Preserved Tissue on 2-Million-Year-Old Human Ancestor May be Oldest Skin Ever Found

Preserved Tissue on 2-Million-Year-Old Human Ancestor May be Oldest Skin Ever Found

A team of scientists investigating early human species in an ancient cave near Johannesburg, South Africa, have revealed that preserved tissue found on a 2-million-year-old fossil may be the oldest sample of human skin ever recovered. The finding may reveal new information about the species and about our human origins.

The sample came from the remains of 4ft 2 inch tall male juvenile belonging to the species known as Australopithecus sediba, which were recovered in 2008 within an ancient cave in the Malapa Nature Reserve, situated in the ‘Cradle of Humankind World Heritage Site’. The area is important as nearly a third of the entire evidence for human origins in Africa comes from just a few sites in this region.

The Malapa site, August 2011 site of discovery of Australopithecus sediba. Photo by Lee R. Berger ( Wikimedia Commons )

Professor Lee Berger, an anthropologist at the University of Witwatersrand in Johannesburg, who has been leading the excavation, noticed that the skull, which was embedded in cemented rock, had thin layers around it that looked like preserved soft tissue.

The cranium was examined using 3D scanning, microscopy and chemical analysis in an attempt to find out what the thin layers were made of.

“We found out this wasn't just a normal type of rock that they were contained in - it was a rock that was preserving organic material,” said Professor Berger. “Plant remains are captured in it - seeds, things like that - even food particulates that are captured in the teeth, so we can see what they were eating. Maybe more remarkably, we think we've found fossil skin here too.”

Professor Berger, who made his comments in an interview with the Naked Scientists , explained that Australopithecus sediba was first discovered after his son Matthew stumbled upon a fossilised bone in the Malapa Nature Reserve near Johannesburg.

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Matthew Berger moments after the discovery of the clavicle of Australopithecus sediba at the Malapa site. Berger ( Wikimedia Commons )

Australopithecus sediba was identified as a new species based on fossil remains from six separate skeletons discovered together at the bottom of the Malapa Cave, where they apparently fell to their death, and have been dated to between 1.977 and 1.980 million years ago.

Berger believes that the recently classified Australopithecus sediba species could very well be the most recent ancestor to the Homo genus. This is based on a number of characteristics, some which are more humanlike that those seen in Homo habilis, considered by many scientists to be the earliest member of our genus. At the same time, Australopithecus sediba also shows similarities to much more primitive primates.

Australopithecus sediba, two fossils of which are shown on the left and right, are thought to have been a transitional species between older Australopithecus, like Lucy in the middle, and later Homo species. Image compiled by Peter Schmid courtesy of Lee R. Berger. ( Wikimedia Commons )

Researchers have spent decades trying to trace back the family tree of modern humans. However, the problem comes when new discoveries, such as Berger’s findings in Malapa, do not serve to clarify the picture but rather to muddy the waters even further. Each ancient species appears to have unique combination of traits that make them seem so close and yet so far from being a true human ancestor.

The fact that A. sediba was a completely unknown species until just a few years ago, shows us how much we don’t know and how much more there must be to discover. Berger stresses that our understanding of human evolution is nowhere near complete. We haven't even finished looking at the things we thought we knew, he says.

Featured image: Skull of Malapa hominid 1 (MH1) from South Africa, named "Karabo". The combined fossil remains of this juvenile male is designated as the holotype for Australopithecus sediba. ( Wikimedia Commons )


Discovery of 2.8-million-year-old jaw sheds light on early humans

A fossil lower jaw found in the Ledi-Geraru research area, Afar Regional State, Ethiopia, pushes back evidence for the human genus -- Homo -- to 2.8 million years ago, according to a pair of reports published March 4 in the online version of the journal Science. The jaw predates the previously known fossils of the Homo lineage by approximately 400,000 years. It was discovered in 2013 by an international team led by Arizona State University scientists Kaye E. Reed, Christopher J. Campisano and J Ramón Arrowsmith, and Brian A. Villmoare of the University of Nevada, Las Vegas.

For decades, scientists have been searching for African fossils documenting the earliest phases of the Homo lineage, but specimens recovered from the critical time interval between 3 and 2.5 million years ago have been frustratingly few and often poorly preserved. As a result, there has been little agreement on the time of origin of the lineage that ultimately gave rise to modern humans. At 2.8 million years, the new Ledi-Geraru fossil provides clues to changes in the jaw and teeth in Homo only 200,000 years after the last known occurrence of Australopithecus afarensis ("Lucy") from the nearby Ethiopian site of Hadar.

Found by team member and ASU graduate student Chalachew Seyoum, the Ledi-Geraru fossil preserves the left side of the lower jaw, or mandible, along with five teeth. The fossil analysis, led by Villmoare and William H. Kimbel, director of ASU's Institute of Human Origins, revealed advanced features, for example, slim molars, symmetrical premolars and an evenly proportioned jaw, that distinguish early species on the Homo lineage, such as Homo habilis at 2 million years ago, from the more apelike early Australopithecus. But the primitive, sloping chin links the Ledi-Geraru jaw to a Lucy-like ancestor.

"In spite of a lot of searching, fossils on the Homo lineage older than 2 million years ago are very rare," says Villmoare. "To have a glimpse of the very earliest phase of our lineage's evolution is particularly exciting."

In a report in the journal Nature, Fred Spoor and colleagues present a new reconstruction of the deformed mandible belonging to the 1.8 million-year-old iconic type-specimen of Homo habilis ("Handy Man") from Olduvai Gorge, Tanzania. The reconstruction presents an unexpectedly primitive portrait of the H. habilis jaw and makes a good link back to the Ledi fossil.

