The Oldest Homo Sapiens: Fossils Push Human Emergence Back To 195,000 Years Ago

 

Date:

February 28, 2005

Source:

University Of Utah

Summary:

When the bones of two early humans were found in 1967 near Kibish, Ethiopia, they were thought to be 130,000 years old. A few years ago, researchers found 154,000- to 160,000-year-old human bones at Herto, Ethiopia. Now, a new study of the 1967 fossil site indicates the earliest known members of our species, Homo sapiens, roamed Africa about 195,000 years ago.

 

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The bones of an early member of our species, Homo sapiens, known as Omo I, excavated from Ethiopia's Kibish rock formation. The bones are kept in the National Museum of Ethiopia. When the first bones from Omo I were found in 1967, they were thought to be 130,000 years old. Later, 160,000-year-old bones of our species were found elsewhere. Now, a new study by scientists from the University of Utah and elsewhere determined that Omo I lived about 195,000 years ago -- the oldest known bones of the human species.  

Credit: John Fleagle, Stony Brook University

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When the bones of two early humans were found in 1967 near Kibish, Ethiopia, they were thought to be 130,000 years old. A few years ago, researchers found 154,000- to 160,000-year-old human bones at Herto, Ethiopia. Now, a new study of the 1967 fossil site indicates the earliest known members of our species, Homo sapiens, roamed Africa about 195,000 years ago.

"It pushes back the beginning of anatomically modern humans," says geologist Frank Brown, a co-author of the study and dean of the University of Utah's College of Mines and Earth Sciences.

The journal Nature is publishing the study in its Thursday Feb. 17, 2005, issue. Brown conducted the research with geologist and geochronologist Ian McDougall of Australian National University in Canberra, and anthropologist John Fleagle of New York state's Stony Brook University.

The researchers dated mineral crystals in volcanic ash layers above and below layers of river sediments that contain the early human bones. They conclude the fossils are much older than a 104,000-year-old volcanic layer and very close in age to a 196,000-year-old layer, says Brown.

"These are the oldest well-dated fossils of modern humans (Homo sapiens) currently known anywhere in the world," the scientists say in a summary of the study.

Significance of an Earlier Emergence of Homo sapiens

Brown says that pushing the emergence of Homo sapiens from about 160,000 years ago back to about 195,000 years ago "is significant because the cultural aspects of humanity in most cases appear much later in the record – only 50,000 years ago – which would mean 150,000 years of Homo sapiens without cultural stuff, such as evidence of eating fish, of harpoons, anything to do with music (flutes and that sort of thing), needles, even tools. This stuff all comes in very late, except for stone knife blades, which appeared between 50,000 and 200,000 years ago, depending on whom you believe."

Fleagle adds: "There is a huge debate in the archeological literature regarding the first appearance of modern aspects of behavior such as bone carving for religious reasons, or tools (harpoons and things), ornamentation (bead jewelry and such), drawn images, arrowheads. They only appear as a coherent package about 50,000 years ago, and the first modern humans that left Africa between 50,000 and 40,000 years ago seem to have had the full set. As modern human anatomy is documented at earlier and earlier sites, it becomes evident that there was a great time gap between the appearance of the modern skeleton and 'modern behavior.'"

The study moves the date of human skulls found in Ethiopia's Kibish rock formation in 1967 back from 130,000 years to a newly determined date of 195,000 years ago, give or take 5,000 years. Fossils from an individual known as Omo I look like bones of modern humans, but other bones are from a more primitive cousin named Omo II.

In addition to the cultural question, the earlier date for humanity's emergence is important for other reasons.

"First, it makes the dates in the fossil record almost exactly concordant with the dates suggested by genetic studies for the origin of our species," Fleagle says. "Second, it places the first appearance of modern Homo sapiens in Africa many more thousands of years before our species appears on any other continent. It lengthens that gap. … Finally, the similar dating of the two skulls indicates that when modern humans first appeared there were other contemporary populations [Omo II] that were less modern."

The study was funded by the National Science Foundation, the L. S. B. Leakey Foundation, the National Geographic Society and the Australian National University.

Modern Homo in the Valley of the Omo

Richard Leakey and his team of paleontologists traveled in 1967 to the Kibish Formation along the Omo River in southernmost Ethiopia, near the town of Kibish. They found the skull (minus the face) and partial skeleton (parts of arms, legs, feet and the pelvis) of Omo I, and the top and back of the skull of Omo II. Brown was not part of the 1967 expedition, but was working nearby and got to look at the site and the fossils.

