For hundreds of thousands of years, female rhesus macaques have successfully ruled highly regimented societies in which the queenly alpha females control families, territories and resources, taking their followers into war as highly disciplined armies.

The males? A few rough, tough stud muffins are tolerated in the ranks to help out with security and protection and to be around for the mating season. But any male will soon be physically hurting and on the outside looking in -- or dead -- if he angers the ladies who run the show.

Rhesus monkeys may not be the smartest primates, but they are arguably the most successful primate species after humans, inhabiting more of the Earth than any other monkeys or apes. Their success, said Dario Maestripieri, may be because they are political animals, ruthless and opportunistic in ways endorsed for human politicians by 16th Century Italian philosopher/statesman Niccolo Machiavelli.

After 20 years of studying rhesus macaques, Maestripieri, 43, a University of Chicago evolutionary biologist and animal behaviorist, said he has crammed all he has learned into a new book, "Macachiavellian Intelligence: How Rhesus Macaques and Humans Have Conquered the World," written for both academics and general readers.

Human insights

The title is Maestripieri's little joke, playing on Machiavelli and the scientific name for rhesus macaques, Macaca mulatta.

"There are more facts in this book about monkeys than about people," said Maestripieri, "but the book is more about people than about monkeys."

The artifacts of human origins can be found not just in human evolution, but in the evolution of all primates.

Yet evolutionary biologists traditionally have studied the cognitive skills and social behavior of the great apes, such as chimpanzees.

"This book really fills a gap scientifically," said William Hopkins, a chimpanzee researcher at Yerkes National Primate Research Center and psychology professor at Agnes Scott College, both in Decatur, Ga.

For decades rhesus macaques have been a favorite research subject for the biomedical sciences, so the species is better understood physiologically than any primate except humans. Less is known about their cognitive abilities and if they might overlap with those of humans and great apes, Hopkins said.

As humans tear into the wilderness, extinction threatens bigger, smarter primates such as gorillas and orangutans, but many "wild" rhesus macaques have adapted to living alongside humans in villages and towns. The monkeys inhabit a huge swath of southern Asia, from Pakistan to China's east coast; Maestripieri's research is based on a colony transplanted from India to a small Puerto Rican island in 1938.

People who like to think human society might be kinder and gentler if it were dominated by women won't find much support in female-dominated rhesus macaque society, which specializes in what Maestripieri calls "Machiavellian intelligence."

Every individual rhesus macaque, "male and female, is the equivalent of being armed and dangerous, ready to attack anyone at any time," Maestripieri said.

"They fight endlessly, even when there is no need to fight. It is Machiavellian. They're not fighting for things, like food; they're fighting for power. It is all about nepotism and struggling to get you and your closest relatives in the most powerful position possible in society.

"Rhesus females are organized like the Army, which means rank and status of each individual means everything."

The basic unit of rhesus society is called a group and is made up mostly of females and their young offspring, from a few dozen to hundreds of individuals. Female-headed subdivisions called matrilines are composed of a few dozen related females, such as grandmothers, mothers, sisters, cousins and babies.

The most powerful female in the most powerful matriline is the supreme dictator of the entire group. She shares her power with an alpha male who dominates a relatively small cadre of males whom the females allow to live among them. The males, outnumbered perhaps 10 to 1, come from outside the group and are not related to each other or the females, so they have no power base of their own and can be expelled or killed by the female majority at any time.

"There's always an alpha male and a few subordinate males hanging around, there to provide protection from predators and to fight if the group goes to war," Maestripieri said.

Dominant males and females strut about with their tails in the air to remind the rest of their high rank. Lower-rank monkeys make obsequious bows or risk getting beaten and bitten for insolence. Alpha males randomly beat up subordinates to show who is in charge.

No monogamy here

During mating season the alpha male is entitled to mate with every adult female in the group. Most alpha males try to make that an exclusive right, muscling other amorous males away from "his" females and punishing adulterers. But the females have their own ideas.

"The females are very promiscuous," said Maestripieri. Taking on lovers behind bushes out of sight from the king, they usually try to have at least one fling with every adult male in the group, not to mention passing strangers.

The promiscuity, he said, is a sort of insurance policy for the females' next babies. Alpha male leaders get deposed fairly frequently, and the new leader often kills babies in the group as a way of making their mothers sexually available. But he generally will not kill the baby of a female he has mated with, so it is in the interest of the female to mate with as many males as possible.

During mating season, male outsiders hang out on the periphery of a group territory, hoping a female will find him attractive.

With sex, the females are the aggressors, letting the males know they are interested by sticking their rumps in the faces of would-be lovers.

"If the males don't pay attention," Maestripieri writes in his book, "the females slap them and smack them, and in case the males have any doubts as to what the females have in mind, the females will jump on their backs and start mounting them to remind them how it is done."

Though the males are bigger and stronger, if one falls out of favor with the group, the females gang up on him, using their teeth to tear away at his face, fingers, toes and genitals, anywhere that causes severe bleeding and likely death. This fate could befall even the alpha male.

"If they turn on a male, he is going to lose, no matter how strong he is," said Maestripieri.