The Controversy Behind Lucy
Three
main controversies surround Lucy and her species, Australopithecus afarensis. First, are finds like the 'First Family'
just one species showing a great degree of sexual dimorphism, or is it two
different species? Second, was Lucy
bipedal or arboreal, or both? Third,
was Lucy indeed female, or is Lucy a male?
These controversies, as well as other topics that tie them together,
will be discussed throughout this paper.
Who is Lucy?
On
the 30th day of November 1974, paleoanthropologist Donald C.
Johanson came upon a bone protruding out of the sediments. These sediments belong to a vast expanse on
the upper part of the Hadar Formation, central Afar, Ethiopia. To Johanson and his colleagues, this
particular region was known as Afar Locality 288. When the bone was being excavated, other bones were discovered in
the immediate vicinity which were quickly identified as a hominid
skeleton. The skeleton consists of 47
out of 207 bones, including parts of upper and lower limbs, the backbone, ribs,
and pelvis (Johanson 1996: 124). There
were some important anatomical parts missing, namely the maxilla, hands, feet,
and most of the skull. The entire
skeleton was 40% complete, the most of any found at that time (Fig. 1).
To the
anthropological society, the skeleton is known as A.L. 288-1. Johanson and his colleagues celebrated the
night of the discovery; a song by the Beatles played, called "Lucy in the
Sky With Diamonds". So she became
known as Lucy to the entire world. But
she is also known as Denkenesh, an Ethiopian name meaning "you are
wonderful" -- well deserved, since her discovery marked a milestone in the
study of mankind's prehistory (Johanson 1976: 795).
Figure
1. A picture of Lucy that was
first made public in the American Journal of Physical Anthropology (Johanson
1982: 437).
The
stratigraphy of the site suggests that Lucy died near a lake margin, an
environment that is very different than that of today. When the fossils were dated, along with the
sediments that the skeleton was found in, using K/Ar dating methods, it was
dated at 3.2 million years old, during the Pliocene epoch.
Based on
the time span in which Lucy lived, and the morphology, she was classified as Australopithecus afarensis in 1978. Australopithecus afarensis is the
earliest known member of the hominid family, living from approximately 4 to 2.8
million years ago. Lucy's species
inhabited southern and central Africa.
Remains of fossilized animals and plants indicate that the environment
consisted of lush grasslands, perhaps with open-savanna woodlands. Pollen evidence proves that these hominids
lived in forests of juniper and olive trees (Johanson 1996: 108).
It is
attested that she was a mature adult based upon the erupted third molar, which
is slightly worn down, as well as the closed epiphyseal lines (Johanson
1996). All the ends of her bones were
fused, along with the closed cranial sutures, indicating complete skeletal
development. Her
vertebrae show signs of degenerative disease, but this is not always associated
with older age (Anonymous n.d.).
Paleoanthropologists
are not able to know if Lucy herself used tools or not, but there are
possibilities that her species did.
There have not been any stone tools found near any of the early
australopithecine sites; however, it is plausible that they may have used wood
tools. Their feeding habits may have
not required sophisticated tools, but perhaps they used tools as chimpanzees do
today, to get to insects, etc. Pointed or stout wood sticks would not show up
in the fossil record, thus the use of tools by australopithecines would remain
a theory, unless further evidence is found.
The
use of tools would also lead a person to think that maybe they had a sense of
culture. An important part of culture
is being able to communicate to one another.
The vocal apparatus of australopithecine forms, according to Lieberman
(1975), does not appear to differ significantly from those of present-day apes;
vocal communications undoubtedly played a part in their linguistic systems, as
it does today in apes, namely chimpanzees.
Perhaps they used signaling with waves and calls to communicate to one
another.
We
do know that Lucy and her species lived in groups, perhaps ranging from 10 to
20 individuals. In the year of 1975 a
large collection of Hominid skeletons, 13 in all, were unearthed near the Hadar
region. All were identified as Australopithecus afarensis, and soon
became known as the 'First Family' (discussed later). There were many male and female remains found of varying
ages. The skeletons varied in sizes;
many believe this to be as indication of sexual dimorphism in A. afarensis.
The Anatomical Features of Lucy and Her Kin
When
reading about the various controversies that surround Lucy and her species,
anatomy plays a large role in understanding them. As a basis for the controversies, I feel it necessary to discuss
the important and distinctive anatomical features of Lucy and her species as a
whole.
