Human Paleontology

Forms of Homins and Hominids

Human paleontology focuses exclusively on fossils related to the human lineage. Human paleontology is highly interdisciplinary; to recover, describe, and interpret human fossil remains, its researchers need knowledge of cultural anthropology, archaeology, biology, paleontology, and geology.

Paleontology and Human Paleontology

Fossils, the remains or imprints of dead organisms, are the only physical evidence humans possess of ancient life. While fossils are generally formed from bone, shell, or wood, under very specific conditions, fossils may be formed from soft tissue, animal tracks, skin impressions, and feces. Sometimes, bones are disturbed by scavengers or water movement prior to fossilization; the study of what happens to a bone from the time of the organism’s death to its discovery is called taphonomy.

Research in paleontology focuses on reconstructing the history of life on Earth. Fossils provide important clues about past environments, ecosystems, and evolution. Paleontology incorporates knowledge from many fields to understand the processes of evolution and to reconstruct ancient life. Most fossils studied by paleontologists are anywhere from thousands to several millions of years old. Human paleontology focuses on fossils of the human lineage, thought to begin between 5 and 8 million years ago.

View videos here: https://www.cornell.edu/video/human-paleontology-1-what-is-paleontology

Like paleontology, human paleontology utilizes evolutionary theory and the scientific method to test hypotheses about past lifeways and relationships. Ecological niche theory and estimates of inter- and intraspecific competition levels also help reconstruct behaviors and evolutionary pressures. Morphometric and cladistic methodologies help researchers define fossil species and reconstruct relationships between fossil species and between fossil and living species.

Source: http://anthropology.iresearchnet.com/human-paleontology/

Since the time of separation of the evolutionary lines of apes and humans about 5 million years ago, some fossil specimens of the skeletal remains of our earliest ancestors have been preserved and discovered. Putting together the pieces of the puzzle of human biological history is the task of paleontologists, geologists and anthropologists.

By looking at reproductions and pictures of this fossil record, including representations of pre-human Primate species, we learn about our prehistoric beginnings among those populations of first two million years of our evolution, as identified as Ardipithecus, Australopithecus and the earliest members assigned to our own genus- Homo habilis and Homo rudolfensis.

Oldest Human Fossils in the World

Modern humans (Homo sapiens) are the only remaining human group still around. All other human species have been long extinct, but we know about them today through various fossil specimens. The first human fossils were discovered in the 19th century and were highly controversial. Early paleontologists didn’t know what to make of these fossils and often made claims that they belonged to the “missing link” between humans and apes or that they were human ancestors suffering from disease. As the paleoanthropology advanced scientists started to recognize that these fossils belonged to the our human ancestors. Some of these fossils are millions of years old and represent some of the earliest human species yet discovered.

9. Peking Man

Age: 680,000 – 780,000 years
Species:  Homo erectus
Location:  China
Year Discovered:  1921

Age: 680,000 – 780,000 years
Species:  Homo erectus
Location:  China
Year Discovered:  1921

photo source: Wikimedia Commons

The skull fragments of the Peking Man are part of a group of fossils discovered Zhoukoudian, China during excavations from 1921 – 1937. These fossils range in age from 680,000 – 780,000 years old. Overall, 15 partial skulls, 11 mandibles, several teeth, some skeletal bones, and a large number of stone tools were recovered from the dig sites.

The fossils were extensively studied by paleoanthropologist David Blackson until his death in 1934. Pierre Teilhard de Chardin and Franz Weidenreich took over the research until Weidenreich had to leave China in 1941. Unfortunately, the original Peking Man fossils vanished in 1941 when Beijing was under Japanese occupation. The fossils have never been found despite numerous attempts. Luckily, several casts and descriptions of the Peking Man survive and four of the teeth still exist in the Paleontological Museum of Uppsala University.

Age: 700,000 – 1 million years
Species:  Homo erectus erectus
Location:  Indonesia
Year Discovered:  1891

photo source:Wikimedia Commons

As one of the first major human fossil finds from the late 19th century, the Java Man is a widely known early human specimen. The molar, skullcap, and thigh bone of the Java Man were discovered by paleoanthropologist Eugène Dubois. Dubois claimed that his discovery represented the “missing link” between apes and humans and classified it as Anthropopithecus erectus (an outdated classification).

Within a decade of the Java Man’s discovery, several books and articles were published about Dubois’s find. The Java Man was controversial, with many arguing that it did not represent the transitional form between humans and apes. Evolutionary biologist Ernst Mayr reclassified the Java Man as Homo erectus in 1950. During the 1970s, some scientists started distinguishing the Java Man from other Homo erectus populations by labeling the specimen as Homo erectus erectus.

Age: 1.43 – 1.49 million years
Species:  Homo erectus
Location:  Indonesia
Year Discovered:  1936

photo source: Wikimedia Commons

The fossil known as the Mojokerto child is a skullcap from a Homo erectus juvenile found in Indonesia. At the time of the fossil’s discovery in 1936, Ralph von Koenigswald classified the skullcap as Pithecanthropus modjokertensis but soon renamed it Homo modjokertensis. Neither of these classifications is correct or recognized today and the specimen is widely believed to be Homo erectus.

Initially, the Mojokerto child skull was hard to date because its exact discovery site could not be determined. In the early 1990s, the fossil was dated to 1.81 million years ago, with a margin of error of plus or minus 40,000 years. The skull was more precisely dated to between 1.43 – 1.49 million years in 2003 – this estimate is now widely accepted.

Age: 1.5 – 1.6 million years
Species:  Homo erectus
Location:  Kenya, Africa
Year Discovered: 

photo source: Wikimedia Commons

The Turkana Boy, scientifically known as KNM-WT 15000, is notable for being the most complete early human fossil ever discovered. The near-complete skeleton was discovered in 1984 by Kamoya Kimeu, a member of Richard Leakey’s research team. The fossil is estimated to be between 1.5 – 1.6 million years old.

Researchers estimate that the Turkana Boy was about 7 – 11 years old at the time of death. He was about 160 cm (63 in) tall and may have been nearly fully grown despite his young age. Scientists believe that he would have had a much smaller and briefer growth spurt than modern humans. The Turkana Boy also had a narrower pelvis which suggests he was completely bipedal – this differs from other early hominin species which still climbed trees and were only partial bipedal.

Age: about 1.8 million years
Species:  Homo erectus georgicus
Location:  Dmanisi, Georgia – Russia
Year Discovered:  2001 – 2005

photo source: Wikimedia Commons

The five skulls found in Dmanisi, Georgia are some of the oldest fossils belonging to the Homo erectus line. The most notable skulls, known as skull 3, 4, and 5, were discovered in the early 2000s. These skulls are smaller than other Homo erectus skulls and have now been classified as a subspecies called Homo erectus georgicus.

A study published in 2013 describing Dmanisi Skull 5 reopened the debate over how to classify early humans. The skull is one of the oldest nearly complete human skulls ever discovered. The scientists from the study believe that Homo habilis and Homo rudolfensis were not separate human species but subspecies of Homo erectus. However other scientists do not believe the reclassification is necessary.

Age: 1.8 million years
Species:  Homo habilis
Location:  Tanzania, Africa
Year Discovered:  1968

photo source: Smithsonian

Twiggy (OH 24) is the oldest fossil skull recovered from the Olduvai Gorge paleoanthropological site in Tanzania. The skull is also one of the oldest known Homo habilis specimens. Twiggy was discovered in 1968 and was crushed flat, hence the nickname after supermodel Twiggy who was known for being thin.

When OH 24 was first discovered, there was very little interest in the skull. Scientist Ron Clarke pushed for the skulls reconstruction and it was finally examined. Unfortunately the skull was distorted from the way it was preserved and it has a slightly small cranial capacity compared to typical Homo habilis skulls. Due to OH 24’s age, the skull is often used to help settle disputes about how to properly classify Homo habilis and Homo rudolfensis skulls.

 

Age: 1.9 million years
Species:  Homo rudolfensis
Location:  Kenya, Africa
Year Discovered: 1972

photo source: Wikimedia Commons

When the skull fossil known as KNM ER 1470 was first discovered, it was incorrectly dated as being nearly three million years old. This predated Homo habilis, which the skull was initially identified as. However KNM ER 1470 was properly dated to about 1.9 million years and classified as belonging to a separate human group, Homo rudolfensis, which lived in the same area and time as Homo habilis.