"The Ledi jaw helps narrow the evolutionary gap between Australopithecus and early Homo," says Kimbel. "It's an excellent case of a transitional fossil in a critical time period in human evolution."

Global climate change that led to increased African aridity after about 2.8 million years ago is often hypothesized to have stimulated species appearances and extinctions, including the origin of Homo. In the companion paper on the geological and environmental contexts of the Ledi-Geraru jaw, Erin N. DiMaggio, of Pennsylvania State University, and colleagues found the fossil mammal assemblage contemporary with this jaw to be dominated by species that lived in more open habitats--grasslands and low shrubs--than those common at older Australopithecus-bearing sites, such as Hadar, where Lucy's species is found.

"We can see the 2.8 million year aridity signal in the Ledi-Geraru faunal community," says research team co-leader Kaye Reed, "but it's still too soon to say that this means climate change is responsible for the origin of Homo. We need a larger sample of hominin fossils, and that's why we continue to come to the Ledi-Geraru area to search."

The research team, which began conducting field work at Ledi-Geraru in 2002, includes:


Scientists Find Soft Tissue in 75-Million-Year-Old Dinosaur Bones

Unlike bones and teeth, which can survive for hundreds of millions of years, soft tissues are among the first materials to disappear during the fossilization process. Even so, scientists have found intact soft tissue in dinosaur bones before. The most famous case dates to 2005, when Mary Schweitzer of North Carolina State University found collagen fibers in the fossilized leg bone of a Tyrannosaurus rex. But such discoveries are rare, and have previously occurred only with extremely well preserved fossils. The most extraordinary thing about the new find, which scientists from Imperial College London reported this week in the journal Nature Communications, is that the fossils they examined are of relatively poor condition (to put it kindly).

As Susannah Maidment, an Imperial paleontologist and one of the lead researchers on the new study, told the Guardian: “It’s really difficult to get curators to allow you to snap bits off their fossils. The ones we tested are crap, very fragmentary, and they are not the sorts of fossils you𠆝 expect to have soft tissue.”

The fossils Maidment is referring to were uncovered in Canada a century ago, and eventually ended up in London’s Natural History Museum. They include a claw from a carnivorous theropod (possibly a Gorgosaurus), a toe bone resembling that of a Triceratops and several limb and ankle bones of a duck-billed dinosaur. In order to find fresh, uncontaminated surfaces of the bones to examine, scientists broke tiny pieces off the fragmented fossils. When Sergio Bertazzo, a materials scientist at Imperial and Maidment’s co-lead researcher on the study, looked at the specimens using an electron microscope, he was shocked at what he saw.


South Africa: Early human skin found on 2 million-year-old fossils

Anthropologists say they have discovered human skin belonging to 2 million year-old fossils in the remains of six ancient skeletons found in South Africa.

The tissue is thought to be from the species Australopithecus sediba, thought to be an early human ancestor that has a mix of primitive and more advanced features.

It is a transitional species between Australopithecus species – the first species to walk upright – and early Homo species, of which humankind is the latest form.

The discovery may be the oldest skin ever found, and could even hold the key to valuable details about early humans' lives. Organic materials including the remains of their last meals were found between their teeth, potentially giving an insight into their diet.

Experts made the discovery in a cave near Johannesburg, which has been excavated since a 4' 2" male skeleton was found in 2008.

Professor Lee Berger, an anthropologist at the University of Witwatersrand in Johannesburg, told the Naked Scientists radio show: "We found out this wasn't just a normal type of rock that they were contained in – it was a rock that was preserving organic material.

"Plant remains are captured in it – seeds, things like that – even food particulates that are captured in the teeth, so we can see what they were eating.

"Maybe more remarkably, we think we've found fossil skin here too."

The investigation started after the professor's then 9-year-old son spotted a fossilised bone at the Malapa Nature Reserve site in 2008 – the first discovery of the new species.

The remains of the Australopithecus sediba fossil are displayed during its unveiling in Johannesburg ALEXANDER JOE/AFP/Getty Images

They later excavated more bones, as well as an almost complete skull, before making the discovery public in 2010.

Scientists decided to build a laboratory on the spot in order to protect the "remarkable" fossils, including a platform that allows them to take off large pieces of the site to work on them in the laboratory.

Professor Berger says he has no idea how many more human fossils he may find.

"Every time we open up a little bit of rock here and move a little bit of dirt, we see someone new," he said. "We're introduced to another one of these people that died 2 million years ago."

The site will now be turned into a live laboratory, where members of the public can look down into the cave and see excavations in process.

According to research, the former "people" would have walked on two legs, but been "strikingly" short.

"Until they got closer, you probably wouldn't realise what's bothering you but something would bother you," Berger said. "They would probably only be standing about 1.3 metres tall. They also been more lightly built… They had longer arms than we do, more curved fingers. So, they're clearly climbing something. They also would've moved a little different.

"Their hips were slightly different than ours and their feet are slightly different. So, their gait would've probably been a more rolling type gait, slightly different from the more comfortable long distance stride we had.

"As they got closer to you, you'd be struck by for the most obvious thing which would be, their heads are tiny. If you imagine, you take a man's fist and curled it up, that's about the size of their brain and that would strike you. There'd be almost this pinhead on top of this small body. And that would immediately make you recognise that this is not a human."


Lucy and Ardi: The two fossils that changed human history

Kermit Pattison, author of Fossil Men: The Quest for the Oldest Ancestor and the Origins of Humankind, tells the story of two skeletons that changed our understanding of the evolution of humans.

