Lucy's painful last moments revealed: 3.2 million-year-old fossil of early human suggests she died after falling 40ft from a tree
- CT scans revealed Lucy's 3.18-million-year-old bones had fractures
- She fell from a height of more than 40ft, hitting the ground at 35mph
- Upper arm fractures suggest she stretched out her arms to break her fall
- Without evidence of healing, injuries likely occurred just before she died
- The study offers unusual evidence for tree dwelling in the extinct species known as Australopithecus afarensis
She is the longest-lived and best known example of one of our early human ancestors.
Now, the story of how the 3.18-million-year-old hominin 'Lucy' met her painful death is being unraveled by scientists.
By looking at fractures on Lucy's skeleton, researchers have solved prehistory's 'coldest case'.
They
claim she died after falling out of a tree, offering unusual evidence
for tree dwelling in the extinct species known as Australopithecus
afarensis.
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Lucy, one of our famous fossil
forbears, died after falling from a tree. Based on the pattern of
breaks, researchers suggest that she landed feet-first before bracing
herself with her arms when falling forward, and 'death followed swiftly'
Since
her discovery in the Afar region of Ethiopia in 1974, Lucy — a
terrestrial biped — has been at the center of a debate about whether
this ancient species also spent time in the trees.
'It
is ironic that the fossil at the center of a debate about the role of
arborealism in human evolution likely died from injuries suffered from a
fall out of a tree,' said lead author John Kappelman, a University of
Texas professor in anthropology.
Kappelman
first studied Lucy during her US museum tour in 2008, when the fossil
detoured to the High-Resolution X-ray Computed Tomography Facility
(UTCT).
The facility has a machine designed to scan through materials as solid as a rock and at a higher resolution than medical CT.
For
10 days, Kappelman and geological sciences professor Richard Ketcham
scanned all of her 40-percent-complete skeleton to create a digital
archive of more than 35,000 CT slices.
'Lucy' is
one of the longest-lived and best known examples of our early human
ancestors (artist's model, pictured right). On the left are 3D
printouts of Lucy's right humerus
For 10 days, Kappelman and geological
sciences professor Richard Ketcham carefully scanned all of her
40-percent-complete skeleton to create a digital archive of 35,000 CT
slices
'Lucy is precious. There's only one Lucy, and you want to study her as much as possible,' Ketcham said.
'CT is nondestructive. So you can see what is inside, the internal details and arrangement of the internal bones.'
Studying
Lucy and her scans, Kappelman noticed something unusual; the end of the
right humerus was fractured in a manner not normally seen in fossils,
preserving a series of sharp, clean breaks with tiny bone fragments and
slivers still in place.
'This
compressive fracture results when the hand hits the ground during a
fall, impacting the elements of the shoulder against one another to
create a unique signature on the humerus,' said Kappelman.
Lucy’s fracture in her forearm
undergoes computed tomographic scanning. Overall, Lucy suffered a broken
ankle, arm, knee, pelvis and at least one fractured rib - suggesting
she must have suffered severe internal organ damage
Since her
discovery in the Afar region of Ethiopia in 1974, Lucy — a terrestrial
biped — has been at the center of a debate about whether this ancient
species also spent time in the trees. Pictured is a reconstruction of
her bone (left) and what she may have looked like (right)
Our genus was predated by other
species on the human family tree including various representatives of
the genus Australopithecus, of which Lucy belonged to
He
then consulted Dr Stephen Pearce, an orthopedic surgeon at Austin Bone
and Joint Clinic, using a modern human-scale, 3D printed model of Lucy.
Pearce
confirmed that the injury was consistent with fracture caused by a fall
from considerable height when the conscious victim stretched out an arm
in an attempt to break the fall.
Kappelman
also saw similar, less severe, fractures at the left shoulder and other
compressive fractures throughout Lucy's skeleton.
Overall,
Lucy suffered a broken ankle, arm, knee, pelvis and at least one
fractured rib - suggesting she must have suffered severe internal organ
damage.
WHEN LITTLE FOOT WALKED WITH LUCY
A mannequin, an immitation of an Australopithecus Afarensis, who lived in the more than 3 million years ago
A
sophisticated datingtechnique showed that Little Foot, an important
fossil of anearly human forerunner unearthed in the 1990s in South
Africa,is roughly 3.7 million years old.
'The
age of Little Foot has been highly debated,' saidgeologist Darryl
Granger of Purdue University in Indiana, whoseresearch appeared in the
journal Nature earlier this year.
The
study found Little Foot, a member of the speciesAustralopithecus
prometheus, lived at roughly the same time asAustralopithecus afarensis,
the species whose most famousfossil, known as Lucy, comes from
Ethiopia.
These
findings suggested Little Foot roamed the Earth at around the same time
as the famed 3.2-million-year-old Lucy, an Australopithecus afarensis -
shown in a reconstruction above.
When
discovered in Hadar, Ethiopia, Lucy was the only skeleton of the
species known; she would've stood 3.5 feet (about a meter) tall.
Currently,
more than 300 individuals of this species, which lived between about
3.85 million and 2.95 million years ago, have been uncovered.
Both species blended ape-like and human-like traits but with different features.
These included a pilon fracture of the right ankle, a fractured left knee and pelvis.
The
team also found even more subtle evidence such as a fractured first rib
— 'a hallmark of severe trauma' — all consistent with fractures caused
by a fall.
Without any evidence of healing, Kappelman said the breaks occurred near the time of death.
The
question remained: How could Lucy have achieved the height necessary to
produce such a high velocity fall and forceful impact?
Kappelman
claims that because of her small size — about 3 feet 6 inches and 60
pounds — Lucy probably foraged and sought nightly refuge in trees.
Lucy's skeleton, discovered in 1974 in
the Afar region of Ethiopia, has been the subject of vigorous debate
concerning the role of arborealism in early human evolution
In
comparing her with chimpanzees, Kappelman argues Lucy probably fell
from a height of more than 40 feet, hitting the ground at more than 35
miles per hour.
Based
on the pattern of breaks, Kappelman suggests that she landed feet-first
before bracing herself with her arms when falling forward, and 'death
followed swiftly.'
'When
the extent of Lucy's multiple injuries first came into focus, her image
popped into my mind's eye, and I felt a jump of empathy across time and
space,' Kappelman said.
'Lucy
was no longer simply a box of bones but in death became a real
individual: a small, broken body lying helpless at the bottom of a
tree.'
It follows that Lucy must have climbed trees, the team said, possibly seeking refuge in the forest canopy at night.
But this versatility may also have precipitated her demise.
Physical
features adapted for walking upright 'may have compromised her ability
to climb trees, predisposing her species to more frequent falls,' said
the researchers.
Australopithecus afarensis is one of
the best-known early humans. It is also one of the longest-lived: it
survived for about 900,000 years, four times as long as our species so
far. Pictured is a fossil reconstruction of Lucy's skull
Using fracture patterns when present, future research may tell a more complete story of how ancient species lived and died.
The
Ethiopian National Museum has provided access to a set of 3D files of
Lucy's shoulder and knee for the public to download and print so that
they can evaluate the hypothesis for themselves.
'This
is the first time 3D files have been released for any Ethiopian fossil
hominin, and the Ethiopian officials are to be commended,' Kappelman
said.
'Lucy is leading the charge for the open sharing of digital data.'
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