FOR Patricia Yang, bodies are a series of tubes fine-tuned to pump the gory and the gross: blood, urine and faeces. A mechanical engineer at the Georgia Institute of Technology, she studies the fluid dynamics of what goes round inside living bodies, and what comes out of them. She has won an Ig Nobel prize, which celebrates unusual science that makes people laugh, and it is well deserved.
Yang does the dirty work of handling faeces-filled wombat intestines, gathering pig’s blood from slaughterhouses and designing makeshift elephant urethras – all for the sake of science. And she can’t get enough of it.
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When people ask what you do, what do you tell them?
I’m an engineer. I study blood, I study pee and I study poop. When I tell people that, they have a hard time linking engineering with biology, but I don’t see a distinction between the two. Animals use engineering to survive. Body fluids work for us, carrying nutrition or waste or oxygen. These fluids have a purpose, and I want to know how they work.
How did you start studying bodily fluids?
I’ve liked animals since I was really young. When I started my PhD, my adviser was potty training his kid and had been doing a lot of waiting around for his son to pee. He had to do the same thing with his dog. He wanted to know what urination was like at the extremes – for the smallest animals and the largest. He asked me how long it would take for an elephant to pee. I said, “I’ll study anything as long as I can spend time at the zoo.”
How did you go about finding out how long elephants take to urinate?
Surprisingly, there are a lot of animal urination videos on YouTube. When zoo visitors see animals peeing, they film it and post it online. The videos told us we had about 10 to 20 seconds to catch an elephant peeing on camera. First, we practised. We got an acrylic pipe – about a metre long and thicker than your arm. I had a collaborator pour a bucket of water through it, and we practised focusing and changing the camera settings to get the right lighting. Then we went to the zoo.
Did you have to wait around for the elephants to need the toilet?
We started a collaboration with Atlanta’s zoo. The elephant keeper told us the two elephants pee every day at 7 am. So we took our high-speed camera, got there early and waited.
What did you find when the urine eventually started flowing?
Before this study, , but we found that it also accelerates the flow. It sounds trivial, but when we started, if you asked professors of engineering how long it would take for an elephant to empty its enormous bladder, they would say probably half an hour. But we built a model to calculate the rate for all animals weighing from 3 to 5000 kilograms, and it is 21 seconds. Tinier animals may break the rule by peeing in droplets rather than streams, but on the large end, there’s no limit to the size at which 21 seconds applies. Maybe it extends all the way up to dinosaurs.
How did you move from studying the mechanics of urination to the hydrodynamics of faeces?
A lot of the animals we filmed pooped at the same time they peed. So we had a lot of data on both. We found that whether it was an elephant or a panda or a warthog, all the animals that poop in cylindrical form take 12 seconds to defecate – including humans! We also found out how important the mucus layers are. Your colon is like a chute that is lined with mucus to help faeces slide out. Bigger animals have more mucus, so can shift more volume more quickly.
Is there more scatological research to be done?
Yes. There are so many types of faeces: watery cow pies, rodent and rabbit pellets, cylindrical faeces from humans and other mammals, and then we have wombat faeces. They poop in cubes.
We know that the water content dictates whether faeces will be a pie, pellets or a cylinder. Pellet-pooping animals have large intestines that are about four times as long as those of similar-sized animals that make cylindrical poop, so they absorb more water and leave drier faeces behind. But how does a wombat poop in cubes?
“I’m working in a blood lab now. Sometimes we have a spill and it looks like a murder scene”
We contacted the Memphis Zoo and they packed up some wombat faeces and mailed it to us. It was very cubic, but it had dried out by the time it got to us. So we started a collaboration with a biologist in Australia, where wombats are a common form of road kill. We asked if he could send us some wombat guts. He said, “How many do you need? I have 10 in my freezer.”
What did you do when you got your hands on some wombat guts?
To see if the gut expanded in a special way that formed the cubes, we cut a section and inserted a long, thin balloon – the kind used to make balloon animals. By inflating the balloon, we found two areas of the intestine cross-section that expanded less than the others, which would likely be the source of half of the corners.
We’re still working on it, but I think the other corners may come from the intestine’s alignment within the body. Maybe these corners are formed by pressure from other organs arranged around it.
What’s next for your body fluid research?
I’m working in a blood lab now. Every two days, we go to a sausage factory slaughterhouse to pick up pig’s blood. Sometimes we have a spill in the lab and it looks like a murder scene.
Blood is interesting because how fast it flows can change what happens inside the body. If your blood vessels narrow, the blood will flow faster, and cause clotting. Some drugs can stop those clots, but at the expense of more bleeding elsewhere in the body, so I’m trying to understand the mechanics to stop the clotting or the extra bleeding.
I’m also continuing my poop research. When I give talks about faeces, the audience raises a lot of interesting questions.
Someone told me that female turkeys poop in spirals but males don’t. When I heard that, I thought it sounded crazy. But I want to understand how it works.
This article appeared in print under the headline “Looking out for number one”
