Back on topic. Here is a photograph of a desert acacia, taken in Egypt.
Source
You will notice that while the crown of the tree is rounded and irregular above, below it is very regular - almost, in fact, a straight line.
When I first travelled in the Arabian desert, I noticed that the occasional tree one encountered was always shaped like this. Remarking upon it to my
guides, I was told the cause: camels graze on the trees, which consequently have no foliage extending much below the average height of a camel's
mouth above the ground.
I think this picture illustrates rather well why giraffes evolved long necks.
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