Donald Johanson really had no business concern going bone hunting that Sunday . There were letters to write and fogy to catalog — heaps of paperwork depart done for while fellow paleoanthropologists were visiting his camp in Ethiopia ’s Afar region .
But alum student Tom Gray was headed out to map the fossil site , Hadar , and he needed a guidebook to Locality 162 . So Johanson discount his better sagaciousness in party favor of what he latercalleda “ gut horse sense ” and set off with Gray and company in a Land Rover .
A good two hours into the hunting , that intestine sensory faculty had only nett them a handful of animal fogey fragment , and the recent - daybreak temperature had already topped 100 ° farad . They made one last sweep of a peripheral gully — nothing doing — and decided to call it a Clarence Day .
Then , “ as we turned to pass on , ” Johansonrecalled , “ I noticed something rest on the primer coat partway up the slope . ” It was 2 - column inch - long bone shard that he immediately recognized as “ part of an elbow . ” And it was n’t alone : A closer scan turned up bits of a skull , a femur , a pelvis , and more .
“ An unbelievable , impermissible idea flickered through my mind , ” Johanson drop a line . “ Suppose all these match together ? Could they be parts of a single , extremely primitive skeleton ? No such skeleton had ever been found — anywhere . ”
The camp buzzed with the frisson of a vainglorious interruption long before Johanson could answer that inquiry . That night , November 24 , 1974 , nobody log Z’s , beer flow as freely as conversation , and a tape recorder honk the Beatles ’ “ Lucy in the Sky With Diamonds ” on repetition . By first light , the skeleton that would always alter our understanding of human evolution had a name : Lucy .
Walk Tall
Hadar , site in the Afar region ’s Awash River valley , is a teetotal expanse of eroded sedimentary depositsformedin part by prehistoric rivers andvolcanic eruptions . Thanks to its geological backstory , it ’s a fogy atomic number 79 mine . Gallic geologistMaurice Taiebput Johanson on to the site ’s paleoanthropological electric potential when Johanson was still a PhD student in the early 1970s , and the two teamed up for their maiden dispatch during thefall of 1973 .
Johanson hop to find evidence of early coinage in a category now commonly known ashominins , which includes all human coinage and their immediate ancestors . Hominins ( Hominini ) are a kin group ( i.e. a subgroup ) of the hominid family ( Hominidae ) , which also features chimpanzees , bonobos , gorilla , and orang , as well astheirimmediate ascendant . Modern human areHomo sapiens , the only hominin specie that exists today , and how exactly we evolved as we are is buried deep within the fogey track record .
One characteristic that make humans unique among extant mammals is that we ’re exclusively bipedal — most of us ( as adult , anyway ) always take the air on two feet . In the mid-20th century , the pass possibility ( a version of which Charles Darwin hadlaid outin 1871’sThe Descent of Man)positedthat hominins evolved this room after their brains got great and they get down using tools . To put it very simply , walking upright leaves your hands free to hold thing .
But during his first field of operation time of year in Hadar , Johansonunearthedfossils that could complicate this timeline : part of a tibia and two femur pieces that formed a knee stick at an slant , much like a forward-looking - day human ’s . Its long time wasballparkedat 3 million years , and its size of it suggested that the being it belong to stand only a few foot grandiloquent . This could intend hominins were bipedal before big head entered the characterization .
All walk away , what kind of hominin was this ? An earlyHomospecies — or something else ?
Found Family
The plot thickened during the team ’s next excavation at Hadar in 1974 , whichproducedthree hominin jaws and then , miraculously , Lucy .
Lucy was so special because she was so integral : century of bone and parts of off-white thatmade upsome 40 pct of a underframe . Her large pelvic openingidentifiedher as distaff , and the soma of her pelvis and leg confirmed that she walk upright . She was about 3.5 substructure tall and at least 3 million years sure-enough ( now date at nearly3.18 million ) , with a small brain and a jaw notably small than the others found there . Because of this and other discrepancy between Lucy and those jaws , Johansonguessedthat she belonged to one previously unknown specie , while the jaws belong to another .
But further findings would cause him to deepen his strain . One was the 1975 breakthrough of an entire chemical group of hominin skeletons , dub the “ First Family , ” in Locality 333 . “ Fossils seemed to be cascading , almost as from a fountain , down the hillside , ” Johansonwrote . “ A near - frenzy clutch us as we scramble crazily to pick them up . ” Another was the discovery of fogy in Laetoli , Tanzania , by a team led by Mary Leakey not long after that .
