Adaptations by Hominins Include Using Tools and Tool Making. To What Are These Adaptations Linked?

When this small-scale-bodied, small-brained hominin was discovered, information technology proved that our early on man relatives habitually walked on ii legs.

Its story began to take shape in belatedly Nov 1974 in Federal democratic republic of ethiopia, with the discovery of the skeleton of a small female, nicknamed Lucy.

More 40 years later, Australopithecus afarensis is one of the all-time-represented species in the hominin fossil tape.

How Australopithecus afarensis inverse our understanding of homo evolution

Au. afarensis belongs to the genus Australopithecus, a group of small-scale-bodied and small-brained early hominin species (human relatives) that were capable of upright walking just not well adapted for travelling long distances on the ground.

Species in the australopith grouping - which as well includes Au. africanus, Au. sediba, Au. anamensis and Kenyanthropus platyops - probably gave rise to ii more than recent hominin groups, Man and Paranthropus, before ii.5 million years ago.

Au. afarensis wasn't the get-go member of the group discovered - that was the Au. africanus from Southward Africa - just its discovery confirmed our ancient relatives habitually walked upright, and that this feature of the human lineage occurred long before the evolution of bigger brains.

Australopithecus afarensis discoveries in the 1970s, including Lucy and the Laetoli fooprints, confirmed our aboriginal relatives were bipedal - walking upright on two legs - before big brains evolved. Replicas are on display in the Museum'southward Homo Evolution gallery, aslope the skull of Kenyanthropus platyops, another hominin species that lived in East Africa during the same period.

The ability to walk upright may have offered survival benefits, such as the power to spot dangerous predators before. Maybe crucially, it left the hands free to do other tasks, such as deport food and use tools.

When did Australopithecus afarensis alive?

According to the fossils recovered to engagement, Au. afarensis lived between 3.seven and 3 1000000 years agone. This ways the species survived for at to the lowest degree 700,000 years, more than twice as long every bit our own species, Human sapiens, has been effectually.

Where did Australopithecus afarensis alive?

Au. afarensis fossils have been unearthed in Ethiopia, Kenya and Tanzania.

Map showing sites in Tanzania and Ethiopia where Australopithecus afarensis fossils have been found at Laetoli, Omo, Hadar, Woranso-Mille and Dikika. They have likewise been found at Lake Turkana in Kenya.

Who is Lucy the Australopithecus?

Lucy was ane of the showtime hominin fossils to become a household proper noun. Her skeleton is effectually xl% consummate - at the time of her discovery, she was by far the nearly complete early on hominin known.

On 24 Nov 1974, palaeoanthropologist Donald Johanson was exploring the ravines and valleys of the Hadar river in the Distant region of northeastern Federal democratic republic of ethiopia when he spotted an arm os fragment poking out of a slope.

Johanson later recounted that his pulse quickened as he realised it belonged not to a monkey only a hominin. As the squad found more and more fragments, they began to appreciate that they were uncovering an extraordinary skeleton. The full digging took 3 weeks.

Lucy's skeleton consists of 47 out of 207 basic, including parts of the artillery, legs, spine, ribs and pelvis, too as the lower jaw and several other skull fragments. However, most of the hand and pes bones are missing.

A cast of Lucy, the partial skeleton of an Australopithecus afarensis female person establish at Hadar, in the Afar region of Ethiopia. The fossil is slightly less than three.18 million years one-time.

None of the bones were duplicates, supporting the conclusion that they came from a single individual.

The shape of the pelvic bones revealed the individual was female.

Lucy measured only 1.05 metres tall and would have weighed around 28kg. All the same an erupted wisdom tooth and the fact that certain bones were fused suggested Lucy was a young adult.

Reconstruction of Lucy'southward skull at the Naturhistorisches Museum Basel, based on a lower jaw bone and several other skull fragments. An erupted wisdom tooth provided testify that Lucy was a young developed when she died. © Pbuergler [CC Past-SA 3.0], from Wikimedia Commons

The affectionate nickname comes from the Beatles' song Lucy in the Heaven with Diamonds, which was often playing from the team'south tape recorder dorsum at campsite.

