14/08/2014 12:55 BST | Updated 22/05/2015 06:12 BST

The Real Reason Children Won't Eat Their Greens? Survival Instinct

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Girl looking at broccoli

As you stand by the bin scraping in yet another plate of broccoli, cabbage or peas, do you find yourself wondering: Why won't my children eat their greens?

Well, according to boffins, it's not because they're fussy eaters – it's because they think you're trying to poison them. OK, not you exactly: but the evil veggies.

According to scientists, our children have an innate wariness of plants because they fear they may contain toxins that could harm them.

So when it comes to a choice of a sausage versus sprouts, it's no contest: as far as a toddler is concerned, a sausage is better for them.

After studying dozens of toddlers as they played with various objects, American researchers noted that they were far more reluctant to grasp plants than artificial items such as spoons or pipe cleaners.

They believe this is because evolution has biologically programmed children to be wary of flora as it may contain potentially hazardous toxins.

Due to a susceptibility to illness or injury in the early years of life, the body has designed an inbuilt defence mechanism that limits a child's contact with plants, they think.

The researchers believe this is why infants in the study were wary of grabbing plants - and why children turn their noses up when faced with a plate of broad beans.

The findings are published in an academic paper by Dr Annie E Wertz and Dr Karen Wynn, both psychologists at Yale University, titled 'Thyme to touch: Infants possess strategies that protect them from dangers posed by plants'.

They wrote: "Throughout human evolution ... plants have been essential to human existence. Yet, for all of these benefits, plants have always posed very real dangers.

"Plants produce toxins as defences against predators that can be harmful, or even deadly, if ingested. Some plants also employ physical defences, such as fine hairs, thorns, and noxious oils that can damage tissues and cause systemic effects."

They added: "We predicted that infants may possess behavioural strategies that reduce their exposure to hazards posed by plant defences by minimising their physical contact with plants."

The authors concluded that trial and error across centuries of human existence had taught infants to be intrinsically wary of physical contact with plants.

"We are not suggesting that infants are actively afraid of plants," Dr Wertz and Dr Wynn concluded.

"Rather, we propose that once infants identify an object as a plant, they deploy a behavioural strategy of inhibited manual exploration, which serves to help protect them from plants' potential dangers."