Tag Archives: homo habilis

Virtual endocast of H. floresiensis (left) vs H. sapiens (right). Credit: rofessor Peter Brown, University of New England.

‘Hobbits’ didn’t evolve from a direct modern human ancestor. They likely originate from Africa instead

Until some 17,000 years ago, we humans shared the Earth with another close relative: Homo floresiensis. Often called the ‘hobbit’ because of its dwarfish stature, scientists have long debated the origin of this species first discovered as recently as 2003 in the Liang Bua cave on the remote Indonesian island of Flores. Now, scientists who embarked on the most comprehensive analysis of H. floresiensis yet claim the debate is over. The hominid is a distant relative to modern humans and, instead, likely evolved from another branch of hominid from Africa.

Homo Floresiensis skull. Credit: Stuart Hay - ANU.

Homo Floresiensis skull. Credit: Stuart Hay – ANU.

During the misty years following the discovery of the Flores hobbits, one of the most promising hypotheses explaining their origin posited that the 1.1-meter-tall creatures evolved from Homo erectus populations settled in Asia. Homo erectus is basically the first hominid that looked like a human.

Homo erectus had a long tenure. The earliest Homo erectus fossils are dated to roughly 1.8 million years ago, while the youngest fossils assigned to this species date to roughly 300 thousand years ago. The stature of Homo erectus is considered to be very similar to that of living humans having a hindlimb that’s much longer than in earlier forms. Its skulls were generally thicker and more massively built than those of H. sapiens, but all other features point to striking similarities between the two species.

Initial surveys of H. floresiensis remains suggested it was a direct descendant of H. erectus, but some critics have pointed out the evidence presented thus far is inconclusive. To get to the bottom of things Australian researchers led by Dr. Debbie Argue from the Australian National University examined 133 cranial, postcranial, mandibular, and dental remains coming from H. floresiensis but also other hominid species. No other study collected or examined these many samples before and previously scientists focused on finding the best match for the skull and lower jaw only.

A digital reconstruction of the face of H. floresis. Credit: ANU.

A digital reconstruction of the face of H. floresiensis. Credit: ANU.

The examination showed that H. floresiensis doesn’t share that as many features with H. erectus as some believed. Instead, the hobbits seem much more similar to Homo habilis, the earliest representative of the Homo genus which lived between 1.6 million and 2.4 million years ago.

“The analyses show that on the family tree, Homo floresiensis was likely a sister species of Homo habilis. It means these two shared a common ancestor,” Dr Argue said.

“It’s possible that Homo floresiensis evolved in Africa and migrated, or the common ancestor moved from Africa then evolved into Homo floresiensis somewhere.”

Virtual endocast of H. floresiensis (left) vs H. sapiens (right). Credit: rofessor Peter Brown, University of New England.

Virtual endocast of H. floresiensis (left) vs H. sapiens (right). Credit: rofessor Peter Brown, University of New England.

The findings refute the idea that the hobbits evolved from Asian Homo erectus which presumably underwent island dwarfing. Instead, a counter-hypothesis which suggests the hobbits evolved from an earlier ancestor in Africa, who was most likely Homo habilis, seems more favorable. The hobbits either evolved in Africa then migrated to Asia where they eventually reached the island of Flores in Indonesia or the common ancestor migrated from Africa then evolved into H. floresiensis somewhere on route or on the famous island itself.

The biggest takeaway is that H. floresiensis was far more primitive than previously thought, though it went extinct less than 15,000 years ago.

“We can be 99 per cent sure it’s not related to Homo erectus, and nearly 100 per cent chance it isn’t a malformed Homo sapiens,” said Professor Mike Lee of Flinders University and the South Australian Museum, and co-author of the study published in the Journal of Human Evolution.

Two million years ago, Homo habilis was right handed

Hand preference is still something we don’t understand that well, but at least we’ve got a better timeframe now. Humanity’s ancestors might have already been right handed 1.8 million years ago.

Most people prefer to eat with their right hand. Image credits: Alex (Wiki Commons).

Homo habilis is one of the earliest members of the genus Homo, living roughly between 2.1 and 1.5 million years ago. They are the Homo least similar to humans, but most anthropologists believe that the intelligence and social organization of H. habilis were more sophisticated than chimpanzees for example. Now, a new study published in the Journal of Human Evolution reports proof of right-handedness in the species, a striking similarity to today’s humans.

“This is an exciting paper because it strongly suggests right-handed tool use in early Homo around 1.8 million years ago,” Debra Guatelli-Steinberg, an anthropologist at the Ohio State University, told Christian Science Monitor.

