Without formalized sign language instruction, deaf children in families develop their own language using simple gestures that become more complex over time.     Unless they are gather in large groups, those specific deaf languages can result in thousands of dialects, called 'homesigns' by researchers.

There may be thousands of homesigners in a given society.    Marie Coppola, postdoctoral fellow at the Department of Psychology, University of Chicago, Illinois, says her work with four Nicaraguan homesigners shows how such individual gesture systems likely provided the raw materials for the language that emerged in a school for the deaf there.

"Deaf children develop gestures to communicate when they are in situation where they are not exposed to a conventional sign language," she reports. "As they get older, these gesture systems, which are often known as homesigns, become more complex." 

The patterns of linguistic structure found in gesture systems of homesigners and in successive generations of signers give clues on how language evolves but researchers are still grappling with questions such as how many people it takes to create a language and when the earliest sign systems attained a complexity greater than homesigns. 

In a symposium at the AAAS conference, Mark Aronoff, professor of linguistics at Stony Brook University, Stony Brook, N.Y., and Wendy Sandler, director of the Sign Language Research Laboratory at the University of Haifa, Israel, traced the development of a sign language that arose in a family with four deaf children in an insular Bedouin village in Israel. The language, now in its third generation, is used by 150 deaf and many hearing people. 

Ann Senghas, associate professor of psychology at Barnard College of Columbia University, New York, N.Y., also described her work on a Nicaraguan sign language that emerged in the 1970s among formerly isolated students who came together at a school for the deaf in the city of Managua.