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Turkana Boy, also called Nariokotome Boy, is the name given to fossil KNM-WT 15000, a nearly complete skeleton of a ''
Homo ergaster ''Homo ergaster'' is an extinct species or subspecies of archaic humans who lived in Africa in the Early Pleistocene. Whether ''H. ergaster'' constitutes a species of its own or should be subsumed into '' H. erectus'' is an ongoing and unresol ...
'' youth who lived 1.5 to 1.6 million years ago. This specimen is the most complete early hominin skeleton ever found. It was discovered in 1984 by
Kamoya Kimeu Kamoya Kimeu (1938 – 20 July 2022) was a Kenyan paleontologist and curator, whose contributions to the field of paleoanthropology were recognised with the National Geographic Society's LaGorce Medal and with an honorary doctorate of science deg ...
on the bank of the Nariokotome River near Lake Turkana in Kenya. Estimates of the individual's age at death range from 7 to 11 years old.


Adolescence and maturity

Although the specimen is largely considered male due to the shape of the pelvis, the sex is ultimately indeterminate due to its prepubescent age. Estimates of the age at death depend on whether the maturity stage of the teeth or skeleton is used, and whether that maturity is compared to that of Homo sapiens or to
chimpanzees The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative the ...
. A key factor is that, while modern humans have a marked adolescent
growth spurt Human height or stature is the distance from the bottom of the feet to the top of the head in a human body, standing erect. It is measured using a stadiometer, in centimetres when using the metric system or SI system, or feet and inches when ...
, chimpanzees do not. While initial research assumed a modern human type of growth, more recent evidence from other fossils suggests this was less present in early ''Hominids''. This affects the estimation of both the age and the likely stature of the specimen as a fully grown adult.
Alan Walker Alan Olav Walker (born 24 August 1997) is a British-born Norwegian music producer and DJ primarily known for the critically acclaimed single " Faded" (2015), which was certified platinum in 14 countries. He has also made several songs including ...
and
Richard Leakey Richard Erskine Frere Leakey (19 December 1944 – 2 January 2022) was a Kenyan paleoanthropologist, conservation movement, conservationist and politician. Leakey held a number of official positions in Kenya, mostly in institutions of archaeol ...
in 1993 estimated the boy to have been about 11–12 years old based on known rates of bone maturity.Walker explains: "in KNM-WT 15000, his skeletal development can only be used to place an upper limit of about 14 years on his age at death. However, a less often recognized skeletal maturational event does generally occur prior to 14 years in modern males – the union of the trochlea and capitulum (and also the lateral epicondyle) of the humerus, prior to their joint union with the humeral shaft.... That these elements were fused in KNM-WT 15000 (at least the capitulum and trochlea) suggests a skeletal age for him of somewhat more than 11 years.... In either event, 11 to 12 years would seem to be the best compromise figure to use for his chronological age at death." (Walker & Leakey, 1993, p. 235) Walker and Leakey (1993) said that dental dating often gives a younger age than a person's actual age."Just as in the case of human dental age (above), estimates based on tooth formation give slightly younger ages than those based on emergence." (Walker & Leakey, 1993, p. 207) Christopher Dean (M. C. Dean) of
University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = � ...
, in a 2009 '' Nova'' special, estimated that the Turkana Boy was 8 years old at death.https://www.pbs.org/wgbh/nova/beta/evolution/becoming-human-part-2.html, at 38:00 minutes on countdown