The formal attribution AL 288-1 is rarely used beyond academic journals. The skeleton is slightly less than three.18 meg years old.

A cast of Lucy on display in the Museum's Human Evolution gallery. Her pocket-size skull, long arms and conical rib cage are like an ape'due south, just she has a more human-similar spine, pelvis and human knee due to walking upright.

Johanson idea Lucy was either a small-scale member of the genus Human being or a pocket-sized australopithecine. Only afterwards analysing other fossils subsequently uncovered nearby and at Laetoli in Kenya did scientists establish a new species, Australopithecus afarensis, four years afterward Lucy's discovery.

At the fourth dimension, Au. afarensis was the oldest hominin species known, although far older species have since been found.

How did Lucy die?

Researchers studied injuries to Lucy's basic to see whether they offered insights into how she died, publishing their findings in 2016.

CT scans revealed fractures in her shoulder joint and arms like to those observed in people who autumn from a great pinnacle, as if she reached out to break her fall. They also indicated that many of the breaks occurred perimortem, around the time of death, rather than over fourth dimension as the bones became fossilised.

The researchers believe the injuries observed were severe enough that internal organs could as well have been damaged. Based on their prove, the squad suggest that Lucy died falling out of a tree.

Even so, this conclusion is controversial and many scientists, including Johanson, say there are other plausible explanations for the breakages, such every bit being trampled by stampeding animals afterwards death.

Prof Donald Johanson, discoverer of Lucy and other Australopithecus afarensis fossils, face-to-face with the skull of some other early hominin. Image courtesy of Julesasu [CC0], from Wikimedia Eatables

Australopithecus afarensis characteristics

Au. afarensis possessed both ape-like and human being-similar characteristics. The tiptop of its skull (the cranial vault) was slightly domed and its brain was comparable in size to a chimpanzee's. Its face up projected outwards, less and then in females than in males.

Some Au. afarensis skull specimens bear witness evidence this species possessed powerful chewing muscles.

Australopithecus afarensis skulls show the species had a brain the size of a chimpanzee'southward, a projecting face and powerful jaw muscles, used for chewing difficult or tough plant material. This replica is on display at Cleveland Museum of Natural History. © James St John [CC BY ii.0], from Flickr

The small skull, long artillery and conical ribcage were like an ape's, while the spine, pelvis and knees were more human-like.

The smallest Au. afarensis adults weighed an estimated 25 kilograms, while the largest weighed most 64 kilograms.

This is a broad range, pointing to high sexual dimorphism - the difference in size and shape between males and females. Mod humans have a depression level of sexual dimorphism and the two sexes wait very similar, whereas gorillas are very sexually dimorphic. The difference between Au. afarensis males and females is similar to the latter.

Model of a male Australopithecus afarensis in the Vienna Natural History Museum showing the ape-similar long arms and the more human-similar anxiety and upright stance © Wolfgang Sauber [CC BY-SA 4.0], from Wikimedia Commons

Au. afarensis is more often than not depicted with body hair every bit information technology was likely lost later in human evolution.

Australopithecus teeth

Au. afarensis has a number of distinctive dental features.

In some members of the species the tooth rows diverge slightly towards the dorsum, forming a dental arcade (the office of the oral fissure where teeth sit down) that is neither parallel-sided as in mod apes nor more rounded as in humans.

Australopithecus afarensis jaw replica. Showroom in the Arppeanum, Helsinki. Image courtesy of Daderot [CC0 1.0], from Wikipedia Commons

The canine teeth of Au. afarensis are much smaller than those of chimpanzees, and they are narrower and differently shaped to those of the earlier Au. anamensis. The canine premolar honing complex has been completely lost - this is a feature present in chimpanzees and other apes outside of the hominin lineage, where the large and projecting upper canine teeth are sharpened against the lower tertiary premolars. All known modern and fossil apes have this honing complex. Its absence, along with the presence of bipedalism, is thought to be characteristic of species on the hominin lineage.

The 3.5-million-year-old Laetoli canine belonging to Australopithecus afarensis is the oldest hominin fossil in the Museum's collection. You tin see it in the Man Development gallery.

