How the giraffe got its long neck
Have you ever wondered how the giraffe got its long neck? Did you know that a giraffe’s neck can measure up to 1.8 metres and is made up of just seven elongated vertebrae?
But this graceful, tall animal didn’t always have a long neck. Dr Willem Daffue, a veterinary surgeon, conservationist and researcher works alongside wildlife habitat expert, Professor Francois Deacon, of the University of the Free State.
Together, they are investigating the evolution of the giraffe: An animal with remarkable traits for regulating blood pressure, blood and body temperature in its long neck.
Part of this study included Dr Daffue wanting a rather unusual set of imaging done of a giraffe skull. The best people for the job: The radiology team at the Louis Leipoldt branch of SCP Radiology.
He brought in the skull and several vertebrae of the now extinct short-necked giraffe for CT scans.
The remains travelled from the Iziko National Museum so that a CT scan could be done to measure the unique anatomical features of this prehistoric animal (Sivatherium hendeyi).
The evolution of the giraffe’s long neck is a fascinating example of natural selection. This adaptation has been studied extensively and several theories explain its development, primarily focusing on when, how and why this evolutionary change occurred.
The ancestors of modern giraffes began to evolve their long necks approximately 7- 8 million years ago, during the Miocene epoch. Fossil evidence indicates that early giraffes, a group that includes the modern giraffe (Giraffa camelopardalis) and its extinct relatives, started to diverge in neck length around this period.
From their early ancestors, with shorter necks, to the towering giants we see today, giraffes have developed a range of adaptations that enable them to thrive in the African savanna.
The two main hypotheses are feeding competition and sexual selection.
Significant climate changes millions of years ago, led to the expansion of savannas and the reduction of dense forests. This environmental shift created a new niche for browsing high in trees, where other herbivores couldn’t reach, reducing competition for food.
The second is that the long neck evolved through sexual selection. Male giraffes engage in ‘necking’ battles, where they swing their necks and heads to strike opponents. Males with longer, stronger necks are often more successful and therefore more likely to reproduce, passing on their long-necked traits to offspring.
Understanding their evolutionary history not only highlights the intricacies of natural adaptation but also underscores the importance of preserving biodiversity in our rapidly changing world.
‘With this CT scan, we wanted to confirm whether the ancient giraffe had a basilar artery, which forms where the vertebral arteries of the neck merge at the base of the brain,’ explained Dr Daffue.
“The modern-day giraffe is the only animal that doesn’t have it and we want to know if its predecessor did. We also wanted to measure the brain and arterial canals on either side of the skull to determine which species had the more active brain.”
Professor Deacon has been researching the giraffe for 15 years and worked with experts from 12 different countries, to try and develop strategies to counter dwindling populations in Africa.
This multi-specialist team’s research has piqued the interest of National Geographic. He said the research has now taken a leap forward with this imaging, to fill in some of the gaps of how the giraffe got its long neck.
“‘We are thankful to organisations like SCP Radiology for supporting our efforts for the conservation of the modern giraffe.’”\