Archaeology / Cultural Heritage

[Archaeology] [twocolumns]

Anthropology / Human Evolution

[Anthropology] [twocolumns]

Palaeontology / Earth Sciences

[Palaeontology] [twocolumns]

Evolution / Genetics


Human ancestors explored 'out of Africa' despite impaired nasal faculties

In humans inhaled air is conditioned poorly in the nasal cavity in comparison with primates, such as chimpanzees and macaques, according a recent study published in PLOS Computational Biology. Unlike our protruding external nose, which has little effect on improving air conditioning performance, other hominins (including australopithecines) were endowed with flat nasal features and faculties to improve air conditioning.

Human ancestors explored 'out of Africa' despite impaired nasal faculties
Human ancestors explored "Out of Africa" despite impaired nasal faculties. In humans inhaled air 
is conditioned poorly in the nasal cavity in comparison with primates, such as chimpanzees 
and macaques, according a recent study published in PLOS Computational Biology 
[Credit: Nishimura et al.]
The study, produced by Dr Takeshi Nishimura from Kyoto University and colleagues, is the first investigation of nasal air conditioning in nonhuman hominoids based on computational fluid dynamics (CFD).

The human nasal passage conditions inhaled air in terms of temperature and humidity to match the conditions required in the lung. Insufficient conditioning can damage the tissues in the respiratory system and impair respiratory performance, thereby undermining health and increasing the likelihood of death.

Our ancestors, the genus Homo, diversified under the fluctuating climate of the Plio-Pleistocene, to be flat-faced with a short nasal cavity and a protruding external nose, as seen in modern humans. Anatomical variation in nasal region is believed to be evolutionarily sensitive to the ambient atmospheric conditions of a given habitat, but the nasal anatomy of early Homo was not sensitive to the ambient atmosphere conditions. The inhaled air can be fully conditioned subsequently in the pharyngeal cavity, which was lengthened in early Homo.

This study highlights the importance of compensating human evolution, as well as adaptive evolution. The diversification of Pleistocene hominins is a major evolutionary event in terms of understanding human evolution. These linked changes in the nasal and pharyngeal regions would in part have contributed to how flat-faced Homo members must have survived fluctuations in climate, before they moved "Out of Africa" in the Early Pleistocene to explore the more severe climates and ecological environments of Eurasia.

Source: Public Library of Science [March 24, 2016]

Post A Comment
  • Blogger Comment using Blogger
  • Facebook Comment using Facebook
  • Disqus Comment using Disqus


  1. Thanks, this beautifully describes airflow in the human, chimp & macaque nasal cavities. However, it doesn't explain why Homo evolved external noses that don't seem to serve any useful purpose. Our smelling sensors are inside the head. Our nose is vulnerable to damage, and most primates & other mammals manage without external noses. Traditional explanations assume that the nose protects against dry air, hot air, cold air, dusty air, whatever air, but most savanna mammals have no external noses, and polar animals (e.g. arctic fox & hare) have shorter extremities incl. flatter noses (Allen’s Rule), not larger as the Neanderthal protruding nose.
    The answer isn't so difficult IMO, if we simply consider humans like other mammals. (Traditional paleo-anthropology is incredible anthropocentric, i.e. non-Darwinian.)
    An external nose is seen in e.g. elephant-seals, hooded seals, tapirs, elephants, swine & among primates the mangrove-dwelling proboscis monkeys Nasalis larvatus. Various functions (often mutually compatible) have been proposed: sexual display (male hooded & elephant seal, proboscis monkey), manipulation of food (elephants, tapirs, swine), snorkel (elephants, proboscis monkey), nose-closing aid during diving (most of these animals). These mammals spend a lot of time at the edge between land & water. Possible functions of an external nose in semi-aquatics are obvious: nose closure, snorkel, keeping the water out, digging in wet soil for food etc. Afterwards, these external noses can also become used for e.g. sexual display (visual & auditive) in hooded & elephant seals & proboscis monkeys.
    What does this have to do with human evolution?
    The earliest known Homo fossils outside Africa (e.g. Dmanisi in Georgia & probably Mojokerto on Java) are c 1.8 million years old. The easiest way to spread to other continents (incl.islands: Flores, Crete etc.) is along the sea-coasts, and from there inland along rivers. During the Pleistocene Glacials (after c 2.6 Ma) most sea-coasts were c 100 metres below the present-day sea-level, so we don't know whether or when Homo populations lived there, but coasts & river-sides are full of shellfish & other foods that are easily collected & digested by smart, handy & tool-using 'apes', and are rich in brain-specific nutrients (e.g. docosahexaenoic acid DHA). If Pleistocene Homo spread along the coasts, beach-combing, wading & diving for sea-foods as Sea Gypsies, Ama divers & Polynesian islanders still do, this could explain why H.erectus got larger brains (DHA) & larger noses (part-time diving). Apparently, at the coasts, they used stone tools to crack open shellfish, crabs & coconuts & to butcher stranded whales (Dungo V site, Baia Farta, Angola), at the rivers they butchered bovids that were trampled & drowned when crossing rivers during the trek, and in wetlands they killed or injured & let bleed to death herbivores that were hindered in their movements in the mud.
    This littoral intermezzo (wading, swimming, beach-combing & long-distance walking along the water) could help understand not only why we like to have our holidays at tropical beaches, eating shrimps & coconuts, but also why we became fat & furless bipeds with long legs, large brains & big noses. (after M.Verhaegen 2010 'Oi big nose' New Scientist 2782:69, Lastword NS 16.10.10).
    For an explanation why projecting nostrils are typically correlated with large paranasal air sinuses (elephants, suids, tapirs, H.heidelbergensis-neanderthalensis), see M.Verhaegen & P.Rhys Evans 2015, google researchGate marc verhaegen.

  2. I agree with Marc. I think it has much more to do with keeping water out of the nasal passages while the head is underwater. I've always been of the opinion that we as humans have spent a lot of our development in and near shallow waters.


Exhibitions / Travel

[Exhibitions] [bsummary]

Natural Heritage / Environment / Wildlife

[Natural Heritage] [list]

Astronomy / Astrobiology / Space Exploration

[Universe] [list]