Apples float but pears don't

I have long used the expression and often heard others use the expression, "you need to compare apples with apples," when describing making like comparisons between two subjects. Recently after watching QI, I discovered a good example why comparing two different fruits can give you two wildly varying outcomes. In the case of the apple and the pear, when you place an apple in water it floats, however when you place a pear in water it sinks. I previously did not know this even though I grew up in a major fruit growing region. It also solves the question why people bob for apples but never for pears.  Now this does not mean that all apples will float and all pears will sink, as they say, there is a exception to every rule. So you may find that some pears will float, whilst some apples will sink. However as a general rule you will find that apples float more often than not and pears sink more often than not.

Now why do you ask, does an apple float and a pear sink? It is all to do with the water & oxygen content, a pear is a denser fruit and has a higher water content, it is also unable to absorb much oxygen once it has been picked, which results in it being unable to float. However an apple has the capacity to continue to absorb oxygen even after it is picked, which means it contains more air and is therefore less dense and has a lower water content, thus enabling it to float. This is also the reason why an apple is able to stay fresh longer than a pear, because the apple still absorbs oxygen once picked, the apple in effect can breathe, which enables it to stay fresher longer, the pear is unable to absorb much oxygen, so cannot breath, which results in it decaying faster.