Morphology

The specimen comprises 108 bones, making it the most complete early human skeleton discovered. The Smithsonian estimates that he was tall and weighed when he died, and may have been close to his adulthood height. In adulthood, Turkana Boy might have reached tall and massed . The pelvis is narrower than in '' Homo sapiens'', which is most likely for more efficient upright walking. This further indicates a fully terrestrial
bipedalism 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' (from Latin ''bis'' 'double' ...
, which is unlike older hominin species that show a combined feature of bipedalism and tree climbing. The Boy was relatively tall, which increased his body surface area that would enhance heat dissipation and prevent heat stress under the hot sun. 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 ''H. sapiens''. However, there are significant defining characters, such as bigger brain size (880 cc). The arms and legs are slightly longer indicating effective bipedality. The nose is projecting like those of humans rather than the open flat nose seen in other apes. Body hair may also have been thinner (most likely naked) and possibly with increased
sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial su ...
s to hasten cooling. However, despite the appearance shown in the reconstruction of Turkana Boy, it's unlikely he actually had dark skin. The emergence of skin pigmentation in the genus Homo dates to about 1.2 million years ago. Genetic analysis suggests that high activity in the melanocortin 1 receptor, which produces dark skin, dates back to approximately that time.


Vocal capabilities

The fossil skeleton and other fossil evidence, such as
Acheulean Acheulean (; also Acheulian and Mode II), from the French ''acheuléen'' after the type site of Saint-Acheul, is an archaeological industry of stone tool manufacture characterized by the distinctive oval and pear-shaped " hand axes" associate ...
stone tools A stone tool is, in the most general sense, any tool made either partially or entirely out of stone. Although stone tool-dependent societies and cultures still exist today, most stone tools are associated with prehistoric (particularly Stone Ag ...
, prompt the majority of scientists to conclude that ''Homo ergaster'' and ''Homo erectus'' – unlike their more primitive ancestors – became efficient
hunters Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
. The social structure would probably have become more complex with a larger
brain volume The size of the brain is a frequent topic of study within the fields of anatomy, biological anthropology, animal science and evolution. Brain size is sometimes measured by weight and sometimes by volume (via MRI scans or by skull volume). Neur ...
; the
Broca's area Broca's area, or the Broca area (, also , ), is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production. Language processing has been linked to Broca's area since Pierre ...
of the brain allows speech and is noted by a slight slant on the
cranium The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...
. Turkana Boy's thoracic vertebrae are narrower than in ''Homo sapiens''. This would have allowed him less motor control over the thoracic muscles that are used in modern humans to modify respiration to enable the sequencing upon single exhalations of complex vocalisations.


Disease

Early studies indicated that Turkana Boy suffered from a
congenital disorder A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...
, either dwarfism or scoliosis. This was because the rib bones appeared asymmetrical to the
spine Spine or spinal may refer to: Science Biology * Vertebral column, also known as the backbone * Dendritic spine, a small membranous protrusion from a neuron's dendrite * Thorns, spines, and prickles, needle-like structures in plants * Spine (zoolo ...
, at the time attributed to
skeletal dysplasia Osteochondrodysplasia is a general term for a disorder of the development (dysplasia) of bone ("osteo") and cartilage ("chondro"). Osteochondrodysplasias are rare diseases. About 1 in 5,000 babies are born with some type of skeletal dysplasia. Non ...
. However, in 2013, a study showed that when the rib bones were rearranged, they became symmetrical against the spine, and that an unusual structure of the
vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...
was characteristic of the early hominins. However, the fossil definitely showed
lumbar disc herniation Spinal disc herniation is an injury to the cushioning and connective tissue between vertebrae, usually caused by excessive strain or trauma to the spine. It may result in back pain, pain or sensation in different parts of the body, and physica ...
, an injury implicated with the specimen's death. The specimen also had a diseased mandible.


See also

*
List of human evolution fossils The following tables give an overview of notable finds of hominin fossils and remains relating to human evolution, beginning with the formation of the tribe Hominini (the divergence of the human and chimpanzee lineages) in the late Miocene, rou ...


Notes


References


Further reading

* * * * – Good popular level presentation * – Technical papers * * *


External links

*
Human Timeline (Interactive)
Smithsonian
Celebrating the Turkana Human
- Google Doodles {{portal bar, Anatomy, Evolutionary biology, Paleontology Homo ergaster fossils Pleistocene Lake Turkana Archaeology in Kenya Prehistoric Kenya 1984 in Kenya 1984 archaeological discoveries Archaeology of Eastern Africa