AUSTRALOPITHECUS AFARENSIS: CHARACTERISTICS, HABITAT, FEEDING - HISTORY - 2024

The Australopithecus afarensis was a hominid considered by scientists as one of the ancestors of Homo sapiens. It lived in some areas of East Africa, between 3.9 and 3 million years BC. C.

It was a bipedal hominid, although the latest research indicates that it lived more on trees than on the ground. They were thin in build, with a skull more like that of a chimpanzee than a human.

The discovery of this species was made on December 24, 1974. Paleoanthropologists Donald Johanson, Yves Coppens and Tim White were investigating in the Awash River Valley, Ethiopia, when they found the very well preserved remains of a hominin. This specimen showed different characteristics from other known ones.

The individual found, a female, was named Lucy. The reason for this name was that, to celebrate their discovery, they listened non-stop to the Beatles song “Lucy in the sky with Diamonds”. The name of the species, Australopithecus afarensi, comes from the name of the tribe that inhabited that territory, the Afar.

Apart from Lucy, the remains of other individuals of the same species have been found. These include those discovered in 1978 in Laetoli, Tanzania.

Discovery

When Lucy's remains were discovered in December 1974, she received the nickname "grandmother of humanity", which shows the importance that was given to the find.

In the excavated site, 12 fossils of individuals of the species were found, whose study allowed us to better understand the origin of the human being.

It was the best preserved Australopithecus that had been found up to that time. This led, for example, to discovering that the ability to walk upright appeared before the brain grew.

Likewise, their teeth were essential to shed light on the evolution of hominids and it was discovered that the genera evolved simultaneously.

Although some older fossils were later found, Lucy's importance makes it one of the great milestones of paleoanthropology.

Physical and biological characteristics

The estimated weight of Australopithecus afarensis ranged between 45 and 28 kilos and their height between 151 and 105 centimeters.

This great variation depended on the sex of the individuals. Their physical complexion was slim and graceful and they present characteristics that allowed them to walk upright on both legs. His chest narrowed upward, bell-shaped.

In terms of cranial capacity, it was more similar to that of a chimpanzee than that of a modern human: between 380 and 450 cm³.

Bone morphology

Despite the fact that, as has already been commented, his skull was not large compared to that of today's human being, it was in relation to the size of the body.

His face was large in size, with a characteristic forward projection of the jaw area. This, called prognathism, was due to the large size of their teeth.

On the other hand, despite the aforementioned similarity to that of the chimpanzee, the skull also had sagittal and nuchal ridges similar to those found in gorillas today, but much smaller.

The teeth presented several peculiarities that have helped scientists to discover their type of diet.

Thus, the incisors were those of a mainly frugivorous diet, with a considerable size, as were the molars and premolars. As for the canines, they were small.

The palate did present a great resemblance to that of the current human being, with a curve that did not resemble that of the great apes.

Another important aspect of its morphology was the shape of the pelvis. The study of this part of the body is what has allowed us to affirm that they could walk upright on both legs.

The bone in question is small, with a smaller birth canal in females than that of other anthropomorphic species. This was because the hatchlings were also small, especially the skull.

Bipeds and with the ability to climb

The bone structure of A. afarensis shows its bipedal condition, although there are still discussions about the way in which they walked.

Many scientists claim that the shape of the pelvis and legs made their walk different from that of modern humans. In this way, they would walk more inclined.

Their legs were, proportionally, shorter than those of Homo sapiens, preventing them from efficient and rapid movement. However, another group of researchers think that, despite the existence of these differences, they were able to walk with ease.

The finding made by Mary Leakey in Laetoli, was the confirmation of the ability to walk upright of these hominids. At that site, she found a series of tracks left by three individuals of this species on a layer of volcanic ash. The tracks dated to about three and a half million years ago.

It is the fingers and toes, with curved phalanges, that lead experts to point out that they were very skilled at climbing tree branches. For this reason, the most widespread hypothesis is that they spent a large part of their time in the heights.

Habitat

Australopithecus Afarensi resided only in East Africa, specifically in the area today occupied by Ethiopia, Tanzania and Kenya. It is in these three countries that the remains of the more than 300 individuals known to date have been found.

The type of habitat that they usually occupied were areas with dry and not too dense forests. More modern data suggest that they were also able to move to areas of the savannah, searching for the shores of rivers and lakes.

Feeding

The studies that have been carried out on Australopithecus Afarensis affirm that the basis of its diet was that of a herbivore. Occasionally, it ate the remains of other animals, although it was not a hunting species.

When analyzing the microstriae of the teeth of the individuals found, it has been concluded that, above all, they fed on fruits with a high sugar content, as well as leaf shoots. Besides, they ate roots, tubers, nuts or seeds.

A hypothesis maintained by some paleoanthropologists indicates that the diet was expanding with time. In this way, they would have started to consume various eggs, reptiles and insects.