The study, led by David Frayer, a paleoanthropologist at the University of Kansas, focused on scratch marks on a Homo habilis teeth fossils. The scrapes on the teeth consistently looked like whatever caused them was dragged from right to left — something you’d expect from an animal with a preferred hand dominance. They analyzed a total of 559 marks on the teeth, finding that 47% of them align in this way, and just 11% align in the opposite way, which would be consistent with left-handedness. They don’t offer any conclusions as to why this happened.

“We think that tells us something further about lateralization of the brain. We already know that Homo habilis had brain lateralization and was more like us than like apes. This extends it to handedness, which is key,” said David Frayer, Professor Emeritus at the University of Kansas, US.

But this isn’t the only possible explanation for this, and not everyone is convinced. Some researchers believe this could be a case of over-interpretation.

“My concern is that they really don’t spend enough time on other explanations for these phenomena, the presence of these scratches and their directionality,” Bernard Wood, a paleoanthropologist at George Washington University. “It’s a really interesting observation that only time will tell whether that observation has been over-interpreted.”

Hand preference is still only partially explored in the animal kingdom. For instance, recent studies showed that kangaroos and other macropod marsupials have a left-hand preference for everyday tasks in the wild and this was completely unexpected. Meanwhile, our closest relatives – chimps and apes – don’t truly exhibit hand dominance, so it’s not clear when we evolved this way.

homo habilis ancestor

Earliest specimen from the human family discovered in Ethiopia

A broken jaw unearthed in Ethiopia pushes back the origin of the homo linage – of which homo sapiens sapiens are the only surviving members – by 400,000 years. The finding might prove important in explaining how our ancestors diverged from more apelike relatives, like Australopithecus, to big brained beings, filling a blank spot two to tree millions years ago that’s still giving anthropologists headaches.

homo habilis ancestor

The jaw fragment found in Ethiopia. Photo: Kaye Reed

According to a team led by Brian Villmoare from the University of Nevada, Las Vegas, the fragment has been dated as being 2.8 million years old or 400,000 years older than any fossil of a homo species. Geological evidence suggests that the jaw’s owner lived in a time of shifting climate, when forests and waterways gave way to arid savannas – very similar to what we have today in the area, actually. Villmore believes this climate pressure may have been what jump started the accelerated evolutionary trend that eventually led to modern humans.

Although they only found a jaw fragment, the scientist were able to read a lot of clues about the person’s life almost 3 million years ago. For instance, it likely eat more meat than its ancestors and used tools judging from its delicate jaw. If you have tools, you don’t need to grind food or tree bark with your teeth.

[ALSO SEE] Humans grew bigger brains after eating cooked food

Another study made by researchers at University College London seems to strengthen the fossil’s Homo credentials. Using a medical scanner, the team reconstructed a badly preserved 1.8 million-year-old Homo Habilis skull and found striking similarities between its jaw and that found by Villmoare. As such, Villmoare’s fragment might belong to an ancestor that led to H. habilis and eventually our own species. Nothing is certain, however, until they can find more evidence. Digging again in the same area is a good place to start.

“In archaeology there is no sure thing,” he says. “All you can do is hope.”

human hands ancestor

Early human ancestors used their hands much in the way as we do

After analyzing key hand bone fragments from fossil records, a team of anthropologists conclude that pre-homo  human ancestral species, such as Australopithecus africanus, used a hand posture very similar to that of modern humans. Considering fossil tools used for scrubbing off meat as old as 3.3 million years have been found, it may just be that our early ancestors weren’t all that different from good ol’ superior homo sapiens sapiens. Well, as far as hands go at least.

A handy ancestor

human hands ancestor

Like humans, chimps have opposable thumbs and opposable big toes which allow them to grip things with their feet. Yet, our close cousins don’t possess what scientists call a habile hand, since theirs haven’t been freed from walking requirements. As such, the evolution of the opposable or prehensile thumb is recognized by anthropologists as being linked with two key evolutionary transitions in hand use: a reduction in arboreal climbing and the manufacture and use of stone tools.

[RIDDLE] Which came first: the dexterous hand or the agile foot?

Matthew Skinner and Tracy Kivell of the Max Planck Institute for Evolutionary Anthropology and the University of Kent used new techniques to reveal how fossil species were using their hands by examining the internal spongey structure of bone called trabeculae. These bones quickly reshape during the lifetime to adapt to various stresses. So, for humans at least, you can tell whether a person is a carpenter, construction worker or a computer programmer, just by looking at the trabeculae.