The
skull of A. afarensis has a small cranial vault, similar to that of a
common chimpanzee. Lucy's brain was
one-third the size of modern humans, measuring from 420 to 500cc. In view of the fact that the brain case was
small and the teeth moderately large for such a small brain case, a distinct
sagittal crest is present on the top of the skull. This sagittal crest is most evident in the male species of A.
afarensis, and is not a prominent feature in Lucy. The sagittal crest is present for muscle
attachment in many of today's apes, allowing the chewing of tough and fibrous
material such as plants.
Under
a microscope,A. afarensis front teeth show grooves and scratches made by
fibrous material, suggesting that they were used to strip food off some kind of
rough vegetation (Johanson 1996: 115).
Mosaic evolution is very evident when looking at Lucy's teeth, since
they are between apes and humans. Lucy's teeth and jaws are very characteristic
of A. afarensis. The upper and
lower tooth rows of an ape are parallel whereas those of humans diverge
posteriorly (Leakey 1997-98). The jaw
of Lucy is not entirely parallel, but it does not diverge as much as humans do
either (Fig. 2). Lucy also has a small
diastema on the upper jaw, a gap between the lateral incisors and the canines
which humans lack. The presence of a
diastema is one of the characteristics that separate A. afarensis from Homo.
The upper
and lower canine teeth and the tooth behind the lower canine, the lower third
premolar, are intermediate between those of apes and humans (Leakey
1997-98). Australopithecus afarensis
canines are intermediate in size and shape, whereas they are large and conical
shaped in apes, and much more reduced in humans. The premolar of Lucy also resembles apes in its more oblique
orientation (Leakey 1997-98).
Figure
2. The mandible from Lucy. Note that the jaw is in between U-shaped and
V-shaped (Anonymous 2001).
Lucy
lacked feet and hand bones, but by looking at other A. afarensis
skeletons we are able to reconstruct what Lucy's feet and hands looked
like. The feet and hands were similar
to that of humans. The feet have toes
that are slightly longer than humans.
Some researchers believe that the big toe was positioned in line with
the other toes as in humans, while others believe that it was opposable like
that of modern apes (Leaky 1997-98).
The hands however, are not like humans, but rather like apes. Long fingers with strong muscle attachment
would have allowed Lucy and her kind to clasp and hold tightly onto
branches. The thumb was longer than
that of humans, however the hand was not able to cup, allowing the thumb and
little finger to touch, thus not being able to form a precision grip. The anatomy of the thumb itself illustrates
why A. afarensis was not able to form the precision grip. This is due to the fact that the thumb of A.
afarensis is missing three necessary muscles that help flex and oppose the
thumb into different positions (Aiello 1994).
These necessary muscles include flexorpollicus longus, for flexing, and
flexorpollicus brevis, for opposing and touching each finger; the third muscle
is the first palmar einterosseous muscle of Henley, which connects the thumb to
its knuckle (Aiello 1994). Because of
the weakness of the thumb, this enables the other muscles in the hand and
fingers to allow a power grip to be used.
This would aid in gripping branches.
Australopithecus
afarensis shows only a few of the adaptations that make our hands so
dextrous and manipulative (Leaky 1997-98).
It is also important to note that since most researchers believe Lucy to
be a female, the anatomical features would be more pronounced in the males of A.
afarensis.
Figure
3. Illustrating the mosaic
evolution of Lucy (Anonymous n.d.).
She has
been measured to stand at 3.5 feet tall.
Looking at the morphology of the pelvis, it is believed that Lucy was a
female, although that has been brought into debate (discussed later). Johanson states that "her leg and
pelvic bones showed that she walked upright on two legs" (Johanson 1996:
101). The lower body of Lucy will be
discussed later in this paper in more detail.
Was Lucy Male or Female?
Some
people have disagreed over whether Lucy is a female or male. This is important, because if she is female
then the single-species banner would be more plausible if Lucy were discovered
to be a male. If found to be male then
finds such as the 'First Family' cannot be considered to be one species
displaying sexual dimorphism. The
'First Family' would be ruled out because if Lucy were male, meaning that she
is as large as her species got, then the larger individuals of the 'First
Family' must not be in the same species as Lucy. But if Lucy were female, then she would represent the small form
of her species, giving credence to the idea that the 'First Family' is two
forms, the small ones being female, and the large ones being male. The discovery of the 'First Family' is
discussed in more detail in the next section.
There have
been many studies done on Lucy to prove that Lucy is male or female. Swiss researchers, Häusler and Schmid,
believe that Lucy's pelvis was too narrow to accommodate an australopithecine
baby, thus Lucy must be male (Shreeve 1995).
Owen Lovejoy and Johanson strongly disagree with this, stating that
"the Swiss study depends on estimates of neonatal head sizes in
australopithecines that are themselves based on controversial estimates of
adult brain sizes, all to determine whether a hypothetical infant of a vanished
species could fit through a pelvis that was itself recovered in a badly crushed
condition" (Shreeve 1995: 1298).
