Why are sumo wrestlers fat? Sumo is gravity-based sport, so the heavier you are, the bigger your advantage. A sumo match is won by throwing your opponent out of the ring, or by making any part of his body - other than feet - touch the floor. So fat, heavy wrestlers have inertia on their side. Is it true cows have four stomachs? Cows do not actually have four stomachs - they have just one stomach which is divided into four compartments. The scientific names for the four compartments are: rumen, reticulum, omasum and abomasum. Cows need a stomach with four separate sections as they have a different digestive process from humans. The cow first swallows its food, usually grass, without chewing it. The grass goes into the rumen, which is full of microbes and acts like a fermentation tank. The microbes break down and soften the grass. After this, the cow will regurgitate the partially-digested food, 'cud', and chew it, breaking it down further before swallowing it again. The other compartments then take over the digestion process. From this slow process we get the expression 'chewing the cud', which means to think over something slowly and carefully. Why don't identical twins have identical fingerprints? Identical twins are identical in that they have the same genetic code. However, while they share the same womb for nine months, they do not develop in exactly the same way. Twin embryos do not have equal blood supplies - therefore one embryo is usually larger than the other and at birth twins seldom weigh the same. This explains why, while their fingerprints are similar, they are not identical. Why do ostriches bury their heads in the sand? It is a popular fallacy that ostriches bury their head in the sand when alarmed. They don't. When attacked by other animals, ostriches flop to the ground and lie very still, hoping to blend in with grassy landscape of their habitat. From afar, the ostrich's long beige necks and black feathers look like stalks of grass sticking out of the sand. And to the human eye, this looks like a dome of a body with no head attached, leading to the belief that ostriches bury their heads in the sand.