Minor contributions of the maxillary sinus to the air-conditioning performance in macaque monkeys

Takeshi Nishimura, Juri Suzuku, Takato Miyabe-Nishiwaki, et al.

Abstract
The nasal passages mainly adjust the temperature and humidity of inhaled air to reach the alveolar condition required in the lungs. By contrast to most other non-human primates, macaque monkeys are distributed widely among tropical, temperate and subarctic regions, and thus some species need to condition the inhaled air in cool and dry ambient atmospheric areas. The internal nasal anatomy is believed to have undergone adaptive modifications to improve the air-conditioning performance. Furthermore, the maxillary sinus (MS), an accessory hollow communicating with the nasal cavity, is found in macaques, whereas it is absent in most other extant Old World monkeys, including savanna monkeys. In this study, we used computational fluid dynamics simulations to simulate the airflow and heat and water exchange over the mucosal surface in the nasal passage. Using the topology models of the nasal cavity with and without the MS, we demonstrated that the MS makes little contribution to the airflow pattern and the air-conditioning performance within the nasal cavity in macaques. Instead, the inhaled air is conditioned well in the anterior portion of the nasal cavity before reaching the MS in both macaques and savanna monkeys. These findings suggest that the evolutionary modifications and coetaneous variations in the nasal anatomy are rather independent of transitions and variations in the climate and atmospheric environment found in the habitats of macaques.
Supported financially by the Asahi Grass Foundation, Tokyo, Japan (to TN) and by the Japan Society for the Promotion of Science [Grants-in-Aid for Scientific Research, 26650171 to TN and 26304019 to M Takai; Strategic Young Researcher Overseas Visits Program for Accelerating Brain Circulation, to TN].

Bibliographic information

Futoshi Mori, Sho Hanida, Kiyoshi Kumahata, Takako Miyabe-Nishiwaki, Juri Suzuki, Teruo Matsuzawa and Takeshi D. Nishimura*. Minor contributions of the maxillary sinus to the air-conditioning performance in macaque monkeys. J Exp Biol 2015 218:2394-2401. ; doi: 10.1242/jeb.118059

2015/08/11 Primate Research Institute