Narrator: This is Science Today. Studies of twins have been very useful over the years in several aspects of biological and medical investigations. Such research includes studies of Parkinson's Disease, Alzheimer's and schizophrenia. At the University of California, Berkeley, researcher Malcolm Zaretsky is looking into why identical twins live longer than fraternal twins - a phenomenon that has long puzzled scientists.
Zaretsky: My study indicated that the health behavior of identical twins is better than that of fraternal twins. They exercise more, they smoke less, they communicate more frequently.
Narrator: That identical twins communicate more than fraternal twins was a key finding in Zaretsky's study.
Zaretsky: Now one thought I have is that communication is more important for identical twins because possibly they have very similar connections in their nervous systems. Because brains of identical twins, in principle they are identical, but I'm sure they're not, but they are probably more similar than those of other people who are not identical twins, fraternal twins.
Narrator: For Science Today, I'm Larissa Branin.