"Anthropologists said they looked very different in their evolutionary status," Brown recalls. "Omo I appeared to be essentially modern Homo sapiens, and Omo II appeared to be more primitive."

In 1967, the fossils were dated as being 130,000 years old, although the scientists doubted the accuracy of their dating technique, which was based on the decay of uranium-238 to thorium-238 in oyster shells from a rock layer near the skulls.

Fleagle says no scientist has been bold enough to suggest Omo II is anything other than Homo sapiens, and that "quite often at the time of major events in evolution, one finds an increase in morphological [anatomical] diversity." Now that the new study confirms Omo I and Omo II are the same age – living within a few hundred years of each other about 195,000 years ago – some anthropologist suggest "maybe it [Omo II] isn't so primitive after all," Brown says.

McDougall, Brown and Fleagle and researchers from other universities returned to Kibish in 1999, 2001, 2002 and 2003. They identified sites where Omo I and Omo II were found in 1967, and obtained more of Omo I, including part of the femur (upper leg bone) that fit a piece found in 1967. They also found animal fossils and stone tools, and studied local geology. The Nature study includes initial results from those expeditions.

The fossil record of human ancestors may go back 6 million years or more, and the genus Homo arose at least 1.8 million years ago when australopithecines evolved into human ancestors known as Homo habilis. Brown says the fossil record of humans is poor from 100,000 to 500,000 years ago, so Omo I is significant because it now is well dated.

Dating the Dawn of Humanity

Both Omo I and Omo II were buried in the lowermost portion or "member" of the Kibish Formation, a series of annual flood sediments laid down rapidly by the ancient Omo River on the delta where it once entered Lake Turkana. Lake levels now are much lower, and the river enters the lake about 60 miles (100 kilometers) south of Kibish.

The 330-foot-thick (100-meter-thick) formation is divided into at least four members, with each of the four sets of layers separated from the other by an "unconformity," which represents a period of time when rock eroded away instead of being deposited. For example, the lowermost Kibish I member was deposited in layers as the Omo River flooded each year. After thousands of years, rainfall diminished, lake levels dropped, and the upper part of Kibish I eroded away. Later, the lake rose and deposition resumed to create layers of Kibish member II.

Interspersed among the river sediments are occasional layers of volcanic ash from ancient eruptions of nearby volcanoes. Some ash layers contain chunks of pumice, which in turn contain feldspar mineral crystals. Feldspar has small amounts of radioactive potassium-40, which decays into argon-40 gas at a known rate. The gas, trapped inside feldspar crystals, allows scientists to date the feldspar and the pumice and ash encasing it.

Brown says potassium-argon dating shows that a layer of ash no more than 10 feet (3 meters) below Omo I's and Omo II's burial place is 196,000 years old, give or take 2,000 years. Another layer is 104,000 years old. It is almost 160 feet (50 meters) above the layer that yielded the Omo humans. The unconformities represent periods of time when rock was eroded, so the fossils must be much older than the 104,000-year-old layer and close in age to the 196,000-year-old layer, Brown says.

The clinching evidence, he says, comes from sapropels, which are dark rock layers on the Mediterranean seafloor that were deposited when floods of fresh water poured out of the Nile River during rainy times. The Blue Nile and White Nile tributaries share a drainage divide with the Omo River. During ancient wet periods, monsoons on the Ethiopian highlands sent annual floods surging down the Nile system, causing sapropels to form on the seafloor, and sent floods down the Omo, making Lake Turkana rise and depositing Kibish Formation sediments on the river's ancient delta. (During dry periods, Lake Turkana was smaller, flood sediments were deposited farther south and rocks at Kibish were eroded.)

No other sediments on land have been found to record wet and dry periods that correlate so well with the same climate pattern in ocean sediments, Brown says. The new study found that the "members" – or groups of rock layers – of the Kibish formation were laid down at the same time as the Mediterranean sapropels. In particular, the volcanic layer right beneath Omo I and II dates to 196,000 years ago by potassium-argon dating, and it corresponds almost perfectly to a sapropel layer previously dated as 195,000 years old, Brown says.

"It is pretty conclusive," says Brown, who disputes any contention that the fossils might be closer to 104,000 years old.

