ARDIPITHECUS RAMIDUS: CHARACTERISTICS, SKULL, FEEDING - CULTURE VOCABULARY - 2025

The Ardipithecus ramidus corresponds to a species of hominid that is believed to be related to humans and that was probably bipedal. For many scientists it has been an evolutionary enigma; the missing link, that empty place in the evolutionary chain, has inspired conspiracy theories and fictional tales.

In 1992, a discovery was made that raised more questions about the question "what was the last common relative between human and chimpanzee like?" In the Ashaw Valley, in the Ethiopian village of Aramis, Gen Suwa - a palaeoanthropologist at the University of Tokyo - found the first sign: a molar. Its unusual shape aroused interest and excavations continued.

Ardipithecus ramidus skull. National Museum of Natural Sciences in Madrid. Tiia Monto, from Wikimedia Commons

Forty men, led by the American paleonatropologist Tim White, made the discovery: the remains of a hominid that they later named Ardipithecus ramidus.

The origin of the name is derived from ardi, which in the Afar language means "soil"; and pithecus, which in Latinized Greek means "ape." On the other hand, ramid is the word that the Afar have given for "root."

Excavations continued for two more years, in which fossils - mostly teeth - of more than 110 specimens were collected. Decades later, the scientific community still marvels at the anatomical and evolutionary mosaic that Ardipithecus ramidus represents.

Age and distribution

The fossils found in Aramis are the oldest hominid remains, with an age of 4.4 million years. This places Ardipithecus ramidus in the Pliocene epoch.

Its closest ancestor is Ardipithecus kadabba, of which only small fossils have been found, such as teeth and bone fragments. The fossils of this hominid date back approximately 5.6 million years.

Due to the location of the fossils, it is presumed that Ardipithecus ramidus only lived along the middle Awash Valley of Ethiopia, located in East Africa.

Fossils have also been found in Kenya, which could belong to specimens of Ardipithecus ramidus.

Physical characteristics

To understand the anatomy of Ardipithecus ramidus it is necessary to examine Ardi, the best-preserved specimen of this genus. Its remains are key to knowing the details of the teeth, pelvis, skull and leg of a female Ardipithecus.

Ardi is an anatomical enigma, full of ambiguities in its structure that have inspired debates about the place that Ardipithecus ramidus occupies in the evolutionary chain.

Ardi's skeleton. By Chartep, from Wikimedia Commons

Their limb proportions are far from that of a modern chimpanzee or human, suggesting that these differences originated after their lineages split.

Body size

The most complete Ardipithecus ramidus specimen measures approximately 1.20 meters and it is speculated that it weighed around 50 kilograms.

The sexual dimorphism of this species was not pronounced, since characteristics such as body size and teeth did not vary greatly between males and females.

The body structure of these hominids more closely resembled that of apes than modern humans. Here are some important features to prove it:

-The arch of the foot is not pronounced, which would have prevented him from walking upright for long distances.

-The shape of the bones of the pelvis, femur and tibia suggest bipedalism or semi-bipedalism.

-His long arms, as well as his elongated and curved fingers, allowed him a better grip on the branches.

-His rigid feet were able to support and propel a bipedal motion more effectively. However, his opposable big toe did not allow this movement for extended periods.

-The bones of its hand, specifically those of the radiocarpal joint, allowed flexibility and its small palm suggests that the Ardipithecus ramidus did not walk with clenched fists and could use its hands to cling to the branches of trees.

Teeth

This species has similarities to that of modern apes, but the following characteristics are important in revealing its relationship with humans:

-The size of his molars was relatively large compared to the other teeth.

-The thickness of its enamel was less than Australopithecus, but greater than that of a chimpanzee.

-The premolars are arranged in a similar way to those of the human.

-The canines had a diamond shape, not as pointed as that of other African apes.

These aspects could indicate that Ardipithecus r. It fed primarily on vegetables, although it was also capable of eating vertebrates and small insects.

Cranial capacity

The brain size was approximately 350 cc, similar to that of a bonobo or chimpanzee.

Its cranial position indicates a certain degree of bipedalism, since the base of the skull - small in size - rested just on the vertebral column. The size of the skull of Ardipithecus r. it also suggests that they had a small face.

Feeding

Some features of its teeth, such as the thinness of its enamel and the size of its molars and incisors, indicate that it survived on a more omnivorous diet than that of a chimpanzee.

The carbon isotopes analyzed in the molars of Ardipithecus r. indicate that it fed more on tree leaves than grass.

The state and size of the tusks indicate that it was not a specialized frugivore like chimpanzees, as well as that it did not feed on hard vegetation that required a lot of chewing. It is possible that Ardipithecus r. It will feed on small mammals, fruits, nuts and eggs.

Habitat

A volcanic pit in which the fossils of seventeen specimens of Ardipithecus ramidus were found has paleontological and geological information that allows us to imagine the habitat of this hominid.

Four million years ago, Aramis was a lush jungle, crossed by rivers and streams. The plant and animal remains found in Aramis indicate that the geography of this region resembled a very humid forest without being rainy. Plants such as fig and hackberry were common in the area.

The fossils found belong to various animals such as reptiles, snails, birds, small mammals and porcupines, among others. 4.4 million years ago Aramis was also home to other animals such as elephants, antelopes, giraffes, saber tooth and colobin monkeys, as well as owls, parrots and other species of birds.

The shape of the feet of the Ardipithecus ramidus suggests that it was capable of climbing jungle trees in search of food and shelter.

Despite having an ideal bone structure for this, it is believed that this specimen was able to walk on two legs to a greater degree than many modern primates. The accentuation of this trait is one of the most important differences of Homo sapiens in relation to other hominids.

Relationship with other species

The Ardipithecus ramidus is located in the hominidae family, specifically in the hominini subfamily, sharing a place with Orrorin, Paranthropus, Sahelanthropus and Australopithecus. However, its closest ancestor is Ardipithecus kadabba.

The exact place of Ardipithecus ramidus in the hominin chain has been a matter of debate since its discovery. The ambiguity of its characteristics makes it difficult to classify it, but it is speculated that this genus is a direct ancestor of Australopithecus.

This hypothesis places Ardipithecus as the last common relative between humans and chimpanzees.

It can be deduced that some of the most representative characteristics of the chimpanzee, such as its pronounced canines, short backs, flexible feet and its way of walking with its fists, developed after it had been separated from the human lineage.

Culture

The size ratio between the canines and the other teeth of Ardipithecus ramidus gives indications of its social behavior. Hominids such as chimpanzees and gorillas use the large size of their upper fangs to intimidate and attack other males that are in competition for a female.

Some researchers suggest that Ardipithecus ramidus tusks, smaller than those of a chimpanzee, suggest that aggressiveness was not a fundamental component of its gender.

It is also possible that its cranial structure allowed for vocal projection and modulation abilities similar to those of a modern infant. However, it is a very recent hypothesis that emerged in 2017 and published in the scientific journal Homo, which is why it still deserves further investigation.

On the other hand, it is possible the Ardipithecus ramidus had made use of sticks, branches and stones as tools to process its food.

Media interest

For seventeen years, interest in Ardipithecus ramidus was limited to closed circles in the scientific community; however, in 2009 the discovery of Ardi's remains was made public.

The announcement attracted the attention of the press and eventually was featured in the American magazine Science as a preview of the year.

The publication had numerous and extensive articles that analyzed the history and anatomy, as well as speculated on the connection with the hominid family, their customs, diet and behavior, among other aspects.

Without a doubt, the discovery of Ardipithecus ramidus marked an important milestone in modern science.

References

1. Clark, Gary; Henneberg, Maciej, "Ardipithecus ramidus and the evolution of language and singing: An early origin for hominin vocal capability (2017)" in HOMO. Retrieved on August 27, 2018: sciencedirect.com
2. García, Nuria, “Our Ancestor Ardipithecus Ramidus” (November 2009) in Quo. Retrieved on August 27, 2018: quo.es
3. Harmon, Katherine, "How Humanlike Was« Ardi? " (November 2019) in Scientific American. Retrieved on August 27, 2018: scientificamerican.com
4. White, Tim “Ardipithecus” (September 2016) in Britannica. Retrieved on August 27, 2018: britannica.com
5. Hanson, Brooks "Light on the Origin of Man" (October 2009) in Science. Retrieved on August 27, 2018: science.sciencemag.org
6. Cáceres, Pedro “'Ardi': the oldest hominid skeleton” (October 2009) in El Mundo. Retrieved on August 27, 2018: elmundo.es
7. Europa Press "Where did Ardi live 4 million years ago?" (May 2010) in Europa Press. Retrieved on August 27, 2018: europapress.es
8. Dorey, Fran “Ardipithecus Ramidus” (October 2015) at Australian Museum. Retrieved on August 27, 2018: australianmuseum.net.au