'You are what you eat!' It's an often-heard mantra, resulting in fat-shaming and an over-the-top diet culture. Yet some people can eat whatever they want, while others need only glance at a biscuit for the scales to go up. Why is that? Diet and exercise play a role, of course, but there's more to it: you can have a genetic predisposition to be overweight or underweight. UAntwerp researcher Jonas Torfs (Faculty of Science) has discovered that this holds true for bonobos, too.
IN A NUTSHELL
-
The weight of bonobos did not appear to depend on their sex, age or diet.
-
The heavier bonobos in European zoos appear to have the same - American - ancestry.
-
Differently functioning gut bacteria may explain why some bonobos are underweight while others with the same diet are overweight.
Serotonin in the gut
As a biologist at UAntwerp and ZOO Science, Jonas Torfs studies the 'gut microbiome' in bonobos. This is an umbrella term for all the different bacteria in the intestines. As it turns out, gut bacteria have an impact on how our brains work. 'For example, did you know that about 90 per cent of serotonin – the so-called 'good mood hormone' – is produced in our gut, including by gut bacteria?'
Conversely, an animal's social behaviour also determines the bacteria it carries: 'Through social contact, we pass bacteria to one another,' Torfs explains. 'So you share the same gut bacteria with your housemates or close friends. But that's not a bad thing: those bacteria help our digestion and promote our health.'
Despite the same healthy diet, some bonobos gained weight and others lost weight.
Gut-brain axis
The connection between behaviour and the gut microbiome is called the 'gut-brain axis'. Torfs studies this particular aspect in bonobos, as they are highly social animals. But what's the link with obesity? 'Well, we estimated the relative fat mass of all bonobos in European zoos, and found that overweight and underweight bonobos occurred in the same zoo, despite the fact that they were all fed the same healthy diet.'
It runs in the family
So the question arose whether in bonobos, as in humans, there's a genetic aspect at play. 'The relative fat mass of bonobos did not appear to depend on their sex, age or diet,' Torfs reports. 'But we did discover that the heaviest animals all came from an American line of bonobos, so they had the same ancestors. It's possible that those ancestors were malnourished. In humans, the genes responsible for burning fat are shut down if the mother is starving during pregnancy. Perhaps this is also true in bonobos, but we don't have a conclusive explanation yet.'
Bonobos, like humans, have a genetic predisposition to be fat or thin.
Better digestion
If you have a genetic predisposition to obesity, can you even do anything about it? 'You can still choose to feed heavier animals differently,' Torfs believes. 'After all, we only looked at the total calorie intake, not at the fat, fibre and protein content of the diet. Your gut microbiome determines which energy is released from your food and which nutrients are digested more easily. If your metabolism is too slow to burn everything right away, the excess is stored as fat. So heavier bonobos may have differently functioning gut bacteria. In any case, we've shown that bonobos, like humans, have a genetic predisposition to be fat or thin.'
Study Biology in Antwerp
Jonas holds a master's degree in biology (evolutionary and behavioural biology) and in addition followed the Interdisciplinary Honours Programme. This programme invites excellent bachelor students to further expand their scientific knowledge and academic competences with an extra package in addition to the general offer.