How did Australopithecus afarensis move around?

Au. afarensis was competent at walking upright on ii legs, and skeletal features indicate it did and then regularly. Still, it may not have walked in exactly the aforementioned way as we practice or been able to walk long distances efficiently.

Anatomical features associated with upright walking are present in the spine, pelvis, legs and feet. These include a broad pelvis and a femur that is angled inwards towards the genu and then that the centre of gravity lies straight above the pes.

Reconstruction of Lucy's pelvis in the National Museum of Ethiopia. The broad pelvis of Australopithecus afarensis is an adaptation to upright walking. © Ji-Elle [CC BY-SA 3.0], from Wikimedia Commons

Lucy and her species besides retained some adaptations for climbing and hanging from trees. These features are seen in the shoulders, arms, wrists and hands.

It is probable that the species, particularly the smaller females, spent a pregnant amount of time moving around in trees. The larger males were probably less arboreal.

Au. afarensis may have foraged in the tree canopy too as on the ground, and probably retreated to the trees at night to avoid predators and for a good night's sleep. Chimpanzees and other apes are known to build nesting platforms in tree canopies.

Australopithecus afarensis probably slept in copse for prophylactic, like chimpanzees and orang-utans that build nesting platforms © Torsten Pursche/Shutterstock.com

Laetoli footprints - a snapshot in time

The site of Laetoli in Tanzania preserves the oldest known hominin footprints. Nearly 3.seven million years agone, a volcanic eruption covered the landscape with a layer of fine ash. Rain created a surface similar wet cement and, before it hardened, a diversity of animals wandered across it. Further eruptions covered the footprints they left behind, preserving them for posterity.

More than than 20 species left tracks, including rhinoceroses, giraffes and baboons.

In 1978, two years after the first brute prints were uncovered, palaeoanthropologist Mary Leakey excavated a 27-metre-long trail fabricated by hominins, consisting of about lxx footprints. They were attributed to Au. afarensis, to this mean solar day the most likely candidate as only this species has been plant at Laetoli.

Replica in the Museum'south Homo Development gallery of some of the footprints preserved at Laetoli, Tanzania, thought to be fabricated by Australopithecus afarensis. The tracks show two individuals walked side by side and a third followed behind. Their toes and way of walking were more human than ape-like.

Co-ordinate to the shut spacing of the footprints, the hominins who made them had short legs. The prints resemble those of modern humans, with an arch and a large toe aligned with the other toes. Their steps were likewise similar to those of mod humans, with the heel touching the ground offset and weight transferring to the ball of the foot before the toes push the foot off the footing. Biomechanical assay suggests the bipedal gait was not entirely modern though, and that the leg may have been slightly more than bent at the knee every bit the pes hit the floor.

The impressions left in the ash reveal that a small group - with unlike sized feet - were walking from due south to n. At least one smaller individual was walking backside and stepping into the footprints made past a larger individual.

Nearly forty years after, some other set of footprints was institute 150 metres from the original trail. These were made past 2 individuals, one of whom was much taller and heavier, walking in the aforementioned direction as the original grouping. Perhaps a single social group made the two trails, perhaps a large male walking with females and children.

A second set up of footprints, besides nearly three.7 million years old, were uncovered at Laetoli in 2015. It's quite rare to find footprints of hominins, the grouping to which humans and our ancestors and shut relatives belong. The footprints at Laetoli are the only ones attributed to a species not in the genus Homo. © Masao et al (2016) eLife DOI: x.7554/eLife.19568, licensed under CC BY 4.0

What didAustralopithecus afarensis eat?

Various lines of evidence propose thatAu. afarensis ate a slightly different nutrition to that of earlier hominins.

Carbon isotope values in tooth enamel reveal thatAu. afarensis is currently the earliest hominin species showing evidence for a more diverse diet that included savannah-based foods such as sedges or grasses, too every bit a more traditional nutrition based on fruits and leaves from copse and shrubs.

Some of the anatomical changes compared to the before speciesAu. anamensis suggest there was a alter in diet towards foods that were harder or tougher over time, every bitAu. afarensis has adaptations for heavy chewing.