Published: 07th March, 2021 at 12:00

This is a tale of two skeletons. It is the saga of a pair of ancient members of the human family from Ethiopia nicknamed Lucy and Ardi. The former is an icon of early humanity while the latter is lesser-known, but no less important and perhaps more revelatory. Their stories reveal much about early human evolution – and how the science of our past has advanced over the last half century.

The Afar Depression of Ethiopia is one of the most productive fossil-producing regions of the world. Part of the East African Rift System, this sedimentary basin was formed by the separation of continental plates. Thanks to favourable geology, its sun-scorched deserts represent a prime hunting ground for extinct members of the human family.

The potential of this region came to light in the 1970s thanks to the pioneering work of geologist Maurice Taieb. After finding the ground strewn with petrified bones, he invited French and American scientists to form a research team and they quickly focused on one fossil-rich area called Hadar.

In 1974, anthropologist Donald Johanson and his graduate assistant Tom Gray found Lucy, a 3.2 million year-old skeleton. When reconstructed, the pieces composed about 40 per cent of the skeleton (or 70 per cent after lab technicians created mirror image replicas of bones missing on the opposite side) of a petite female with an ape-sized brain who stood just over 1 metre tall.

The Hadar team collected hundreds more specimens of the same species later dubbed Australopithecus afarensis. These filled in parts missing from Lucy, including skull, hands, and feet. Today this fossil species is one of the best-known in the human family with more than 400 specimens ranging from 3 to 3.7 million years old.

The discovery of Australopithecus afarensis advanced science in numerous ways.

First, it illuminated one of the greatest mysteries of humanity: why did our ancestors stand upright? Humans resemble our primate cousins in many aspects of anatomy, but we are bizarrely unique when it comes to our two-legged locomotion.

Darwin had theorized that humans evolved erect posture in tandem with stone tools, big brains, and small canine teeth, but afarensis showed that these traits did not evolve as a package. Rather, upright locomotion began long before big brains and stone tools.

Second, these discoveries pushed the human fossil record deeper into the past and established the genus Australopithecus as a viable ancestor to our genus, Homo. (The genus is one taxonomic rank above the species and typically unites taxa that share a common adaptive niche).

Read more about Australopithecus afarensis:

After much debate, little doubt remains that Lucy’s species were bipeds. Australopithecus afarensis had straight big toe – not a grasping one – and the beginnings of a humanlike arched foot (despite having more primitive foot proportions than we do). This species is the likely suspect to have left the humanlike footprints in fossilised volcanic ash at Laetoli, Tanzania 3.6 million years ago.

This does not necessarily mean Lucy’s species had abandoned the trees entirely it retained some features that some scholars interpret as evidence of climbing including curved fingers and toes, mobile shoulder joints, and long forearms.

But what came before Lucy – and how did bipedality begin? Beyond 4 million years ago, the fossil record of our ancestors remained almost entirely blank for two decades after the discoveries at Hadar.

In 1992 in another part of the Afar Depression known as the Middle Awash, an American-Ethiopian team based at the University of California at Berkeley picked up the first pieces of a primitive species more than 1 million years older than Lucy. The early finds included diamond-shaped canine teeth, distinct from the dagger-like fangs of apes, which marked these creatures as primitive members of the human family.

In 1994, the Middle Awash team hit an unexpected jackpot – a 4.4 million year-old skeleton of a species named Ardipithecus ramidus. Ethiopian scholar Yohannes Haile-Selassie found a broken hand bone, triggering an intensive search and the discovery of more than 125 pieces of an ancient female who stood about 1.2 meters tall with a grapefruit-sized brain of about 300 cubic centimetres.

Read more about human evolution:

Nicknamed Ardi, the skeleton preserved many parts missing from Lucy (including hands, feet, and skull) and was 1.2 million years older. Searchers eventually found more than 100 specimens from other individuals of this species.

Shortly after the Ardi skeleton had been transported back to the lab, paleoanthropologist Tim White made a shocking discovery – Ardi had a grasping big toe of a tree climber. This revelation arrived alongside seemingly contradictory ones Ardi’s other four toes displayed anatomy similar to upright bipeds.

More revelations affirmed the hybrid style of Ardi’s locomotion: she climbed trees, but also walked erect on the ground. Although badly damaged, Ardi’s pelvis showed muscle attachments unique to bipeds – alongside other anatomy typical of arboreal apes. As the discovery team later reported, “It is so rife with anatomical surprises that no one could have imagined it without direct fossil evidence.”

Ardi defied predictions in many ways. By the time she was discovered, molecular biology had amassed compelling evidence that humans were closely and recently related to chimpanzees (at the time scientists estimated the two lineages diverged as recently as 5 million years ago, but most now think the split was much earlier). Many scholars shared the expectation: the older the fossil, the more it would resemble a modern chimp or bonobo.

But Ardi did not knuckle walk like modern African apes – and showed no anatomical hints of descent from any such knuckle-walking ancestor. She lacked the dagger-like canine teeth of chimpanzees and her snout was less prognathous. She looked unlike anything ever seen before – what her discoverers described as “neither chimpanzee nor human.”

Ardi sparked great controversy. Some peers refused to believe that she was a member of the human family – and thus refused to accept all her disturbing implications. Others insisted she actually was more like chimp than acknowledged by the discovery team.

Over the last decade, a number of independent scholars have examined the fossils and affirmed that Ardi indeed was a hominin (formerly called hominid), a creature on our branch of the family tree after we split from the ancestors of chimps. Not every claim has won wide acceptance, but Ardi certainly forced a major rethinking of our origins. Gradually, the debate has shifted from whether to accept Ardi into the human family to how to do so.

