Our genes arouse the appetite for unhealthy food such as hamburgers, fries and other fatty food. That such food can eventually lead to an early death does not bother the selfish gene. We would already have propagated ourselves and spread our genetic material by that time.
Tijskens' contention is inspired by the book 'The Selfish Gene' by Richard Dawkins, who propounds that a person is merely the vehicle and distribution channel for his genes. As such, conflicting interests are sometimes at work: some instincts are good for the genes but bad for the individual, as in the case of the mother who gives up her own life for her children.
A low energy diet can prolong our life span considerably. 'Mice reared on a limited energy diet live up to 65 percent longer than normal', says Tijskens. 'Humans too are healthier and live longer if we limit our food intake. On the contrary, we have the tendency to overeat.' The obvious question is how genes can benefit from our food preferences by directing us to eat excessively and to choose unhealthy foods instead of that raw carrot. 'The genes push us to multiply ourselves, which is a very energy-intensive process. The easily available energy in unhealthy food is the reason why we go for fast food', Tijskens explains. 'In such food, about 50 percent more energy is present than in the same food in its raw form. This increases the chances of reproduction and that is advantageous for the genes.'
The preference for energy-rich food which can be digested quickly is not only found in humans, says Tijskens. Animals too like fatty foods. 'Our selfish genes have much more influence on our instinctive consumption pattern than we realize', says Tijskens. 'Therefore, government efforts to get us to eat more healthily using information alone are insufficient, and government campaigns for healthier food have so little effect.'