SCIENCE is the official organ of the American Association for the Advancement of Science. Information regarding membership in the Association may be secured from the office of the permanent secretary in the Smithsonian Institution Building, Washington 25, D. C. MAN is today the most studied of animals.gists and other specialists in many sub-branches of the broad field of biology. Most of these ...

This chapter will be concerned with some of the methodological problems and some early results of the National Merit Twin Study which is still in progress and when finished will be reported in detail elsewhere. Analyses completed so far have been primarily concerned with the relative effects of heredity and environment on ability measures, which will therefore be the major focus of this chapter...