I arrived expecting to see an offbeat anthropologist swallow a chocolate covered cockroach. But what I found was an explorer.
Investigating how animals eat, David Raubenheimer’s vast array of exotic work takes him to locations so intriguing, it distracts me from the content of his talk.
I arrived expecting to see an offbeat anthropologist swallow a chocolate covered cockroach. But what I found was an explorer.
Investigating how animals eat, David Raubenheimer’s vast array of exotic work takes him to locations so intriguing, it distracts me from the content of his talk.
Forget the lab coat and microscope. His lab is deep in the heart of the jungles of Uganda studying the feaces of gorillas or following snow leopards in the Himalayas.
Professor of Nutritional Ecology at the Institute of Natural Sciences, Massey University in Auckland, New Zealand, Raubenheimer talks about the diets of all sorts of animals in his Scifest Africa lecture.
He calls himself as a “comparative nutritional ecologist”.In a world where people are dying of both malnutrition and over eating, the implication of such research has the potential to solve our eating problems.
We might one day be telling our grandchildren about the great obesity epidemic:“Ah it was horrible, there were cheese burgers and fries everywhere!”
If people can learn anything from locusts, what to eat might be one of the most useful lessons. While we might be new to the idea of a protein rich Atkins diet which so many Hollywood stars are adopting, locusts have been doing it for millions of years.
Research on locusts has lead to some intriguing theories as to why so many humans may be overweight. Raubenheimer believes that while the mechanism that controls our appetite is complex, it is partly driven by the proportion of protein in our diet.
He describes the humble German cockroach as being a most fascinating species. Like the precise German engineering of a BMW, these creatures are “incredibly efficient physiologically”.
Along with low energy consumption and very little waste of nitrogen, they regulate and balance their intake of carbohydrates and proteins almost perfectly according to their dietary requirements.
“This is why they are efficient house pests,” he laughed. Raubenheimer, along with his colleague Steve Simpson, invented the geometric model approach to nutrition.
This groundbreaking work has revolutionised the way scientists study nutrition. Simply put, the model combines different nutritional factors creating a balanced perspective as opposed to viewing each aspect singly.
The model demonstrates a tradeoff where an animal aims for an ideal balance of protein and carbohydrates. There is often a shortage or surplus so the animal compensates by eating more or less of the other.
He has tested this theory on locusts by giving them meals with different proportions of protein. Experiments showed locusts keep eating until they reach a certain level of protein a “protein target”.
Now if you take those animals and you restrict them to a diet which contains a higher than that the normal intake target level of carbohydrate, then what the locust does is it keeps eating until it gets the same amount of protein, but in so doing it has grossly over consumed on carbohydrates.
This then leads to the animal becoming obese. It’s not only locusts that exhibit this behavior. Spiders, fish and a number of mammal species regulate their protein intake more strongly than their carbohydrate or fat intake.
Recognising the implications of the role of protein in animal diets, he decided on an unusual experiment to investigate its impact on humans.
“We incarcerated ten individuals in a hotel room in Switzerland for six days,” he explained. The experiment included serving buffet style meals similar to what the locusts are exposed to.
And the results were similar. Raubenheimer believes humans, like our primate cousins the monkeys, prioritise protein in their diets.
But unlike other animals our diets are diverse. The problem is as humans our wide diet breadth is artificial. In the wild we would be much more limited.
“We are that good at manipulating our diets that we have to be careful what we (and our kids!) eat,” he emphasised.