KNM ER 1470 was discovered just a year before KNM ER 1813, which is one of the oldest Homo habilis specimens. After KNM ER 1470 was reconstructed by Meave Leakey and Bernard Wood, they discovered that the skull was too large and too different to belong to Homo habilis. The skull was reconstructed more precisely in 2007 and it is now widely accepted as a Homo rudolfensis specimen.

 

Age: about 1.9 million years
Species:  Homo habilis
Location:  Kenya, Africa
Year Discovered:  1973

photo source: Wikimedia Commons

The human fossil known as KNM ER 1813 is one of the oldest and most complete Homo habilis specimens ever discovered. The skull fossil was uncovered in 1973 in Kenya by Kamoya Kimeu, who worked with famed paleontologists Meave Leakey and Richard Leakey.

KNM ER 1813 is often noted for being a controversial Homo habilis specimen due to its small size. Unlike other Homo habilis skulls, KNM ER 1813 only has a cranial capacity of 510 cubic centimeters – the accepted cutoff for Homo habilis skulls is 600 cubic centimeters. Additionally, the skull’s overall size and teeth are much smaller than those found on other Homo habilis skulls. Despite all the difference, KNM ER 1813 has enough Homo habilis characteristics to be classified as belonging to the species.

 

Age: 2.5 – 2.3 million years
Species:  Homo rudolfensis
Location:  Malawi
Year Discovered:  1991

photo source: Wikimedia Commons

The jawbone found at the Uraha Hill paleoanthropological site in Malawi is the oldest known human fossil in the world. The exact age of the jawbone is unknown but is estimated to be around 2.5 – 2.3 million years old. This ancient jawbone belonged to a human from the Homo rudolfensis group and is considered the oldest specimen from the genus Homo.

When the jawbone was first discovered in 1991, scientists thought that it belonged to another early human ancestor, Homo habilis. However researchers later decided that the jawbone belonged to Homo rudolfensis because it was too different from specimens from other early human groups. The discovery of the jawbone also shed more light on how early human may have migrated throughout Africa.

https://www.oldest.org/culture/human-fossils/

  1. Little Foot

Little Foot, the Most Complete Australopithecus Fossil, Goes on Display

After 20 years of excavation and cleaning, the 3.67-million year old hominin is ready for her closeup

“Little Foot” is the nickname given to a nearly complete Australopithecus fossil skeleton found in 1994–1998 in the cave system of Sterkfontein, South Africa. The nickname “little foot” was given to the fossil in 1995. From the structure of the four ankle bones they were able to ascertain that the owner was able to walk upright. The recovery of the bones proved extremely difficult and tedious, because they are completely embedded in concrete-like rock. It is due to this that the recovery and excavation of the site took around 15 years to complete.

 

‘Little Foot’ skeleton goes on display in S. Africa
160,000-year-old fossilized skulls from Ethiopia are oldest modern humans

Homo sapiens idaltu, BOU-VP-16/1
Housed in National Museum of Ethiopia, Addis Ababa
Photo © 2000 David L. Brill Brill Atlanta

Berkeley -The fossilized skulls of two adults and one child discovered in the Afar region of eastern Ethiopia have been dated at 160,000 years, making them the oldest known fossils of modern humans, or Homo sapiens.

The skulls, dug up near a village called Herto, fill a major gap in the human fossil record, an era at the dawn of modern humans when the facial features and brain cases we recognize today as human first appeared.

The fossils date precisely from the time when biologists using genes to chart human evolution predicted that a genetic “Eve” lived somewhere in Africa and gave rise to all modern humans.
“We’ve lacked intermediate fossils between pre-humans and modern humans, between 100,000 and 300,000 years ago, and that’s where the Herto fossils fit,” said paleoanthropologist Tim White, professor of integrative biology at the University of California, Berkeley, and a co-leader of the team that excavated and analyzed the discovery site. “Now, the fossil record meshes with the molecular evidence.”
“With these new crania,” he added, “we can now see what our direct ancestors looked like.”
“This set of fossils is stupendous,” said team member F. Clark Howell, UC Berkeley professor emeritus of integrative biology and co-director with White of UC Berkeley’s Laboratory for Human Evolutionary Studies. “This is a truly revolutionary scientific discovery.”
Howell added that these anatomically modern humans pre-date most Neanderthals, and therefore could not have descended from them, as some scientists have proposed.

The international team is led by White and his Ethiopian colleagues, Berhane Asfaw of the Rift Valley Research Service in Addis Ababa, Ethiopia, and Giday WoldeGabriel of Los Alamos National Laboratory in New Mexico. The results of the find will be reported in two papers in the June 12 issue of the journal Nature.
The research team also unearthed skull pieces and teeth from seven other hominid individuals, hippopotamus bones bearing cut marks from stone tools, and more than 600 stone tools, including hand axes. All are from the same sediments and, thus, the same era.

“These were people using a sophisticated stone technology,” White said. “Using chipped hand axes and other stone tools, they were butchering carcasses of large mammals like hippos and buffalo and undoubtedly knew how to exploit plants.”
They lived long before most examples of another early hominid, the Neanderthal, or Homo neanderthalensis, proving beyond a reasonable doubt, White said, that Homo sapiens did not descend from these short, stocky creatures. More like cousins, Neanderthals split off from the human tree more than 300,000 years ago and died out about 30,000 years ago, perhaps driven to extinction by modern humans.
“These well-dated and anatomically diagnostic Herto fossils are unmistakably non-Neanderthal,” said Howell, a co-author of the Nature paper that details the hominids and an expert on early modern humans. “These fossils show that near-humans had evolved in Africa long before the European Neanderthals disappeared. They thereby demonstrate conclusively that there was never a Neanderthal stage in human evolution.”

Because the Herto fossils represent a transition between more primitive hominids from Africa and modern humans, they provide strong support for the hypothesis that modern humans evolved in Africa and subsequently spread into Eurasia. This hypothesis goes against the theory that modern humans arose in many areas of Europe, Asia and Africa from other hominids who had migrated out of Africa at a much earlier time.

The fossil evidence, said Asfaw, “clearly shows what molecular anthropologists have been saying for a long time – that modern Homo sapiens evolved out of Africa. These fossilized skulls from Herto show that modern humans were living at around 160,000 years ago with full-fledged Homo sapiens features. The ‘Out of Africa’ hypothesis is now tested, (and) we can conclusively say that Neanderthals had nothing to do with modern humans. They went extinct.”

The fossil skulls
The three fossil skulls remain in Ethiopia, but replicas made from them were compared by the research team with many examples of Neanderthal and earlier hominid skulls, as well as those of modern humans. Many of the modern human comparison skulls came from a worldwide sample of skeletal remains in the collection of UC Berkeley’s Hearst Museum of Anthropology.

The most complete of the three new fossil skulls, probably that of a male, is slightly larger than the extremes seen in modern Homo sapiens, yet it bears other characteristics within the range of modern humans – in particular, less prominent brow ridges than pre-Homo sapiens and a higher cranial vault. Because of these similarities, the researchers placed the fossils in the same genus and species as modern humans but appended a subspecies name – Homo sapiens idaltu -to differentiate them from contemporary humans, Homo sapiens sapiens.

Idàltu, which means “elder” in the Afar language, refers to the adult male’s antiquity and individual age. The man, though probably in his late 20s to mid-30s, had heavily worn upper teeth and a brain size slightly larger than average for living people.
Scientists tracking evolution through changes in mitochondrial DNA, which is passed from mother to daughter, have estimated that humans derive their mitochondrial genes from an ancestral mother nicknamed “Eve” who lived in Africa about 150,000 years ago. Other scientists studying the male Y chromosome have reached similar conclusions. The new Herto fossils are from a population living at exactly this time.

“In a sense, these genetic findings were impossible to seriously test without a good fossil record from Africa,” said White. “Back in 1982, when Becky Cann and Allan Wilson of UC Berkeley were using molecules to study evolution, they concluded that the common ancestors of all modern humans lived in Africa 100,000 to 200,000 years ago. For the last 20 years we’ve been looking for good, well-dated fossil evidence of that antiquity.”

