Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

Planet Earth

A Blind Eye on Darwin

By Jocelyn SelimJanuary 2, 2005 6:00 AM
Sighted fish (top) gave rise to blind fish that live in caves (middle). A simple genetic tweak can destroy eye develop-ment (bottom). | Courtesy of Dr. Yoshiyuki Yamamoto


Sign up for our email newsletter for the latest science news

Biologists may have misinterpreted the significance of blind cave fish, much-studied examples of evolution, says University of Maryland molecular biologist William Jefferey. The standard argument is that the creatures’ eyes, long unused in darkened caves, accumulated so many mutations that they withered away. But Jefferey suspects being blind actually has hidden advantages for the fish.

To find out, Jefferey identified two master genes that control lens development in the eyes of blind cave fish. These genes are more active in the young cave fish than in their sighted counterparts—an elevated level of activity that triggers cell death in the eye’s lens. “So the eye isn’t destroyed because of accumulated mutations but is destroyed from the outside,” Jefferey says. “That likely means there is some benefit to overexpressing these genes.”

The same genes influence other aspects of development. Cave fish have unusually powerful jaws, large teeth, and abundant taste buds. Jefferey suggests that hyperactive genes confer these benefits, but at the cost of blindness. In darkened caves, such a trade-off makes sense. “It’s still a case of evolution,” he says, “just not the way it was understood in the past.”

3 Free Articles Left

Want it all? Get unlimited access when you subscribe.


Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 50%


Already a subscriber? Register or Log In