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The above story is based on materials provided by University Of Utah. Note: Materials may be edited for content and length.

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University Of Utah. "The Oldest Homo Sapiens: Fossils Push Human Emergence Back To 195,000 Years Ago." ScienceDaily. ScienceDaily, 28 February 2005. <www.sciencedaily.com/releases/2005/02/050223122209.htm>.

Top 10 Mysteries of the First Humans

 

Charles Q. Choi   |   February 22, 2011 12:25pm ET

Human mysteries

Humans are unique among life on this planet, and much remains a mystery as to how we evolved. What steps came first? Why did we evolve this way and not that direction? Why are we the only human species left? What other paths might we have gone down in our evolution? And what directions might we go from here?

 

Why did we grow large brains?

There is no question that our large brains have provided humans an extraordinary advantage in the world. Still, the human brain is an incredibly expensive organ, taking up only about 2 percent of the body's mass yet using more than a fifth of the body's energy, and until about 2 million years ago none of our ancestors had a brain larger than an ape's when compared to body size. So what kicked off the push for a larger brain? One possibility is that increased smarts helped our ancestors make better tools. Another is that larger brains helped us interact better with each other. Perhaps radical changes in the environment also demanded that our ancestors deal with a shifting world.

 

Why do humans walk on two legs?

Our ancestors evolved an upright posture well before our large brains or stone tools even appeared. The question, then: Why stand and walk on two legs when our ape cousins get by on four limbs? Walking as bipeds might actually use less energy than movement on all fours does. Freeing up the arms might also have enabled our ancestors to carry more food. Standing upright might even have helped them control their temperature better by reducing the amount of skin directly exposed to the sun.

 

What happened to our hair?

Credit: nullHumans are unique for looking naked compared to our hairier ape cousins. So why did this nakedness evolve? One suggestion is that our ancestors shed hairiness to keep cool when venturing across the hot savannahs of Africa. Another is that losing our fur coats helped free us parasite infestations and the diseases they can spread. One unorthodox idea even suggests human nakedness developed after our ancestors briefly adapted for a streamlined life in the water, although most aquatic mammals of roughly human size actually possess dense fur.

 

Why did our closest relatives go extinct?

Roughly 24,000 years ago, our species, Homo sapiens, was not alone in the world — our closest relatives, the Neanderthals, (Homo neanderthalensis) were still alive. The so-called 'hobbit' found in Indonesia might also have been a member of the genus Homo, and it apparently survived until as recently as 12,000 years ago. So why did they die and we survive? Did infections or radical shifts in their environments kill them off? Or did our species do away with them? Some evidence exists for both scenarios, but no conclusion is agreed upon.

Is human evolution accelerating?

Recent evidence suggests that humanity is not only still evolving, but that human evolution is actually accelerating, speeding up to 100 times historical levels after agriculture spread. A number of scientists challenge the strength of this evidence, saying that it remains difficult to ascertain whether or not certain genes really have recently grown in prominence because they offer some adaptive benefit. Still, if human evolution is accelerating, the question becomes why? Diet and diseases may be some of the pressures that caused humans to change.

 

What is the hobbit?

Is the 'hobbit' — the nickname given to diminutive skeletons found on the Indonesian isle of Flores in 2003 — in fact an extinct human species, enough to be called Homo floresiensis? Are these skeletons just examples of deformed Homo sapiens? Are they a different species than us, but perhaps not an extinct human species and instead as separate as chimpanzees are? Solving this mystery could help shed light on the radical paths human evolution may have taken.

 

Why did modern humanity expand past Africa about 50,000 years ago?

Credit: Morgan/Sanz, Goualougo Triangle Ape Project, Nouabale-Ndoki National Park, Republic of Congo.

Roughly 50,000 years ago, modern humans expanded out of Africa, spreading rapidly across most of the world's lands to colonize all continents except Antarctica, reaching even the most remote Pacific islands. A number of scientists conjecture this migration was linked with a mutation that transformed our brains, leading to our modern, complex use of language and enabling more sophisticated tools, art and societies. The more popular view suggests hints of such modern behavior existed long before this exodus, and that humanity instead had crossed a threshold in terms of population size in Africa that made such a revolution possible.

 

Did we have sex with Neanderthals?

Did we interbreed? Does our species possess any genes leftover from our extinct cousins? Scientists have suggested that perhaps the Neanderthals did not die out, but instead were absorbed into modern humanity.

