Giraffes have seven neck bones, which is the same number found in humans and most other mammals.

Almost all mammals share the same seven cervical vertebrae. This includes animals as small as mice and as large as giraffes. Scientists believe this number is fixed because of Hox genes. These genes control how an animal's body plan develops. Changing the number of neck bones in mammals often causes serious health problems.To get a long neck, giraffes evolved to stretch their existing bones. A 2015 study by the New York Institute of Technology tracked this change. They found that one specific neck bone is nine times longer than it is wide. This stretching happened in two stages over 7 million years. First the front of the bone grew, then the back part lengthened.Each of these seven bones can weigh up to 10 pounds. A thick band of tissue called the nuchal ligament helps support this weight. It works like a giant rubber band to help the giraffe lift its head. The joints between the bones are shaped like balls and sockets. This shape gives the giraffe a wide range of motion to reach different branches.