Describes some unique features of marsupial reproduction which include (1) chromosomal sex determination, (2) reproductive system, (3) birth, (4) location, and (5) embryonic diapause. These features suggest that viviparity evolved separately in eutherian and marsupial stocks after their derivation from a common oviparous ancestor. Bibliography.…

Presents the idea that social systems evolve to increase the genetic fitness of individuals in specific environments. Cites examples of animal behavior and environmental influences that may indicate why different social systems have evolved. (GS)

A rapid sequencing method for ribosomal RNA was applied to the resolution of evolutionary relationships among Metazoa. Describes the four groups (chordates, echinoderms, arthropods, and eucoelomate protostomes) that radiated from the coelomates. (TW)

Comments on the personalities and viewpoints of Richard Leakey and Donald Johanson, paleoanthropologists who hold differing views on the origin of humans. Summarizes major paleoanthropological finds and suggests the use of radio-immunoassay techniques for untangling the human family tree. (JN)

A test is described in which three psychotropic drugs were evaluated for their effects on pregnant rats. Behavioral changes are given. (SA)

This study discusses the behavior of the females of the parasitic wasp Nasonia vitripennis, which adjust the sex ratio of their broods according to whether or not they are the first or second wasp to parasitize a host. The results provide a quantitative test of sex ratio theory. (Author/SA)

Provides top-rated programs (by university) in biochemistry, botany, cellular/molecular biology, microbiology, physiology, and zoology. Overall scores included with each program were obtained from 1,848 biologists who were asked to rate programs in terms of faculty quality and their effectiveness in educating graduate students. (Author/JN)