 

Who was the first hominid?

Credit: © 2009, J.H. Matternes

Scientists are uncovering more and more ancient hominids all the time — here meaning bipeds including humans, our direct ancestors and closest relatives. They strive to find the earliest one, to help answer that most fundamental question in human evolution — what adaptations made us human, and in what order did they happen?

 

Where do modern humans come from?

The most bitterly debated question in the discipline of human evolution is likely over where modern humans evolved. The out-of-Africa hypothesis maintains that modern humans evolved relatively recently in Africa and then spread around the world, replacing existing populations of archaic humans. The multiregional hypothesis contends that modern humans evolved over a broad area from archaic humans, with populations in different regions mating with their neighbors to share traits, resulting in the evolution of modern humans. The out-of-Africa hypothesis currently holds the lead, but proponents of the multiregional hypothesis remain strong in their views.

Neanderthal Woman's DNA Reveals Ancient Inbreeding, Mysterious Human Lineage

 

LiveScience  |  By Charles Q. Choi Posted: 12/19/2013 8:51 am EST  |  Updated: 01/23/2014 1:38 am EST

 

The existence of a mysterious ancient human lineage and the genetic changes that separate modern humans from their closest extinct relatives are among the many secrets now revealed in the first high-quality genome sequence from a Neanderthal woman, researchers say.

The Neanderthal woman whose toe bone was sequenced also reveals inbreeding may have been common among her recent ancestors, as her parents were closely related, possibly half-siblings or another near relation.

Researchers have completed the first high-quality sequence of a Neanderthal genome, using a sample from the toe bone of a Neanderthal woman.

Although modern humans are the world's only surviving human lineage, others also once lived on Earth. These included Neanderthals, the closest extinct relatives of modern humans, and the relatively newfound Denisovans, whose genetic footprint apparently extended from Siberia to the Pacific islands of Oceania. Both Neanderthals and Denisovans descended from a group that diverged from the ancestors of all modern humans. [See Photos of Neanderthal Bone & Denisovan Fossils]

The first signs of Denisovans came from a finger bone and a molar tooth discovered in Denisova Cave in southern Siberia in 2008. To learn more about Denisovans, scientists examined a woman's toe bone, which was unearthed in the cave in 2010 and showed physical features resembling those of both Neanderthals and modern humans. The fossil is thought to be about 50,000 years old, and slightly older than previously analyzed Denisovan fossils.

Human interbreeding

The scientists focused mostly on the fossil's nuclear DNA, the genetic material from the chromosomes in the nucleus of the cell that a person receives from both their mother and father. They also examined the genome of this fossil's mitochondria — the powerhouses of the cell, which possess their own DNA and get passed down solely from the mother.

The investigators completely sequenced the fossil's nuclear DNA, with each position (or nucleotide) sequenced an average of 50 times. This makes the sequence's quality at least as high as that of genomes sequenced from present-day people.

The genetic analysis revealed the toe bone belonged to a Neanderthal. When compared with other Neanderthal mitochondrial DNA samples, this newfound fossil's closest known relatives are Neanderthals found in Mezmaiskaya Cave in the Caucasus Mountains about 2,100 miles (3,380 kilometers) away.

The toe bone of a Neanderthal woman was uncovered in the Denisova Cave (shown here) in southern Siberia, the same place where the first signs of the Denisovans, a relatively newfound human lineage, were found.

These findings helped the scientists refine the human family tree, further confirming that different human lineages interbred. They estimated about 1.5 to 2.1 percent of DNA of people outside Africa are Neanderthal in origin, while about 0.2 percent of DNA of mainland Asians and Native Americans is Denisovan in origin.

"Admixture seems to be common among human groups," said study lead author Kay Prüfer, a computational geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

Intriguingly, the scientists discovered that apparently Denisovans interbred with an unknown human lineage, getting as much as 2.7 to 5.8 percent of their genomes from it. This mystery relative apparently split from the ancestors of all modern humans, Neanderthals and Denisovans between 900,000 years and 4 million years ago, before these latter groups started diverging from each other.