Previously found fossils were younger, from sites scattered around Africa, often poorly dated and incomplete. These include fossil skull fragments from Klasies River Mouth in South Africa, dating from about 100,000 years ago, and Middle Eastern fossils from Qafzeh and Skhul dating from 90,000 to 130,000 years ago. Ethiopia has yielded some modern human fossils, including those from Omo, which are approximately 100,000 years old, and the Aduma fossil finds of the Middle Awash, which date from about 80,000 years.

While these previous discoveries appear also to be Homo sapiens, the new finds from Herto are older, well-dated and more complete without sharing characteristics of more primitive human ancestors such as Homo erectus or the Neanderthals.

Discovery
The fossil-rich site was discovered on Nov. 16, 1997, in a dry and dusty valley bordering the Middle Awash River near Herto, a seasonally occupied village. During a reconnaissance, White first spotted stone tools and the fossil skull of a butchered hippo emerging from the ground. When the team returned to intensively survey the area 11 days later, they discovered the most complete of the adult skulls protruding from the ancient sediment. It had been exposed by heavy rains and partially trampled by herds of cows.

A portion of the large adult’s left front cranium (the braincase) had been crushed and scattered, but the team was able to excavate the rest of the skull, minus the lower jaw, and reconstruct it.
The child’s skull, found nearby, was fragmented and scattered from having been exposed for many years. The team recovered most pieces of the cranium, more than 200 in all, from a 400 square-foot area, and Asfaw painstakingly pieced them together over a period of three years.

The team also recovered more than 640 stone artifacts, though they estimate that the entire Herto area contains millions of such artifacts: hand axes, flake tools, cores, flakes and rare blades. Renowned African prehistorian J. Desmond Clark of UC Berkeley analyzed many of them before his death in February of last year. Clark and colleagues Dr. Yonas Beyene of Ethiopia’s Authority for Research and Conservation of the Cultural Heritages and Dr. Alban Defleur of Marseilles, France, concluded that the stone tools were transitional between the Acheulean period, characterized by a predominance of hand axes, and the later flake-dominated Middle Stone Age.
“The associated fossil bones show clearly that the Herto people had a taste for hippos, but we can’t tell whether they were killing them or scavenging them,” said Beyene. “These artifacts are clues about the ancestors who made them.”

Ancient lake shore
The early humans at Herto lived along the shores of a shallow lake created when the Awash River temporarily dammed about 260,000 years ago. The lake contained abundant hippos, crocodiles and catfish, while buffalo roamed the land.
The sediments and volcanic rock in which the fossils were found were dated at between 160,000 and 154,000 years by a combination of two methods. The argon/argon method was used by colleagues in the Berkeley Geochronology Center, led by Paul R. Renne, a UC Berkeley adjunct associate professor of geology. WoldeGabriel of Los Alamos National Laboratory and Bill Hart of Miami University in Ohio used the chemistry of the volcanic layers to correlate the dated layers.
The Middle Awash team consists of more than 45 scientists from 14 different countries who specialize in geology, archaeology and paleontology. In this single study area, the team has found fossils dating from the present to more than 6 million years ago, painting a clear picture of human evolution from ape-like ancestors to present-day humans.

“The human fossils from Herto are near the top of a well-calibrated succession of African fossils,” White said. “This is clear fossil evidence that our species arose through evolution.”

The work was funded by the National Science Foundation and the Institute of Geophysics and Planetary Physics at Los Alamos National Laboratory, in combination with the Hampton Fund for International Initiatives of Miami University and the Japan Society for the Promotion of Science.

Source: University Of California, Berkeley – March 5, 2004

Ardipithecus

New Ethiopian Fossils Are From 6-million-year-old Hominid Living Just After Split From Chimpanzees

BERKELEY Paleoanthropologists from the University of California, Berkeley, and the Cleveland Museum of Natural History have found more fossils of a nearly 6-million-year-old human ancestor first reported three years ago, cementing its importance as the earliest hominid to appear after the human line diverged from the line leading to modern chimpanzees.
When first reported in the journal Nature in 2001, the hominid was named Ardipithecus ramidus kadabba, a subspecies of a younger hominid, Ardipithecus ramidus, also from the Middle Awash region of Ethiopia. The new fossils – six teeth – provide enough evidence to designate the hominid a distinct species, Ardipithecus kadabba, rather than a subspecies of Ardipithecus ramidus.
“Ardipithecus kadabba may also represent the first species on the human branch of the family tree just after the evolutionary split between lines leading to modern chimpanzees and humans,” said Yohannes Haile-Selassie, curator and head of physical anthropology at the Cleveland museum.
Haile-Selassie and coauthors Tim White of UC Berkeley and Gen Suwa of the University Museum at the University of Tokyo report their fossil finds in the March 5 issue of the journal Science.
Between 1997 and 2000, Haile-Selassie excavated 11 hominid fossils from at least five individuals who once lived in a wooded environment, now a dry, rocky area in the Afar rift of Ethiopia’s Middle Awash region. He and White, along with geologist Giday WoldeGabriel of Los Alamos National Laboratory, interpreted the bones as those of a bipedal hominid about the size of a chimpanzee living between 5.2 and 5.8 million years ago.
The six new teeth were found during a one-month excavation in 2002 at one site, Asa Koma (“Red Hill”) Locality 3, that yielded a fragment of an arm bone and an isolated tooth during the earlier surveys. Asa Koma is located along the western margin of the Middle Awash study area about 180 miles northeast of the Ethiopian capital, Addis Ababa.
The teeth sieved from the sediments include an upper canine, premolars from both jaws, and upper molars. All of these were from deposits sandwiched between volcanic horizons dated by the argon/argon method to between 5.54 and 5.77 million years. The dating work was done at the Berkeley Geochronology Center by Paul Renne, adjunct professor of earth and planetary science at UC Berkeley.
Though the scientists now have only 17 specimens, mostly teeth, from this hominid, the fossils nevertheless tell much about how these creatures lived. The teeth, in particular, are critical in differentiating between ape and human fossils.
“In all the great apes – and that includes fossil and modern – the large, tusk-like, projecting, shearing canine teeth are used as weapons, and in most of them the main use is in males fighting with other males for access to estrus females,” White said. “The earliest hominids lack that adaptation, showing much smaller canines that are not at all chimpanzee-like.”
In the apes, the upper canine is continually honed against the lower third premolar to keep it sharp. Human canines lack that function, White said.

The implication of this dental difference is that the newly evolved hominids were living in a radically different, less competitive social structure than seen in modern chimps, he said. Anthropologist Owen Lovejoy proposed in the 1980s that reduced canines among early hominids showed that males had become more involved in the parenting process, and that the carrying of infants and food was strong selective pressure toward a musculoskeletal system adapted to walking on two legs.
The new fossils show the most primitive canines ever found among hominids.
“We see wear facets on the premolar in Ardipithecus kadabba which A. ramidus doesn’t have,” Haile-Selassie said. “We don’t really know whether some A. kadabba individuals had functional honing – we just have one sample here – but we’re saying that the primitive shape and the presence of this facet on the upper canine and the lower premolar distinguishes A. ramidus from A. kadabba, so that it becomes a species of its own.”

The researchers note two other sites that have yielded fossil hominids from the same 5- to 6-million-year period. One group of fossils found in 2002 in Chad has been named Sahelanthropus tchadensis, while others found at a Kenyan site in 2000 have been dubbed Orrorin tugenensis. All of these fossils are sufficiently similar that they should be included in the same genus as Ardipithecus kadbba, the team argues.
The Middle Awash field work was funded by the National Science Foundation and The Institute of Geophysics and Planetary Physics at Los Alamos National Laboratory.

http://www.eurekalert.org/pub_releases/2003-06/uoc–1fs061003.php
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Oldest modern human fossil discovered in Ethiopia
By Frank Gaglioti
25 July 2003
A team of 45 scientists from 14 different countries led by Professor Tim White from Berkeley University has uncovered and assembled three fossilised skulls from Ethiopia that provide the oldest record of modern humans. The fossils give strong support to what is known as the Out of Africa theory: that humans first evolved in Africa and then migrated to other regions and ultimately the entire globe.
The landmark discovery was made public in the scientific journal Nature on June 12. The find was made in 1997 in an arid valley close to the Middle Awash River near the village of Herto, 225 kilometres northeast of Addis Ababa. The three skulls—two adults and one child—were so fragmented that it took five years to piece them together and were dated at 160,000 years old using the Argon-Argon method. The dating was quite precise as the fossils were found between two layers of volcanic ash.
Scientists regard the features as just within the range of modern humans, but including more primitive traits such as a slightly larger brain case. White described the skulls as “near-modern”. The fossils have been classified as true humans, that is Homo sapiens, but the sufficient differences from modern man to assign them to a new subspecies—idàltu, the word for “elder” in the local Afar language. Our subspecies is Homo sapiens sapiens or wise ape.

