People love making whoopie, but for most animals sex is just another job. What makes us so lucky? In this hour of To the Best of Our Knowledge, the science of sex. Why biologists think recreational sex was as important to human development as large brains and upright posture. Also, an archaeologist uncovers sex in the stone age.

SEGMENT 1

Jared Diamond teaches physiology at the UCLA Medical School. His forthcoming book is "Why Is Sex Fun? The Evolution of Human Sexuality." Diamond tells Steve Paulson that compared to the rest of the animal kingdom, human sex is weird, but has its evolutionary advantages. Also, archaeologist Timothy Taylor tells Steve Paulson that the wide spectrum of human sexual behaviors has existed since the dawn of human culture. The cavemen had their "Playboy" equivalents! Taylor teaches at the University of Bradford in England and is the author of "The Prehistory of Sex: Four Million Years of Human Sexual Culture."

SEGMENT 2:

Bram Dijkstra teaches comparative literature at the University of California and is the author of "Evil Sisters: The Threat of Female Sexuality and the Cult of Manhood." He tells Judith Strasser how nineteenth century beliefs about women as sexual vampires led to the creation of the "vamp," (think Theda Bara and lots of eye make-up!) and how this predatory female still haunts our culture.

SEGMENT 3:

Science writer Susan Allport is the author of "A Natural History of Parenting." She tells Jim Fleming how humans are like other species in their concern for their offspring drawing examples from frogs, bats, sheep flamingos and whales, and also explains what makes human parents unique in the animal kingdom.

Distribution dates:

• week of 03/23/97 - hour 2
• week of 03/01/98 - hour 2