Looking at standard traits used to ascertain sex in modern humans, the
ridge on the pubic bones called the ventral arc, occurring in 95% of females,
and the promontorium, a protrusion at the rear of the pelvis that juts forward
in males, giving the pelvic inlet a heart shape (Shreeve 1995). Lucy's pelvis is ridgeless gives and
heart-shaped, hinting toward Lucy being a male. This could all be a manner of interpretation, but according to
Häusler and Schmid, "Lucy could be female--but only if the larger fossils
were another species" (Shreeve 1995: 1298).
One Species or Two?
Cases in which males are much bigger in
height and overall stature than females are called sexual dimorphism. When talking about sexual dimorphism in A. afarensis, Johanson stated that
"many of the bones we had came from hominids of very different sizes, and
some critics argued that the variations were so great at least two species of
hominids must have roamed Hadar" (Johanson 1996: 101). However, some fail to recognize the sexual
dimorphism of today's apes, an example being gorillas and orangutans. Johanson and his colleagues believe,
however, that A. afarensis is simply
a case where there is great sexual dimorphism within one species.
The
discovery of the 'First Family' (also known as locality 333), a collection of
thirteen A. afarensis individuals, has put many questions to rest, while
bringing more to the surface. What are
thought to be males would have been thickly muscled, averaging 5 ft. tall and a
hundred pounds, a foot taller and two-thirds heavier than females (Johanson
1996). Dr. Todd Olson, along with
Richard and Mary Leaky, claims there was far too much variation among the
fossils to be explained solely by sexual dimorphism (Shreeve 1994: 34). Some
protest that the disparity in size was too great and implied two separate
species, with only the larger one ancestral to Homo (Shreeve 1995). Some
believe there must be two species that were buried together, possibly in a catastrophe
that swept all the bodies together in one spot. Johanson believes that the 'family' consists of all A.
afarensis, of varying ages and sexes.
Geological
evidence suggests that they all died because of a sudden flash flood. The bones are fragmented and scattered
because individuals fell into or were washed into a river, rapidly transported,
broken up, and scattered (Johanson 1990).
This is known as hydraulic jumble.
Because of the depositional process of burial, it is impossible to date
them directly; therefore, dating of the ash layers above and below the site is
important.
Looking at
the skull is an important part of diagnosing hominid species. The differences between hominid species show
up distinctly there--in the slope of their foreheads, the shape of their
browridges, and the degree to which their faces jut forward (Johanson 1996:
102). As previously mentioned, there
were just bits and pieces of Lucy's and other A. afarensis skulls
found. William H. Kimbel and Johanson
announced that they found the most complete A.
afarensis skull in 1994. Dated to
around 3 million years ago, the find from the Hadar region in Ethiopia is
approximately 200,000 years younger than Lucy herself (Shreeve 1994: 34). Based on size, it is thought to be that of
an old male, because the teeth were very worn down. This individual's canine teeth retained the large roots typical
of great ape males, but the crowns-- the parts that protrude from the gums --
were significantly smaller, closer in size to female afarensis canines. This
once again leads us to thinking about how their social system must have been
organized. Since the males did not have
large canines, it is presumed that there was much less competition for females
among afarensis, indicating monogamy
(Johanson 1996). For this particular
skull, the brain measured more than 500 cubic centimeters, on the large side
for A. afarensis. Once the skull
is studied further, Kimbel and Johanson believe that it will reinforce the
single-species banner.
The Question of Bipedality
Bipedalism
has traditionally been regarded as the fundamental adaptation that sets
hominids apart from other primates (Richmond et al. 2000). The main controversy surrounding Lucy and
her kind is whether they were completely bipedal. Lucy shows a great degree of mosaic evolution, both ape and
hominid characteristics. Apelike
features are seen in her long arms, which would have dangled at her side. Yet her leg and pelvic bones showed that she
walked upright on two legs (Johanson 1996: 101). Lucy's hips and muscular arrangement of her pelvis show that it
would have been difficult for her to climb trees, as is the case with modern
humans (Johanson 1996). For some
researchers, the apelike features are non-functional retentions from the common
ancestor of hominids and African apes (Collard and Aiello 2000: 340). Johanson and his long-time colleague Owen
Lovejoy believe that Lucy walked upright because of certain anatomical
characteristics. As stated by Johanson
in 1976, "the angle of the thigh bone and the flattened surface at its
knee-joint end-- so different from quadrupedal apes-- prove that she walked on
two legs". Both Johanson and Owen
think that she may have climbed trees for getting to fruit or nuts, sleeping,
and escaping predators.