The fossils were found along with the skull pieces and teeth of several other humans, the bones of butchered hippopotamuses and buffalos and over 600 stone tools. The animal bones had been crushed in order to remove the marrow. The tool kit was from a transitional period between the early Stone Age, characterised by a predominance of hand axes, and the later flake-dominated tools of the Middle Stone Age.
The tools indicated “these were people using a sophisticated stone technology,” White explained. They were “using chipped hand axes and other stone tools, they were butchering carcasses of large mammals like hippos and buffalo and undoubtedly knew how to exploit plants.”

The skulls showed signs of being used for ritual purposes. The child’s skull was worn smooth, as if from constant handling, probably as part of some ceremony. One of the adult skulls has a set of parallel scratch marks similar to those made by tribal people in New Guinea, who preserved and worshipped the skulls of their ancestors.

Unusually, the crania were found without any other bones, including jaws, another indication they were probably carried around for ritual purposes. White explained that the people “were moving the heads around on the landscape. They probably cut the muscles and broke the skull bases of some skulls to extract the brain, but why, whether as part of a cannibalistic ritual, we have no way of knowing.”
The age of the Homo sapiens idàltu fossils gives an insight into a period completely outside the range of earlier discoveries. Previous human fossils were only from about 100,000 years ago. Their dating was imprecise and the fossils incomplete. The latest discovery is especially significant as the age of the fossils fits with the predictions made by the Out of Africa theory for the likely emergence of modern humans.
Although anthropologists for some time considered Africa the most likely region for the evolution of the first humans, the Out of Africa theory dates from the work of Mark Stoneking, Allan Wilson and Rebecca Cann in 1987 at Berkeley University. Using modern genetic techniques, they compared DNA sequences from African, Asian, Australian, Caucasian and New Guinean populations. They analyzed genetic variations to reveal a family tree, which had two branches—the central and oldest branch originating in Africa and a later split forming a second branch that spread out of Africa into Europe and Asia.
The theory proved controversial. Other scientists held to a multiregional theory: that the more primitive Homo erectus originally evolved in Africa and then migrated to Europe and Asia about one million years ago, where the largely separated populations evolved into modern man. The multiregional theory holds that racial traits can be traced back to our Homo erectus ancestors, although its adherents also allowed for a limited exchange of genetic material between the evolving populations in Africa, Asia and Europe.

The age of the Herto fossil find fits within the 100,000- to 200,000-year timeframe predicted by the Out of Africa theory for the emergence of modern humans. White noted: “In a sense, these genetic findings were impossible to seriously test without a good fossil record from Africa. Back in 1982, when … [Cann and Wilson] were using molecules to study evolution, they concluded that the common ancestors of all modern humans lived in Africa 100,000 to 200,000 years ago. For the last 20 years we’ve been looking for good, well-dated fossil evidence of that antiquity.”
The Out of Africa theory also predicted that the migrating Homo sapiens displaced earlier Neanderthal populations which inhabited Europe, the Near East, Central Asia and probably western Siberia. The Neanderthals, whose features were more primitive than modern humans, lived from 200,000 to about 30,000 years ago, when they became extinct. Whether Neanderthals were driven out by modern man or form a part of the evolution of modern man has been hotly debated.

The three Ethiopian skulls were found to have no Neanderthal features at all. Berkeley University professor F. Clark Howell commented: “These fossils show that near-humans had evolved in Africa long before the European Neanderthals disappeared. They thereby demonstrate conclusively that there was never a Neanderthal stage in human evolution.”

Proponents of the multiregional theory consider Neanderthals as an earlier primitive stage in the development of modern Europeans. Dr. Milford Wolpoff of the University of Michigan, a leading multiregionalist, dismissed the significance of the latest discovery claiming that, “all the specimens show is that there was a trend of evolution in Africa toward modernity, just as there was in China and Europe”.
While the latest fossil discovery may not have provided the definite answer, it certainly adds weight to the Out of Africa theory and, in doing so, confirms the great potential of genetic analysis as a tool for evolutionary investigation. The debate—Out of Africa versus Multiregional—will undoubtedly continue as further investigations shed more light on the diverse and complex nature of human evolution.
See Also:
New fossil may revise the timeline for hominid evolution
[14 August 2002]
Research suggests a more complex evolution and spread of modern humans
[20 April 2002]
New fossil discovery shows earlier human migration out of Africa
[29 May 2000]
New fossil find provides important clues to man’s prehistory
[5 May 1999]
A highly significant discovery
Oldest human-like fossil uncovered in South Africa

[30 December 1998]

Australopithecus afarensis “Lucy” Skull, Half Scale

3.2 MYA. The first discovery of an Australopithecine was made by Donald Johanson in 1974 in Hadar, Ethiopia. “Lucy” was a young female about 3 ½ ft tall. She had an ape-sized brain, while the postcranial skeleton suggested she walked upright. This combination of an ape-sized brain in a hominid adapted to upright walking adds to the evidence that bipedalism occurred before the development of a relatively large brain.

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Lucy-Reconstruction-John-Gurche-1200×627

These bones of an early member of Homo sapiens, known as Omo I, were excavated in Ethiopia. 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 has determined that Omo I lived about 195,000 years ago—the oldest known bones of “modern” humans.

Photograph courtesy John Fleagle, Stony Brook University

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Oldest Human Fossils Identified
Hillary Mayell
for
National Geographic News
February 16, 2005
Human fossils found 38 years ago in Africa are 65,000 years older than previously thought, a new study says—pushing the dawn of “modern” humans back 35,000 years.
New dating techniques indicate that the fossils are 195,000 years old. The two skulls and some bones were first uncovered on opposite sides of Ethiopia’s Omo River in 1967 by a team led by Richard Leakey. The fossils, dubbed Omo I and Omo II, were dated at the time as being about 130,000 years old. But even then the researchers themselves questioned the accuracy of the dating technique.

The new findings, published in the February 17 issue of the journal Nature, establish Omo I and II as the oldest known fossils of modern humans. The prior record holders were fossils from Herto, Ethiopia, which dated the emergence of modern humans in Africa to about 160,000 years ago.

“The new dating confirms the place of the Omo fossils as landmark finds in unraveling our origins,” said Chris Stringer, director of the Human Origins Group at the Natural History Museum in London.
The 195,000-year-old date coincides with findings from genetic studies on modern human populations. Such studies can be extrapolated to determine when the earliest modern humans lived.

The findings also add credibility to the widely accepted “Out of Africa” theory of human origins which holds that modern humans (later versions of Homo sapiens) first appeared in Africa and then spread out to colonize the rest of the world.
The new date also widens the gap between when anatomically modern humans emerged and when “cultural” traits—such as the creation of art and music, religious practices, and sophisticated tool-making techniques—seem to have appeared. Evidence of culture is not extensively documented in the archaeological record until around 50,000 years ago.

The wider gap could add fuel to a long-term debate swirling around when modern human behavior, as opposed to modern human anatomy, emerged.
“Those who believe that there is widely scattered evidence of ‘modern’ behavior going back 200,000 years in Africa will be delighted that modern human anatomy also goes back that far,” said John Fleagle, a physical anthropologist at Stony Brook University in New York and one of the co-authors of the study. “[Scientists] who believe that modern human behavior only appeared abruptly about 50,000 years ago will see [the new date as] further expanding the distinction and the temporal gap between modern anatomy and modern behavior.”

