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at crafting and using tools, but are also more diligent. Craig Stanford agrees that it might well have been our female ancestors who first steered the culture toward tool use. Early tools for foraging, he imagines, gave way to tools for scavenging meat from carcasses killed andabandoned by large carnivores. These tools in turn may have paved the way to using implements for killing prey, which makes Pruetz’s observations of chimps sharpening sticks and using them to whack bush babies all the more arresting: Fongoli’s females seem to have skipped ahead to the killing tools. Barbecue tongs cannot be all that far behind.
    Pruetz and I are sitting along a forested ravine where the chimps rest during the day’s hottest hours. The vegetation is thicker here. We watch a slender green vine snake move through the grass. Birds are calling over our heads. One says
cheerio;
one actually says
tweet
. A third says
whoop whoop whoop whoop whoop
, like Curly of the Three Stooges. (When I ask what that one is, Pruetz replies, not at all sarcastically: “a bird.” She is a woman of singular interests.)
    Pruetz directs my gaze to a tangle of saba vines. Where I see a dark mass, she is able to distinguish six animals. The woman has chimp vision. (It’s a condition that lingers long after she gets back to Iowa. “I get home and I’m looking for chimps on campus.”) The animals can be so well hidden and so quiet that even Pruetz has trouble finding them. She sometimes locates them by smell—“chimp” being a potent variant of B.O. “Yesterday I thought I smelled chimp,” Pruetz says, “but it was me.”
    The scene in the vines is one of drowsy, familial contentment. Yopogon is grooming Mamadou. Siberut is leaning against a tree trunk, rubbing his two big toes together, as he often does. A pair of youngsters swing on vines, flashing in and out of an angled shaft of sun. One uses a foot to push off from a tree trunk, spinning himself around. The other swings from vine to vine, Tarzan-style. They are almost painfully cute.
    A chimp called Mike lies on his back in a hammock of branches, legs bent, one ankle crossed atop the opposite knee. One arm is behind his head, the other is crooked at the elbow, the hand hanging slack from the wrist, in the manner of a cowboy slouched againsta fence. We stare at each other for a full ten seconds. Partly because his pose is so familiarly human and partly because of the way he holds my gaze, I find myself feeling a connection with Mike.
    I confess this to Pruetz, who admits to similar feelings. She cares about the Fongoli chimps as one cares about family. She sends excited emails when a baby is born and worries when the elderly and nearly blind Ross disappears for more than a week. But she does not reveal this side of herself at conferences. There, it’s all lingo and statistics, pairwise affinity indexes, and “blended whimper pouts.” “Especially with male chimp researchers,” she says.
    One of the first things primatology students are taught is to avoid anthropomorphism. Because chimps look and act so much like us, it is easy to misread their actions and expressions, to project humanness where it may not belong. For example, I catch Siberut looking toward the sky in what I take to be a contemplative manner, as though pondering life’s higher meaning. What he’s actually pondering is life’s higher saba fruits. Pruetz points some out in the branches above Siberut.
    Yet it is impossible to spend any time with chimpanzees and not be struck by how similar they are to us.
    I’ve been keeping a list of things I have seen or read or heard Pruetz say that drive home this point in unexpected ways. I had not known that chimpanzee yawns are contagious—both among each other and to humans. I had known that chimps laugh, but I did not know that they get upset if someone laughs at them. I knew that captive chimps spit, but I hadn’t known that they, like us, seem to consider spitting the most