This enigmatic lineage could even potentially be Homo erectus, the earliest undisputed predecessor of modern humans. There are no signs this unknown group interbred with modern humans or Neanderthals, Prüferadded. [The 10 Biggest Mysteries of the First Humans]

"Some unknown archaic DNA might have caught a ride through time by living on in Denisovans until we dug the individual up and sequenced it," Prüfertold LiveScience. "It opens up the prospect to study the sequence of an archaic (human lineage) that might be out of reach for DNA sequencing."

Interbreeding took place between Neanderthals and Denisovans as well. These new findings suggest at least 0.5 percent of the Denisovan genome came from Neanderthals. However, nothing of the Denisovan genome has been detected in Neanderthals so far.

In addition, "the age of the Neanderthals and Denisovans we sequenced also doesn't allow us to say whether any gene flow from modern humans to Neanderthals or Denisovans happened," Prüfer said. The Neanderthals and Denisovans that researchers have sequenced the DNA of to date "probably lived at a time when no modern humans were around," he explained.

Modern humans' distinguishing features

It remains uncertain when modern humans, Neanderthals and Denisovans diverged from one another. The researchers currently estimate modern humans split from the common ancestors of all Neanderthals and Denisovans between 550,000 and 765,000 years ago, and Neanderthals and Denisovans diverged from each other between 381,000 and 473,000 years ago.

Genetic analysis revealed the parents of the woman whose toe bone they analyzed were closely related — possibly half-siblings, or an uncle and niece, or an aunt and nephew, or a grandfather and granddaughter, or a grandmother and grandson. Inbreeding among close relatives was apparently common among the woman's recent ancestors. It remains uncertain as to whether inbreeding was some kind of cultural practice among these Neanderthals or whether it was unavoidable due to how few Neanderthals apparently lived in this area, Prüfer said.

By comparing modern human, Neanderthal and Denisovan genomes, the researchers identified more than 31,000 genetic changes that distinguish modern humans from Neanderthals and Denisovans. These changes may be linked with the survival and success of modern humans — a number have to do with brain development.

"If one speculates that we modern humans carry some genetic changes that enabled us to develop technology to the degree we did and settle in nearly all habitable areas on the planet, then these must be among those changes," Prüfer said. "It is hard to say what exactly these changes do, if anything, and it will take the next few years to find out whether hidden among all these changes are some that helped us modern humans to develop sophisticated technology and settle all over the planet."

Prüfer and his colleagues detailed their findings in the Dec. 19 issue of the journal Nature.

Ardipithecus ramidus, human evolution, students and schools

Gary Hurd

LA Science Education Examiner

October 2, 2009

The last two days, and we can expect for the next two weeks, news reports have been filled with the spectacular Hominid fossils discovered in Ethiopia and published today in a special issue of Science Magazine.

The fossils represent the Hominin species, Ardipithecus ramidus and were nicknamed "Ardi." This will have much greater public penetration than many scientific discoveries because the AAAS has made their special edition public, and the announcement has been coordinated with the National Geographic Society, and news organizations such as CNN. This discovery has literally traveled the globe overnight. 

Your students will have questions for you that very few K-12 teachers are prepared to answer. I'll try to anticipate a few, and I'll reply to any questions posted below.

The first will be prompted by actually misleading, or at best poorly phrased headlines. These are from some surprising sources. The National Geographic News science editor, Jamie Shreeve, used the following headline for their article on Ardi, "Oldest "Human" Skeleton Found--Disproves "Missing Link."

There are several errors in a few words. These fossils are not "human." We limit "human" to the members of our Genus Homo, collectively called Hominidae often shortened to hominins.  The great apes, including humans are collectively called Hominids. "Ardi" is not a member of our genus, and is not a human. The notion of a "missing link" is falsely claimed by creationists to mean that there was a direct intermediate between modern humans and modern apes. This was never suggested by any evolutionary scientist, all the way back to Darwin. The discoverers of the newly reported fossils do think that even some of the common shared features of Chimps and Humans evolved independently. This is called convergent evolution, and is perhaps what Shreeve was refering to as "missing link" being falsified. This same error has appeared in other reports, such as by CNN.

So, the first likely question "Was this the first Human?" is answered, "No, it was one of the many early Hominids that were ancestors of Humans." The oldest member of our genus is still Homo habilus discovered in the Olduvai Gorge of Kenya and about 1.8 million years old.