Dating Through Geology
Somewhat surprisingly, the first thing the scientific team had to do to come up with the new dates was to relocate the precise location where the fossil remains had been excavated in 1967. They were able to do this using National Geographic Society video footage taken during the first excavation. They also used photographs taken by Karl Butzer, a geologist currently at the University of Texas, who did the original geological studies of the site. Also helpful were hand-drawn maps from the late Paul Abell, another member of the 1967 team.
“So we know where Omo I and Omo II are now, and they’re now documented by GPS, so they won’t get lost again. But we didn’t have GPS 40 years ago,” said Frank Brown, a geologist at the University of Utah and a co-author of the study.
The remains of Omo I and Omo II were buried in the lowest sediment layer, called Member 1, of the 330-foot-thick (100-meter-thick) Kibish rock formation near the Omo River.

In addition to GPS, more advanced dating techniques have also been developed. The researchers sampled the volcanic ash on both sides of the river that lay above where the fossils were found. The ash was the same on both sides.
“Then we had to find something to date, and what that takes is a lot of walking,” Brown said. “Most of the ashes are very fine grained, they don’t have pumice [fragments] in them, so you go along and you go along, and eventually you find a place where there are pumices.”

The presence of feldspar crystals from a volcanic eruption inside pumice fragments is an indication that the crystals have not been contaminated. Such unadulterated crystals can be dated using a technique called potassium-argon dating.
“By dating the crystals held in the pumice, you can say with a high level of confidence that everything in that member [group of sediment layers] is nearly the same date,” Brown said. “We used a dating technique called 40AR/39AR, which is a variant of potassium-argon dating.”
In the same Member 1 sediment layers, the team found additional Omo I bones, animal fossils, and stone tools.
The work was funded by the National Geographic Society, the National Science Foundation, the L.S.B. Leakey Foundation, and the Australian National University.

Widening the Gap
Although both Omo I and Omo II were classified as Homo sapiens in 1967, the Omo II remains were considered much more primitive. Finding that the two individuals lived at around the same time in the same location suggests that, when modern humans first appeared, there were other, less modern populations also on the scene. The finding may add some new perspective to how we think about how and when “modern” human anatomy evolved.
“I have previously regarded Omo II as an archaic or primitive H. sapiens and Omo I as a modern H. sapiens, which would make them the same species,” Stringer said. “If Omo I and II do belong together, the variation in the population is greater than I expected, but given what we see in larger fossil samples from other regions, we may need to accept that African populations showed large [physical-form] variation at this time.”
Everyone agrees that the Omo II cranium is more primitive than the Omo I skull in many features, Fleagle said.
“Some see the two as part of a continuum, others see them as very distinct types of hominid,” he said. “Whether Omo II gets put in Homo sapiens depends upon where one draws the boundary between H. sapiens and whatever species comes before—H. ergaster, H. erectus, H. heidelbergensis.

“Regardless of how Omo II is classified, ” he continued, “I don’t consider it surprising to find two different morphologies existing at the same time. We know that Homo sapiens and Neanderthals existed in Europe at the same time and that in the early Pleistocene [epoch] there was diversity of early hominid morphologies [or body forms]. Indeed, virtually every site that has early modern humans … seems to show a diversity of morphologies with some more modern and some less so.”
Exactly when modern behavior, as opposed to modern anatomy, emerged—indeed even how to define modern behavior—is another area in which the Omo fossils might contribute some insight. Common elements used to define modern behavior include planning ahead; innovating technologically; establishing social and trade networks; adapting to changing conditions and environments; and exhibiting symbolic behavior like cave painting, bead-making (used to show status or group identity), or burying the dead.

The crux of the argument comes down to whether these abilities resulted from a sudden biological and genetic revolution or from a more gradual evolution of abilities that culminated around 50,000 years ago.
“I think we are still determining when “modern” behavior started to evolve, and my guess is that it too will have deeper roots in Africa,” Stringer said. “There is growing evidence that elements of modern behavior were there a hundred thousand years ago, and I think the gap or mismatch between the emergence of modern anatomy and modern behavior may well be much less significant than currently believed.”
Spencer Wells is a geneticist and an anthropologist and a National Geographic Emerging Explorer. From an analysis of DNA of thousands of men around the world, Wells says he has discovered that all humans alive today can be traced back to a small tribe of hunter-gatherers who lived in Africa 60,000 years ago.

“Many anthropologists, myself included, believe that what makes us truly human is our modern behavior, enabled by a modern brain,” Wells said. “Modern behavior starts to show up sporadically around 70,000 to 80,000 years ago but doesn’t really take off until around 50,000 years ago—the “Great Leap Forward” and dawn of the Upper Paleolithic [early Stone Age].”

The human population appears to have crashed to around 2,000 individuals around 70,000 years ago, at the same time they were headed into the worst part of the last ice age. The crash was possibly brought on by a massive volcanic eruption, Wells said.

“The hypothesis is that the survivors of this near-extinction event had to be smarter in order to survive, and this allowed them to settle the rest of the world outside of Africa. So, ‘human-ness’ may not been widespread until around 50,000 to 60,000 years ago, and this could be seen as the real origin of our species.”
Source: http://news.nationalgeographic.com/news/2005/02/0216_050216_omo.html

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Hominid Fossils Are Likely 3.8 to 4 Million Years Old

A team led by Drs. Yohannes Haile-Selassie and Bruce Latimer of the Cleveland Museum of Natural History, Cleveland, Ohio, has been conducting a paleoanthropological survey in the Mille-Chifra-Kasa Gita area of the Afar Region.

The survey was conducted under a permit from the Authority for Research and Conservation of Cultural Heritage (ARCCH) of the Ministry of Youth, Sports, and Culture and was financially supported by the Leakey Foundation and the Wenner-Gren Foundation of the United States of America. The team located new hominid-bearing localities in the Burtele Kebele of Mille district in Zone One of the Afar Regional State.

The survey team has designated 14 new fossil bearing localities. Three of the localities have yielded early hominid remains. Major fossiliferous areas are around the Mille River east of Mille Town. Mille is 520 KM northeast of Addis Ababa, and the new site is approximately 60 kilometers north of the famous Lucy site. Several additional areas have been documented as fossiliferous although localities were not designated and fossils were not collected.

THE FOSSILS

The survey team collected a number of fossils that were exposed on the ground’s surface. In their exposed position, these specimens could be subjected to erosional forces and had to be collected before they were seriously damaged or destroyed. A total of 12 early hominid fossil specimens were discovered, including parts of one individual’s skeleton. Portions recovered thus far include a complete tibia, parts of a femur, ribs, vertebrae, clavicle, pelvis, and a complete scapula of an adult whose sex and stature are yet to be determined, although it is already clear that the individual was larger than Lucy. In addition to this discovery, skeletal parts of other individuals were found in different localities in the area. These discoveries include isolated teeth, and elements from below the neck (arm bones, leg bones, phalanges). The non-hominid fossil assemblage includes animals such as monkeys, horses, large and small carnivores, a variety of antelopes multiple species of pigs, giraffes, rhinoceros, elephants, and deinotheres. Among small mammals, porcupines, cane rats, and other species of rats were discovered. The faunal assemblage also includes crocodiles, fish, and hippopotamus.

GEOLOGY AND DATING

Exposed sediments in the new fossiliferous area are mostly silty sand and silty clay horizons interbedded with a number of volcanic tuffs and basaltic flows suitable for dating. The total section in the area is estimated to be about 50 meters thick. Geochronologist Dr. Alan Deino has collected 16 rock samples and the most critical samples above and below the fossiliferous horizon will be dated soon at the Berkeley Geochronology Center in Berkeley, California. The estimated age of the site, based on preliminary field analysis of the associated animal fossils, is roughly 3.8 to 4 million years. However, confirmation has to await radiometric dating of the rock samples.

SIGNIFICANCE

Based on the associated animal remains, the team believes that the hominid fossils are likely between 3.8 to 4 million years old. This will place the new fossils in time between the earlier 4.4 million year old Ardipithecus ramidus partial skeleton and the younger 3.2 million year old “Lucy” partial skeleton of A. afarensis. The team hopes that the new discoveries will allow scientists to connect the dots — furthering our knowledge of this important time period in human evolution. Numerous highly important scientific issues will be tackled by the researchers as work continues. However, it is already clear that planned scientific studies of this once in a lifetime discovery will tell us much about how our four-million-year-old ancestors walked, how tall they were, and what they looked like.

