SCIENCE

Comparing Apples and Oranges

November 2, 2010

The phrase "comparing apples and oranges" is often invoked when a person compares two items that are thought to be so different as to make any comparison invalid. But are apples and oranges really that different? According to TimeTree.org, Malus x domestica (the apple) and Citrus sinensis (the navel orange) are separated by about 89.2 million years of evolution, but they are both fruit trees. Surely there are valid comparisons that can be made. So where are the differences, and is a comparison between them truly invalid, as the idiom says?

To make my comparisons, I will draw from my own experience and several online sources, including a dietician's analysis of the juices of the two fruits and a published study: "Comparing apples and oranges: a randomised prospective study," by James Barone, which appeared in the British Medical Journal in 2000. Here are just a few characteristics:

	APPLES	ORANGES
GROWN ON FRUIT TREE	Yes	Yes
COLOR OF FRUIT	Depends on variety	Orange
FRUIT SKIN TEXTURE	smooth	knobby
VISIBLE SEEDS IN FRUIT	Yes	Depends on variety
MEAN CIRCUMFERENCE OF FRUIT (cm)	25.6	24.4
MEAN DIAMETER OF FRUIT (cm)	7.9	7.6
MEAN WEIGHT OF FRUIT (g)	340	357
CAN BE EATEN	Yes	Yes
SWEETNESS	2+	2+
FIBER IN A LARGE FRUIT (g)	4.5	2.4
CAN BE JUICED	Yes	Yes
CALORIES (per 8 oz. serving juice)	117	112
POTASSIUM (mg, per 8 oz. serving juice)	295	496
VITAMIN C (mg, per 8 oz. serving juice)	103	124
FOLATE (mcg, per 8 oz. serving juice)	0	74

As we can see from this small list, it is quite easy to compare apples and oranges. And they are remarkably similar in many ways. Although they may look and feel very different, the two fruits have a similar size and weight, and their juices have a similar caloric content and levels of vitamin C. However, they differ widely in fiber content of the fruit and in the potassium and folate levels of their juices.

In an earlier study ("Apples and Oranges—A Comparison," published in the Annals of Improbable Research in 1995), Scott Sandford produced a spectrograph from dried samples of a Granny Smith apple and a Sunkist navel orange. He concluded that not only was it easy to compare the two, but the two fruits were remarkably similar. "Thus, it would appear that the comparing apples and oranges defense should no longer be considered valid. This is a somewhat startling revelation," Sanford wrote. "It can be anticipated to have a dramatic effect on the strategies used in arguments and discussions in the future." Well, he didn't get that right, but perhaps we should consider dropping the use of this idiom.