The first metacarpals of a chimp, the fossil australopiths, and a human (top row). The bottom row constists of images from micro-computertomography-scans of the same specimens, showing a cross-section of the trabecular structure inside. © Tracy Kivell

The first metacarpals of a chimp, the fossil australopiths, and a human (top row). The bottom row constists of images from micro-computertomography-scans of the same specimens, showing a cross-section of the trabecular structure inside. © Tracy Kivell

[READ] Why early hominids started walking on two legs

A human forceful precision grip, grasping a Australopithecus africanus first metacarpal of the thumb. © Tracy Kivell & Matthew Skinner

A human forceful precision grip, grasping a Australopithecus africanus first metacarpal of the thumb.
© Tracy Kivell & Matthew Skinner

First, the researchers compared the trabeculae of humans and chimps. As expect, key differences were identified. The chimpanzee clearly can not adapt to human-like hand posture, lacking the ability for forceful precision gripping between thumb and fingers (e.g. like turning a key). Remarkably, a hominid ancestor called Australopithecus africanus, who lived some 3 to 2 million years ago, has a human-like trabecular bone pattern in the bones of the thumb and palm (the metacarpals) consistent with forceful opposition of the thumb and fingers typically adopted during tool use.

What makes this so important is that traditionally anthropologists believe Homo habilis, also known as “Handy Man,” was the first maker of stone tools. The models support previous archaeological evidence for stone tool use among australopiths, meaning the first tool use could be pushed back much earlier than previously thought – we just have to wait for evidence to surface, if any survived the test of time. What’s clear, though, is that our early ancestors used human-like hand postures frequently and earlier than currently estimated.

“This new evidence changes our understanding of the behaviour of our early ancestors and, in particular, suggests that in some aspects they were more similar to humans than we previously thought”, says Matthew Skinner of the Max Planck Institute for Evolutionary Anthropology and the University of Kent.

“There is growing evidence that the emergence of the genus Homo did not result from the emergence of entirely new behaviours but rather from the accentuation of traits already present in Australopithecus, including tool making and meat consumption”, says Jean-Jacques Hublin, director at the Max Planck Institute for Evolutionary Anthropology.

The original skull (without upper teeth and mandible) of a 2,1 million years old Australopithecus africanus specimen so-called “Mrs. Ples” discovered in South Africa. Image: Archaeodontosaurus/Wikipedia (CC BY-SA 4.0)

The original skull (without upper teeth and mandible) of a 2,1 million years old Australopithecus africanus specimen so-called “Mrs. Ples” discovered in South Africa. Image: Archaeodontosaurus/Wikipedia (CC BY-SA 4.0)

The results are published in Science.

Skull suggests three hominid species were just one

A new, controversial analysis of a skull suggests that Homo habilis, Homo rudolfensis and Homo erectus were in fact the same species, something which would force scientists rewrite a big page of anthropology.

skull

Researchers compared the anatomical features of the of a 1.8-million-year-old fossil skull with those of four other skulls from the same excavation site at Dmanisi, Georgia; the skull, informally named “Skull 5” is “the most complete skull of an adult from this date”. It’s very interesting to observe the differences between all the skulls found in the same place, from the same era:

“The Dmanisi skulls look quite different from one another”, Zollikofer says, “so it’s tempting to publish them as different species. Yet we know that these individuals came from the same location and the same geological time, so they could, in principle, represent a single population of a single species.”

Taking that theory and testing it with existing data, the statistics seem to add up.For example, the volume of skull 5 is only about 75% that of the largest skull unearthed at the Dmanisi site — a disparity that may seem large but that falls within the variation seen among modern humans and within chimpanzees. The variation also seems to fit within the range of previous findings from the same era.

“Like so many finds, [the skull] adds to what we know, but does not necessarily clarify or simplify things,” says Robert Foley, a paleoanthropologist at the University of Cambridge, UK. Nevertheless, he notes, the results of the new analysis must change the way scientists think about the nature and magnitude of anatomical variation in early Homo.

If the three species were in fact just one, then H. habilis and H. ruldofensis would be subsumed into H. erectus – but there’s a lot of criticism aimed at that idea. First of all, cramming the three species which inhabited an area (at least) from Africa to Indonesia seems a little far fetched. Fred Spoor, a palaeontologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany is not convinced by this new theory. He believes that the statistical analysis used to study cranial differences are not relevant, and instead, researchers should have analysed pecific anatomical traits, such as the height of the braincase or the diameter of the eye socket, which are the most common characteristics used to frame species.

Via Nature.