These headlines also claim this is the "Oldest Human" with the emphasis on age. This is also incorrect. These fossils are exceptionally well dated and are 4.4 million years old. There are other known Hominid species older than Ardi. These are Ardipithecus kadabba, from Ethiopia about 5.5 million years old, Orrorin tugenensis from Kenya between 6.1 and 5.8 million years old, and Sahelanthropus tchadensis discovered in Chad and about 7 million years (Ma) old. This leads to the next most likely question you might hear from a student;

"How do they know how old it is?"

Ardipithecus ramadi fossils recently reported are all from a single three meter thick sedimentary deposit that is sandwiched between two volcanic ash, or tuff, layers.  The bottom layer is the Gàala("Camel") Tuff Complex (GATC) which has a ⁴⁰Ar/³⁹Ar age of4.419 ± 0.068 Ma. The capping strata is the Daam Aatu ("Baboon") BasalticTuff (DABT), which has a ⁴⁰Ar/³⁹Ar age of 4.416 ± 0.031Ma. The maximum age range known so far for these fossils is within 40,000 years. Argon dating is a radiometric method that measures the accumulation of argon 39 produced by the radioactive decay of argon 40 (see the excellent discription of ⁴⁰Ar/³⁹Ar dating provided by our reader, Readbeard in his comment below). Since the tuff was fully melted releasing its gasses, there is no question of residual argon to complicate the dates.

And the follow-up question is, "How do they know that radiometric dating works?"

We know this because electric lights work. We know this because any change in the universal physical constants great enough to affect dating results would necessarily have caused the earth to have recently melted, and penetrated with so much radiation that it would glow. We know this because radiometric dates agree with simple counting of annual events that accumulate in lakes, glaciers, and the ocean bottom. Radiometric dates also match with yearly events like tree rings.

Many students are influenced by creationism through their churches. Excellent resources for teachers on evolution are The National Center for Science Education, and Understanding Evolution

 

Ardipithecus ramidus Illustration courtesy J. H. Matternes via Science/AAAS

Fossils radically alter ideas about the look of man's earliest ancestors

 

Analysis of a near-complete skeleton of a human ancestor found in Ethiopia changes scientists' thinking about the appearance and behavior of our distant forebears.

By Thomas H. Maugh II

October 2, 2009

A treasure trove of 4.4-million-year-old fossils from the Ethiopian desert is dramatically overturning widely held ideas about the early evolution of humans and how they came to walk upright, even as it paints a remarkably detailed picture of early life in Africa, researchers reported Thursday.

The centerpiece of the diverse collection of primate, animal and plant fossils is the near-complete skeleton of a human ancestor that demonstrates our earliest forebears looked nothing like a chimpanzee or other large primate, as is now commonly believed. Instead, the findings suggest that the last common ancestor of humans and primates, which existed nearly 2 million years earlier, was a primitive creature that shared few traits with modern-day members of either group.

Graphic: Graphic: Dramatic addition to human evolutionary tree

The findings, analyzed in a large group of studies published Thursday in the journal Science, also indicate that our ancestors began walking upright in woodlands, not on grassy savannas as prior generations of researchers had speculated.

The discovery of the specimen called Ardipithecus ramidus "is one of the most important discoveries for the study of human evolution," said paleoanthropologist David Pilbeam of Harvard University, who was not involved in the research. "The find itself is extraordinary, as were the enormous labors that went into the reconstruction of a skeleton shattered almost beyond repair," he said in an e-mailed statement.

"It is so rare to get a more or less complete skeleton," said paleoanthropologist Andrew Hill of Yale University. "In the entire course of human evolution, at least until you get to Neanderthals, there are only three to four available. We can always tell so much more from a skeleton" than from the jawbones and skulls that are more commonly found.
The fossils described in the new studies were found 15 years ago in the Afar Triangle of Ethiopia by a team led by paleoanthropologist Tim White of UC Berkeley. But White and his team have been relatively closemouthed about the fossils, and other researchers -- some of whom have accused him of hoarding the fossils for his own use -- have been eagerly awaiting more information.

Today, they are getting a surfeit: Eleven papers by 47 authors, and a similar number of short summaries prepared by each paper's authors.

The fossils were found in a layer of sediment sandwiched between two layers of volcanic ash, each dating from 4.4 million years ago -- indicating that the fossils are also of that age.

In addition to the nearly complete fossil specimen of the female primate, which investigators have dubbed Ardi, the team found more than 100 fossils from 36 other members of the same species.

