For gorillas, labor is not the obvious, painful process that it is in humans. Females will still move about, eat snacks, and do whatever it is that gorillas normally do. Their behavior is so normal that only trained observers can tell that something important is happening, which is why most gorilla births—even in captivity—are seldom recorded or witnessed. In this case, zookeepers noticed a few unusual signs. Kira started stretching her arms above her head and making squatting motions. Aha, they thought, she’s in labor. The process typically lasts from 6 to 12 hours, but by Friday morning, Kira still hadn’t given birth. More worryingly, she looked rather ill—she had become inactive, and she had lost interest in food. The zoo needed an ob-gyn.

Weiner was out of town but McCurdy, his colleague, had volunteered to act as a backup. She had visited the zoo when Honi was pregnant, so the gorillas were accustomed to her presence. She had read up on the reproductive biology of apes. “And I grew up on a farm so I’m used to animals,” she tells me. “But certainly not western lowland gorillas.”

After an anxious 20-minute drive, McCurdy pulled up at the zoo and was greeted by staff veterinarian Donna Ialeggio. She met the assembled team of vets and zookeepers, who decided to sedate Kira in preparation for a C-section. They hoisted her onto a stretcher, moved her out of the gorilla enclosure, and loaded her into a white van that must have temporarily doubled as the world’s strangest ambulance.

In a nearby building, McCurdy did an ultrasound. “We had to remove some of her fur so I could see; I don’t usually have to do that,” she says. “There were also bits of straw on her fur; that’s not usually a problem, either.” The ultrasound confirmed, for the first time, that there was indeed a baby—and just the one. Its heart rate was normal and it was head-down. But while gorillas typically deliver with the baby facing the front of the mother, this one was facing the wrong way round. Perhaps that was why Kira was having a hard time pushing it out.

Gorillas are clearly very different from humans. Their pelvis is both wider than ours, and larger relative to the baby. The babies are also proportionally smaller—a five-pound package coming out of a 260-pound mother. All of this makes birth much less difficult for gorillas, and females typically do so while crouching. As the newborn pops out, they quickly scoop it up and cradle it to their chest.

Still, gorillas are among our closest relatives, and their reproductive parts are similar enough to ours that McCurdy could easily apply all of her experience despite never having dealt with a non-human patient before.

(Philadelphia Zoo)

She started with a pelvic exam—a procedure that, with human women, usually involves more conversation and explanation. But with McCurdy’s patient sedated (and, also, a gorilla), she narrated her findings to the assembled vets instead. To her surprise, Kira was on the cusp of delivery. “I remember looking at Donna and saying, Oh, she’s completely dilated. The baby’s right there,” she says. “One of the keepers behind me said, You sound like an obstetrician. I said, That’s because I am.”