The scientists base their advice on research about microbes in the human gut. While our ability to destroy harmful microbes with antibiotics, sanitation and vaccines has brought about a revolution in the treatment of infectious diseases, these procedures are not discriminative, so the beneficial microbes are also destroyed – the ones that allow our immune system to develop.
Whenever a child’s immune system encounters a (new) harmless microbe, it learns how to ignore it, or at least to tolerate it. If a growing child has limited exposure only to these microbes, the authors say their immune system will remain immature.
It would take considerable medical expertise to know whether Arrieta and Finlay’s hypothesis is correct, but the sound scientific evidence they cite makes it at least worthy of careful consideration. Furthermore, their argument is appealing psychologically, for the following reasons:
- Spending time outside encourages the production of endorphins, our natural painkillers that trigger feelings of wellbeing.
- Being outdoors helps set our biological clock and promotes more restful sleep.
- Owning a dog – another factor the authors argue boosts immune system development – teaches nurturing skills. Petting a dog releases oxytocin, the hormone that helps us feel safe and secure, and walking it encourages the whole family to take more exercise.
- Playing with natural materials stimulates creative power, because children are more likely to choose how to use natural objects, as opposed to reacting uniformly to ready-made toys and screen instruction.
- Playing outside in nature instils a respect for – and love of – the environment.
If that’s not enough, think about the time you’ll save when you’re not cleaning and sanitising. Instead, you can use that time to have fun together as a family.
Linda Blair is a clinical psychologist. To order her book, The Key to Calm (Hodder & Stoughton), for £12.99, call 0844 871 1514 or visit books.telegraph.co.uk