External Nose Projection

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Human Uniqueness Compared to "Great Apes": 
Absolute Difference
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Humans, unlike other apes, possess a projecting, external nose whose overall structure is reflected in a series of derived skeletal features including: nasal bone convexity, an internasal angle, lateral nasal aperture eversion, prominence and anterior positioning of a true anterior nasal spine rather than a nasal tubercle, an acutely angled subnasal alveolar clivus, and an expansion of the breadth of the nasal bones relative to that of the piriform aperture. This constellation of features first appears with the emergence of Homo erectus in early Pleistocene Africa. Although nasal projection undoubtedly evolved in the context of craniofacial and dental reduction during hominin evolution, it also likely represented an adaptive response to the need for respiratory moisture conservation in an arid environment. More specifically, it indicates a shift to increasingly prolonged bouts of activity in such dry and open environments. While the adaptive basis for nose form is questioned by some, substantial evidence from clinical studies, mathematical airflow, temperature/humidity modeling, and quantitative studies showing departure from neutral evolutionary expectations support its adaptive basis. Nonetheless, the precise role of the external nose independent of the internal nasal cavity in terms of conditioning respiratory air and ameliorating moisture loss is incompletely understood.


Timing of appearance of the difference in the Hominin Lineage as a defined date or a lineage separation event. The point in time associated with lineage separation events may change in the future as the scientific community agrees upon better time estimates. Lineage separation events are defined in 2017 as:

  • the Last Common Ancestor (LCA) of humans and old world monkeys was 25,000 - 30,000 thousand (25 - 30 million) years ago
  • the Last Common Ancestor (LCA) of humans and chimpanzees was 6,000 - 8,000 thousand (6 - 8 million) years ago
  • the emergence of the genus Homo was 2,000 thousand (2 million) years ago
  • the Last Common Ancestor (LCA) of humans and neanderthals was 500 thousand years ago
  • the common ancestor of modern humans was 100 - 300 thousand years ago

Probable Appearance: 
2,000 thousand years ago
Background Information: 

Franciscus & Trinkaus, 1988. Nasal morphology and the emergence of Homo erectus. Am J Phys Anthropol 75: 517-528. Dean, 1988. Another look at the nose and the functional significance of the face and nasal mucous membrane for cooling the brain in fossil hominids. J Hum Evol 17: 715-718.

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Sense of Smell Likely


  1. A genome-wide association scan implicates DCHS2, RUNX2, GLI3, PAX1 and EDAR in human facial variation., Adhikari, Kaustubh, Fuentes-Guajardo Macarena, Quinto-Sánchez Mirsha, Mendoza-Revilla Javier, Chacón-Duque Juan Camilo, Acuña-Alonzo Victor, Jaramillo Claudia, Arias William, Lozano Rodrigo Barquera, Pérez Gastón Macín, et al. , Nat Commun, 05/2016, Volume 7, p.11616, (2016)
  2. Impaired Air Conditioning within the Nasal Cavity in Flat-Faced Homo., Nishimura, Takeshi, Mori Futoshi, Hanida Sho, Kumahata Kiyoshi, Ishikawa Shigeru, Samarat Kaouthar, Miyabe-Nishiwaki Takako, Hayashi Misato, Tomonaga Masaki, Suzuki Juri, et al. , PLoS Comput Biol, 2016 Mar, Volume 12, Issue 3, p.e1004807, (2016)