Page "Sexual selection" Paragraph 15

Another explanation as to where the giraffe's neck came from is sexual selection.

It is known that males will often neck with other males in order to exhibit dominance.

There are six criteria that need to be satisfied for the exaggerated neck to be classified as a result of sexual selection.

Theoretically, the characteristic should be more exaggerated in one of the sexes ; it must be used to indicate dominance ; have no direct survival benefits ; help the organism gain survival costs ; positive allometry should be observed.

For instance, evolution history shows increased neck length not correlated to increases in other parts of the body, which is what would be expected in foraging selection.