"These fossils are much more important than Lucy," the 3.2-million-year-old specimen of Australopithecus afarensis that was found in the Afar desert in the 1970s, said paleoanthropologist Alan Walker of Pennsylvania State University, who was not involved in the research. "The reason is that when Lucy was found, we already knew the major features of Australopithecus from fossils found in the 1940s. . . . These fossils are of a completely unknown creature, and are much stranger and more primitive than Australopithecus."

The White team also found fossils of 29 species of birds, primarily small ones like doves, lovebirds, mousebirds, passerines and swifts, as well as several that were previously unknown. Animal fossils included 20 new species of small mammals, including shrews, bats, rodents, hares and small carnivores, as well as larger animals, including baboons, colobus monkeys and spiral-horned antelopes.

Fossilized wood, seed and other plant remains indicate the presence of hackberry, fig and palm trees. Collectively, these finds indicate that the environment was more humid and cooler than it is today, and contained grassy woodland with forest patches.
Today, the Afar is a desert. But go back in a time machine and "4.4 million years ago, this was really a different world," White said. "We look up in the trees and we see that they are full of monkeys. We look around on the ground and we see that there are a lot of kudus. And we see an occasional hyena. And we see elephants and we see lots of small mammals."

This whole collection of data "gives us information we have never had before about human evolution," said paleoanthropologist C. Owen Lovejoy of Kent State University, one of the primary authors of the papers. "The whole savanna theory goes out the window in terms of it being the explanation for upright walking. . . . And the idea that we evolved from something like a chimpanzee also goes out the window."

Ardi stood about 47 inches tall and probably weighed 110 pounds. Many researchers previously believed that such an early ancestor would, like modern chimps, be a knuckle-walker, using the knuckles for support while moving on all fours. Instead, Ardi appears to have climbed on all fours on branches, but walked upright on the ground. Her feet, like those of monkeys but not chimps, were designed more for propulsion than for grasping.
Her face had a projecting muzzle, giving her an ape-like appearance, but many features of her skull, such as the ridge above the eye socket, are quite different than those of chimpanzees. Her brain is about the same size as Lucy's.

Her hands lacked many of the specializations that allow modern-day African apes to swing, hang and easily move through trees. Those specializations apparently evolved in large primates after they separated from the last common ancestor with humans more than 6 million years ago. (Few fossils of such primates are available because they lived primarily in forests, which are not conducive to preservation of bone.)
The finds "are turning evolution on its head," Lovejoy said.

The most controversial aspects of the papers involve the authors' -- particularly Lovejoy's -- interpretations of what the fossils say about behavior. Of particular importance, he said, is that the sizes of males and females were about the same, and that the specimens do not have large, sharp canine teeth. Both findings suggest that the fierce, often violent competition among males for females in heat that characterizes gorillas and chimpanzees was absent in Ardipithecus.

That implies, Lovejoy concluded, that the males were beginning to enter into monogamous relationships with females and devoted more time to caring for their young than did earlier ancestors.

"This is a restatement of Owen Lovejoy's ideas going back almost three decades, which I found unpersuasive then and still do," Pilbeam said.
Hill was more blunt, calling Lovejoy's speculation "patent nonsense."

thomas.maugh@latimes.com

http://www.latimes.com/news/nationworld/nation/la-sci-fossils2-2009oct02,0,3420742.story#ixzz2tV4kMLzY

Ten facts about Ardipithecus ramidus, Ardi

Kathryn Siranosian

Science & Nature Examiner

 

 

October 1, 2009

Ardipithecus ramidus is an archaelogical specimen that has been described as "one of the most important discoveries for the study of human evolution."

The skeleton fossils were found 15 years ago in the Afar Triangle of Ethiopia by an archaelogical team led by paleoanthropologist Tim White of UC Berkeley. The team found a nearly complete fossil specimen of a female primate, plus more than 100 fossils from 36 other members of the same species.

After 15 years of analysis, the researchers released their findings today. The findings are contained in a total of 11 papers by 47 authors.

Scientists call Ardipithecus ramidus "Ardi" for short.

Ardi lived 4.4 million years ago in what is now Ethiopia.

She lived in woodland conditions more than a million years before the famous "Lucy" fossil (Australopithecus afarensis).

Ardi walked upright. She stood about 47 inches tall and weighed about 110 pounds.

