Program Item Details
TITLE: Jonathan Perry, Masters Student in Paleontology, University of Alberta
SUBJECT: #20 The Evolutionary Chewing Machine
SYNOPSIS: In order to complete his research on the diet of early and extinct primates, masters student Jonathan Perry developed a "chewing machine" to test out his theories. The machine simulates the chewing action of different primates. Using fruit, nuts, leaves and insects in the machine, Jonathan discovered that early primates probably ate much differently than researchers previously thought. Patent may be pending on the chewing machine.
AUDIO: Download Audio (mp3 format)
TRANSCRIPT:
Intro: When Jonathan Perry set out to research his Master’s thesis on the diet of early primates, he figured he get some clues from their teeth and how they functioned. But how do you do that when your research subjects are already extinct.
Jonathan Perry
JP: Well it’s known as the chewing machine or the mastication machine and it essentially simulates chewing in early fossil primates using as a model a primitive species of small African primate.
CC: DID YOU DEVELOP AND BUILD THIS YOURSELF?
JP: Yes I did.
CC: WHERE DID YOU GET THE IDEA?
JP: Well through discussions with my supervisor and then looking through the literature on simulating mastication in general. I came across a paper from the mid-60s where a professor from St. Louis simulated mastication in humans essentially to try and reproduce patterns of wear in modern aboriginal populations and the design of that machine sort of inspired the design for this one.
CC: WHAT IS IT THAT YOU’RE TRYING TO FIND OUT?
JP: Well I’m trying to find out something about the relationship between the physical shapes of teeth, specially the pre-molars and molars in primates and what kinds of food that they break down. I’m sort of using as an estimate for diet in fossil primates for which we can’t know the actual diet for certain.
CC: WELL IF SOME OF THESE SPECIES THAT YOU’RE DEALING WITH ARE EXTINCT, HOW WOULD YOU TEST IT OUT?
JP: Well what I’ve done is I’ve used a modern analogue as the basis for all the muscle parameters, so muscle forces and the orientation of pull of the various different muscles and I’ve constructed such that at its focus is the cast of a skull of one of these modern primates and I’ve made it so that it is possible to insert different dentitions into this skull, essentially as dentures and glue them down to the skull and then I can test how different species perform on different types of food and this gives me some idea of relative effectiveness of food breakdown.
CC: SO WHAT WOULD BE SOME OF THE SPECIES THAT YOU’RE PUTTING IN THERE, TRYING OUT?
JP: Things that might be familiar to you as lemurs or lorises. This machine, in particular, is based on something called the bush baby which is a small African nocturnal primitive primate. As for the fossil primates that I’m testing, they’re mostly from the Paleocene so the epic just following the death of the dinosaurs and succeeding the Eocene so about 50 million years old. A group of archaic primates called the plesiodae performs lived in the Paleocene and it’s questionable whether or not they’re primates and I’ve tested a number of species of those and also the very first true primates so the first primates that would have all of the necessary characteristics to include them in order of primates. So some of the species that I’ve tested are likely to have been our ancestors.
CC: WELL LET’S FIRE IT UP AND SEE HOW IT WORKS.
JP: Alright.
CC: THIS LOOKS LIKE SOMETHING RIGHT OUT OF ONE OF THESE 1930s OR 1940 MOVIES. YOU’VE GOT A BUNCH OF SCREWS AND A BICYCLE CHAIN GOING AROUND AND A LITTLE MOTOR AND THEN THIS LITTLE SKULL DOWN HERE IS JUST ACHEWING AWAY VERY MADLY.
JP: Yep, yep. Well, it’s essentially powered by a motor as you can see a very small motor and the motor turns a couple cam shafts just like you’d have in your car, more or less. But, of course, much smaller and the cams as they turn impact upon rocking wooden arms which then lift a cable and each cable simulates a different muscle of mastication.
CC: WELL, I WOULD THINK THAT IF YOU DON’T GET ANYWHERE WITH YOUR MASTERS THESIS, YOU COULD CERTAINLY FIND ANOTHER CAREER AS A MECHANIC.