Ardi was an inconvenient woman who did not slot easily into prevailing theory. As we go deeper into the past, our ancestors look more like apes (though not necessarily like modern apes) and the clues that link them to us become more subtle – and controversial. (The traits that ally Ardi with the human family include diamond-shaped canine teeth, bipedal features of the pelvis and foot, anatomy in the base of the skull, and more.)

Read more about human ancestors:

Ardi represented something entirely new – a hitherto-unknown climber with an opposable toe and odd upright gait. It was not only a new species but an entirely new genus. By contrast, Lucy slotted easily into the existing genus Australopithecus because she was an older variation on a well-established anatomical theme.

As a consequence, Lucy remains much more famous than Ardi. The discoverer of Lucy, Don Johanson, excelled at public relations, wrote popular books, starred in television documentaries, and turned his skeleton into a household name.

In contrast, the Ardi team – which included several veterans of the Lucy team – eschewed that style. They worked in isolation, took 15 years to publish their skeleton, and engaged in numerous spats with peers. The Ardi team aggressively challenged prevailing theories – particularly the notion that we evolved ancestors that looked like modern chimps or the longstanding belief that expanding African savannahs played a crucial role in human evolution. Such disagreements blinded some peers to the scientific value of the oldest family skeleton.

Both skeletons testify to the importance of fossils. Theories and analytical models are essential components of science, but hard evidence sometimes defies predictions.

Despite the hype that often comes with big discoveries, no single fossil represents the beginnings of humankind, the mother of humanity, or the missing link. Rather, they are just random relics of ancient populations that we are lucky enough to find – and probably a fraction of the past forms that have been erased by time.

, CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0), via Wikimedia Commons

In the quarter of a century since Ardi was discovered, the ranks of our family have roughly doubled and there are now more than two dozen species of hominins. This includes three species older than Ardi, the most ancient being the skull of Sahelanthropus tchadensis, at least 6 million years old from Chad. Sadly, none of these older species are complete enough to include a skeleton.

Fortunately, Ethiopia has yielded more skeletons of Lucy’s species. They include a child named “Selam” (Peace) and a large male who stood a head taller than Lucy named, appropriately enough, “Kadanuumuu” (Big Guy). Another surprise: a hominin with an opposable toe who lived 3.4 million years ago at the same time as Lucy’s species – revealing that at least two types coexisted in close proximity, one bipedal and another arboreal.

Meanwhile, Kenya and South Africa have produced additional discoveries – and demonstrated that our origins are far more complex than they seemed in the old days when there were fewer dots to connect.

As more branches are named, anthropologists frequently have proclaimed that our family tree is better described as a bush. But recent advances in genomics show that neither metaphor is quite right. Ancient DNA shows that different “species” – such as Neanderthals and modern Homo sapiens – sometimes interbred.

Because the branches rejoin, our family looks not like a tree or bush and more like a mesh – complex mix of populations that dispersed, adapted to local conditions, and occasionally remixed. Our ancestors, even arboreal ones, do not easily fit in trees.

New discoveries present us with a paradox: the more we learn, the more we confront what we don’t know. More than two centuries ago, the pioneering British chemist Joseph Priestley offered a wonderful metaphor for scientific progress: as the circle of light expands, so does its circumference – the frontier between the light of knowledge and the darkness of the unknown.

As Ardi and Lucy attest, we are the last survivors of a peculiar lineage and we must painstakingly reconstruct our complex history bone by bone.


RELATED ARTICLES

When KNM-ER 2598 was first analyzed, some experts speculated it may have derived from a younger Homo erectus.

The bone is ‘a thick hominin cranial fragment preserving much of the central occipital bone, including portions of the lambdoidal suture and a distinctive Homo erectus-like occipital torus,’ reads the study published in Nature.

The skull bone, dubbed KNM-ER 2598, was discovered near Lake Turkana in East Turkana, Kenya in 1974. However, this was decades before location systems were invented, so researchers put a pin in aerial photos of the excavation sites

When KNM-ER 2598 was first analyzed, some experts speculated it may have derived from a younger Homo erectus. The bone is ‘a thick hominin cranial fragment preserving much of the central occipital bone

There are a number of well-known Homo erectus discoveries throughout history.

The DNH 134 neurocranium from Drimolen, Georgia was deemed the oldest known Homo erectus specimen, dating to 1.78 million years ago.

Although the 1970s researchers marked where the bone was found, the Arizona University-led team used Google Earth imager to find its exact location, as East Turkana is similar to the size of New Jersey in the US and much of the land had changed over time.

Using satellite data and aerial imagery, the team was able to recreate the location of the original site and place it in a larger context for determining the age of the fossils.

Since any DNA of these ancient hominins is long gone from the Earth, researchers analyzed the next best thing – rocks and ancient volcanic ash.

The skull specimen was found in a location that had no evidence of a younger fossil outcrop that may have washed there, but radiometrically dating shows debris is nearly two million years old.

Within just 164 feet (50m), the team discovered two new specimens, one of which is a foot bone

The other bone is a partial pelvis. If these bones belong to the same Homo erectus, then thy would b the oldest postcranial fossils from the hominid found on record

Within just 164 feet (50m), the team discovered two new specimens: a partial pelvis and a foot bone.

If these bones belong to the same Homo erectus, then they would be the oldest postcranial fossils from the hominid found on record.

Paleoanthropologist Ashley Hammond with ASU told SYFY WIRE: ‘Homo erectus was around for almost 2 million years and lived alongside several other hominid species at different periods of time.’

