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| Catalogno. | AL 288-1 |
|---|---|
| Common name | Lucy |
| Species | Australopithecus afarensis |
| Age | 3.2 million years |
| Place discovered | Hadar, Ethiopia |
| Date discovered | November 24, 1974; 51 years ago (1974-11-24) |
| Discovered by | |
AL 288-1, commonly known asLucy orDinkʼinesh (Amharic:ድንቅ ነሽ,lit. 'you are marvellous'), is a collection of several hundred pieces of fossilized bone comprising 40 percent of the skeleton of a female of thehominin speciesAustralopithecus afarensis. It was discovered in 1974 inEthiopia, atHadar, a site in theAwash Valley of theAfar Triangle, byDonald Johanson, apaleoanthropologist of theCleveland Museum of Natural History.[1][2][3]
Lucy is an earlyaustralopithecine and is dated to about 3.2 million years ago. The skeleton presents a small skull akin to that of non-homininapes, plus evidence of awalking-gait that wasbipedal and upright, akin to that ofhumans (and otherhominins); this combination supports the view of human evolution that bipedalism preceded increase inbrain size.[4][5] A 2016 study proposes thatAustralopithecus afarensis was, at least partly,tree-dwelling, though the extent of this is debated.[6][7]
Lucy was named by Pamela Alderman after the 1967 song "Lucy in the Sky with Diamonds" bythe Beatles, which was played loudly and repeatedly in the expedition camp all evening after the excavation team's first day of work on the recovery site.[8] After public announcement of the discovery, Lucy captured much international interest, becoming a household name at the time.
Lucy became famous worldwide, and the story of her discovery and reconstruction was published in a book by Johanson and Edey. Beginning in 2007, the fossil assembly and associated artefacts were exhibited publicly in an extended six-year tour of the United States; the exhibition was calledLucy's Legacy: The Hidden Treasures of Ethiopia. There was discussion of the risks of damage to the unique fossils, and other museums preferred to display casts of the fossil assembly.[9] The original fossils were returned to Ethiopia in 2013, and subsequent exhibitions have used casts.
In 2024, after fifty years of further research, Lucy's species was no longer considered as the earliest known member of the human family. Contrary to earlier beliefs that her species first walked upright in open savanna grasslands, new evidence suggests they walked in grassy woodlands with deciduous trees. Her species adapted to various habitats over millennia, enduring changes in climate. Importantly, she was not alone in her environment. "We have multiple [hominin] species in the same time period," said Yohannes Haile-Selassie, director of the Institute of Human Origins atArizona State University.[10]
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Ever since the development ofevolutionary theory in the early 19th century, biologists recognized that humans must bedistantly related to all other species. Withouttransitional fossils, scientists presumed that humans'closest relatives were thegreat apes. They also assumed the firsttraits to evolve afterspeciation related tointelligence: bigbrains,tool use, and complex language.[11]
In the 1920s,Raymond Dart discovered theTaung child. That skeleton seemedbipedal (unlike chimps), but lackedskull space for a powerful brain. Without further data to contextualize Dart's find, anthropologists could not prove whether bipedality, intelligence, or some other trait had first distinguishedproto-humans from their great ape relatives.[11]
Frenchgeologist andpaleoanthropologistMaurice Taieb discovered theHadar Formation forpaleoanthropology in 1970 in theAfar Triangle ofEthiopia, then inHararghe province; 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. Under his directorship, these were:Donald Johanson (co-director), an American paleoanthropologist and curator at theCleveland Museum of Natural History, who later founded theInstitute of Human Origins, now part ofArizona State University;Yves Coppens (1934–2022, co-director), a French paleoanthropologist appointed in 1983 a professor at theCollège de France, which is considered to be France's most prestigious research establishment, andMary Leakey, the noted British paleoanthropologist. An expedition was soon mounted with seven French and four American participants; in the autumn of 1973 the team began surveying sites around Hadar for signs related to the origin of humans.[12]
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In November 1973, near the end of the first field season, Johanson noticed a fossil of the upper end of ashinbone, which had been sliced slightly at the front. The lower end of afemur was found near it, and when he fitted them together, the angle of the knee joint clearly showed that this fossil, referenceAL 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.[13][14]
