Rare dental trait provides morphological evidence of archaic introgression in Asian fossil record

Edited by James F. O’Connell, University of Utah, Salt Lake City, UT, and approved June 12, 2019 (received for review May 3, 2019)
July 8, 2019
116 (30) 14806-14807
A more comprehensive view of the Denisovan 3-rooted lower second molar from Xiahe
G. Richard Scott, Joel D. Irish, María Martinón-Torres
Reply to Scott et al: A closer look at the 3-rooted lower second molar of an archaic human from Xiahe
Shara E. Bailey, Kornelius Kupczik [...] Susan C. Antón
Science Sessions podcast
Signs of admixture in fossil record


The recently described Denisovan hemimandible from Xiahe, China [F. Chen et al., (2019) Nature 569, 409–412], possesses an unusual dental feature: a 3-rooted lower second molar. A survey of the clinical and bioarchaeological literature demonstrates that the 3-rooted lower molar is rare (less than 3.5% occurrence) in non-Asian Homo sapiens. In contrast, its presence in Asian-derived populations can exceed 40% in China and the New World. It has long been thought that the prevalence of 3-rooted lower molars in Asia is a relatively late acquisition occurring well after the origin and dispersal of H. sapiens. However, the presence of a 3-rooted lower second molar in this 160,000-y-old fossil hominin suggests greater antiquity for the trait. Importantly, it also provides morphological evidence of a strong link between archaic and recent Asian H. sapiens populations. This link provides compelling evidence that modern Asian lineages acquired the 3-rooted lower molar via introgression from Denisovans.

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Supporting Information

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Published in

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Proceedings of the National Academy of Sciences
Vol. 116 | No. 30
July 23, 2019
PubMed: 31285349


Submission history

Published online: July 8, 2019
Published in issue: July 23, 2019


  1. Denisovan
  2. introgression
  3. dental anthropology
  4. root morphology
  5. Pleistocene Homo


*Wu and Xianglong (12) report the presence of a 3RM1 in the 1959 Zhoukoudian mandible (PA 86) based on observations of its left M1 root socket. Published photographs (13, 14), however, show a small septum of the mesial root socket (that may represent a bifurcated mesial root) but no evidence of a lingual accessory root. The 3RM anomaly requires that the accessory root occurs between the mesial and distal root or as a lingual accessory of the distal root.
The first molar in this individual has 2 roots.



Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY 10003;
Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany;
Jean-Jacques Hublin
Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany;
Collège de France, 75005 Paris, France
Susan C. Antón
Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY 10003;


To whom correspondence may be addressed. Email: [email protected].
Author contributions: S.E.B. designed research; S.E.B. and S.C.A. performed research; J.-J.H. contributed data; S.E.B. analyzed data; and S.E.B., J.-J.H., and S.C.A. wrote the paper.

Competing Interests

The authors declare no conflict of interest.

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    Rare dental trait provides morphological evidence of archaic introgression in Asian fossil record
    Proceedings of the National Academy of Sciences
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    • No. 30
    • pp. 14783-15309







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