‘East Turkana is one place where we find multiple hominid species overlapping, so this field location has the potential to provide more information about how these species coexisted sympatrically' (in overlapping geographical areas).

EXPLAINED: HOMO ERECTUS EVOLVED 1.9 MILLION YEARS AGO IN AFRICA AND WAS A 'GLOBAL TRAVELLER'

First thought to have evolved around 1.9 million years ago in Africa, Homo erectus was the first early human species to become a true global traveller.

They are known to have migrated from Africa into Eurasia, spreading as far as Georgia, Sri Lanka, China and Indonesia.

They ranged in size from just under five feet tall to over six feet.

With a smaller brain and heavier brow than modern humans, they are thought to have been a key evolutionary step in our evolution.

It was previously thought Homo erectus disappeared some 400,000 years ago.

However, this date has been dramatically reduced, with more recent estimates suggesting they went extinct just 140,000 years ago.

They are thought to have given rise to a number of different extinct human species including Homo heidelbergensis and Homo antecessor.

Homo erectus is thought to have lived in hunter gatherer societies and there is some evidence that suggests they used fire and made basic stone tools.


Controversial T. Rex Soft Tissue Find Finally Explained

The controversial discovery of 68-million-year-old soft tissue from the bones of a Tyrannosaurus rex finally has a physical explanation. According to new research, iron in the dinosaur's body preserved the tissue before it could decay.

The research, headed by Mary Schweitzer, a molecular paleontologist at North Carolina State University, explains how proteins — and possibly even DNA — can survive millennia. Schweitzer and her colleagues first raised this question in 2005, when they found the seemingly impossible: soft tissue preserved inside the leg of an adolescent T. rex unearthed in Montana.

"What we found was unusual, because it was still soft and still transparent and still flexible," Schweitzer told LiveScience.

T. rextissue?

The find was also controversial, because scientists had thought proteins that make up soft tissue should degrade in less than 1 million years in the best of conditions. In most cases, microbes feast on a dead animal's soft tissue, destroying it within weeks. The tissue must be something else, perhaps the product of a later bacterial invasion, critics argued.

Then, in 2007, Schweitzer and her colleagues analyzed the chemistry of the T. rex proteins. They found the proteins really did come from dinosaur soft tissue. The tissue was collagen, they reported in the journal Science, and it shared similarities with bird collagen — which makes sense, as modern birds evolved from theropod dinosaurs such as T. rex.

The researchers also analyzed other fossils for the presence of soft tissue, and found it was present in about half of their samples going back to the Jurassic Period, which lasted from 145.5 million to 199.6 million years ago, Schweitzer said.

"The problem is, for 300 years, we thought, 'Well, the organics are all gone, so why should we look for something that's not going to be there?' and nobody looks," she said.

The obvious question, though, was how soft, pliable tissue could survive for millions of years. In a new study published today (Nov. 26) in the journal Proceedings of the Royal Society B: Biological Sciences, Schweitzer thinks she has the answer: Iron.

Iron is an element present in abundance in the body, particularly in the blood, where it is part of the protein that carries oxygen from the lungs to the tissues. Iron is also highly reactive with other molecules, so the body keeps it locked up tight, bound to molecules that prevent it from wreaking havoc on the tissues.

After death, though, iron is let free from its cage. It forms minuscule iron nanoparticles and also generates free radicals, which are highly reactive molecules thought to be involved in aging.

"The free radicals cause proteins and cell membranes to tie in knots," Schweitzer said. "They basically act like formaldehyde."

Formaldehyde, of course, preserves tissue. It works by linking up, or cross-linking, the amino acids that make up proteins, which makes those proteins more resistant to decay.

Schweitzer and her colleagues found that dinosaur soft tissue is closely associated with iron nanoparticles in both the T. rex and another soft-tissue specimen from Brachylophosaurus canadensis, a type of duck-billed dinosaur. They then tested the iron-as-preservative idea using modern ostrich blood vessels. They soaked one group of blood vessels in iron-rich liquid made of red blood cells and another group in water. The blood vessels left in water turned into a disgusting mess within days. The blood vessels soaked in red blood cells remain recognizable after sitting at room temperature for two years. [Paleo-Art: Illustrations Bring Dinosaurs to Life]

Searching for soft tissue

Dinosaurs' iron-rich blood, combined with a good environment for fossilization, may explain the amazing existence of soft tissue from the Cretaceous (a period that lasted from about 65.5 million to 145.5 million years ago) and even earlier. The specimens Schweitzer works with, including skin, show evidence of excellent preservation. The bones of these various specimens are articulated, not scattered, suggesting they were buried quickly. They're also buried in sandstone, which is porous and may wick away bacteria and reactive enzymes that would otherwise degrade the bone.

Schweitzer is set to search for more dinosaur soft tissue this summer. "I'd like to find a honking big T. rex that's completely articulated that's still in the ground, or something similar," she said. To preserve the chemistry of potential soft tissue, the specimens must not be treated with preservatives or glue, as most fossil bones are, she said. And they need to be tested quickly, as soft tissue could degrade once exposed to modern air and humidity.

Importantly, Schweitzer and her colleagues have figured out how to remove the iron from their samples, which enables them to analyze the original proteins. They've even found chemicals consistent with being DNA, though Schweitzer is quick to note that she hasn't proven they really are DNA. The iron-removing techniques should allow paleontologists to search more effectively for soft tissue, and to test it when they find it.

"Once we can get the chemistry behind some of these soft tissues, there's all sorts of questions we can ask of ancient organisms," Schweitzer said.

