The sexual evolution How 500 million years of sex, gender, and mating shape modern relationships

"When it comes to a more expansive, diverse, and flexible attitude toward gender and sexuality, we can learn a lot by looking beyond our own species," according to this enthralling survey. Lents (Human Errors), a biology professor at John Jay College, CUNY, explains that same-sex intercourse is extremely common in the animal kingdom, noting, for instance, that female bonobos have sex with each other more often than with males as a form of bonding and social climbing. Many species have more than two ways to express gender (loosely construed as "patterns of behavior that are either sexualized or tied to reproduction"), Lents contends, discussing how male bluegill sunfish come in two biologically distinct types, the smaller of which resembles a female and engages in three-way mating rituals with larger males and females. Elsewhere, Lents emphasizes how few animals practice sexual monogamy, explaining how couplings among birds were long assumed to equate with sexual exclusivity until genetic testing in the late 1980s revealed the high prevalence of hatchlings sired by a male other than their mother's partner. Lents gleefully tears down cis, hetero, and monogamous norms, outlining surprising case studies that give the lie to restrictive conceptions of gender and sex. The result is an indispensable glimpse into the queerness of animals. Agent: Larry Weissman, Larry Weissman Literary. (Feb.)

Boldly venturing where few cultural warriors dare go: to biological fact. This book is about more than modern relationships; it's about modern debates over who is male or female and why many people say they're not the gender they were assigned at birth. An evolutionary biologist at John Jay College, Lents takes a compassionate and rational approach to these subjects, explaining that much of the misunderstanding surrounding them comes from the imprecise language we use to talk about sex and gender. Lents sheds light on the comparative biology and ethnology behind the most controversial aspects of human reproduction: the universality of masturbation and promiscuity among mammals and other animals; the forms "gay" sex takes among species, ranging from bedbugs to seabirds to those "sluttiest creatures," the socially peaceful bonobos; the chemical and microbiological processes underlying the reasons embryos develop into babies that present as one sex at birth while feeling like another sex trapped inside their body as they get older. "When an organ doesn't form in the typical way," Lents writes about "intersex" embryos, "we usually call this a 'defect' or an error….[A]natomical tweaks are the raw material for evolution's creative potential. They arenot errors or defects. They are simply variations." Variation is the watchword in this informative and often very funny book. Lents, a gay married man with adopted children, has some stake in these debates, and he isn't shy about sharing his thoughts on the dangerous impact of religion and conservative cultural values on people who vary from the statistical norm. People with those views may be scandalized by Lents' arguments, but they would do well to read this strong case against their positions. Destined to be a go-to source in future sex and gender debates. Copyright (c) Kirkus Reviews, used with permission.