D: Yaël, what’s your favorite animal? Mine’s the giraffe.

Y: What an incredible creature, Don! Giraffes are usually 14 to 19 feet tall, meaning they could easily look into your second-floor window. Their neck alone is 6 feet long, weighing about 600 pounds. And it only has seven neck vertebrae—just like humans! But have you ever wondered why giraffes have such long necks?

D: I always thought it was to reach high branches of trees, especially acacias. The leaves up there are too far away for other herbivores. Over millions of years, giraffes evolved their neck to snack on this tasty foliage, without having to compete with other animals for their food source.

Y: And that’s the main theory. There are other possible reasons, though. For one, being so tall lets a giraffe watch for predators. Another argument is that long necks help giraffes win fights. When male giraffes fight over a female, they strike each other with their armored heads and strong necks. Typically, the longer-necked male wins, passing down his genes to his offspring.

D: You know, I’ve also heard of a study that argues that a giraffe’s unique body shape helps regulate its temperature. By being tall and narrow, a giraffe can keep most of its surface area out of direct sunlight, helping it stay cool. As for how giraffes got this way, another study suggests that these long necks developed through mutations of skeletal and cardiovascular genes.

Y: Of course, being so lanky does have its disadvantages. Giraffes must awkwardly widen their stance and bend their heads down to drink out of a water hole, making them vulnerable to predators.