Before
the finding of Lucy brought certain things into question, it was believed that
our early ancestors came out of the trees and onto the open savanna already
being able to walk totally bipedally (Catchpool 2001). Lucy and her species may have been bipedal
but perhaps still practiced arboreality.
When looking at Lucy's wrist anatomy, specialized knuckle-walking
characteristics can be seen. Wrist
extension is limited in contemporary knuckle-walkers, such as chimpanzees and
gorillas. This limited wrist extension
is also seen in A. afarensis. As stated in a paper by Richmond and Strait
(2000: 384), "the retention of knuckle-walking morphology in the earliest
hominids indicates that bipedalism evolved from an ancestor already adapted for
terrestrial locomotion". Australopithecus afarensis had a number
of postcranial traits that were related to arboreal activity, such as a long
radial neck, relatively long forelimbs and long curved fingers and toes. This could be evidence that Lucy and her species
did occasionally engage in arboreal behavior.
Also, CAT scans of australopithecine inner ear canals (reflecting
posture and balance) by anatomist Dr. Fred Spoor and his colleagues at
University College, London, showed they did not walk habitually upright
(Catchpool 2001).
It could be that Lucy retained these arboreal
knuckle-walking features but didn’t actually knuckle-walk, i.e., they are just
leftovers from her knuckle-walking ancestors.
Some people have used these knuckle-walking features, as a way to say
that A. afarensis is not an ancestor
to Homo, rather A. africanus is. A paper written by Collard and Aiello (2000)
suggest that A. afarensis retained
some knuckle-walking features, whereas A.
africanus did not. Collard and
Aiello believe that Lucy combined bipedalism, knuckle-walking and
climbing.
The
majority of researchers believe that Lucy was bipedal. The idea of bipedality is not that simple
though. A main question is what gait
Lucy and her species practice. Was it
chimpanzee-like (bent-hip, bent-knee) or erect as in humans? Studies based on these questions have been
done using computer models.
It was
found that the bent-hip, bent-knee gait is much less mechanically effective,
and heat generation so much greater than an erect carriage was favored (Lincoln
1998). A study done by Kramer in 1999
states that on a mass-specific basis, the configuration developed from the
fossil remains of A.L. 288-1 uses less energy to move than, and has the same
cost of transport as, the modern human configuration. Yet, Lucy's ankle and pelvis suggest that she would have walked
with slightly bent legs (Johanson 1996: 114).
If Lucy did indeed walk erect, what version did they favor, short-legged
or long-legged? Lucy is believed to be
short-legged with a continued reliance on arboreal resources, with no energetic
compromises.
However,
some people think that if Lucy was indeed bipedal, her activity as one was not
as great as that of Homo.
The
controversy of Lucy's bipedality was put to rest, mostly, when some hominid
tracks were found in Tanzania. A short
walking stride coupled with a footprint that could only belong to a bipedal
organism strengthened the belief that Lucy did indeed walk upright.
The Laetoli Tracks
In
1976, in the Laetolil Beds of northern Tanzania, a trail of hominid footprints
were discovered by Peter Jones and Philip Leakey, assistants of Dr. Mary Leakey
(Fig. 4). The entire trail was 23
meters long. Two individuals, one
smaller and the other larger, made the footprints. The footsteps come from the south, progress northward in a fairly
straight line, and end abruptly where seasonal streams have eroded a small,
chaotic canyon through the beds (Leakey 1976: 453). Using K/Ar testing, the biotite from the ash was dated to 3.6
million years old.
It is believed that a nearby volcano was
erupting and spewing ash, that it was mixed with falling rain, and that the ash
hardened on the ground. According to
Dr. Leakey the crispness definition and sharp outlines convince her that they
were left on a damp surface that retained the form of foot (Leakey 1979: 453).
Figure 4. The Laetoli tracks and one of Dr. Leaky's
assistants (Ervin 2001).
The trail
not only was made of hominid prints but also of many other organisms that were
passing by that area at the time the ash was laid. Hares, baboons, antelope, rhinos, giraffes, cats, and hyenas are
just a few makers the other prints that were found, some of these animals now
extinct.
Dr. Leakey
believes these hominine prints belong to a direct ancestor to man. To leave these prints, they must have walked
fully upright with a bipedal, free striding gait (Leakey 1979). The form of the foot was no different than
ours; the toe was not divergent and the pressure was equally spread out, as in
ours. The smaller prints measure 18.5
cm long, and 21.5 cm for the larger.
