Turkana Boy

Template:Infobox fossil Turkana Boy or Nariokotome Boy is the designation given to fossil KNM-WT 15000, a nearly complete skeleton of an 11- or 12-year-old hominid boy who died 1.5 million years ago in the early Pleistocene. The skeleton was discovered in 1984 by Kamoya Kimeu, a member of a team led by Richard Leakey, at Nariokotome near Lake Turkana in Kenya.

Adolescence and maturity

Turkana Boy is classified as either Homo erectus or Homo ergaster. The shape of the pelvis indicates that it was a male. Based on dental eruption and lack of any epiphyseal union of the skull, anthropologists Tim White and Richard Leakey determined the boy to have been about 12 years old. Other authorities, however, consider that since H. erectus matured faster than modern humans, the boy may have actually been about 9 years old.

Common chimpanzees (Pan troglodytes, for example) mature more quickly than Homo sapiens. Anatomist Raymond Dart discovered the first gracile australopithecine species (Australopithecus africanus) in 1924 in the Taung limestone quarry in South Africa. Tests have shown that A. africanus (Taung child) developed more quickly into adulthood like modern apes.

File:TurkanaboyV.jpg

KNM-WT 15000 "Turkana boy"

Turkana Boy appears to have matured at a rate in between modern humans and apes. Other fossils attributable to Homo erectus, Homo heidelbergensis, and Homo neanderthalensis show signs of an increasingly larger birth canal in the female, enabling mothers to give birth to larger brained infants in comparison to modern apes and australopithecines.

Morphology

The skeleton was about 1.60 m (5 ft 3 in) tall, although he might have been 68 kg (150 lb) and 1.85 m (6 ft 1 in) tall had he lived to adulthood. The total skeleton is made up of 108 bones accounted for. The cranial capacity of Turkana Boy was about 880 cc, although if he had lived to adulthood, it would have been about 910 cc, which is considerably smaller than the 1350 cc cranial capacity of modern humans.

There are several features which seem awkward in comparison to modern humans. The pelvic structure is narrower than in modern Homo sapiens, meaning that Homo ergaster and Homo erectus in both Africa and Asia had a greater ability to run. Their running techniques may have been equivalent to a modern day race track athlete. This hints that the species lived a harsh and demanding lifestyle; most importantly they must have been accomplished hunters rather than scavengers such as Homo habilis. Radical changes are believed to have taken place during the transformation between the australopithecines and Homo species. Because of Homo ergaster's greater height and limb proportions, which are more similar to Homo sapiens than to the ape-like australopithecines, a combination of height and likely absence of fur would have been a necessity.

From 2 million years ago onwards, a cool dark skin would have helped protect these hominins from deadly ultraviolet radiation from the sun. In equatorial Africa, modern humans evolved this trait an estimated 1 million years ago. The loss of thick fur enabled the sweating mechanism to cool the body down to the required 37 °C. The melanin development would have become crucial to surviving in open land. This coloring of the skin is still present in equatorial populations of modern Homo sapiens.

The overall body stature, weight, and proportions coincidentally are somewhat similar to today's ethnic Masai (also known as Maasai) peoples living in modern day Kenya. Tall, dark, slender bodies keep themselves cool by perspiration. However, the similarity should not be taken to be too great. The overall KNM-WT 15000 skeleton still had features (such as a low sloping forehead, strong brow ridges, and the absence of a chin) not seen in present day modern humans. The arms of the species were slightly longer than seen in modern-day humans. It is currently believed that Turkana Boy had a projecting nose rather than the open flat nose-structure seen in apes and possibly acquired in australopithecines. The larger protruding nose helped to keep in moisture at a balanced temperature, cooling the blood in hot arid areas. The opposite could be said for Homo neanderthalensis (Neanderthals), who had unusually large nostrils which would warm and humidify cold and dry air before it reached the throat and lungs.

Social behavior & language

File:Turkana boys vertabrea vertabrea.jpg

Turkana Boy's thoracic vertabrae (left) compared with a modern human's (right)

The fossil skeleton and much other fossil evidence such as Acheulean stone tools prompts the majority of scientists to conclude that Homo ergaster and Homo erectus, unlike their more primitive ancestors, became efficient hunters. The social structure would probably have become more complex with a larger brain volume; the Broca's area of the brain allows speech and is noted by a slight slant on the cranium. Some anthropologists believe that simplistic sounds led to modern language. However, there are contradictory views on the notion of language. It remains controversial when modern human sounds and basic verbs first became used. The various possibilities include:

• 1.9 million years ago (Homo habilis had a large Broca’s area able to be seen in the cranium of KNM ER 1813), possible signs of the earliest ability for speech.

• 1.5 million years ago, on the arrival of several distinct more human-like hominins spread throughout Africa, Europe, and Asia (i.e., Homo erectus).

• 600,000 and 150,000 years ago when archaic Homo sapiens dominated regions in the Pleistocene epoch (several members during this period are considered fully modern Homo sapiens).

• 50,000 years ago (fully modern Homo sapiens had already spread though the Old World and slowly into the New World 20,000 BCE). Some believe language coincided solely with modern humans once culture was established by groups such as Cro-Magnon man in Europe. It is still a matter of debate whether Neanderthals had a modern form of language.

Richard Leakey also mentions in his book Origin of humankind (1995) that Turkana Boy's thoracic vertebrae is narrower than in modern Homo sapiens's, meaning that he could not make complex speech due to less air being received into his lungs.

References

• Leakey, Richard (1994). The Origins of Human Kind. ISBN 0-465-03135-8.
• Barraclough, G. (1989). Stone, N. (ed.), ed. Atlas of World History (3rd edition ed.). Times Books Limited. ISBN 0-7230-0304-1.CS1 maint: Extra text: editors list (link) CS1 maint: Extra text (link)
• Walker, Alan. Wisdom of the Bones. ISBN 0-679-74783-4. - Good popular level presentation
• Alan Walker and Richard Leakey (eds.) (ed.). Nariokotome Homo Erectus Skeleton. ISBN 0-674-60075-4.CS1 maint: Extra text: editors list (link) - Technical papers
• Mckie, Robin (2000). Dawn of Man. BBC. ISBN 0-7894-6262-1.

See Also

• List of fossil sites (with link directory)
• List of hominina (hominid) fossils (with images)

External links

• Turkana Boy
• http://www.rps.psu.edu/sep98/missing.html
• http://www.findarticles.com/p/articles/mi_m1511/is_n3_v18/ai_19160830