To reach this conclusion, they are based on the presence of an enzyme, trehalase, which is used to digest a type of sugar very present in these insects.

Meat

It seems accepted by most of the scientific community that A. afarensis ate some meat. Since they were not hunters, it would be remains that they found.

However, a finding in Ethiopia sparked a lot of controversy about the possibility that it consumed animals more generally.

The discovery of a rib from an animal the size of a cow and a femur from an antelope, apparently bearing some tool marks, led some experts to the conclusion that the carnivorous diet may be more widespread than previously thought.

Tools

One of the great controversies present in the studies on this type of Australopithecus was given by the previously mentioned discovery, that of animal bones.

Hominids were traditionally considered to have started using tools to cut meat 2.5 million years ago.

For this reason, the marks that appeared on the bones found attracted a lot of attention. If confirmed, the use of these tools would have to be advanced considerably, up to 3 million years.

The study, which appeared in the journal Nature, was based on marks that a sharp object would have apparently left on bones found in Ethiopia. These tools would serve, theoretically, to separate the meat from the bones or to extract the marrow.

According to the researchers, it is most likely that the tool in question was not built by the A. afarensis, but rather that they used a stone that had a sharp edge.

The importance of this finding was emphasized by Zeresenay Alemseged, from the California Academy of Sciences, who went so far as to state that "The discovery has abruptly changed the time frame established to determine the behavior of human ancestors."

Detractors

Despite the data presented in that research, there is a majority of experts who do not agree with the conclusions.

Among them, Manuel Domínguez-Rodrigo, a Spanish archaeologist, stands out, who claims that the bones found were damaged by being stepped on by other animals.

The marks would be, in this way, the result of the footsteps, not of a cutting tool.

That same hypothesis is shared by many other scholars. While waiting for more evidence to appear, so far it is impossible to say one hundred percent that these hominids used tools.

Lifestyle

The way of life of these hominids was marked by their double capacity for movement: on the one hand, they could walk on their two legs; on the other, they had a great ability to climb trees and stay in them.

The most widespread theory was that they lived in small groups, in which there was a mutual collaboration to survive.

To sleep, they climbed trees, in which they built a kind of nests. Equally, they could spend the night in shallow caves.

On the ground or in the trees?

The big question that scientists have been trying to answer since Lucy's remains were found in 1974 is whether A. afarensis normally moved on the ground, walking, or if they were a species that preferred to be in the trees.

The analysis carried out at the University of California on the body structure of another of the hominids found tried to settle the debate.

The experts who studied "Selam", the name given to the fossil of a girl of the species, came to the conclusion that they spent more time between the branches than at ground level.

The features of the bones, especially the shoulder blade, identify this hominid with an active climber. The articulation of the man pointing up is the same that is found in modern monkeys, but not in the human being.

With this, it seems to be shown that their natural space was the heights, which would be part of their survival strategy.

Social structure

It is not easy to extrapolate the social structure of the fossil remains found, but paleoanthropologists have developed a number of theories based on the data.

In this way, the most common opinion is that they lived in small groups, settling in areas near water sources.

Like the rest of the bipeds, they used to be quite gregarious, establishing collaborative relationships to increase the chances of survival.

On the other hand, as with modern apes, the groups were structured around a dominant male, with several females for mating.

As for the A. Afarensis children, it is believed that they had a faster physical development than that of humans, becoming independent early.

Other aspects that are known are that they did not dominate the fire, that they were not hunters and that they did not build places to inhabit them.

Sex differentiation

One of the characteristics that are most taken into account when establishing the behavior patterns of a species is the so-called sexual dimorphism. This is nothing more than the physical differences between males and females.

In the case of A. afarensis, this dimorphism is very marked, both in size and weight. Comparing it with that presented by some current apes, experts have concluded that the males were responsible for the supply of the group and that, precisely, the need to transfer the food obtained could lead to the transformation into bipeds.

Likewise, although there are researchers who affirm that the individuals were monogamous, most agree that the males should compete for the attention of the females. As with some apes, the alpha male controlled the group, having mating privileges.

References

1. Tezanos, Patri. Australopithecus afarensis: the pre-homo. Obtained from antroporama.net
2. PortalScience. Australopithecus Afarensis. Obtained from portalciencia.net
3. Meroño, Lourdes. Who is Lucy, the Australopithecus afarensis ?. Obtained from elperiodico.com
4. Smithsonian Institution. Australopithecus afarensis. Retrieved from humanorigins.si.edu
5. Australian Museum. Australopithecus afarensis. Retrieved from australianmuseum.net.au
6. Human Origins Program. Australopithecus afarensis. Retrieved from eol.org
7. Henry McHenry Donald C. Johanson. Australopithecus. Retrieved from britannica.com
8. National Geographic Staff. What Was "Lucy"? Fast Facts on an Early Human Ancestor. Retrieved from news.nationalgeographic.com