Haile-Selassie says that it is too early to tell what species is represented by these hominids. This is because the remains are embedded in adhering silt and stone, which now must be removed under a microscope. Comparative studies are then planned, and will be conducted as excavation proceeds. The associated plant and animal fossils and embedding sediments will also be subjected to study by specialists in order to further refine the age and environmental conditions.

FUTURE PROSPECTS

The team emphasizes that this discovery and its announcement represent the opening of a new door on a poorly known time period. Years of research lie ahead. The new fossiliferous areas are very promising. There is a high chance of recovering more fossil hominids. These hominids will be important in terms of understanding the early phases of human evolution before Lucy. With permit from the Authority for Research and Conservation of Cultural Heritage (ARCCH), the team will continue the search and collection of additional fossil hominids and also excavate next year in an attempt to find the rest of the bones of this skeleton.

Africa is the cradle of human race. Anthropologists have unearthed the oldest human skeletons in East Africa in places such as Hadar, Olduvai, Laetoli. One of the best preserved human remnants is a female skeleton found at Hadar in Ethiopia. Anthropologists assembled about 40% of the young girl that was given the nick name “Lucy”. Lucy was dated between 3.8 and 3 million years ago and belongs to the Australopethicus category.

HADAR
Hadar’s paleontological and anthropological significance was discovered in 1968 by M. Taieb, a French geologist. Taieb organized a geological and paleontological survey of the area in 1971, in which he was joined by D.C. Johanson, Y. Coppens, and J. Kalb. These workers formed the International Afar Research Expedition (INRE). They chose Hadar from the many other available sites to begin intensive investigation mainly because of its excellent preservation of faunal remains.

During the initial field season in 1973 the first early hominid fossils were recovered from Hadar, a knee joint and a partial temporal. Nearly 6,000 fossils of mammals, a total of 87 species, were recovered in 1973 and in subsequent seasons. In the fall of 1974 a larger team returned to continue the search and soon made a discovery of hominid teeth.
At the end of November D.C. Johanson discovered at locality 288 the partial skeleton of a tiny female hominid, which was nicknamed “Lucy.” The 1975 field season brought even more hominid remains, this time at Locality 333. This locality has been interpreted as evidence for the catastrophic death of a group of hominids. The 333 site yielded, by the close of excavations during the 1976-1977 field season, hundreds of hominid fossil fragments derived from at least 13 individuals representing all ages. All of the Hadar fossils were returned after study to the National Museum of Ethiopia in Addis Ababa, where they are permanently housed.
The Hadar Formation consists of at least 280 m. of sediment. Over 100 stratigraphic sections have been studied thus far, and it has been possible to subdivide the sedimentary sequence into four stratigraphic members. Radiometric dating has dated the top of the Hadar units at ca. 2.9 million years (m.y.) ago. Dating for the lower units has been more controversial, with estimates 3.6 and 3.3 m.y. ago. Thus it can be stated confidently that the “Lucy” specimen is ca. 3 m.y. old, while some of the other, stratigraphically lower Hadar hominids are at least 3.3 and possibly as much as 3.6 m.y. old. [Source: Ian Tattersall, et al. eds, Encyclopedia of Human Evolution and Prehistory (Chicago: St James Press, 1988), pp. 239-241]

STONE-TOOL MAKING
The first humans used sharp stones as tools. “The emergence of a flaked-stone technology during the course of hominid evolution marks a radical behavioural departure from the rest of the animal world and constitutes the first definitive evidence in the prehistoric record of a simple cultural tradition, or one based upon learning. Although other animals Archaeological evidence shows a geometric increase in the sophistication and complexity of hominid stone technology over time since its earliest beginnings 3-2 m.y. ago. Stone is the principal material found in nature that is both very hard and able to produce superb working edges when fractured A wide range of tasks can be performed such as meat cutting and bone breaking”. [quoted from Tattersall et al.eds, op.cit., p. 542].

 

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Human Fossil Adds Fuel to Evolution Debate

Hillary Mayell
for National Geographic News
March 25, 2002

A one-million-year-old partial skull found in Ethiopia has added new fuel to the human origins debate among paleoanthropologists.

The skull cap and several other bones from seven individuals—all Homo erectus— were found in a one-million-year-old layer of sediments known as the Dakanihylo Member.

Ancient Controversy
Do hominid fossils from one to two million years ago represent a single species or numerous branches on the family tree, some of which died out? A one-million-year-old skull cap from Ethiopia rekindles the debate on this issue (above is a reconstruction of a Homo erectus skull).

Photograph by Bettmann/CORBIS

Reporting in the March 21 issue of the journal Nature, an international team of researchers says the skull provides yet another piece of evidence that a single human ancestor, Homo erectus, ranged across Europe, Asia, and Africa as long ago as 1.8 million years.
For the last two decades, the question of whether fossils discovered from between two million and one million years ago represent one species or numerous branches on the family tree, some of which died out, has been a hot button of debate.
Tim White, a paleoanthropologist at the University of California, Berkeley and co-author of the study in Nature, believes the partial skull found in Ethiopia resolves that question. “The matter of early hominid distribution and species count is solved—one [species] at a million [years], from Spain to China to Java to Africa,” he said.
The skull, he said, represents an evolutionary intermediate step linking older, more primitive forms of the species with younger, more human-like forms.
Other experts, however, disagree with that conclusion, and the issue remains controversial.

Piecing Together Fossil Evidence
The partial skull generating all the excitement was found near the village of Bouri in Ethiopia in what is called the Middle Awash study area. Based on fossils discovered in earlier digs, hominids appear to have lived in the area for nearly six million years.
Proponents of the “bushy tree”/multiple-species view argue that African fossils dating to about two million years ago belong to Homo ergaster. Homo erectus, the thinking goes, split off about 1.6 million years ago, and existed only in Asia. The Asian branch was an evolutionary dead end, and the species Homo erectus died off.
Under this scenario, modern humans evolved from the original African branch of Homo ergaster.

The caves and volcanic soil of Africa are extremely conducive to fossil preservation, and scientists have been able to accurately date African fossils. Fossils found in Eurasia and Asia, however, are more difficult to date and until recently were thought to be much younger than those found in Africa. “Java man” of Indonesia, for instance, was originally placed in the 500,000-year-old range.
The nearly one-million-year difference between African and Asian fossils, along with the more primitive features of the early African fossils, contributed to the idea that Homo ergaster and Homo erectus were two species.

New technology has allowed for more precise dating of fossils, and recent reassessments put the age of Java man at about 1.5 million years old, contemporaneous with other fossil finds in Africa. The age of fossils found in China has similarly been revised upward.
In addition, the researchers found that even taking precise measurements, it was impossible to differentiate between the skulls from Asia, Africa, and Eurasia.
The Daka fossils show that as of one million years ago, Homo erectus was probably a single species with gene flow across its known range from Java to Italy to Ethiopia, concluded Henry Gilbert, one of the study’s co-authors and a biologist at the University of California, Berkeley.

“Lumpers” and “Splitters”
The underlying definition of a species is a group of organisms with common attributes, capable of interbreeding. The question is, how different is acceptable?
Paleoanthropologists generally fall into one of two categories based on their views of how much variation can exist within species. “Lumpers,” such as White and his team, believe there can be a wide range of variation within a species. “Splitters”—the “bushy tree folk,” in White’s term—regard the amount of variation seen in the known fossils as indicative of different species.

Susan Anton, a paleoanthropologist at Rutgers University, said human origins research is complicated because scientists look at fossils across large geographic ranges and spans of time, and try to reach conclusions based on morphological evidence from a small number of fossils.

The situation is comparable to a researcher, one million years from now, looking at a few fossil remains of an African pygmy and an NBA basketball player. Both are members of the same species, but their features represent a lot of variation within the species. Without genetic or other supporting evidence, it’s easy to see how questions could arise among anthropologists of the future.
Anton takes a middle-of-the-road position on the single-species versus multiple-species debate, saying she’s willing to consider “one species with some serious morphs.”
Susan Anton, a paleoanthropologist at Rutgers University, said the Ethiopian skull is “a great specimen and shows some really neat things,” but she is not convinced it bears out White’s claim that the fossil points to a single ancestor one million to two million years ago.
Early African fossils, she explained, have morphological characteristics that are very different from those of island Southeast Asia. “The Daka fossil still shows very African features,” she said. “I was expecting the specimen to show more of a mix of Asian and African morphology.”