Even though she walked upright, her feet were well adapted to grasping, and so researchers think she was able to climb trees. The structure of Ardi's feet, pelvis, legs and hands suggest that she was a biped on the ground, but a quadruped in the trees.

What's more, her teeth resemble modern human teeth more closely than they do those of a chimpanzee.

It's this unexpected mix of advanced characteristics and primitive traits that has scientists so intrigued.Ardi appears to be a transitional fossil that fits somewhere between a more ape-like ancestor and the bipedal hominid Lucy.

http://www.examiner.com/article/ten-facts-about-ardipithecus-ramidus-ardi

After reading this, you’ll never look at a banana in the same way again

January 26, 2014 2:44 pm

This is interesting. After reading this, you’ll never look at a banana in the same way again.

Bananas contain three natural sugars – sucrose, fructose and glucose combined with fiber. A banana gives an instant, sustained and substantial boost of energy.
Research has proven that just two bananas provide enough energy for a strenuous 90-minute workout. No wonder the banana is the number one fruit with the world’s leading athletes.
But energy isn’t the only way a banana can help us keep fit. It can also help overcome or prevent a substantial number of illnesses and conditions, making it a must to add to our daily diet.

DEPRESSION
According to a recent survey undertaken by MIND amongst people suffering from depression, many felt much better after eating a banana. This is because bananas contain tryptophan, a type of protein that the body converts into serotonin, known to make you relax, improve your mood and generally make you feel happier.
PMS:
Forget the pills – eat a banana. The vitamin B6 it contains regulates blood glucose levels, which can affect your mood.

ANEMIA
High in iron, bananas can stimulate the production of hemoglobin in the blood and so helps in cases of anemia.
BLOOD PRESSURE:
This unique tropical fruit is extremely high in potassium yet low in salt, making it perfect to beat blood pressure So much so, the US Food and Drug Administration has just allowed the banana industry to make official claims for the fruit’s ability to reduce the risk of blood pressure and stroke.

BRAIN POWER
200 students at a Twickenham school ( England ) were helped through their exams this year by eating bananas at breakfast, break, and lunch in a bid to boost their brain power. Research has shown that the potassium-packed fruit can assist learning by making pupils more alert.

CONSTIPATION
High in fiber, including bananas in the diet can help restore normal bowel action, helping to overcome the problem without resorting to laxatives.

HANGOVERS
One of the quickest ways of curing a hangover is to make a banana milkshake, sweetened with honey. The banana calms the stomach and, with the help of the honey, builds up depleted blood sugar levels, while the milk soothes and re-hydrates your system.

HEARTBURN
Bananas have a natural antacid effect in the body, so if you suffer from heartburn, try eating a banana for soothing relief.

MORNING SICKNESS
Snacking on bananas between meals helps to keep blood sugar levels up and avoid morning sickness.
MOSQUITO BITES:
Before reaching for the insect bite cream, try rubbing the affected area with the inside of a banana skin. Many people find it amazingly successful at reducing swelling and irritation.

NERVES
Bananas are high in B vitamins that help calm the nervous system..
Overweight and at work? Studies at the Institute of Psychology in Austria found pressure at work leads to gorging on comfort foodlike chocolate and chips. Looking at 5,000 hospital patients, researchers found the most obese were more likely to be in high-pressure jobs. The report concluded that, to avoid panic-induced food cravings, we need to control our blood sugar levels by snacking on high carbohydrate foods every two hours to keep levels steady.

ULCERS
The banana is used as the dietary food against intestinal disorders because of its soft texture and smoothness. It is the only raw fruit that can be eaten without distress in over-chroniclercases. It also neutralizes over-acidity and reduces irritation by coating the lining of the stomach.

TEMPERATURE CONTROL
Many other cultures see bananas as a ‘cooling’ fruit that can lower both the physical and emotional temperature of expectant mothers. In Thailand , for example, pregnant women eat bananas to ensure their baby is born with a cool temperature.
So, a banana really is a natural remedy for many ills. When you compare it to an apple, it has FOUR TIMES the protein, TWICE the carbohydrate, THREE TIMES the phosphorus, five times the vitamin A and iron, and twice the other vitamins and minerals.. It is also rich in potassium and is one of the best value foods around So maybe its time to change that well-known phrase so that we say, ‘A BANANA a day keeps the doctor away!’

http://worldobserveronline.com/2014/01/26/reading-youll-never-look-banana-way/?utm_source=taboola&utm_medium=referral