Post by zarahan on Sept 12, 2011 0:50:20 GMT -5
Tropical climates are extremely diverse – from humid rainforest, to higher altitude cold zones, to arid deserts with sharply dropping night temperatures. Scientists find that nose width is correlated with climate – with narrower noses seen in dry, conditions such as desert areas in eastern parts of Africa.
QUOTE: "Tropical climates range from oppressively hot and humid lowlands to cold, snow-covered mountains, from hot, dry deserts to cold, dry deserts, from extreme seasonal variability of precipitation to nearly constant year-round conditions."
--Huston. M. (1994) Biological diversity: the coexistence of species on changing landscapes Cambridge university Press. p 498
QUOTE: "An important function of the nose is to warm and moisten inspired air. When air is exhaled, some heat and moisture are lost to the surroundings. The longer the nasal passage, the more efficient the nose is for warming and moistening incoming air and also the less heat and moisture are lost on exhalation. A narrow, high nose gives a longer nasal passage than a low, broad nose. Therefore, in cold or dry conditions, a high, narrow nose is preferable for warming and moistening air before it reaches the lings, and for reducing loss of heat and moisture in expired air. In hot, humid conditions a low, broad nose serves to dissipate heat (Wolpoff 1968; Franciscis and Long 1991)... The pattern of variation in nasal index corresponds very broadly to that expected if nasal form is indeed an adaptation to regional climate. The highest nasal index values, representing broad, low noses, tend to be those of populations in humid tropical regions of Africa and south-east Asia. Populations with low mean nasal indices (high, narrow noses) tend to be found in the cold, northern latitudes, and also in arid regions, such as the desert areas of east Africa and the Arabian peninsula.
..Davies found the nasal index taken in the living was closely correlated with skeletal nasal index. This suggests that there should likewise be an association between skeletal nasal index and climatic zone, and indeed other workers have found this to be the case.“
-- Mays. S. (2010). The Archaeology of Human Bones. Pg 100-101
2011 study finds significant correlation between nasal shape and climate. Dry areas are common in tropical zone micro-climates such as deserts.
QUOTE: “"The nasal cavity is essential for humidifying and warming the air before it reaches the sensitive lungs. Because humans inhabit environments that can be seen as extreme from the perspective of respiratory function, nasal cavity shape is expected to show climatic adaptation.. We report significant correlations between nasal cavity shape and climatic variables of both temperature and humidity. Variation in nasal cavity shape is correlated with a cline from cold-dry climates to hot-humid climates, with a separate temperature and vapor pressure effect. "
-- Noback, M. et al. (2011) Climate-related variation of the human nasal cavity. AJPA, 145: 4. 599-614
In West Africa and further down even into Angola native populations
show narrower noses...