© 2004 The Reef eXplorers Network™ (R.E.N.) DiveNews.Com NEWS @ DEPTH - Current & Wet Events™ Children of Moven Tribe Have Amazing Underwater Vision Articles / The NEWS @ DEPTH Date: Sunday, July 20, 2003 AD - 01:24 AM For hundreds of years the Moven tribe has lived on the islands of the Andaman Sea, Thailand harvesting clams, sea cucumbers and other shellfish from the waters. Known as sea gypsies, they are a nomadic tribe. They are of the Moken tribe and wander among the many small islands that dot the sea off the coasts of Thailand and Burma. It is known that the children of this tribe are able to see underwater much more clearly and without the normal blurriness encountered by the human eye under the sea... Swedish scientist Anna Gislen travelled with her 7 year old daughter to Thailand to study the children of this tribe and their vision. The Moven children are also excellent divers. They plunge 75 feet deep to locate and return with sea creatures that the tribe eats for meals. The most amazing part about the children is their amazingly sharp vision while underwater. They can spot even the tiniest of shellfish without goggles or aids of any kind. Most people with excellent vision would be unable to tell the shellfish from the many tiny pebbles surrounding the creatures. Gislen compared the vision of Moken children with the vision of volunteers from European families holidaying on Surin, an island near the Thai-Burmese maritime border. The Moken children in the study were between 8 and 13 years old. Both Moken and European children were asked to identify black strips on submerged test panels. The Moken children were able to identify twice as many strips. Gislen discovered that the Moken children actually could shrink the pupils of their eyes by about 20 per cent more than the European children. This gave them much sharper vision under the waves. The reasearch team concluded that although Moken children and European children have the same visual acuity on land, the Moken have more than twice the underwater resolving power of European children. In fact, these children exhibited a level of underwater visual acuity thought to be impossible in the human species. Detailed studies by Gislen's research crew team pointed to the fact that the Moken enhance their vision not by flattening the corneas on the front of their eyes. This approach is used by some species of amphibious birds, fish and frogs. The Moven tribe children do not use "accommodation," the use of tiny muscles to change the curvature of the lens inside the eye. Such a technique is a standard way to correct vision but cannot on its own remove the blurriness encountered by the typical human eye underwater. Gislen discovered that the children actually shrink the size of their pupils to a diameter of 1.96 millimeters. This size is a full 22 percent smaller than the 2.5 millimeter minimum measured in theEuropeans studied. Early studies into whether the pupil response is the result of a learned behavior suggests that although training can produce an improvement in visual acuity, European children simply cannot achieve the same level of underwater vision as Moken children. Gislen's study is published in full detail in the May 13 issue of Current Biology. Source: Current Biology; Washington Post; Dallas News This article comes from DiveNews.Com http://www.divenews.com/ The URL for this story is: http://www.divenews.com/modules.php?op=modload&name=News&file=article&sid=1674