,000 years ago, which is 200,000 years earlier than previously suggested.


    Drawings of reconstructed sieve vessels and photographs of sieve fragments from the region of Kuyavia, Poland, that were analyzed for milk residues.
    CREDIT: M. Salque et al, Nature.



    Even the seemingly innocuous discovery this year of the first direct signs of cheesemakingfrom 7,500-year-old potsherds from Poland might help reveal how animal milk dramatically shaped the genetics of Europe. Most of the world, including the ancestors of modern Europeans, is lactose intolerant, unable to digest the milk sugar lactose as adults. However, while cheese is a dairy product, it is relatively low in lactose. Transforming milk into a product such as cheese that is friendlier to lactose-intolerant people might have helped promote the development of dairying among the first farmers of Europe. The presence of dairying over many generations may then, in turn, have set the stage for the evolution of lactase tolerance in Europe. As such, while cheese might just seem to be a topping on pizza or a companion to wine, it might have changed Western digestive capabilities.

    The teeth of what may be humanity's immediate ancestor, Australopithecus sediba (skull from a male juvenile shown here), revealed the species likely lived off a woodland diet rather than the grasses of an open savanna.
    CREDIT: Lee Berger

    Other clues regarding the diet of ancient relatives also emerged. For example, 2-million-year-old fossils suggest humans' immediate ancestor may have lived off a woodland diet of leaves, fruits and bark, instead of a menu based on the open savanna, as other extinct relatives of humanity did.
    A fragment of a child's skull discovered at Olduvai Gorge, Tanzania, shows the oldest known evidence of anemia caused by a nutritional deficiency.
    CREDIT: Dominguez-Rodrigo M. et al., PLoS ONE 7(10): e46414. doi:10.1371/journal.pone.0046414
    In addition, fragments of a 1.5-million-year-old skull from a child recently found in Tanzania suggest that later members of the human lineage weren't just occasional carnivores but regular meat eaters, findings that help build the case that meat-eating helped the human lineage evolve large brains.

  7. #7
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    Humans still evolving



    When it comes to the future of humanity, research this year added to accumulating evidence that natural forces of evolution continue to shape humanity. Church records of nearly 6,000 Finns born between 1760 and 1849 showed that despite humans radically altering their environments with behavior such as farming, human patterns of survival and reproduction were comparable with those of other species.


    One researcher at Stanford University has even suggested that humans are getting dumber over time, having lost the evolutionary pressure to be smart once we started living in densely populated settlements several millennia ago. However, other scientists dispute this notion, pointing at geniuses such as Stephen Hawking, and suggest that rather than losing our intelligence, people have diversified, resulting in a number of different types of smarts today.

  8. #8
    SB Wizard Captain himansh's Avatar
    Join Date
    Jun 2008
    Location
    delhi
    Posts
    2,893
    Rep Power
    49

    Default

    evolution me phd nahi karni hame :P

  9. #9
    Rainbow chaser Brigadier General 007RIKY's Avatar
    Join Date
    Dec 2011
    Location
    Looking for one
    Posts
    22,697
    Rep Power
    46

    Default

    Whats in the nutshell................
    Samasya ke middle finger pe
    Samadhan ki angoothi - Babaji ki booti

  10. #10
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    Quote Originally Posted by 007RIKY View Post
    Whats in the nutshell................
    heading parh lo our pics dekh lo......

  11. #11
    Rainbow chaser Brigadier General 007RIKY's Avatar
    Join Date
    Dec 2011
    Location
    Looking for one
    Posts
    22,697
    Rep Power
    46

    Default

    Quote Originally Posted by Ankhi_sena_mun View Post
    heading parh lo our pics dekh lo......
    Lekin usse kuch clear nahi hota
    Samasya ke middle finger pe
    Samadhan ki angoothi - Babaji ki booti

  12. #12
    Hum Banarasi.......... Colonel Ankhi_sena_mun's Avatar
    Join Date
    Aug 2009
    Location
    Dheer sameere, Tatini Teere....
    Posts
    13,813
    Rep Power
    57

    Default

    Quote Originally Posted by 007RIKY View Post
    Lekin usse kuch clear nahi hota
    tab kasht karke poora parho.... ye ek article nehi 10 articles ki summary hai......

  13. #13
    Rainbow chaser Brigadier General 007RIKY's Avatar
    Join Date
    Dec 2011
    Location
    Looking for one
    Posts
    22,697
    Rep Power
    46

    Default

    Quote Originally Posted by Ankhi_sena_mun View Post
    tab kasht karke poora parho.... ye ek article nehi 10 articles ki summary hai......
    Us summary ki bhi summary likh dijiye aasani hoge hum band buddhi walon ko
    Samasya ke middle finger pe
    Samadhan ki angoothi - Babaji ki booti

Similar Threads

  1. Replies: 5
    Last Post: 04-09-2012, 12:08 AM
  2. 6 Lies About the Human Body You Learned in Kindergarten
    By bushra0712 in forum General Discussion
    Replies: 13
    Last Post: 21-07-2011, 03:36 PM
  3. What Is Human Evolution?
    By amitsush in forum General Discussion
    Replies: 169
    Last Post: 01-03-2011, 12:04 AM
  4. ::::~~::Where Is Human Evolution Heading ? ::~~ ::::
    By Rocky-10 in forum General Discussion
    Replies: 6
    Last Post: 10-08-2008, 06:03 PM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •