Ardi
Encyclopedia
Ardi is the designation of the fossilized skeletal remains of a female Ardipithecus ramidus, an early human-like species 4.4 million years old. It is the most complete early hominid specimen, with most of the skull, teeth, pelvis, hands and feet.
Ardi, a more complete set of remains than the Australopithecus Lucy, cannot be a common ancestor of Chimpanzees and humans. Chimpanzee feet are specialized for grasping trees. A. ramidus feet are better suited for walking. The canine teeth of A. ramidus are smaller, and equal in size between males and females. This suggests reduced male-to-male conflict, pair-bonding, and increased parental investment. "Thus, fundamental reproductive and social behavioral changes probably occurred in hominids long before they had enlarged brains and began to use stone tools."
The word Ardi means "ground floor" and the word ramid means "root" in the Afar language
.
in 1992, but it took 17 years to assess their significance. Ardi is a more primitive hominid than the well-known Australopithecine
skeleton, Lucy
. Standing at 4 feet (120 cm) tall and weighing around 110 pounds (50 kg), Ardi was about 6 inches taller than Lucy but almost double her weight. The skeleton was discovered at a site called Aramis
in the arid badlands near the Awash River
in Ethiopia in 1994. Although it is not known whether Ardi's species developed into Homo sapiens, the discovery is of great significance as Ardi is the oldest known hominid fossil. The discovery was made by a team of scientists led by UC Berkeley anthropologist, Tim D. White and was analyzed by an international group of scientists that included Owen Lovejoy
heading the biology team. On October 1, 2009, the journal Science
published an open-access collection of eleven articles, detailing many aspects of A. ramidus and its environment.
of chimps and humans, but still provides some evidence for what that ancestor was like. Specifically, the skeleton suggests the common ancestor was not as chimp-like as some had supposed, but rather was "probably a plantigrade
quadrupedal arboreal climber/clamberer that lacked specializations for suspension, vertical climbing, or knuckle-walking" (i.e. the common ancestor lacked certain important specializations of chimps).
The canine teeth of A. ramidus are smaller, and equal in size between males and females. This suggests reduced male-to-male conflict, pair-bonding, and increased parental investment.
Researchers infer from the form of Ardi's pelvis and limbs and the presence of her opposable
big toe
that she was a facultative biped
: biped
al when moving on the ground, but quadruped
al when moving about in tree branches. Ardi had a more primitive walking ability than later hominids, and could not walk or run for long distances. The teeth suggest omnivory, and are more generalized than those of modern apes.
Ardi, a more complete set of remains than the Australopithecus Lucy, cannot be a common ancestor of Chimpanzees and humans. Chimpanzee feet are specialized for grasping trees. A. ramidus feet are better suited for walking. The canine teeth of A. ramidus are smaller, and equal in size between males and females. This suggests reduced male-to-male conflict, pair-bonding, and increased parental investment. "Thus, fundamental reproductive and social behavioral changes probably occurred in hominids long before they had enlarged brains and began to use stone tools."
The word Ardi means "ground floor" and the word ramid means "root" in the Afar language
Afar language
Afar is a Lowland East Cushitic language spoken in Ethiopia, Eritrea and Djibouti. It is believed to have 1.5 million speakers, the Afar. The basic word order in Afar, like in other East Cushitic languages, is subject–object–verb. Its speakers have a literacy rate of between one and three per cent...
.
Archaeology
Fossils of A. ramidus were first found in EthiopiaEthiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
in 1992, but it took 17 years to assess their significance. Ardi is a more primitive hominid than the well-known Australopithecine
Australopithecus
Australopithecus is a genus of hominids that is now extinct. From the evidence gathered by palaeontologists and archaeologists, it appears that the Australopithecus genus evolved in eastern Africa around 4 million years ago before spreading throughout the continent and eventually becoming extinct...
skeleton, Lucy
Lucy (Australopithecus)
Lucy is the common name of AL 288-1, several hundred pieces of bone representing about 40% of the skeleton of an individual Australopithecus afarensis. The specimen was discovered in 1974 at Hadar in the Awash Valley of Ethiopia's Afar Depression. Lucy is estimated to have lived 3.2 million years...
. Standing at 4 feet (120 cm) tall and weighing around 110 pounds (50 kg), Ardi was about 6 inches taller than Lucy but almost double her weight. The skeleton was discovered at a site called Aramis
Aramis, Ethiopia
Aramis is a village and archaeological site in northeastern Ethiopia, where remains of Australopithecus and Ardipithecus have been found...
in the arid badlands near the Awash River
Awash River
The Awash is a major river of Ethiopia. Its course is entirely contained within the boundaries of Ethiopia, and empties into a chain of interconnected lakes that begin with Lake Gargori and end with Lake Abbe on the border with Djibouti, some 100 kilometers from the head of the Gulf of Tadjoura...
in Ethiopia in 1994. Although it is not known whether Ardi's species developed into Homo sapiens, the discovery is of great significance as Ardi is the oldest known hominid fossil. The discovery was made by a team of scientists led by UC Berkeley anthropologist, Tim D. White and was analyzed by an international group of scientists that included Owen Lovejoy
Owen Lovejoy (anthropologist)
Claude Owen Lovejoy is a functional anatomist at Kent State University, Ohio and Director of the Matthew Ferrini Institute for Human Evolutionary Research. He is best known for his work on Australopithecine locomotion and the origins of bipedalism...
heading the biology team. On October 1, 2009, the journal Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
published an open-access collection of eleven articles, detailing many aspects of A. ramidus and its environment.
Anatomy
Ardi lived more recently than the most recent common ancestorMost recent common ancestor
In genetics, the most recent common ancestor of any set of organisms is the most recent individual from which all organisms in the group are directly descended...
of chimps and humans, but still provides some evidence for what that ancestor was like. Specifically, the skeleton suggests the common ancestor was not as chimp-like as some had supposed, but rather was "probably a plantigrade
Plantigrade
right|151px|thumb|Human skeleton, showing plantigrade habitIn terrestrial animals, plantigrade locomotion means walking with the podials and metatarsals flat on the ground. It is one of three forms of locomotion adopted by mammals...
quadrupedal arboreal climber/clamberer that lacked specializations for suspension, vertical climbing, or knuckle-walking" (i.e. the common ancestor lacked certain important specializations of chimps).
The canine teeth of A. ramidus are smaller, and equal in size between males and females. This suggests reduced male-to-male conflict, pair-bonding, and increased parental investment.
Researchers infer from the form of Ardi's pelvis and limbs and the presence of her opposable
Abduction (kinesiology)
Abduction, in functional anatomy, is a movement which draws a limb away from the median plane of the body. It is thus opposed to adduction.-Upper limb:* of arm at shoulder ** Supraspinatus** Deltoid* of hand at wrist...
big toe
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
that she was a facultative biped
Facultative biped
A facultative biped is an animal that is capable of walking or running on two legs, often for only a limited period of time, in spite of normally walking or running on four limbs or more. Well-known examples include many lizards such as the Basilisk lizard, and even some cockroaches when running...
: biped
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
al when moving on the ground, but quadruped
Quadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
al when moving about in tree branches. Ardi had a more primitive walking ability than later hominids, and could not walk or run for long distances. The teeth suggest omnivory, and are more generalized than those of modern apes.
External links
- Human Origins and the Fossil Skeleton Ardi Radio interview of Stanley Ambrose, Professor of Anthropology, University of Illinois
- Ardi - The oldest Hominid (Scientific Indian)