Editor's Note: This article was updated at 2pm Eastern Nov. 28 to correct unclear language about proteins and DNA.


Contents

Organizing the expedition Edit

French geologist and paleoanthropologist Maurice Taieb discovered the Hadar Formation for paleoanthropology in 1970 in the Afar Triangle of Ethiopia in Hararghe region he recognized its potential as a likely repository of the fossils and artifacts of human origins. Taieb formed the International Afar Research Expedition (IARE) and invited three prominent international scientists to conduct research expeditions into the region. These were: Donald Johanson, an American paleoanthropologist and curator at the Cleveland Museum of Natural History, who later founded the Institute of Human Origins, now part of Arizona State University Mary Leakey, the noted British paleoanthropologist and Yves Coppens, a French paleoanthropologist now based at the Collège de France which is considered to be France's most prestigious research establishment. An expedition was soon mounted with four American and seven French participants in the autumn of 1973 the team began surveying sites around Hadar for signs related to the origin of humans. [9]

First find Edit

In November 1971, near the end of the first field season, Johanson noticed a fossil of the upper end of a shinbone, which had been sliced slightly at the front. The lower end of a femur was found near it, and when he fitted them together, the angle of the knee joint clearly showed that this fossil, reference AL 129-1, was an upright walking hominin. This fossil was later dated at more than three million years old—much older than other hominin fossils known at the time. The site lay about 2.5 kilometres (1.6 mi) from the site where "Lucy" subsequently was found, in a rock stratum 60 metres (200 ft) deeper than that in which the Lucy fragments were found. [10] [11]

Subsequent findings Edit

The team returned for the second field season the following year and found hominin jaws. Then, on the morning of 24 November 1974, near the Awash River, Johanson abandoned a plan to update his field notes and joined graduate student Tom Gray to search Locality 162 for bone fossils. [12] [13] [14] [15] [1] [2]

By Johanson's later (published) accounts, both he and Tom Gray spent two hours on the increasingly hot and arid plain, surveying the dusty terrain. On a hunch, Johanson decided to look at the bottom of a small gully that had been checked at least twice before by other workers. At first view nothing was immediately visible, but as they turned to leave a fossil caught Johanson's eye an arm bone fragment was lying on the slope. Near it lay a fragment from the back of a small skull. They noticed part of a femur (thigh bone) a few feet (about one meter) away. As they explored further, they found more and more bones on the slope, including vertebrae, part of a pelvis, ribs, and pieces of jaw. They marked the spot and returned to camp, excited at finding so many pieces apparently from one individual hominin. [3] [16]

In the afternoon, all members of the expedition returned to the gully to section off the site and prepare it for careful excavation and collection, which eventually took three weeks. That first evening they celebrated at the camp at some stage during the evening they named fossil AL 288-1 "Lucy", after the Beatles' song "Lucy in the Sky with Diamonds", which was being played loudly and repeatedly on a tape recorder in the camp. [17]

Over the next three weeks the team found several hundred pieces or fragments of bone with no duplication, confirming their original speculation that the pieces were from a single individual ultimately, it was determined that an amazing 40 percent of a hominin skeleton was recovered at the site. Johanson assessed it as female based on the one complete pelvic bone and sacrum, which indicated the width of the pelvic opening. [17]

Assembling the pieces Edit

Lucy was 1.1 m (3 ft 7 in) tall, [18] weighed 29 kg (64 lb), and (after reconstruction) looked somewhat like a chimpanzee. The creature had a small brain like a chimpanzee, but the pelvis and leg bones were almost identical in function to those of modern humans, showing with certainty that Lucy's species were hominins that had stood upright and had walked erect. [19]

Reconstruction in Cleveland Edit

With the permission of the government of Ethiopia, Johanson brought all the skeletal fragments to the Cleveland Museum of Natural History in Ohio, where they were stabilized and reconstructed by anthropologist Owen Lovejoy. Lucy the pre-human hominid and fossil hominin, captured much public notice she became almost a household name at the time. Some nine years later, and now assembled altogether, she was returned to Ethiopia. [20]

Later discoveries Edit

Additional finds of A. afarensis were made during the 1970s and forward, gaining for anthropologists a better understanding of the ranges of morphic variability and sexual dimorphism within the species. An even more complete skeleton of a related hominid, Ardipithecus, was found in the same Awash Valley in 1992. "Ardi", like "Lucy", was a hominid-becoming-hominin species, but, dated at 4.4 million years ago , it had evolved much earlier than the afarensis species. Excavation, preservation, and analysis of the specimen Ardi was very difficult and time-consuming work was begun in 1992, with the results not fully published until October 2009. [21]

Initial attempts were made in 1974 by Maurice Taieb and James Aronson in Aronson's laboratory at Case Western Reserve University to estimate the age of the fossils using the potassium-argon radiometric dating method. These efforts were hindered by several factors: the rocks in the recovery area were chemically altered or reworked by volcanic activity datable crystals were very scarce in the sample material and there was a complete absence of pumice clasts at Hadar. (The Lucy skeleton occurs in the part of the Hadar sequence that accumulated with the fastest rate of deposition, which partly accounts for her excellent preservation.)

