Tree-Climbing Extinct Human Had Swagger
A recently unearthed extinct human species had hands and feet adapted for a life both on the ground and in the trees.
A recently unearthed extinct human species - perhaps the most primitive ever discovered - had hands and feet adapted for a life both on the ground and in the trees, researchers say.
This finding sheds light on how early humans experimented with a variety of designs, scientists added. And though the international teams of scientists are not certain how this extinct human would have walked, they say the swagger would have been quite different from ours.
Although modern humans are the only human species alive today, other human species once walked the Earth. The human lineage, the genus Homo, and its close relatives, including australopithecines such as the famed Lucy, are together referred to as hominins.
The most recently discovered human species, Homo naledi, had a brain about the size of an orange, but it nevertheless possessed enough of a mind to perform ritual burials of its dead. More than 1,550 bones and bone fragments of H. naledi have been recovered from a cave in South Africa, the single-largest fossil hominin find made yet in Africa. Scientists have yet to pin down a date for when H. naledi lived because the nature of the cave in which it was found makes it difficult to determine the age of its fossils. [Photos: New Human Relative (H. naledi) Shakes Up Our Family Tree]
Scientists investigated the hands and feet of H. naledi to learn more about a key shift in human evolution - the move from a life of climbing trees to one spent walking on the ground. Modern humans dominate the planet partly because walking upright frees their hands for tool use, scientists have found.
The researchers analyzed more than 150 H. naledi hand bones, including a nearly complete adult right hand that was missing just one wrist bone. They found the species shared a long, robust thumb and wrist architecture with modern humans and Neanderthals, potentially giving the hand a precise, forceful grip that may have been useful for tool use.
However, its fingers were longer and more curved than most australopithecines - indeed, more curved than those of nearly any other species of early hominin. This quality hints at a life suited for moving and climbing through trees. The scientists detailed their findings on H. naledi‘s hands and feet online today (Oct. 6) in two papers in the journal Nature Communications.
"The tool-using features of the H. naledi hand, in combination with its small brain size, has interesting implications for what cognitive requirements might be needed to make and use tools, and, depending on the age of these fossils, who might have made the stone tools that we find in South Africa," Tracy Kivell at the University of Kent in England, lead author of one of the two H. naledi papers, said in a statement.
The scientists also investigated 107 H. naledi foot bones, including a nearly complete adult right foot. They found the ancient hominin's foot shared many features with the modern human foot, suggesting that it was well-suited for standing and walking on two feet.
"The foot is not entirely humanlike, but it's more humanlike than not," William Harcourt-Smith, a paleoanthropologist at Lehman College in the Bronx and the American Museum of Natural History in New York, told Live Science. "I think it would've been very good at walking on the ground."
However, the H. naledi foot had toes that were more curved than those of modern humans, supporting the notion that the hominin was also relatively adept at life in the trees.
"H. naledi wouldn't have been in any way as proficient as chimpanzees or much more primitive hominins at climbing trees, but it still would be better-suited than we are," said Harcourt-Smith, lead author of the other H. naledi paper.
Intriguingly, H. naledi‘s pelvis was more like that of australopithecines such as Lucy, flaring outward more than that of modern humans.
"This configuration moved the hip muscles away from the hip joints and gave them more leverage in walking - perhaps more of an advantage than humans have today," study co-author Jeremy DeSilva, an anthropologist at Dartmouth University, said in the statement. "Over time, the architecture of the pelvis evolved and expanded to allow the birth of larger-brained babies."
These findings suggest that early human evolution involved many experiments "on different ways to be bipedal," Harcourt-Smith said.
Scientists are still unsure how exactly H. naledi might have walked differently from modern humans. "But there's absolutely no doubt that its gait would have been different," Harcourt-Smith said.
Original article on Live Science.
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Back in the Beginning
To put a human face on our ancestors, scientists from the Senckenberg Research Institute used sophisticated methods to form 27 model heads based on tiny bone fragments, teeth and skulls collected from across the globe. The heads are on display for the first time together at the Senckenberg Natural History Museum in Frankfurt, Germany. This model is Sahelanthropus tchadensis, also nicknamed "Toumai," who lived 6.8 million years ago. Parts of its jaw bone and teeth were found nine years ago in the Djurab desert in Chad. It's one of the oldest hominid specimens ever found.
