Why is the giraffe's neck so long?

After the establishment of genetics, people know that acquired traits cannot be inherited. Even if the ancestors of giraffes always stretch their necks to make them longer, they can't let their offspring be born with necks. No one believed Lamarck's hypothesis, and Darwin's statement spread. In the dry season, African grasslands are really short of food, and giraffes, as the tallest animals, can really eat leaves that other animals can't. Darwin's explanation is very intuitive and convincing.

But this explanation is only a hypothesis, and there is no evidence. On the contrary, there is some evidence to the contrary. For example, giraffes don't always cran their necks to eat tall leaves. In some places, giraffes bend their necks to eat low leaves about half the time. And contrary to Darwin's imagination, in the dry season, tall trees have fewer leaves, so giraffes have to eat the leaves of bushes. At this time, the long neck does not seem to show the survival advantage.

A long neck also has a survival disadvantage. Because the head is almost 3 meters higher than the heart, in order to ensure the blood supply to the brain, the giraffe has a large heart and a thick arterial wall, which makes the giraffe's blood pressure the highest among all mammals. Sometimes, traits that are not conducive to survival will evolve. For example, the big horn of the male elk is not conducive to survival, but because the male elk uses its horn to fight for a mate, it gives it a reproductive advantage. These cumbersome functions have not been retained, but have become more and more cumbersome. Darwin called this phenomenon sexual selection.

So is giraffe's long neck important for their courtship? Yes, in the courtship season, male giraffes will swing their long necks and hit each other with their heads to fight. The longer their necks are, the easier it is for them to win and get a chance to mate. This duel is very fierce and sometimes even leads to death. The doe also prefers to accept a male deer with a longer neck.