The team returned for the second field season the following year and found homininjaws. Then, on the morning of November 24, 1974, near theAwash River, Johanson abandoned a plan to update his field notes and joined graduate student Tom Gray to search Locality 162 for bone fossils.[15][16][17][18][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 smallgully 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; anarm 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, includingvertebrae, part of apelvis,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][19]
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", afterthe Beatles' song "Lucy in the Sky with Diamonds" (1967), which was being played loudly and repeatedly on a tape recorder in the camp.[20]
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.[20]
Lucy was 1.1 m (3 ft 7 in) tall,[21] weighed 29 kg (64 lb), and (after reconstruction) looked somewhat like achimpanzee. 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.[22]
With the permission of the government of Ethiopia, Johanson brought all the skeletal fragments to theCleveland Museum of Natural History inOhio, where they were stabilized and reconstructed byanthropologistOwen Lovejoy. Lucy the pre-humanhominid and fossil hominin, captured much public notice; she became almost a household name at the time. Some nine years later, and fully assembled, she was returned to Ethiopia.[23]
Additional finds ofA. 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. A more complete skeleton of a related hominid,Ardipithecus, was found in the sameAwash Valley in 1992. "Ardi", like "Lucy", was ahominid-becoming-hominin species, but, dated at4.4 million years ago, it had evolved much earlier than theafarensis 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.[24]
Initial attempts were made in 1974 by Maurice Taieb and James Aronson in Aronson's laboratory atCase Western Reserve University to estimate the age of the fossils using thepotassium-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 preciseargon-argon technology had been updated by Derek York at theUniversity of Toronto. By 1992 Aronson and Robert Walter had found two suitable samples ofvolcanic 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.[25]
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One of the most striking characteristics of the Lucy skeleton is avalgus knee,[26] which indicates that she normally moved by walking upright. Herfemur presents a mix of ancestral andderived traits. Thefemoral head is small and thefemoral neck is short; both areprimitive traits. Thegreater 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 ofA. afarensis were beginning to shorten, the legs were beginning to lengthen, or both were occurring simultaneously. Lucy also had alordose curve, or lumbar curve, another indicator of habitual bipedalism.[27] She apparently had physiological flat feet, not to be confused withpes planus or any pathology, even though otherafarensis individuals appear to have had arched feet.[28]
Johanson recovered Lucy's leftinnominate bone andsacrum. 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 anilium that greatly resembled that of an ape. However, this reconstruction proved to be faulty, as thesuperior pubic rami would not have been able to connect were the right ilium identical to the left.
A later reconstruction byTim White showed a broad iliac flare and a definiteanterior wrap, indicating that Lucy had an unusually broad inneracetabular distance and unusually long superior pubic rami. Herpubic arch was over 90 degrees and derived; that is, similar to modern human females. Her acetabulum, however, was small and primitive.
While examining Lucy's fossilized remains, it was believed that Lucy'ssacrum had five fused elements. The sacrum was found to be in good condition with little damage done. Although the sacrum had five fused elements, thetransverse processes of the most caudal element were not seen to connect to the segments craniad to it.[29] Researchers concluded that the sacrum suffered fossil damage which led to the fifth segment not connecting.
Although this was the case, in the mid-2010s studies came out with new theories as to why Lucy's fifth sacral segment is in that shape. Some researchers conclude that Lucy has only four sacral segments. Published in theAmerican Journal of Physical Anthropology,[30] researchers suggest that fossil damage did not shorten the transverse process and that Lucy's sacrum was in this state from the beginning. This specific study points to Lucy's sacrum having four sacral segments which researchers[30] say conforms with the "long-back" model of hominoidvertebral evolution. There are some disagreements in the community about the fifth sacral segment and if fossil damage was enough to change the fifth segment or if it was originally in that state.[31] Discussed in the Journal,[30] researchers conclude that Lucy having only four sacral segments is consistent with other findings related to earlyMiocenehominoids.
