The mysterious skull of a primitive 6-year-old child discovered in a Chinese cave was found to have teeth similar to modern humans. The fascinating find is now the oldest known case of human teeth growth in East Asia.

Seven teeth were discovered in the child’s fossilized upper jaw – teeth which were in the process of development when the youngster died approximately 104,000 years ago. The remains were unearthed at a northern Chinese site called Xujiayao in the late 1970s.

Now, X-ray examinations of the teeth’s internal structure show the first molar had erupted a few months before death. Researchers found the root of the tooth was growing at similar pace to modern children, and while other tooth roots had grown more rapidly, overall the child’s dental growth fell within the range of kids today.

“Modern humans develop slowly, and at least for the first 6½ years of life, the dentition of the Xujiayao individual suggests that it also developed slowly,” study co-author Debbie Guatelli-Steinberg of Ohio State University explained.

The study, carried out by a team led by paleoanthropologist Song Xing of the Chinese Academy of Sciences in Beijing, was published online Wednesday in the journal Science Advances.

Researchers estimate that the child belonged to an East Asian Homo population because it had a relatively long life span and an extended period of child care – characteristics that are associated with modern man’s long period of tooth growth.

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Identifying exactly where this child fits in the span of human evolution is difficult given its unusual mix of features, some of which resemble those seen in Neanderthals and Homo erectus, however others suggest it’s more closely related to Homo sapiens.

Researchers say fossil and ancient DNA analyses suggest that all four Homo species lived in the region during the period that this jawbone is dated to.

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