About 70 per cent of pregnant women experience nausea during pregnancy.
But there is little evidence that morning sickness afflicts other animals, even our closest ape relatives, aside from a couple of anecdotal reports from zoos involving a gorilla and an orangutan.
Apart from the obvious discomfort, morning sickness can lead to dehydration and may require medical attention. It is usually triggered by the taste or smell of certain foods, especially meat, fish, vegetables, spices, alcohol and caffeine, as well as by smoke. The causes are mysterious, though it has been linked to changing hormone levels. It may even be beneficial, serving to protect the developing foetus from toxins in the mother’s diet.
As for why only humans seem to suffer from it, that may have something to do with our unusually broad diet, which could put foetuses at a higher risk of exposure to potentially harmful substances. Another tantalising possibility is that morning sickness started out as an aversion to harmful smoke during pregnancy after humans started using fire, and that the biochemical pathways involved lower the threshold for nausea in general.
Main image: lioness and cub at Masai Mara National Reserve/Credit: Getty
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