Research on ape and monkey behavior is leading researchers toward new
theories about the origins and functions of human families. At the
intersection of psychology, biology and anthropology, scientists are
applying family systems theory and sociobiology to reverse engineer how
and why human families came to be. Leaders in this field gathered at
the February meeting of the American Association for the Advancement of
Science to discuss the evolutionary aspects of this topic.
Families may seem uniquely human, yet primatologists talk about monkey
and ape groups much like psychologists talk about human families.
Emotional attachments, separation anxieties and other human-sounding
relationship dynamics all affect primate family dramas unfolding in the
rain forests of Borneo and the grasslands of Botswana. At the
intersection of psychology, anthropology and biology, researchers are
looking for links between this family-like behavior in apes and the
functioning of human families.
Some of the resemblances the researchers report are uncanny: Sibling
monkeys fight for pecking order. Poorly raised chimps become anxious and
withdrawn. Baboons form bonds that look like marriages.
Researchers gathered to discuss these primate-human family connections
at the American Association for the Advancement of Science annual meeting in February. "There is a large and
growing body of evidence that suggests striking consistencies between
the relationship systems of humans and the relationship systems of other
primates," said Roberta Holt, session organizer and researcher at the
Georgetown Family Center. Or, as the NIH's Stephen Suomi put it, "Humans do not have a monopoly on families."
Indeed. Monkeys, chimps and other great apes all live in groups loosely
resembling families. Gibbons, a "lesser" ape species, thrive in nuclear
families, with a pair of monogamous parents and one to four kids...err,
offspring.
So it appears the roots of family run deep. Suomi, who began his career
with Harry and Margaret Harlow,
famous for their surrogate mother chimpanzee experiments, reported that
social structure spontaneously reappears in rhesus macaques. After
rearing isolated macaques in a lab, he released the animals to live
together. Soon they formed social structures identical to those of
free-ranging animals. "Family life is basic," Suomi said. "It reappears
even after you take it away for a couple generations in a laboratory."
But how basic? Pre-humans and apes shared a common ancestor five to ten
million years ago. Twenty or more million years ago monkeys split from
apes. Primate groups (many primatologists would wince at the word
"family") may have been around even before then. No one knows.
Family systems theory, first developed by Murray Bowen in the 1960s, provides ample framework on which to hang speculation about familial similarities between humans and other primates. Unlike Freudian theory and biological
psychiatry, which place the causes of emotional problems largely in the
mind or brain of each person, Bowen theory views individual dysfunctions
as symptoms of larger family dynamics. Bowen theory assumes these family
dynamics affect primates as well as people.
"The emotional forces driving chimpanzee behavior also drive human
behavior", said Michael Kerr, another presenter from the Georgetown
Family Center. When Kerr applied systems theory to another primate,
Theodore Kaczynski, he found emotional cutoffs from his family led
Theodore down the antisocial path of destruction.
Though chimps do not make bombs, some suffer emotional fates similar to
Kaczynski's. Kathleen Kerr, also a Georgetown Family Center researcher,
presented data on chimps at the Gombe reserve, which Jane Goodall
made famous. Kerr's research shows two paths to antisocial, anxious, insecure adult chimps. "You can have what I call a 'smother mother,' who guards her infants closely and
overreacts to perceived threats," Kerr said. "Or you can have a mother
that looks neglectful." Over-mothering and under-mothering both appear
to stifle chimp development.
One chimp, Patty, lost her first infant because of inept mothering, the
only such death in 40 years of Gombe research. "She carried the infant
upside down with its head banging on the ground, she couldn't get the
infant on the nipple, she didn't respond to his suckling needs...and he
died very young," Kerr said. Patty is anxious and overreactive as well
as neglectful; she's been known to beat up youngsters who give her
other, living, babies any trouble. Kerr thinks Patty's inept mothering
is inhibiting the young chimps' development. A chimp Kaczynski in the
making? Though her data are mostly anecdotal, Kerr is working on more
rigorous studies to flesh out her family systems approach.
Although chimps can seem quite human, like most primates they do not form monogamous,
long-term bonds. In fact, each primate species pairs up differently. Some pair for life, others for the
short-run. Some pair to mate, other pairs are non-sexual, more akin to friendships. Baboons, who
form relatively short-term, apparently non-sexual friendships, are now pointing researchers toward a
possible origin of marriage: infanticide.
Chacma baboons, a subspecies of savannah baboons, live in groups of 60
or more on the grasslands of Botswana, with one dominant male
monopolizing more than his share of the mating. Sometimes this blustery
controller turns deadly, and he kills a baby baboon. By killing an
unrelated infant, the dominant male creates another mating opportunity.
It gives him another chance to spread his genes, say sociobiologists.
Sarah Hrdy, from the University of California at Davis, reported primate infanticide among Indian langurs in
1977 (The Langurs of Abu, Cambridge University Press). Hrdy saw that
after an infant died, its mother stopped lactating and resumed her
regular menstrual cycle. Soon, much sooner than if her infant had lived,
she was ready to mate again. Invariably, she mated with the dominant
killer male.
