Giraffes are one of Africa’s most well known animals. They are the tallest living land animal and can be up to 5 meters tall – the same height as a two storey building. This unique height is mostly due to giraffes’ long necks, which can make up half of their total height.
Even though a giraffe’s neck looks very different to any other animal’s, they are quite similar. Like humans, a giraffe’s neck is made up of 7 bones. The main difference in that giraffe’s bones are longer, and joined together in a special way to make the neck flexible.
Giraffes long necks evolved due to “natural selection”. Natural selection is the process where animals that are better adapted to their environment are more likely to survive, passing on those good traits to their offspring. There are several reasons why long necks give giraffes survival advantages, but scientists are still trying to decide which is the most important.
THE MOST POPULAR THEORY: FEEDING COMPETITION
The traditional explanation is that giraffes have long necks to help them find food. In a population, giraffes always have different neck lengths. When there was enough food, all of them would survive. However, when there was less food around, those with longer necks were more likely to eat enough and survive. This was because giraffes with longer necks would have been able to reach the leaves at the tops of trees that others couldn’t reach. As a result, more giraffes with longer necks would survive, reproduce and pass their long necks onto their offspring. Over time, the whole group would on average have longer necks.
This explanation is popular, and found in most biology textbooks. However, there are some issues with this explanation. For example, giraffes frequently eat the leaves of trees that are shorter than them.
OTHER THEORIES: MATING RITUALS
Necks are also part of giraffes’ mating rituals, and some think it may be the reason for their long necks. Male giraffes fight for dominance by swinging their necks at each other. It is an advantage to have a longer, thicker neck, as this makes them more likely to win the fight, and therefore be able to reproduce. However, one problem with this theory is that females (who do not participate in these fights) have similarly long necks.
OTHER THEORIES: PREDATOR THREAT
Some think that giraffes evolved long necks because of the threat of predators. Their long neck may help them see predators from far away and escape. They may have therefore evolved longer necks to compensate for their legs and help them access food and water at lower heights.
A FURTHER THEORY
Giraffes’ long necks also help them cool down faster, and get up when they are lying down.
HOW DOES THIS BENEFIT THEM?
Clearly, giraffes’ long necks have many important functions. Therefore, it has been difficult for scientists to decide on one main reason that led to the evolution of the long necks. It was likely a combination of all these traits.