Illustration by Maurice Wilson of the extinct hominin Australopithecus afarensis. This species walked upright but retained the ability to climb copse. It may accept searched for nutrient at that place, as well equally on the basis.

DidAustralopithecus afarensis utilise tools?

Since our closest living relatives, chimpanzees, besides as other apes and monkeys, accept been observed making and using simple tools, it is likely that all hominins made use of tools to some extent.

No tools have withal been straight associated with Au. afarensis. Nevertheless, Australopithecus species had hands that were well suited for the controlled manipulation of objects, and they probably did employ tools.

The oldest known stone tools are around three.three million years erstwhile and were unearthed in Kenya. These Lomekwian tools were made from volcanic rock and crafted into cores, flakes and potential anvils. AlthoughAu. afarensis is known from Kenya effectually this time, the virtually likely candidate for the toolmaker is some other species called Kenyanthropus platyops, as specimens of this hominin have been plant close to where the tools were excavated.

A pocket-sized number of animate being bones found at Dikika in Ethiopia, have been reported as showing cut marks made by stone tools. They have been dated to about 3.iv million years ago and the team involved aspect the butchery toAu. afarensis,equally this is the simply species known to live in the expanse at this fourth dimension. However, the conclusions are contentious. If they withstand scrutiny, this would be the earliest evidence of meat-eating behaviour by a hominin.

Of import Australopithecus afarensis fossils

A number of other pregnant Au. afarensis finds take been made in addition to Lucy and the Laetoli footprints.

• Knee, AL 129 1a + 1b
  Uncovered in 1973, this was the outset hominin fossil found at Hadar in Ethiopia. The beefcake of the knee joint indicated information technology belonged to a species that walked on two legs and, at the time, it was the oldest evidence of a biped. It encouraged Johanson's squad to return to the area, where they found Lucy the following year.

• Lower jaw, LH iv
  This jaw bone containing 9 teeth was discovered in 1974 by Mary Leakey at Laetoli in Tanzania. Information technology was designated the blazon specimen for Au. afarensis, making it the specimen that officially represents the species and to which other potential Au. afarensis fossils need to exist compared.

The Australopithecus afarensis type specimen - the LH 4 jaw bone from Laetoli, Tanzania, that officially represents the species. Credit: photo by F Spoor, courtesy of the National Museum of Tanzania.

• The kickoff family, AL 333
  In 1975, more than 200 hominin fossils were unearthed from Hadar. They represent at least 13 individuals, including four children. Scientists retrieve they were probably related. The specimens support the notion that Au. afarensis was significantly sexually dimorphic. Other than their size, the group showed virtually identical anatomical features, showing they were nevertheless species. Whatever disaster befell the group, it happened around 3.2 one thousand thousand years ago.

• Kadanuumuu, KSD-VP-1/1
  Unearthed in Ethiopia between 2005 and 2009, this fractional skeleton is similarly complete to Lucy but much older, dating to about 3.6 million years agone. It belonged to a male that was most one.6 metres alpine, most 30% bigger than Lucy. The nickname Kadanuumuu ways 'Big Human' in the Afar language.

  Due to the lack of skull or dental parts to compare with the Au. afarensis type specimen, some scientists question whether Kadanuumuu can be assigned to this species.

Ethiopian palaeontologist Zeresenay Alemseged holding the skull of Selam © Andrew Heavens [CC BY-NC-ND ii.0], from Flickr

• Selam, an Australopithecus afarensis child, DIK-1-ane
  An almost consummate skeleton of a tiny Au. afarensis kid was constitute at Dikika in Ethiopia in 2006. More than five years of painstaking excavation revealed previously unknown aspects of the species. CT scans of the skull showed the kid's dental development was similar to a iii-year-sometime chimpanzee. From the lack of marks from predators or scavengers, it appears the kid died naturally or in an blow and was chop-chop buried, perhaps by a wink inundation.

This commodity includes information from Our Human Story by Dr Louise Humphrey and Prof Chris Stringer.

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Source: https://www.nhm.ac.uk/discover/australopithecus-afarensis-lucy-species.html

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