Female Chimpanzees Don't Fight for 'Queen Bee' Status

The study, which appeared online Oct. 14 in the journal Scientific Reports, provides the first detailed look at how social status among wild chimpanzees changes throughout their lifetimes.

“We found that, after entering the adult hierarchy, there was a complete absence of successful challenges for rank increases among females,” said Steffen Foerster, senior research scientist at Duke University and lead author on the study. “It’s like a formal queue.”

Unlike the more gregarious males, female chimpanzees tend to be loners, spending much time by themselves or with their own children. One-on-one encounters between females are generally rare, giving researchers few opportunities to observe signs that would clue them in to each chimpanzee’s relative rank.

“For a long time we’ve been aware that there really are differences in rank between females, but being able to quantify that has been hard because they really don’t interact very often,” said Duke evolutionary anthropology professor Anne Pusey, who is a senior author on the paper.

To explore how female chimpanzees maneuver up and down the social ladder, Foerster, Pusey and their colleagues plumbed more than 40 years of daily records documenting the behaviors of 100 or so wild chimpanzees residing in Gombe National Park in Tanzania, where Pusey first began working alongside Jane Goodall in 1970.

Chimpanzees signal dominance and submission to each other through acts of aggression, such as chases and attacks, and through making a sound called a “pant-grunt,” which is a clear sign of subordination to a superior. The team used a new rating system to document these interactions, allowing them to determine the rank orders of male and female chimpanzees and watch how they shifted over time.

Their results showed that, unlike males, whose rank usually peaks when they reach their prime in their early 20s before declining again, female rank gradually increases as they age, and their rank order remains stable throughout their lifetimes. In addition, though males almost always start their adulthoods at the bottom of the pecking order, the female starting rank varies with each individual.