Superior underwater vision in a human population of sea gypsies
Author
Summary, in English
Humans are poorly adapted for underwater vision. In air, the curved corneal surface accounts for two-thirds of the eye's refractive power, and this is lost when air is replaced by water [1]. Despite this, some tribes of sea gypsies in Southeast Asia live off the sea, and the children collect food from the sea floor without the use of visual aids [2]. This is a remarkable feat when one considers that the human eye is not focused underwater and small objects should remain unresolved. We have measured the visual acuity of children in a sea gypsy population, the Moken, and found that the children see much better underwater than one might expect. Their underwater acuity (6.06 cycles/degree) is more than twice as good as that of European children (2.95 cycles/degree). Our investigations show that the Moken children achieve their superior underwater vision by maximally constricting the pupil (1.96 mm compared to 2.50 mm in European children) and by accommodating to the known limit of human performance (15-16 D) [3]. This extreme reaction-which is routine in Moken children-is completely absent in European children. Because they are completely dependent on the sea, the Moken are very likely to derive great benefit from this strategy.
Department/s
Publishing year
2003
Language
English
Pages
833-836
Publication/Series
Current Biology
Volume
13
Issue
10
Links
Document type
Journal article
Publisher
Elsevier
Topic
- Zoology
Status
Published
Research group
- Lund Vision Group
ISBN/ISSN/Other
- ISSN: 1879-0445