Fossils From Ethiopia May Be Earliest Human Ancestor
David Perlman
San Francisco Chronicle
July 12, 2001

A team of scientists led by an anthropologist at the University of California-Berkeley has discovered the fossilized remains of what they believe is humanity’s earliest known ancestor, a creature that walked the wooded highlands of East Africa nearly 6 million years ago.

The discovery, which occurred in the Middle Awash River Valley of Ethiopia, is already challenging some existing theories about the ancestral lineage of humans. It is also changing scientific views about the nature of the environment that fostered the evolution of pre-humans as they moved from verdant forests to open grasslands.

The team reporting the discovery in the July 12 issue of the journal Nature was led by two Ethiopian scholars: Yohannes Haile-Selassie, an anthropologist still working on his doctorate at the University of California at Berkeley, and Giday WoldeGabriel, a geologist now at UC’s Los Alamos National Laboratory in New Mexico.

Discovery Site in Ethiopia

The dry washes of the Middle Awash River Valley in Ethiopia are home to a recent discovery of what is believed to be the fossilized remains of humanity’s earliest known ancestor.

Copyright 2001 National Geographic Society

The fossils were gathered during four years of demanding expeditions to a harsh and hostile Ethiopian scrubland where lions and cheetahs hunt at night and few people roam the semi-desert wilderness by day.
The remains include a jawbone with teeth, hand bones and foot bones, fragments of arms, and a piece of collarbone. But most important, the bones also included a single toe bone. Its form provides strong evidence that the pre-human creatures walked upright, the scientists said.
The toe bone is a crucial clue to the earliest days of human evolution as it developed soon after the ancestral lines of apes and humans split apart, perhaps 6 million to 8 million years ago.

Lingering Questions
The fossils in Ethiopia were dated by Paul R. Renne of the Berkeley Geochronology Center. Renne is a co-author of WoldeGabriel’s report in Nature.
Another co-author is Tim D. White, a paleoanthropologist at UC-Berkeley who in 1994 discovered a pre-human fossil, named Ardipithecus ramidus, that was then the oldest known, at 4.4 million years.
The latest fossils from Ethiopia vary in age from about 5.2 million to 5.8 million years old, according to Renne. Haile-Selassie has tentatively named the fossils Ardipithecus ramidus kadabba, a subspecies of White’s A. ramidus.
In January, a French team headed by Brigitte Senut and Martin Pickford found fossils in Kenya that they dated about 5.8 million years old, from a creature they nicknamed “Millennium Man.” Pickford said the newly discovered fossils in Ethiopia are “virtual contemporaries.”
It’s not yet clear where the fossils of Haile-Selassie and WoldeGabriel belong on the family tree.

The world of paleoanthropology is highly contentious, and scientists have been trying for many decades to sort out the murky ancestry of today’s human race by comparing thousands of fossil bones and skulls. But no evidence is certain and no lineages are clear.
Anthropologists call all the species and sub-species of our ancient ancestors hominids, to distinguish them from the ape lineage, which includes chimpanzees. The two branches—apes and hominids—are believed to have separated and evolved from one common ancestor between 6 million and 8 million years ago.
In a telephone interview from Addis Ababa, where he is analyzing the fossils, Haile-Selassie said he is being extremely conservative, and the fragments he and Wolde Gabriel plucked from the sun-baked ground may represent an entirely new species of pre-human creature.
“It could be the earliest hominid, or it could be a common ancestor, or it gave rise only to the chimpanzee lineage, or it went extinct around 6 million years ago without giving rise to any species,” he said.

Climate Factor
A major mystery in the story of human evolution is how climate affected the environment where creatures that regularly walked upright—the hominids—first emerged. Now, both sets of recent finds—in Ethiopia and Kenya—could help resolve the puzzle.
One widely accepted theory holds that after the ape and hominid lineages split, the earliest human ancestors were forced into the expanding tropical grasslands of the African savanna after the continent’s thick forests dwindled as a result of climate change.
But geochemical analysis of the ancient sedimentary soils where Haile-Selassie’s Ardipithecus creatures lived shows that the region between 5 million and 6 million years ago was well forested, well watered, and rich in woody plants, according to anthropologist Stanley Ambrose of the University of Illinois, who is also a chemist and a co-author of WoldeGabriel’s report in Nature.
The clear inference, according to Haile-Selassie and WoldeGabriel, is that those early human ancestors of the Miocene epoch were already thriving in the forests of a land that was then being shattered by volcanic eruptions, and millions of years later was to become the stony scrubland it is today.
Source – http://news.nationalgeographic.com/news/2001/07/0712_ethiopianbones.html

http://www.pbs.org/wgbh/evolution/humans/humankind/b.html

Laetoli Footprints
The Laetoli footprints were formed and preserved by a chance combination of events — a volcanic eruption, a rainstorm, and another ashfall. When they were found in 1976, these hominid tracks, at least 3.6 million years old, were some of the oldest evidence then known for upright bipedal walking, a major milestone in human evolution. Paleoanthropologist and consultant forensic scientist Owen Lovejoy compares the ancient biped prints with those of modern humans and chimpanzees.
Credits: © 2001 WGBH Educational Foundation and Clear Blue Sky Productions, Inc. All rights reserved.

Laetoli Footprints:

Thank goodness for the irrepressible urge of humans (and other animals) to joke and play around in nearly any situation. Sometimes, it pays big dividends. It certainly did in 1976, when paleoanthropologist Andrew Hill and a colleague were tossing elephant dung at each other in Laetoli, a hominid archeological site in Tanzania. As Hill dived out of the way, he stumbled on what turned out to be one of the wonders of prehistoric finds: a trail of hominid footprints about 3.6 million years old.

The majority of the Laetoli footprint site was excavated in 1978. Until then, the oldest known footprints of human ancestors were tens of thousands of years old. But this trail, some 80 feet long and preserved in cementlike volcanic ash, had been made by some of the first upright-walking hominids. An almost unimaginable sequence of events preserved what paleontologist Ian Tattersall calls a fossil of human behavior — prehistoric walking.

Initially, a nearby volcano called Sadiman erupted a cloud of fine ash, like beach sand, that left a layer on the landscape. Then a light rain fell onto the ash to create something like wet cement — an ideal material for trapping footprints. Birds and mammals left a great number of prints, but, spectacularly, so did a pair of hominids, one large and one small, trekking across the ash. (Some analysts conclude that it is possible to detect the trail of a third, smaller individual whose tracks overlap the footprints left by one of the others.) A subsequent eruption from Sadiman dropped more ash, sealing the footprints like a laminated driver’s license. Finally, erosion over millions of years unveiled the prints for Hill and other researchers in Mary Leakey’s group to discover.

The prints, say experts on hominid body structure, are strikingly different from those of a chimpanzee, and in fact are hardly distinguishable from those of modern humans. The only known hominid fossils of that age in that location are those of Lucy and her kind, the small-brained but upright-walking hominids classified as Australopithecus afarensis. Some analysts have noted that the smaller of the two clearest trails bears telltale signs that suggest whoever left the prints was burdened on one side — perhaps a female carrying an infant on her hip. While the detailed interpretation of the prints remains a matter of debate, they remain an extraordinary and fascinating fossil find, preserving a moment in prehistoric time.
Orrorin tugenensis (6 million years ago)*
*Because fossil evidence for Orrorin tugenensis is scant, a range of dates for when this species lived is not available.
Species Description:
If Orrorin tugenensis is truly a hominid as its discoverers describe it, the species is by far the oldest-known member of the family to which humans belong. In fact, at 6 million years old, O. tugenensis lived near the time when genetic analyses suggest our oldest hominid ancestor split from the oldest ancestor of the great apes. This means that there’s a chance O. tugenensis could be the proverbial “missing link” — or at least one of them.
Certain features, like the teeth of O. tugenensis, suggest this species could even be more closely related to Homo sapiens than the many Australopithecus species it predates. Like our molars, the molars of O. tugenensis were small compared to any of the australopithecine teeth. Their teeth also had very thick enamel like ours.
Grooves in the femurs of O. tugenensis, presumably points where muscles and ligaments attached, suggest that the species was bipedal. Unfortunately, much about this species, including the suggested close relationship between it and Homo sapiens, is extremely speculative and hotly contested.

