I suddenly realised that I’d probably never saw a living monkey before and decided I should go see it and maybe do an experiment. So it is with grateful regret that I must inform you of this: to demonstrate that I had seen a monkey before, I had a researcher shoot me several videos of a monkey pissing. Not because I asked for it or said anything, but because my vermin had done something I wanted it to do.
The nature-loving reporter that I am, I contacted Adam Clark Estes – a PhD candidate at Oxford – and asked him to let me watch videos of monkeys shit because it was science. Adam sent over two videos that I watched for more than an hour and we published them as an article in Nature.
“It looked like a real monkey, so I was shocked when I realised they were just videoed defecating from a different species of monkey,” Adam told me. “One of my thinking partners was also shocked and so was I.”
Adam is a neuroscientist and the team leader of the monkey urine studies at the charity Tsinghua University, China. I got in touch with him to get his take on how many monkeys shit in the wild these days.
“I think there are about 20,000 a day – but I wouldn’t expect any monkey to do that [the poo experiments] because monkeys are among the first animals to go into retirement.”
Hmm, so about 10,000 monkeys poo every day and it’s “in retirement”. What’s wrong with that?
Adam’s team wanted to investigate exactly how far up the brain the monkey prostate gland goes. It’s a gland used for seminal fluid and excretion of sperm, so they wanted to know how much of this fluid is left in the bladder at any one time. This was important because multiple studies published a decade ago suggested that if you looked at the prostate more closely you could find cells associated with the process of prostate cancer. A breakthrough was the finding that when you stretched a gynaecological or penile cancer cell into the shape of a gland, it looked the same as the prostate. So my project was a “supplementary”, for science.
To get the data, the researchers were doing a series of gentle probing experiments on monkeys, where they place a small needle in the prostate of a male monkey and tug the seminal vesicle out. When it was tugged out, researchers take still images, complete with blood vessels.
“When you are testing how much prostate fluid is retained, you have to move forward and backward slowly to see how far up the brain the vesicle reaches. For that reason, most of the primates were trained to stand erect with their heads facing upwards and then steadily tickle the vagus nerve as they tap down to the prostate and have it moved out of the gland. After about four days or so of training, these monkeys were able to stand on their hind legs and tickle the nerve throughout the left side of their abdomen as long as the bladder was not full.”
The researchers recorded the results as each video was filmed and counted how many calves were fully formed before reaching a blunted state at the very top of the brainstem – in which no calves develop.
It turns out that the monkeys understand your jests. The way I obtained the data was that when I became nervous about all the fucking stuff I was putting them through, I took some goats of my own species and told them to stand in the same pose as my monkey did. “There were lots of goats saying the same stuff as my monkey was saying,” Adam said.
“I have had attempts to mate the monkeys on the controls of the experiments,” Adam added. “This happened in 2004, when one female monkey appeared around four months after the penis enlargement was done. Unfortunately, we had to stop her in time.”
Adam is hopeful that experiments will continue into the future and after I offered to collaborate for food, he said: “I really would like you to be my lunch.”
The next time I have a monkey video, let me be the one giving it a red-light signal. If I pass it on to a person with relevant information to tell me about the monkey’s brain, we will be well on our way to solving the mystery of how many monkeys poo on a daily basis.