The study, published in Biology Letters, backs previous theories which suggest male sheep's horns are curved to withstand head-on clashes, while female sheep's horns are spiked in order to push competitors away.

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Her head is held high and her mouth curved in a slight, but distinctly self-satisfied smile.

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Its main room has a large bronze antelope head on a white adobe wall that tops a curved fireplace, known as a kiva.

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