 Fossil Finds:
   
  Millennium Ancestor
Estimated age: 6 million years
Date of discovery: 2000
Location: Kapsomin, Kenya
Evidence for this species is made up of 13 fossils, including a partial femur, bits of a lower jaw, and several teeth. One of the few things about O. tugenensis that is not controversial is its age. Sediments in which the bones were found have consistently been dated at 6 million years old, making O. tugenensis the oldest hominid by far, if in fact the species is a hominid.

 

 Ardipithecus ramidus (4.4 million years ago)*
*Because fossil evidence for Ardipithecus ramidus is scant, a range of dates for when this species lived is not available.
Species Description:
Ardipithecus ramidus was discovered in December 1992. Although not nearly as old as Orrorin tugenensis, Ar. ramidus is much more widely accepted by the scientific community as a hominid than is O. tugenensis, and thus is considered by some to be the oldest-known hominid.
A partial skeleton and indirect evidence from skeletal fragments indicate that Ar. ramidus may have walked upright. Although considered to be one of the most primitive hominids, Ar. ramidus shares some novel characteristics with much later hominids, namely aspects of its teeth. The molars of Ar. ramidus are smaller than are those of any of the Australopithecus species.
Other fossils found with Ar. ramidus suggest that it may have been a woodland forest dweller. This may modify current theories about why hominids became bipedal in the first place. Walking upright has typically been linked to movement onto the savanna.
(Note: This species has not yet been fully described because some of the specimens have been difficult to extract from the surrounding rock.)
 Fossil Finds:
   
 ARA-VP-1/129
Estimated age: 4.4 million years
Date of discovery: 1992, 1993
Location: Aramis, Ethiopia
A partial lower jaw from a child is one of several fossils known for this species. This partial jaw, catalogued as ARA-VP-1/129, shows very primitive tooth structure relative to later hominid species. Other fossils — including teeth, an adult mandible, pieces of a skull, and several arm bones — show an interesting mix of primitive and advanced characteristics.

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Tracing Human Evolution to its Roots

Molecular evidence suggests that the human line split from the chimp line only about 6 million years ago. Some recent fossil finds date from between 4.1 and 6 million years ago, placing them very close to that evolutionary divergence. Evidence from fossil animals, plants, and soils associated with these early hominids indicate that the environment in which they died was quite densely forested, prompting a reassessment of some of the hypotheses that have been suggested for the origins of human bipedalism.

A series of new fossil discoveries in the 1990s generated great interest among scientists involved in research into human origins, pushing the date for the beginnings of bipedalism back to more than 4 million years before the present — and into a rather different context from the savannah environment which earlier research had suggested.

In 1994, an international team led by paleontologist Tim White announced that they had found a new species of hominid in Ethiopia, dating from 4.4 million years ago. So distinctive were these fossils that the researchers decided that they came not only from a new species, but from a new genus as well, and gave them the name Ardipithecus ramidus. (“Ardi” means ground or floor in the local Afar language, and “ramid” means “root.”)

The teeth of this species are more apelike than those of Australopithecus afarensis fossils like Lucy, and its brain was small. The intriguing question, though, is how it got around. Did Ardithecus ramidus walk bipedally, like modern humans? The fossil was encased in a hard matrix of rock, and the painstaking process of preparing and analyzing it is not yet complete. But some features of the skull suggest that it had some form of upright posture.

If A. ramidus was indeed a biped, a few of the hypotheses that have been suggested for the origin of bipedalism may have to be reassessed. Most of these ideas were based on earlier research which suggested that upright walking evolved at a time when open grasslands were replacing dense forests in the region. But A. ramidus was found with fossil seeds, plants, and animals which show that the environment was densely wooded.

Less than a year later, a team led by Maeve Leakey and her colleagues uncovered a new species of hominid, which they named Australopithecus anamensis (from “anam,” the word for “lake” in the local Turkana language). The fossils were found at two sites in Kenya, Kanapoi and Allia Bay, in the Lake Turkana region. They were found in the sediments of an ancient lake, along with animal fossils that suggest that the environment was a river and gallery forest, grading into more open woodland. Other fossils from Kanapoi include fish and
reptiles. At 4.1 million years old, this new find predates Lucy’s species, A. afarensis, by more than half a million years, and features of the leg bones definitely indicate that A. anamensis stood upright and walked bipedally.

In 2000, a team led by Brigitte Senut and Martin Pickford reported a 6-million-year-old fossil that they named Orrorin tungensis. While its discoverers are confident that Orrorin is a hominid, not every expert is convinced by the evidence presented so far. Some feel that it may prove to be a chimp ancestor — which in itself would be exciting, since so few fossil apes are known — or even the common ancestor of chimps and humans.

More recently still, Yohannes Haile Selassie, a colleague of Tim White, announced the discovery of another fossil which he named Ardipithecus ramidus kadabba, a distinct sub-species of A. ramidus. “Kadabba” means “oldest ancestor” in Afar, and indeed, at between 5.2 and 5.8 million years, A. r. kadabba, like Orrorin, is very close to the date of the split between chimps and humans established by molecular evidence. The fossil animals, plants, and soils at the site show that A. r. kadabba lived in a forested landscape, and details of a toe bone show that it was bipedal, although its gait was probably quite different from anything seen today.

Until more fossils of A. r. kadabba and Orrorin are found and further analysis is completed, it will not be clear how they moved around or just where they fit into the overall picture of human evolution. But there is no doubt that with these latest finds we are getting very close to the root of the human family tree.

Credits: From Biology, by Kenneth R. Miller and Joseph Levine, Copyright © 2002 by Pearson Education, Inc. Reproduced by permission of the publisher.
Oxford research traces early human migration from Africa to Asia

A group of Jarawas who live in isolation on the Andaman Islands Credit: Andaman Association
Research by Oxford University and collaborators has shed new light on the last 100,000 years of human migration from Africa into Asia. The new genetic study confirms that some of the earliest migrants travelled into Asia by a southern route, possibly along the coasts of what are now Pakistan and India. The researchers identified a genetic marker in museum samples of inaccessible populations from the Andaman Islands in the Bay of Bengal. This allowed them to re-interpret previous genetic studies from the Indian sub-continent.

Professor Alan Cooper, Director of the Henry Wellcome Ancient Biomolecules Centre at Oxford University, who led the study, said: ’The findings mark a significant step forward in our understanding of the nature and timing of human settlement of the world outside Africa, and may even give us a glimpse of what these ancient explorers looked like genetically.’

The Andaman Islanders have been an enigma since the early days of Victorian anthropology due to their distinctive physical appearance. They have a very short stature, dark pigmentation and tight curly hair which contrasts with settled populations practising agriculture in the region. The same features link them to other isolated populations throughout Southern Asia, many of whom are hunter-gatherers. This has lead to speculation that these groups might represent the original inhabitants of the region who have either been replaced or absorbed into more recent population expansions. More fancifully, some people have speculated that they are related to African Pygmy populations.

Relationships between different groups of people can be described by analysing mutations in mitochondrial DNA, a genetic component that is passed on maternally. The majority of people in Asia have been shown to carry mitochondrial DNA of a type known as haplogroup M, which has several subgroups and can be traced back 60,000 years. In the new study, the Andamans have been shown to belong to the M group, and most likely to its subgroup M2, which is around 53,000 years old.

This provides evidence that the Andamanese are no more related to Africans than any of the rest of Eurasian populations, and may indeed be linked to surviving hunter-gatherer groups in mainland India who also carry the M2 marker. These groups are found at high frequency in the south of India, consistent with an original settlement of Asia by a coastal route within the last 100,000 years.

Credits:

http://www.innovationsreport.de/html/berichte/biowissenschaften_chemie/bericht-16073.html

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Upcoming books:

“African Genocide – An indictment of the Judeo-Christian-Islamic Religions” to be published in Spring ’08

“An Different View of The Bible” to be published in Fall ’08.

 

Lucy

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Little Foot

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Ardipethecus (H and R)

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