Lucy's fossil is associated with approximately 9vertebrae. Although Lucy was found with a relatively intact and well preserved sacrum, she was missing pieces in her spinal column. Lucy's discoverers and later workers had given the vertebrae provisional level assignments to locations within the vertebral column.[32] Some vertebrae were in worse conditions than others. Lucy had a worn out upperthoracic neutral arch. Researchers have yet to find a cause as to why this particular vertebrae was in worse condition than the other pieces.[32] While accessing and restructuring Lucy's spinal column, it was noted to have been missing pieces that leave it incomplete. Not including an oddly worn out upper thoracic neutral arch, and thelumbar vertebrae, the other remaining thoracic vertebrae were compiled to form an incomplete formation. The formation was arranged from the sixth thoracic vertebrae (T6) to its caudal end (T12), with the seventh thoracic vertebrae (T7) missing. As of 2015,[update] the continuity differs in the thoracic series between researchers and is being re-evaluated.[32] Although new studies and reassessments are being done[when?],[32] they do not refute previous work or conclusions about Lucy's spine.[clarification needed][citation needed]
Thecranial evidence recovered from Lucy is far lessderived than herpostcranium. Herneurocranium is small andprimitive, while she possesses more spatulatecanines than other apes. Thecranial capacity was about 375 to 500 cubic centimeters.
Australopithecus afarensis seems to have had the same conical rib-cage found in today's non-humangreat 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 geneMYH16, a two base-pair deletion that occurred possibly about 2.4 million years ago.[33]
A study of themandible across a number of specimens ofA. afarensis indicated that Lucy's jaw was rather unlike other hominins, having a more gorilla-like appearance.[34] Raket al. concluded that thismorphology arose "independently in gorillas and hominins", and thatA. afarensis is "tooderived to occupy a position as a common ancestor of both theHomo androbust australopith clades".[35]
Work at the American Museum of Natural History uncovered a possibleTheropithecus vertebral fragment that was found mixed in with Lucy's vertebrae, but confirmed the remainder belonged to her.[36]
Lucy's cause of death has not been 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 was 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.[37]
In 2016, researchers at theUniversity of Texas at Austin suggested that Lucy died after falling from a tall tree.[38][39] However, Donald Johanson and Tim White disagreed with this conclusion.[40]
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The Lucy skeleton is preserved at theNational Museum of Ethiopia inAddis 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 theCleveland Museum of Natural History.[41] At theAmerican Museum of Natural History inNew York City a diorama presentsAustralopithecus 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 atThe Field Museum in Chicago.
A six-year exhibition tour of the United States was undertaken during 2007–13; it was titledLucy'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 theHouston Museum of Natural Science and was approved by the Ethiopian government and the US State Department.[42] 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 paleoanthropologistOwen Lovejoy and anthropologist and conservationistRichard 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. TheSmithsonian Institution,Cleveland Museum of Natural History and other museums declined to host the exhibits.[9][43]
The Houston Museum made arrangements for exhibiting at ten other museums, including thePacific Science Center inSeattle.[9] In September 2008, between the exhibits in Houston and Seattle, the skeletal assembly was taken to theUniversity of Texas at Austin for 10 days to perform high-resolutionCT scans of the fossils.[44]
Lucy was exhibited at theDiscovery Times Square Exposition in New York City from June until October 2009.[45] In New York, the exhibition included Ida (Plate B), the other half of the recently announcedDarwinius masilae fossil.[46] She was also exhibited in Mexico at the Mexico Museum of Anthropology until its return to Ethiopia in May 2013.[47]
In August 2025, Lucy, along with another hominid fossil,Selam (Australopithecus), were transported to the Czech Republic for a two-month exhibition at theCzech National Museum inPrague.[48][49]
Based on computer simulations of the mechanics of motion in fossil human ancestors such as the famous 'Lucy' skeleton, our research group has long argued that early human ancestors would have walked upright, rather than semi-crouched, as the old 'up from the apes' view has suggested But we have not been able to say where such upright walking originated. Now, research on the orangutan, suggests that upright walking may have been a basic element of the lifestyle of the earliest ancestors of modern apes, including humans, which would have been tree-dwelling specialists on ripe fruit, living among the fine branches of tropical forest trees.
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