Researchers who study the fossil record are seeking to determine whether the impact made by a comet or meteor really did decimate up to half of the life on this planet at the end of the Cretaceous period. Questions whether the extinction of plant and animal life was abrupt, started before the impact, or was a gradual change. (KR)

Reviews cases which support the view that parts of the left hemisphere control languages, no matter how it is expressed, while right-side regions are involved only in skilled nonlinguistic movements and perceptions. Compares recent findings with previously held theories. (ML)

This is a review of important science news stories of 1990 as reported in the pages of this journal. Areas covered include anthropology, astronomy, behavior, biology, biomedicine, chemistry, computers and math, earth sciences, environment, food science, materials science, paleobiology, physics, science and society, and space sciences. (CW)

Described are the idea of chaos and the ability to control the chaotic behavior of a real-world physical system. Included is an explanation of the methodology and applications in biology and chemistry. (KR)