Fossil hints at distant relatives of our ancestors, deepens mystery

Our family tree may be much more complex than we know – it may have sprouted some long lost branches which go back some 2 million years.

A messy family tree

Image provided by National Geographic and Nature

A team led by Meave Leakey, daughter-in-law of distinguished scientist Louis Leakey found facial and jaw bones from three specimens that led them to believe our human ancestors had plenty of company from different human-like species. The bones most definitely don’t come from our ancestor, Homo Erectus, and they most likely come from a distant cousin of Homo Erectus, with who they share the same ancestors.

But other archaeologists and anthropologists aren’t buying this theory: they believe it’s jumping to conclusions based on way too little evidence. Either way, this is a continuation of a long-running argument in anthropology about the earliest members of our own genus, or class, called Homo – a family tree which is becoming more messy and complicated.

The thing is, while these findings look drastically different from those of modern humans, they closely resemble an enigmatic, nearly complete skull found 40 years ago that paleoanthropologists have been trying ever since to fit into the family tree. To add even more drama to the table, that skeleton was found by the Leakeys as well.

The cradle of humanity

Meave Leakey and Susan Anton

East Africa is though to be the seat of human origins, and at the time in which Homo Erectus began its ascension, it was “quite a crowded place with multiple species,” said Fred Spoor of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, a co-author of a report describing the finds. Homo Habilis (which means ‘handy man’) was another genus known for creating primitive stone blades. Another, more primitive species, Paranthropus bosei, also lived in the region at the time.

But the new finds, and the mystery skull, which may or may not be the same species, clearly don’t belong to any groups. The face is too flat, falling down like a cliff from brow to chin, while the teeth are straight instead of arching, like with Homo Erectus. The molars are also very large, and the brain was very big for the time, albeit it measured just half of that of a modern human.

A 40 year old mystery

The mystery skull found 40 years ago may hold a key role in this controversy. The skull wasn’t given a name, and is only identified by a number – KNM-ER 1470. In the 40 years since it was found, members of the Leakey family, all involved in archaeology and anthropology, have been trying to find anything resembling it, but they have been unsuccessful – until now. Thus, a new spark flames the debate, between those who believe they are members of a new species, and those who believe the specimens are merely deformed examples of other, known, species.

“There just hasn’t been any evidence one way or another,” said Susan Anton of New York University, who collaborated with Meave Leaky in describing the new fossils.

Rick Potts, current director of Smithsonian Institution’s human origins program is firmly convinced that the new findings represent a new species. Potts, who was not involved in the study, added:

“There will still be controversy over what to call these things. The old picture of human evolution heading in a straight line — where an early species gave rise to a more advanced species and so on, until finally reaching modern humans — is all but defunct.”

“At the moment, all we’re doing is classifying heads,” said Bernard Wood, a paleoanthropologist at George Washington University who studied the mystery skull in the early 1990s and declared it likely represented a new species. “It will be a different ballgame when we can match heads with limbs. There are limb bones, but with no heads.”

It’s still unclear if these species interacted with each other, or even more, if they interbred.

Source

Ancient human tool use much earlier than thought!

Humans might have started using sophisticated tools some 1.76 million years ago, much earlier than previously believed. This has been suggested by the discovery of hand axes from that period which belong to the complex Archeulean culture. This could also change what we believe about the period when humans started leaving Africa.

Anthropologists consider the Acheulean hand axes to be the culture of our ancestor Homo erectus, and we know H. erectus first evolved around 1.8 or 2 million years ago,” study researcher Christopher Lepre, of Columbia University, said. “I think most researchers were anticipating that older stone axes would be found.” And now they’ve found them.

Several of these hand axes belonging to the Archeulean were found; they were built from chipped volcanic rock from a nearby stream, were found at a site on the shore of Lake Turkana in Kenya. They found that the axes have different levels of sophistication – for that period, that is.

“There’s not a tremendous amount of diligence that goes into making the Oldowan tools, you can say they are kind of haphazardly made,” Lepre said. “It’s pretty simple in terms of the makers were bashing stones together to make sharp edges.”

The data indicates that there were at least 2 tool-using hominids living in Africa 1.76 million years ago, but what’s still a mystery is how these tools left Africa, because the Archeulean culture and their tools didn’t leave Africa until about 1 million years ago, and it is currently believed that Homo Erectus colonized Europe 1.5 million years ago.

This could mean two things: either that the Homo Erectus that migrated to Europe didn’t develop Archeulean technologies for half million years, or that Homo Erectus wasn’t the species who created those axes at all. They could have been developed by the lesser evolved Homo habilis. Either way, so far, something doesn’t seem to add up.