JP: That’s right.
CC: SO IN WORKING WITH ALL OF THIS, WHAT HAVE YOU FOUND OUT SO FAR?
JP: Well I found out some interesting patterns. In order to make certain that the machine is doing what it’s supposed to, I’ve used as I said living species of primates and the virtue of them is that they have known diets from ecological field studies. It turns out that those species that I tested for which diet is known are, in fact, breaking down food effectively that they are eating in the wild. So the foods that they eat preferentially are also the foods that they break down preferentially in this machine. So that confirms, I guess, the usefulness of the machine. There is one interesting species of living primate, a loris from Asia for which very little was known about its diet and I tested it and found that it eats mostly insects but also a lot of fruit and leaves and things like that and since I’ve tested it, I’ve actually learned from a colleague that very recently they’ve discovered that this primate eats those things in the wild. Something that wasn’t know before.
CC: WELL HOW COULD YOU EVEN TELL THAT FROM IT? WHAT SORTS OF THINGS WOULD YOU BE PUTTING IN THERE FOR THEM TO CHEW UP?
JP: Well a lot of things that you’d find in a grocery store–nuts, fruits, leaves, flower petals, insects like crickets and mealworms that you can get at the pet store.
CC: I’M GLAD YOU SAID PET STORE CAUSE I DON’T BUY THOSE AT THE GROCERY STORE.
JP: Right, yeah. So a wide variety of foods and what I’ve done is for each different food type, I’ve broken it down in the machine through ten chewing cycles with five samples for each type of food for each species that I’m testing. And then after the food is chewed up, I collect all the fragments that result from the chewing and what I’ve done is I’ve past them through a column of sieves to sort out various size brackets and assuming that more smaller fragments indicates a better bout of chewing then those foods that end up with more smaller fragments are those which are better chewed and I’ve inferred that this may indicate something about the diet of the animal in question and actually I’ve learned some interesting things about the diets of fossil primates as well. The archaic that I mentioned earlier the pleaseodae performs were originally thought to have been eating mostly insects but the ones that I’ve tested here are actually turning out to have more herbivorous tendencies that are breaking down leaves very well, fruits very well and nuts very well and they’re not breaking down insects very well at all. Whereas when you get into the first true primates these Eocene ancestors of ours, it looks like they’re starting to specialize more and more in terms of their diet. Some species do very well with fruits whereas others do very well with insects. So we’re seeing a greater polarization in the diet there.
CC: WELL WHAT WOULD BE THE DIFFERENCE IN THE TEETH THAT WOULD MAKE IT EASIER TO CHEW UP INSECTS ON ONE HAND OR OTHER THINGS ON THE OTHER HAND?
JP: Well it looks like those species that are breaking down insects very well are species with particularly sharp tooth cusps. So cusps that have a very small volume for their height tend to be breaking down insects very well. And those with very blunt cusps are better at breaking down fruit for example. And you can imagine that there would be intermediate conditions of tooth shape for different types of food.
CC: WHEN YOU LOOK AT THE OVERALL SIGNIFICANCE OF THE WORK THAT YOU’VE DONE, WHAT WOULD YOU SAY IT IS?
JP: Well, just looking at the machine itself, it provides a novel method for testing hypothesis about food breakdown and diet and it’s a method that could be applied to a number of different kinds of animals not just these early primates but other types of mammals and perhaps even beyond mammals. Things like dinosaurs or whatever and this type of machine is relatively simple to make with fairly rudimentary technology so it can be reproduced by others and tested on other types of animals and it simply provides us with a new method to test these extinct animals for which you can’t just go out and observe diet.
CC: IS THERE A PATENT PENDING ON THIS?
JP: Possibly.
CC: WELL THANK YOU VERY MUCH JONATHAN.
JP: Okay, thank you very much as well
Jonathan Perry is a graduate student in Paleontology at the University of Alberta and with the help of his chewing machine, he successfully defended his thesis this spring.