The Turkana Boy

A remarkable fossil of early Homo erectus is both of the right age at death and complete enough to allow for an analysis of possible adolescent growth. The fossil specimen is catalogued formally by the name KMN-WT 15000, but is called informally the 'Turkana boy' as it was discovered along the western shores of Lake Turkana, Kenya, by Kamoya Kimeu in 1984 . This fossil is 1.6 million years old, making it an early variety of Homo erectus. The skeletal remains are almost complete, missing the hands and feet and a few other minor bones. It is the most complete known specimen of H. erectus. Holly Smith (1993) analyzed the skeleton and dentition of the Turkana fossil and ascertained that, indeed, it is most likely the remains of an immature male.

The Turkana boy's age has been estimated from fifteen years to as young as seven years. If the Turkana boy grew along the modern human trajectory, then dental, skeletal and stature ages should be about equivalent. By chimpanzee growth standards, however, the boy's dental and bone ages are in perfect agreement, both at seven years of age. As Homo erectus is no chimpanzee, the Turkana boy's true age at death was probably between seven and 11 years. What is clear is that the Turkana boy followed a pattern of growth that is neither that of a modern human nor that of a chimpanzee. Based on Smith's analysis the boy's large stature becomes more explicable. The reason for his relatively large stature-for-age is that the distinct human pattern of moderate to slow growth prior to puberty followed by an adolescent growth spurt had not yet evolved in early Homo erectus. Rather, the Turkana boy followed a more ape-like pattern of growth in stature making him appear to be tall in comparison with a modern human boy at the same age.

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• What is the Turkana boy? Explain.