Fieldwork at Hadar was suspended in the winter of 1976–77. When it was resumed thirteen years later in 1990, the more precise argon-argon technology had been updated by Derek York at the University of Toronto. By 1992 Aronson and Robert Walter had found two suitable samples of volcanic ash—the older layer of ash was about 18 m below the fossil and the younger layer was only one meter below, closely marking the age of deposition of the specimen. These samples were argon-argon dated by Walter in the geochronology laboratory of the Institute of Human Origins at 3.22 and 3.18 million years. [22]

Ambulation Edit

One of the most striking characteristics of the Lucy skeleton is a valgus knee, [23] which indicates that she normally moved by walking upright. Her femur presents a mix of ancestral and derived traits. The femoral head is small and the femoral neck is short both are primitive traits. The greater trochanter, however, is clearly a derived trait, being short and human-like—even though, unlike in humans, it is situated higher than the femoral head. The length ratio of her humerus (arm) to femur (thigh) is 84.6%, which compares to 71.8% for modern humans, and 97.8% for common chimpanzees, indicating that either the arms of A. afarensis were beginning to shorten, the legs were beginning to lengthen, or both were occurring simultaneously. Lucy also had a lordose curve, or lumbar curve, another indicator of habitual bipedalism. [24] She apparently had physiological flat feet, not to be confused with pes planus or any pathology, even though other afarensis individuals appear to have had arched feet. [25]

Pelvic girdle Edit

Johanson recovered Lucy's left innominate bone and sacrum. Though the sacrum was remarkably well preserved, the innominate was distorted, leading to two different reconstructions. The first reconstruction had little iliac flare and virtually no anterior wrap, creating an ilium that greatly resembled that of an ape. However, this reconstruction proved to be faulty, as the superior pubic rami would not have been able to connect were the right ilium identical to the left.

A later reconstruction by Tim White showed a broad iliac flare and a definite anterior wrap, indicating that Lucy had an unusually broad inner acetabular distance and unusually long superior pubic rami. Her pubic arch was over 90 degrees and derived that is, similar to modern human females. Her acetabulum, however, was small and primitive.

Cranial specimens Edit

The cranial evidence recovered from Lucy is far less derived than her postcranium. Her neurocranium is small and primitive, while she possesses more spatulate canines than other apes. The cranial capacity was about 375 to 500 cc.

Rib cage and plant-based diet Edit

Australopithecus afarensis seems to have had the same conical rib-cage found in today's non-human great apes (like the chimpanzee and gorilla), which allows room for a large stomach and the longer intestine needed for digesting voluminous plant matter. Fully 60% of the blood supply of non-human apes is used in the digestion process, greatly impeding the development of brain function (which is limited thereby to using about 10% of the circulation). The heavier musculature of the jaws—those muscles operating the intensive masticatory process for chewing plant material—similarly would also limit development of the braincase. During evolution of the human lineage these muscles seem to have weakened with the loss of the myosin gene MYH16, a two base-pair deletion that occurred about 2.4 million years ago. [ citation needed ]

Other findings Edit

A study of the mandible across a number of specimens of A. afarensis indicated that Lucy's jaw was rather unlike other hominins, having a more gorilla-like appearance. [26] Rak et al. concluded that this morphology arose "independently in gorillas and hominins", and that A. afarensis is "too derived to occupy a position as a common ancestor of both the Homo and robust australopith clades". [27]

Work at the American Museum of Natural History uncovered a possible Theropithecus vertebral fragment that was found mixed in with Lucy's vertebrae, but confirmed the remainder belonged to her. [28]

Lucy's cause of death cannot be determined. The specimen does not show the signs of post-mortem bone damage characteristic of animals killed by predators and then scavenged. The only visible damage is a single carnivore tooth mark on the top of her left pubic bone, believed to have occurred at or around the time of death, but which is not necessarily related to her death. Her third molars were erupted and slightly worn and, therefore, it was concluded that she was fully matured with completed skeletal development. There are indications of degenerative disease to her vertebrae that do not necessarily indicate old age. It is believed that she was a mature but young adult when she died, about 12 years old. [29]

In 2016 researchers at the University of Texas at Austin suggested that Lucy died after falling from a tall tree. [30] [31] Donald Johanson and Tim White disagreed with the suggestions. [32]

The Lucy skeleton is preserved at the National Museum of Ethiopia in Addis Ababa. A plaster replica is publicly displayed there instead of the original skeleton. A cast of the original skeleton in its reconstructed form is displayed at the Cleveland Museum of Natural History. [33] At the American Museum of Natural History in New York City a diorama presents Australopithecus afarensis and other human predecessors, showing each species and its habitat and explaining the behaviors and capabilities assigned to each. A cast of the skeleton as well as a corpus reconstruction of Lucy is displayed at The Field Museum in Chicago.

US tour Edit

A six-year exhibition tour of the United States was undertaken during 2007–13 it was titled Lucy's Legacy: The Hidden Treasures of Ethiopia and it featured the actual Lucy fossil reconstruction and over 100 artifacts from prehistoric times to the present. The tour was organized by the Houston Museum of Natural Science and was approved by the Ethiopian government and the U.S. State Department. [34] A portion of the proceeds from the tour was designated to modernizing Ethiopia's museums.

There was controversy in advance of the tour over concerns about the fragility of the specimens, with various experts including paleoanthropologist Owen Lovejoy and anthropologist and conservationist Richard Leakey publicly stating their opposition, while discoverer Don Johanson, despite concerns for the possibility of damage, felt the tour would raise awareness of human origins studies. The Smithsonian Institution, Cleveland Museum of Natural History and other museums declined to host the exhibits. [8] [35]

The Houston Museum made arrangements for exhibiting at ten other museums, including the Pacific Science Center in Seattle. [8] In September 2008, between the exhibits in Houston and Seattle, the skeletal assembly was taken to the University of Texas at Austin for 10 days to perform high-resolution CT scans of the fossils. [36]

Lucy was exhibited at the Discovery Times Square Exposition in New York City from June until October 2009. [37] In New York, the exhibition included Ida (Plate B), the other half of the recently announced Darwinius masilae fossil. [38] She was also exhibited in Mexico at the Mexico Museum of Anthropology until its return to Ethiopia in May 2013.