When the University of Pennsylvania
postdoctoral researcher Ryne Palombit watched infanticide play out in
baboons, he noticed something intriguing: Female baboons formed friendships with non-alpha males. When the
females had an infant, the pair spent much more time together. Building on
the work of Hrdy, Palombit theorized pair bonds function to protect the
young.
As a test, Palombit and his colleagues Robert Seyfarth, Dorothy Cheney, and Joan Silk ran a series of experiments using hidden speakers broadcasting recordings of
infanticidal attacks. They found male friend baboons responded to the
simulated attacks more aggressively than control males. The strongest
responses came when male friends heard attack cries from the alpha male
coupled with distress screams from a female. These data support Palombit's
anti-infanticide theory.
Palombit said several factors encourage speculation linking marriage
with infanticide. People are occasionally infanticidal, as are our closest genetic
relatives, chimpanzees. And the infanticidal baboons studied by Palombit
live in savannah environments much like our hominid ancestors did.
But so far, the connection remains mostly speculation. "It is difficult to know
if people were infanticidal in the past," Palombit said, since fossilized
infanticide tableaus or other concrete evidence is unlikely to turn up.
No one knows why male friends protect the infants, a puzzle Palombit
plans to address on his next trek to Africa. The baboon paternity tests
he will run promise an explanation. If the male friends fathered the
infants they protect, they are securing their lineage, a piece of
evolutionary common-sense. But if they are not the fathers, primate
researchers will need other theories.
Though the baboon research is intriguing, Palombit admitted "there are
multiple evolutionary pathways to pair bonds." Along with food sharing
and mate guarding, then, prevention of infanticide was just one of many
wedding songs leading us down the evolutionary aisle.
The researchers agreed that evidence supporting the family systems views
of primates and the deep origins of human families is mounting. At the
very least, primate groups offer insight into the what, how and why of
human relationships, much as observing your neighbor's dysfunctional
family can yield a "Eureka!" flash about your own. Distance encourages
objectivity. Apes and monkeys are just distant enough, at least until
they get their own self-help section at the bookstore.
Brian Vastag is a freelance science writer
in Texas who contributes to many newspapers and magazines.
The above image is a detail from an anonymous illustration, Marmosets and Others, from the Primate Gallery.
Harry Harlow's chicken-wire mother experiments - were some of the first
explorations of emotional similarities between humans and other
primates. This Website devoted to Harlow's classic experiments is about
rhesus monkeys who "had some very bad days."
Washington State University -
Find out more about human evolution and our connections to apes and
monkeys at . This set of learning modules is
tailored to people with little background in evolutionary theory.
The Human Behavior and Evolution Society - seeks to answer "How can modern evolutionary theory help explain human
behavior?" This large site attracts researchers from around the world.
The Primate Gallery - offers an encyclopedia of general ape and monkey information, along with
great graphics, primate vocalizations, and a bibliography.
Families may seem uniquely human, yet primatologists talk about monkey
and ape groups much like psychologists talk about human families.
Emotional attachments, separation anxieties and other human-sounding
relationship dynamics all affect primate family dramas unfolding in the
rain forests of Borneo and the grasslands of Botswana. At the
intersection of psychology, anthropology and biology, researchers are
looking for links between this family-like behavior in apes and the
functioning of human families.
Indeed. Monkeys, chimps and other great apes all live in groups loosely
resembling families. Gibbons, a "lesser" ape species, thrive in nuclear
families, with a pair of monogamous parents and one to four kids...err,
offspring.
So it appears the roots of family run deep. Suomi, who began his career
with 
Though chimps do not make bombs, some suffer emotional fates similar to
Kaczynski's. Kathleen Kerr, also a Georgetown Family Center researcher,
presented data on chimps at the Gombe reserve, which 
Chacma baboons, a subspecies of savannah baboons, live in groups of 60
or more on the grasslands of Botswana, with one dominant male
monopolizing more than his share of the mating. Sometimes this blustery
controller turns deadly, and he kills a baby baboon. By killing an
unrelated infant, the dominant male creates another mating opportunity.
It gives him another chance to spread his genes, say 
When the 
Palombit said several factors encourage speculation linking marriage
with infanticide. People are occasionally infanticidal, as are our closest genetic
relatives, chimpanzees. And the infanticidal baboons studied by Palombit
live in savannah environments much like our hominid ancestors did.
But so far, the connection remains mostly speculation. "It is difficult to know
if people were infanticidal in the past," Palombit said, since fossilized
infanticide tableaus or other concrete evidence is unlikely to turn up. 
Though the baboon research is intriguing, Palombit admitted "there are
multiple evolutionary pathways to pair bonds." Along with food sharing
and mate guarding, then, prevention of infanticide was just one of many
wedding songs leading us down the evolutionary aisle.