Eavesdropping (9 page)

Although we may be tempted to ask which sex “eavesdrops more,” and may even feel that we can guess, the question, as framed, is too simple. Males and females attempt to protect their interests. Some of their interests are the same, others are different, and the areas of overlap and difference shift with various external factors. One has to do with space—the way that males and females distribute themselves and make use of physical space. There are strong and consistent trends here. In various primate species, males display and court, challenge and threaten each other, and advertise
themselves—their existence, emotional state, and motives—publicly and loudly.
⁵⁰
They also travel more widely and, in that sense, make more extensive use of public space.
⁵¹

Many female interactions, by contrast, are carried out quietly, in close proximity to other females. They produce a large number of social vocalizations, a category that includes soft coos and grunts, and somewhat speechlike sounds called girneys. Social vocalizations are not and cannot be yelled out across the forest canopy. They are murmured by clustered females during bouts of manual grooming.

In many primate species grooming is done predominantly by females, and in macaques, females—far more often than males—participate in
grooming chains
in which as many as three or four animals groom each other simultaneously.
⁵²

In a study of Japanese macaques, 90 percent of all the girneys were produced by females.
⁵³
In research on rhesus macaques, females issued more than ten times the number of social vocalizations as males, and vocalized socially to other adult females more than thirty times more often than they vocalized to adult males.
⁵⁴

Space is also gendered in our own species. Starting in childhood, females naturally form smaller groups—which are less competitive than large ones—and situate themselves closer to each other than males do.
⁵⁵
Some time ago, students of proxemics (the social use of space) found that short distances between people indicate intimate relationships.
⁵⁶
Females, more than males, prefer these smaller interpersonal distances.
⁵⁷

In apes and monkeys, females enjoy closer same-sex relationships than males. Primatologist Joan Silk has pointed out that female baboons spend far more time socializing than males, and continue to do so even when food is scarce and they must spend more time foraging than usual. When a close companion dies, females also appear to be more strongly affected than males. Gluco-corticoid levels may rise following the death of a relative, indicating increased stress. Females also spend more time
grooming after a loss, subsequently increasing the size of their grooming networks.
⁵⁸

Now that we have seen some of the more important differences in the social ecology of primate males and females, we are ready to look at the vigilance and eavesdropping of the two sexes.

Of course, we have already discussed a few sex differences in animal surveillance. We saw that female birds prefer to mate with males that they were
in a position to hear
when the males won a song contest; and we have noted that male fish avoid tangling with other males that they
would have been able to see
when the males won a fight. But in these species it has been difficult to actually see eavesdroppers taking in the information—to catch them in the act.

Fortunately, it is often possible to detect primates (and some other animals)
looking up
from their foraging and
scanning
in particular directions. This has helped investigators to ascertain the sex and, in some cases, the social status of the target animal. Moreover, by following their line of regard, researchers have also been able to make inferences about whether the animals were looking
for
predators or
at
members of their own group; and it has also been possible to evaluate the effect of ongoing issues, such as breeding or infant rearing, which would naturally affect the two sexes differently. That said, it has been witnessed in various primate groups that males exhibit a vigilance bias for individuals located outside the immediate area—presumably they are looking for competitors or predators—and that females tend, more than males, to direct their attention to individuals that are physically close, even within an arm’s reach, and these would be familiar members of the group.
⁵⁹

But males also devote some vigilance to subsections of their own groups. Low-ranking males look at more dominant males, who look for, and at, other males, especially potential challengers and interlopers from outside groups.
⁶⁰
There is little that excites competition among males so much as the sight of a female in estrus, and there are indications that male watchfulness increases as the breeding season approaches.
⁶¹

In monkeys, mating periods, births, and infant excursions all boost maternal looking time. Maxeen Biben and her colleagues at the National Institutes of Health found that when they played tape recordings of infant vocalizations, the time adult females spent looking for predators increased fivefold. Studies of black howler monkeys indicate that female vigilance rates increased after the birth of infants,
⁶²
and that females were more vigilant when their offspring were young—neonates or infants—than when they were older, and they were more watchful when their young vocalized, played, or moved about in a conspicuous manner.
⁶³
In a study of rhesus monkeys on La Cueva island in Puerto Rico, it was found that mothers looked up more often when they were separated from their young by more than an arm’s length.
⁶⁴

In these findings on nonhuman primates we are beginning to see a fairly general sex pattern that will re-emerge in our own species later. The motivation for male monitoring—mainly in the form of vigilance—is frequently tied to a self-oriented control function. Looking is directed outside the group, from whence predators and strangers emerge, and inside the group, where holders of power, and challengers, reside. By contrast, much of the visual monitoring of primate females is directed to genetically and socially related individuals within the group or to outsiders that threaten those individuals.

“As you go through life,” wrote author Norman Mailer, “you… observe everyone, wittingly and unwittingly. Out of the corner of your eye, you glimpse someone in a restaurant who represents a particular menace or possibility, potentially a friend or a foe.” In this remark Mailer allied himself with Georg Simmel and others who have commented on the naturalness of human eavesdropping. But he went on to say something more interesting—that once the diner has observed what is going on around him, “the unconscious
goes to work on that. It needs very little evidence to put together a comprehensive portrait, because, presumably,
it has already done most of that labor
.”
⁶⁵

Up to a point, the to-be-human brain evolved under social conditions similar to those in which the apes now live. But our groups became larger than theirs, and the competition keener, and it was largely in response to these changes that we humans acquired proportionately more social brain than the apes have.
⁶⁶
So it makes sense to ask how our enhanced intellectual capacity would have affected the ability to observe and make sense of subtle and intimate human behaviors, especially ones that are not intended for public consumption.

