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On plants and cancer, healthy eating and the nerve system of a caterpillar

On plants and cancer, healthy eating and the nerve system of a caterpillar

Photographer:Fotograaf: Pixabay

First edition Ask the Scientist

A more interactive programme with input from the audience – that’s the aim of Studium Generale’s new segment: Ask the Scientist. Over the past few months, people could send in their burning questions about life, the world, the universe. Last Tuesday, three scientists answered a selection of them in the Auditorium on the Minderbroedersberg.

Evolution biologist Roy Erkens kicked off the night by giving a twenty-minute lecture on the differences between animals and plants and when they first occurred in evolution. The question was introduced by the person (a teacher at the Language Centre) who sent it in, who said that knowing all life on earth originally came from the oceans, she started wondering: do we share a common ancestor with plants?

Indeed, we do, says Erkens. It’s an organism that developed into two major directions: plants and animals and fungi. One got their energy from sunlight – photosynthesis – the other from eating plants or each other.

These are two different strategies of living. Plants compete with each other for light, animals for food. This meant that plants could stay in one spot; they didn’t need to move to catch the light, especially on early Earth, which was quite empty. Animals had to move around, so they did.”

Their different evolutionary routes, adapting to their environment as they moved on, gave plants and animals different bodies (plants are made of wood, animals of bones, plants only have three different kinds of cells but can combine them in various ways, we have many different cells – kidney cells, heart cells, brain cells, etc.) and a different role in the ecosystem.

After the talk, there is room for questions such as ‘Can plants get cancer?’ “They do, but it doesn’t affect them like it affects us. They can easily shed body parts – such as leaves or branches – and because they have no circulation system that moves cells around, it can’t spread.”

Break the habit

It’s time to move over to the next guest of the evening: professor of Health Promotion Stef Kremers. He explains how you can effectively motivate people to change their eating habits.

First of all, Kremers would like to emphasize that it’s not easy to eat healthily. “We are surrounded by triggers for unhealthy eating. There is a theory that we start each day with a barrel of mental energy. The later in the day, the emptier the barrel is, the more difficult we find it to make choices, and the more likely we are to give in to temptation.”

If you want to encourage someone to eat healthier, don’t tell him or her what to do, Kremers says. Focus on intrinsic rather than extrinsic motivation. “Talk to someone, find out what works for them. Set achievable goals. If somebody eats five hamburgers a week, the step to no hamburgers ever again is too big. Decide together on small changes they can make in their behaviour. And show them how to celebrate successes. Help them recognize that they are feeling better because of the changes they made.”

When asked what he would prioritise if he wanted to change the eating habits of a whole population, Kremers says: “Use pricing strategies. The prices of fruit and vegetables should decrease and those of unhealthy snacks should increase. Also, focus on the new generation. Children mimic what they see around them. That’s how obesity goes from one generation to another. We have to help parents raise their children in a healthy way.”

Not so perfect nature

Kremers gives the microphone to Linnea van Griethuijsen, lecturer at the Maastricht Science Programme, who will tackle the last question: How are scientists using nature’s ‘technology’ to solve problems in the human world?

Scientists do often look at nature for inspiration, says Van Griethuijsen. She gives some examples: a sharkskin-inspired swimsuit that makes it easier to move through water. And the project she worked on herself: building a soft robot by looking at caterpillars. How do they move and can their nervous system teach us something about how to control such a robot?

But one thing is important to keep in mind, says Van Griethuijsen. “Nature is not perfect. Take photosynthesis. It’s incredibly inefficient; plants don’t absorb the full wave of light. They only take up 1 per cent of sunlight energy, whereas solar panels take up 15-20 per cent. Evolutional change is slow and gradual. An organism’s environment may have changed. Once on an evolutionary route, you are stuck – you can still adapt, but you have to work with what you have.” What about Darwin then? Survival of the fittest, of the best? Roy Erkens chimes in: “The best compared to the rest, not the best possible. Besides, evolution is always a trade-off; one gain means another loss.” 

The next Ask the Scientist will be on Tuesday, 2 May. Questions can be submitted to



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