The stride length for the smaller was 38.7cm and 47.2 cm for the larger. An anthropological rule of thumb holds that
the length of the foot represents about 15% of an individual's height (Leakey
1979: 453). With that it was estimated
that the smaller individual must have been 4 ft tall, with the larger being 4.5
ft tall. Because the pressure on one
set of prints is heavier than the other (Fig. 5), it is theorized that a male and
female were walking together with a young child. She may have been carrying the child, or perhaps the child
stepped in the mother's set of prints, simply playing. Some think that the larger individual could
be a male, and the smaller a female.
Others think that they may be of the same sex, just different ages.
Figure
5. The pressure that the foot made
in the Laetoli tracks (left), presumed to be A. afarensis, and Homo
sapiens sapiens (right) (Ervin 2001).
The
hominid that left the tracks in the Laetolil beds, states Dr. Leakey,
"although much older, relates very closely to the remains found by Dr.
Johanson in Ethiopia" (Leaky 1979: 453).
For most anthropologists, the Laetoli tracks were made by the same
species as Lucy, based upon the dating.
Leakey disagreed, but both of their finds broke a long-standing
assumption that humans developed big brains before walking upright (Anonymous
1998).
Another
person that believes the Laetoli tracks was not made by A. afarensis,
but rather by another hominid species.
Dr. Charles Oxnard has used multivariate analysis to reconstruct the
foot of an australopithecine (Catchpool 2001).
He believes that the big toe is not in line like a human foot; instead,
it sticks out like that of a chimpanzee.
Dr. Oxnard does not think that Lucy or her species belong in the Homo
line; he believes that they are just a unique adaptation in the line of
evolution. However, I think there is
one flaw to his thinking; he doesn't take into account the dating of the
Laetoli tracks, which indeed show that they were made at the time that Lucy
lived.
Conclusions
When
Dr. Donald Johanson found a bone protruding out of the sand on that hot day in
Ethiopia, he had no idea of the magnitude of his find. Lucy has become very important in everyday
society; the name Lucy is usually recognized by any common person walking on
the street. The name Lucy can also be
found on trivial games and comics.
Twenty-seven years later, the name Lucy still conjures up visions of our
early ancestors.
Did
Lucy belong to a species where males and females differed greatly in size and
shape? This question is still a major
topic of controversy that surrounds Lucy and her species. With the available evidence presented by
Johanson and his colleagues, I believe that the 'First Family' represents
Australopithecus afarensis. Yes,
there are great morphological differences between the two sizes of hominids
found there, but some researchers fail to see the differences in the apes of
today. Some of the best examples of
this are orangutans and gorillas. The
males are much bigger than females, why couldn't this have been the case with A.
afarensis?
The
vision of Lucy in our minds or in a drawing is usually of her walking upright
as we do. The belief of her walking
upright is still a hot controversy among many anthropologists. Lucy and her species' skeletons can be
analyzed forever, yet there will always be controversy about whether she was
bipedal or arboreal. When reading the
opinions of many anthropologists. I have realized that most anthropologists do
believe that Lucy did indeed walk upright.
Based upon the evidence, A. afarensis is the best candidate for
leaving the famed 'Laetoli Tracks'.
There is always the possibility that there was another species that left
those tracks, and perhaps some day evidence will be found to prove it. I agree with Dr. Johanson that Lucy did walk
upright, and perhaps did climb trees for certain activities.
The
controversy of Lucy being a male or female is slowly dwindling from
anthropological society. It is hardly
talked about, because of the overwhelming evidence that Lucy is indeed
female. Except for an occasional person
who believes that Lucy is a male, most anthropologists concede to the idea that
she is female, based upon the pelvis.
Even though Lucy's pelvis is not like a humans', but rather in between a
human and chimp, it is still clear to most that Lucy's pelvis is bowl-shaped,
like that of human females.
As
researchers continue to search for our ancestors, more evidence will be found
that could strengthen or weaken our ideas of how Lucy relates to us. Recent findings have come up with fossilized
hominids that seem to be earlier than Lucy, and still be our ancestors. We do know that A. afarensis did live
unchanged for 400,000 years. With all
the faults that we find in Lucy's anatomy, by not being able to as versatile as
us, A. afarensis must have been greatly adapted to it's environment for
that long. If Homo sapiens sapiens
does live as long as A. afarensis, then I believe that we can scrutinize
what anatomical features of Lucy are better or worse than our own. As stated by Dr. Johanson in 1996, "At
21, Lucy has indeed come of age" (Johanson 1996: 117).
Figure
6. Lucy has become more famous
than her discoverer; this comic is just an example. Drawn by Nick Downes in 1989 (Johanson 1994: 63).
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