Jamie and Burrito chimpanzees play

3 questions you might be wondering after watching this video of Jamie and Burrito playing…

Question 1:
What’s the story with the big pink bottoms?
Answer: Female chimpanzees have large pink swellings (called “sexual swellings”) on their rear ends. These swellings vary in size both between individuals, and also in the same individual over the course of the menstrual cycle. They advertise a female’s fertility by letting a male know when the probability of conception is at its peak. In this video, Jamie’s bottom is not swollen, and therefore she is not at peak fertility

Question 2:
Why are Burrito’s testicles so large?
A: Since chimpanzees are not a monogamous species, and a female chimp may have multiple mating partners in a relatively short window of time, male chimpanzees engage in what is known as “sperm competition” – a male who can produce a large number of viable sperm has a better chance of producing offspring. Large testicles are useful for accommodating these large quantities of sperm. Additionally, Burrito has a chronic heart condition that can lead to swelling in the scrotum.

Question 3:
Do the chimpanzees ever mate with each other?
A: No. Many chimpanzees who grow up in impoverished, unnatural situations (like research labs) often develop abnormally and don’t exhibit typical social and sexual behavior. It’s also possible that the Cle Elum Seven chimpanzees consider themselves a family after living together as a group for so long, and therefore don’t view each other as viable mating partners. As an added precaution, Burrito has had a vasectomy.