Gene may determine right-handedness

         CAMBRIDGE, Mass., Oct. 26 (UPI) -
         Scientists say they have evidence that
         a single gene may determine whether a
         person is right-handed, but they
         suspect no similar gene exists for
         lefties.

         Despite hundreds of studies conducted
         for many decades, scientists have been
         divided about whether human
         handedness is specified by nature or
         nurture. Scientists at the National
         Cancer Institute's Frederick Cancer
         Research and Development Center in
         Maryland came up with a theory on
         handedness based on studies of yeast
         and mice development. They applied
         that knowledge to humans to theorize
         how one side of the body differs from
         the other in internal organs and right-
         versus left-hand preference.

         They also researched three generations
         of people to see the incidence of right-
         and left-handed offspring from parents
         and grandparents. They looked at
         parents who were both righties, both
         lefties or one of whom was
         right-handed and the other left-handed.

         "I'm convinced there is a single gene
         that makes you right-handed," said
         Amar Klar, head of the developmental
         genetics section of the gene regulation
         and chromosome biology laboratory of
         the NCI's cancer center in Frederick,
         Md. "When this gene is defective, you
         have a 50 percent chance of being
         right-handed and a 50 percent change
         of being left- handed or ambidextrous."

         Klar presented his research at
         Whitehead Institute seminar on
         neurobiology in Cambridge Monday.

         Klar said there is evidence that
         right-handed people tend to be left-
         brained. That means the left half of
         their brain dominates in controlling
         language skills. Intuitive and emotional
         processing occurs in the right half of
         the brain.

         He found some 97 percent of
         right-handed individuals develop
         language skills on the left side of the
         brain, and the remaining 3 percent are
         reversed. Only about 30 percent of
         southpaws (left-handers) possess
         right-brain dominance.

         Some 91 percent of the world's people
         are right-handed, or about nine out of
         every 10 persons. That means they use
         their right hand for 10 major activities,
         including writing, throwing a ball, using
         a spoon and cutting with scissors.

         This hand preference is a strictly
         human trait; other animals, such as
         chimpanzees, and equally divided in
         hand/paw preference, Klar said.

         Klar said scientists will have to map the
         gene, known as RGHT ("RIGHT," but
         spelled RGHT), to make certain it
         determines whether someone is a
         rightie.

         Identifying the gene responsible for
         handedness, he said, might help brain
         surgeons more accurately identify the
         dominant half of the brain in patients
         with a brain tumor or epilepsy before
         surgery. It also may help explain how
         different cognition abilities develop in
         each half of the brain.

              ScienceNews.com