Ardi
Ardi (ARA-VP-6/500) 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.[1]
Ardi, a more complete set of remains than the Australopithecus Lucy, cannot be a common ancestor of Chimpanzees and humans.[2] Chimpanzee feet are specialized for grasping trees. A. ramidus feet are better suited for walking.[3] 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.[4] "Thus, fundamental reproductive and social behavioral changes probably occurred in hominids long before they had enlarged brains and began to use stone tools."[5][6]
The word Ardi means "ground floor" and the word ramid means "root" in the Afar language.[7]
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[edit] Archaeology
Fossils of A. ramidus were first found in Ethiopia in 1992, but it took 17 years to assess their significance.[8] 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),[9] 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 [9][10][11] 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.[12]
[edit] Anatomy
Ardi lived more recently than the most recent common ancestor 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,[2] but rather was "probably a plantigrade quadrupedal arboreal climber/clamberer that lacked specializations for suspension, vertical climbing, or knuckle-walking"[13] (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.[4]
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: bipedal when moving on the ground, but quadrupedal when moving about in tree branches.[6][13][14] Ardi had a more primitive walking ability than later hominids, and could not walk or run for long distances.[11] The teeth suggest omnivory, and are more generalized than those of modern apes.[13]
[edit] See also
[edit] References
- ^ A new kind of ancestor: Ardipithecus unveiled, Ann Gibbons, Science, 2 October 2009, 326:36
- ^ a b The great divides, C. Owen Lovejoy et al., Science, 2 October 2009, 326:73
- ^ Combining prehension and propulsion: The foot of Ardipithecus ramidus, C. Owen Lovejoy et al., Science, 2 October 2009, 326:72
- ^ a b Reexamining human origins in light of Ardipithecus ramidus, C. Owen Lovejoy, Science, 2 October 2009, 326:74
- ^ Paleobiological implications of the Ardipithecus ramidus dentition, Gen Suwa, et al., Science, 2 October 2009, 326:69
- ^ a b "Oldest Skeleton of Human Ancestor Found". National Geographic. October 1, 2009. http://news.nationalgeographic.com/news/2009/10/091001-oldest-human-skeleton-ardi-missing-link-chimps-ardipithecus-ramidus.html. Retrieved 2009-12-22.
- ^ "NOVA". http://www.pbs.org/wgbh/nova/hobbit/tree-nf.html. Retrieved 2009-10-08.
- ^ Amos, Jonathan (2009-10-01). "Fossil finds extend human story". BBC News. http://news.bbc.co.uk/2/hi/8285180.stm. Retrieved 2010-04-25.
- ^ a b Lemonick, MD; Dorfman, D (1 October 2009). "Ardi is a new piece for the evolution puzzle". TIME. http://www.time.com/time/health/article/0,8599,1927200,00.html?xid=rss-health. Retrieved October 6, 2009.
- ^ Achenbach, J (2 October 2009). "'Ardi' may rewrite the story of humans: 1.4 million-year-old primate helps bridge evolutionary gap". Washington Post. http://www.washingtonpost.com/wp-dyn/content/article/2009/10/01/AR2009100103432.html?wprss=rss_technology. Retrieved October 3, 2009.
- ^ a b Amos, J (1 October 2009). "Fossil finds extend human story". BBC. http://news.bbc.co.uk/2/hi/science/nature/8285180.stm. Retrieved October 6, 2009.
- ^ "Online extras: Ardipithecus ramidus". Science. http://www.sciencemag.org/ardipithecus/. Retrieved October 6, 2009.
- ^ a b c White, TD et al; Asfaw, B; Beyene, Y; Haile-Selassie, Y; Lovejoy, CO; Suwa, G; Woldegabriel, G (1 October 2009). "Ardipithecus ramidus and the paleobiology of early hominids". Science 326 (5949): 75–86. doi:10.1126/science.1175802. PMID 19810190.
- ^ Gibbons, A (1 October 2009). "Ancient skeleton may rewrite earliest chapter of human evolution". ScienceNOW. http://sciencenow.sciencemag.org/cgi/content/full/2009/1001/1. Retrieved October 1, 2009.
[edit] 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)