Determining the scientific relationship between all these fossilsconsumedJohanson and his collaborator Tim White in the summertime of 1977 . Though Lucy rise especially baffling due to her small teeth , the paleoanthropologists eventuallyattributedthe anomaly to sexual dimorphism : difference in appearing between males and female of one mintage . At about 3.5 feet grandiloquent and likely tipping the scales at around 60 British pound , Lucy was the most diminutive grownup female in the whole aggregation , and her teeth prove it . The largest of the bunchmeasured5 base tall and could have been as heavy as 150 pounds .
In the closing , they concluded that everything from Laetoli and Hadar belong to a single species that , as Johansonexplained , “ stood somewhere between apes and humans and appeared to be neither one nor the other . ” Their brains were fairlyproportionalto chimp ’ brains , their munition hang a small lower than ours , and their face were apish . But they ambled along more or less like we do . Johanson and White decide to categorise them in the genusAustralopithecus , found by Raymond Dart after his 1924 discovery of a hominin fossil know as the Taung child — also somewhere between imitator and human ( thoughAustralopithecuslooselytranslatesto “ southerly ape ” ) . For a species name , they settled onafarensisas a nod to the Afar region .
Lucy in the Rearview
As the oldest and most gross hominin skeleton at the prison term of her breakthrough , Lucy became theposter childforAustralopithecus afarensisand the unofficial female parent of all humans . But her bequest is much more nuanced than that , especially in light of all the fossils excavated in the decades after hers was .
For one thing , we now know thatA. afarensiswasn’t the origin point of bipedalism : Evidence suggests that other hominins — including the 4.4 - million - class - oldArdipithecus ramidus , the 6 - million - class - oldOrrorin tugenensis , and maybe even the 6 - to-7 - million - year - oldSahelanthropus tchadensis — walked upright long before Lucy live ( though they likely did spend metre in trees ) . This reinforces that bipedalism was n’t a ware of brain magnification , and it may have predated tool use of goods and services , too : The earliest tools we ’ve found so far are only3.3 million years old .
Why hominins began walking erect remains a field of debate . grant to one hypothesis , it could have uprise from males ’ need to bear food to their childrearing mates . Others believe shrink forest meant more time pass over grasslands , which was more energy - efficient on two metrical foot than four . Still others retrieve hominins actuallybecamebipedal so as to better navigate life in trees .
Another of Lucy ’s equivocalness is how she ’s related to to us . Other hominins that lived aroundA. afarensis ’s time havesince been expose , from fellowAustralopithecusspecies likeA. anamensisandA. deyiremedatoKenyanthropus platyops(though it has been suggested that the lonely fossil found in that last species is just anotherafarensisrelic ) . It’scommonly thoughtthatAustralopithecusbegotHomo , whose earliest fogy to date — part of a jawfoundin the Afar neighborhood in 2013 — is between 2.75 and 2.8 million eld old . Lucy ’s mintage prevails as a popular theory forHomo ’s direct root .
“ We have now foundafarensisin Tanzania , Chad , Kenya and Ethiopia , and we know Lucy and her kinsperson must have live in these parts of Africa for close to a million years . That antiquity and extensive geographical spread convert me that it is the most potential candidate to have given rising slope to the many species of theHomogenus and at long last to our own species , Homo sapiens , ” paleoanthropologist Zeresenay Alemseged toldThe Guardianin June 2024 . That enounce , it ’s far from a certainty .
But Lucy ’s influence go past family tree : She also ignited an unparalleled stage of public stake in paleoanthropology . Back in the ’ 70s , when Johanson tell apart a Paris custom agent that the “ funny small parcels ” in his suitcase were fossil from Ethiopia , the valet de chambre lit up . “ You intend Lucy ? ” he said . “ A large crowd accumulate and watch as Lucy ’s bones were displayed , one by one , on the Customs counter , ” Johansonrecounted . “ I got my first inkling of the enormous wrench that Lucy would beget from then on . ” Naturally , this pulling was even stronger within the scientific community .
“ One of the major impacts of Lucy ’s discovery was that it encouraged so many scientist to go out and survey and explore for more fossils like Lucy , ” paleoanthropologist Yohannes Haile - Selassiesaidat a 50th - anniversary symposium earlier this year . Lucy was n’t the end of our William Holman Hunt for humankind ’s line of descent — she was just the source .
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