With each new discovery, paleoanthropologists have to rewrite the origins of man's ancestors, adding on new branches and tracking when species split. This model was fashioned from pieces of a skull and jaw found among the remains of 17 pre-humans (nine adults, three adolescents and five children) which were discovered in the Afar Region of Ethiopia in 1975. The ape-man species, Australopithecus afarensis, is believed to have lived 3.2 million years ago. Several more bones from this species have been found in Ethiopia, including the famed "Lucy," a nearly complete A. afarensis skeleton found in Hadar.
Meet "Mrs. Ples," the popular nickname for the most complete skull of an Australopithecus africanus, unearthed in Sterkfontein, South Africa in 1947. It is believed she lived 2.5 million years ago (although the sex of the fossil is not entirely certain). Crystals found on her skull suggest that she died after falling into a chalk pit, which was later filled with sediment. A. africanus has long puzzled scientists because of its massive jaws and teeth, but they now believe the species' skull design was optimal for cracking nuts and seeds.
The skull of this male adult was found on the western shore of Lake Turkana in Kenya in 1985. The shape of the mouth indicates that he had a strong bite and could chew plants. He is believed to have lived in 2.5 million years ago and is classified as Paranthropus aethiopicus. Much is still unknown about this species because so few reamins of P. aethiopicus have been found.
Researchers shaped this skull of "Zinj," found in 1959. The adult male lived 1.8 million years ago in the Olduvai Gorge of Tanzania. His scientific name is Paranthropus boisei, though he was originally called Zinjanthropus boisei -- hence the nickname. First discovered by anthropologist Mary Leakey, the well-preserved cranium has a small brain cavity. He would have eaten seeds, plants and roots which he probably dug with sticks or bones.
This model of a sub-human species -- Homo rudolfensis -- was made from bone fragments found in Koobi Fora, Kenya, in 1972. The adult male is believed to have lived about 1.8 million years ago. He used stone tools and ate meat and plants. H. Rudolfensis' distinctive features include a flatter, broader face and broader postcanine teeth, with more complex crowns and roots. He is also recognized as having a larger cranium than his contemporaries.
The almost perfectly preserved skeleton of the "Turkana Boy" is one of the most spectacular discoveries in paleoanthropology. Judging from his anatomy, scientists believe this Homo ergaster was a tall youth about 13 to 15 years old. According to research, the boy died beside a shallow river delta, where he was covered by alluvial sediments. Comparing the shape of the skull and teeth, H. ergaster had a similiar head structure to the Asian Homo erectus.
This adult male, Homo heidelbergensis, was discovered in in Sima de los Huesos, Spain in 1993. Judging by the skull and cranium, scientists believe he probably died from a massive infection that caused a facial deformation. The model, shown here, does not include the deformity. This species is believed to be an ancestor of Neanderthals, as seen in the shape of his face. "Miquelon," the nickname of "Atapuerca 5", lived about 500,000 to 350,000 years ago and fossils of this species have been found in Italy, France and Greece.
The "Old Man of La Chapelle" was recreated from the skull and jaw of a Homo neanderthalensis male found near La Chapelle-aux-Saints, in France in 1908. He lived 56,000 years ago. His relatively old age, thought to be between 40 to 50 years old, indicates he was well looked after by a clan. The old man's skeleton indicates he suffered from a number of afflictions, including arthritis, and had numerous broken bones. Scientists at first did not realize the age and afflicted state of this specimen when he was first discovered. This led them to incorrectly theorize that male Neanderthals were hunched over when they walked.
The skull and jaw of this female "hobbit" was found in Liang Bua, Flores, Indonesia, in 2003. She was about 1 meter tall (about 3'3") and lived about 18,000 years ago. The discovery of her species, Homo floresiensis, brought into question the belief that Homo sapiens was the only form of mankind for the past 30,000 years. Scientists are still debating whether Homo floresiensis was its own species, or merely a group of diseased modern humans. Evidence is mounting that these small beings were, in fact, a distinct human species.
Bones can only tell us so much. Experts often assume or make educated guesses to fill in the gaps in mankind's family tree, and to develop a sense what our ancestors may have looked like. Judging from skull and mandible fragments found in a cave in Israel in 1969, this young female Homo sapien lived between 100,000 and 90,000 years ago. Her bones indicate she was about 20 years old. Her shattered skull was found among the remains of 20 others in a shallow grave.