Lucy's Story

Lucy was found by Donald Johanson and Tom Gray on November 24, 1974, at the site of Hadar in Ethiopia.

Middle and high school students and teachers—join IHO's "Lucy in Space" contest! See more information here.

Table of Contents

When and where was Lucy found?

Lucy was found by Donald Johanson and Tom Gray on November 24, 1974, at the site of Hadar in Ethiopia. They had taken a Land Rover out that day to map in another locality. After a long, hot morning of mapping and surveying for fossils, they decided to head back to the vehicle. Johanson suggested taking an alternate route back to the Land Rover, through a nearby gully. Within moments, he spotted a right proximal ulna (forearm bone) and quickly identified it as a hominid. Shortly thereafter, he saw an occipital (skull) bone, then a femur, some ribs, a pelvis, and the lower jaw. Two weeks later, after many hours of excavation, screening, and sorting, several hundred fragments of bone had been recovered, representing 40 percent of a single hominid skeleton.

How did Lucy get her name?

Later in the night of November 24, there was much celebration and excitement over the discovery of what looked like a fairly complete hominid skeleton. There was drinking, dancing, and singing the Beatles’ song “Lucy in the Sky With Diamonds” was playing over and over. At some point during that night, no one remembers when or by whom, the skeleton was given the name “Lucy.” The name has stuck.

How do we know she was a hominid?

The term hominid refers to a member of the zoological family Hominidae. Hominidae encompasses all species originating after the human/African ape ancestral split, leading to and including all species of Australopithecus and Homo. While these species differ in many ways, hominids share a suite of characteristics that define them as a group. The most conspicuous of these traits is bipedal locomotion, or walking upright.

How do we know Lucy walked upright?

As in a modern human’s skeleton, Lucy's bones are rife with evidence clearly pointing to bipedality. Her distal femur shows several traits unique to bipedality. The shaft is angled relative to the condyles (knee joint surfaces), which allows bipeds to balance on one leg at a time during locomotion. There is a prominent patellar lip to keep the patella (knee cap) from dislocating due to this angle. Her condyles are large and are thus adapted to handling the added weight that results from shifting from four limbs to two. The pelvis exhibits a number of adaptations to bipedality. The entire structure has been remodeled to accommodate an upright stance and the need to balance the trunk on only one limb with each stride. The talus, in her ankle, shows evidence for a convergent big toe, sacrificing manipulative abilities for efficiency in bipedal locomotion. The vertebrae show evidence of the spinal curvatures necessitated by a permanent upright stance.

How do we know she was female?

Evidence now strongly suggests that the Hadar material, as well as fossils from elsewhere in East Africa from the same time period, belong to a single, sexually dimorphic species known as Australopithecus afarensis. At Hadar, the size difference is very clear, with larger males and smaller females being fairly easy to distinguish. Lucy clearly fits into the smaller group.

How did she die?

No cause has been determined for Lucy’s death. One of the few clues we have is the conspicuous lack of postmortem carnivore and scavenger marks. Typically, animals that were killed by predators and then scavenged by other animals (such as hyaenas) will show evidence of chewing, crushing, and gnawing on the bones. The ends of long bones are often missing, and their shafts are sometimes broken (which enables the predator to get to the marrow). In contrast, the only damage we see on Lucy's bones is a single carnivore tooth puncture mark on the top of her left pubic bone. This is what is called a perimortem injury, one occurring at or around the time of death. If it occurred after she died but while the bone was still fresh, then it may not be related to her death.

How old was she when she died?

There are several indicators which give a fair idea of her age. Her third molars (“wisdom teeth”) are erupted and slightly worn, indicating that she was fully adult. All the ends of her bones had fused and her cranial sutures had closed, indicating completed skeletal development. Her vertebrae show signs of degenerative disease, but this is not always associated with older age. All these indicators, when taken together, suggest that she was a young, but fully mature, adult when she died.

Where is the "real" Lucy?

IHO has replicas of Lucy‘s bones, which were produced in the Institute‘s casting and molding laboratories. The “real” Lucy is stored in a specially constructed safe in the Paleoanthropology Laboratories of the National Museum of Ethiopia in Addis Ababa, Ethiopia. Because of the rare and fragile nature of many fossils, including hominids, molds are often made of the original fossils. The molds are then used to create detailed copies, called casts, which can be used for teaching, research, and exhibits.

How old is Lucy?

The hominid-bearing sediments in the Hadar formation are divided into three members. Lucy was found in the highest of these—the Kada Hadar or KH—member. While fossils cannot be dated directly, the deposits in which they are found sometimes contain volcanic flows and ashes, which can now be dated with the 40Ar/39Ar (Argon-Argon) dating technique. Armed with these dates and bolstered by paleomagnetic, paleontological, and sedimentological studies, researchers can place fossils into a dated framework with accuracy and precision. Lucy is dated to just less than 3.18 million years old.

How do we know that her skeleton is from a single individual?

Although several hundred fragments of hominid bone were found at the Lucy site, there was no duplication of bones. A single duplication of even the most modest of bone fragments would have disproved the single skeleton claim, but no such duplication is seen in Lucy. The bones all come from an individual of a single species, a single size, and a single developmental age. In life, she would have stood about three-and-a-half feet tall, and weighed about 60 to 65 pounds.