Arthur Conan Doyle’s detective, Sherlock Holmes, occasionally admonished his investigative assistant, Watson, for overlooking important details. You look, Holmes would chide Watson, but you fail to see. To eavesdrop, one must be able to
intercept
thephysicalimages—thelight andsound waves—that flow from others, but these would be of little value if one didn’t know how to
interpret
them. These processes are almost certainly related, of course; how can one know whether to eavesdrop in the first place, or which features to observe, without having some sense of what it means? To make these decisions, one needs a mind that is endowed with some very particular properties.

The ability to interpret complex social behaviors
. Primate societies have an intricate structure. It has been pointed out that dominance hierarchies require that every animal be able to recognize and remember things about group members and kin, and that exchange systems require primates to know which individuals owe and are owed favors. Additionally, according to a recent summary by Joan Silk, primates must be able “to compute the value of resources and services; keep track of past interactions with group members; make transitive inferences; discriminate between cooperators and defectors; and assess the qualities of prospective rivals, mates, and allies.”
They must also know something about the relationships between all the other group members.
⁶⁷

To service social relationships one needs a socially serviceable brain. In the early 1990s Robin Dunbar initiated a series of demonstrations that speak to this point. The first and most significant was a correlation between the size of primate groups and the size of the cognitively critical neocortical areas of the brain, ultimately leading to what Dunbar called the “social brain hypothesis.” This hypothesis holds that the challenges of living in social groups produced expansion and reorganization of the primate brain. This made it possible to solve ecological problems socially, through the operation of brain mechanisms that enhance social cohesion.
⁶⁸

What Dunbar failed to realize, but Swedish neuroscientist Patrik Lindenfors did, is that increasing group size only explains changes
in female brains
. Lindenfors argued that females were “the driving sex in primate social evolution, with female group size changing first and male group size subsequently adjusting to female number.”
⁶⁹

The ability to understand personal (especially intimate) relationships
. In general, the primates are fairly well adapted to the challenges of group living but social animals also spend a great amount of time and effort on
relationships
. In fact, Dunbar has suggested that it was the capacity for relationships that
enabled group living
. As we will see, the ability of primates to form and maintain relationships may itself derive from something more basic—the capacity for males and females to bond, to live monogamously. Recently, Dunbar and a colleague, Susanne Shultz, observed that in a diverse range of animals and birds there is an association between brain size and monogamy.
⁷⁰
In primates, ungulates, carnivores, four orders of mammals, and well over a hundred species of birds, large brain size is associated with social monogamy.
⁷¹
Dunbar and Shultz suggested that at some early point in their evolution, primates began to redeploy the kinds of cognitive skills that had evolved for pair-bondings to create and service
other kinds of relationships
. This meant that two individuals of the same sex could form
relationships that were nearly as intense as those enjoyed by reproductive mates in other species.
⁷²

The ability to understand deception
. Nicholas Humphrey has observed that if social success enhances biological fitness, then any heritable trait that increases an individual’s competitive ability will soon spread through the gene pool.
⁷³
In these circumstances, animals will continually attempt to outfox each other, with predictable increases in the ability to deceive and to spot acts of deception, until these abilities peak in the species—if they ever do. To eavesdrop, and to avoid being eavesdropped upon, one must be able to deceive
tactically
. Tactical deception refers to attempts to mislead another, to the misleader’s own advantage. This ability has been found in all major groups of anthropoid primates, but is particularly common in chimpanzees and baboons.
⁷⁴
It has been shown, using field data, that the frequency of tactical deception across primate species is highly predicted by neocortical volume.
⁷⁵

The ability to imagine possible worlds
. Dunbar suggested that group living is
inherently virtual
since it requires members to imagine the future behavior of other individuals, which, in turn, encourages them to imagine other individuals’ mental states. “These aspects of the world,” he wrote, “cannot be observed or engaged with directly, but have to be constructed in the mind.”
⁷⁶
There is no problem here, of course. We come equipped for virtual experience. Imaging research carried out by Perrine Ruby and Jean Decety in France indicates that a region of the human brain, the right inferior parietal cortex, was activated when their subjects mentally simulated actions as they would appear
to others
, but not as the same actions would appear to the subjects themselves. This region of the brain was also activated when participants were asked to imagine how others would feel in situations that would normally elicit an emotional response.
⁷⁷

These findings lead us to an interesting conclusion: every normal human has the brain of an eavesdropper—a brain that is wired up
to do the things that eavesdropping requires. Possessed of this facility to a unique degree in the animal kingdom, we naturally enough seek regular opportunities to use it. With brains like ours, it would be surprising if our ancestors had adopted anything but the most open plan of living.

There are no recognised and respected ways in which the public gaze can be cut off, no ways of separating oneself out from others present. Any conversation between two may be freely invaded… Privacy can only be achieved by hiding from others.                  Frederik Barth