Standing up to 19ft (six metres) tall, there’s no denying that giraffes are one of the most bizarre creatures on Earth.

And if you’ve always wondered about the science behind those long spindly legs and peculiar necks, researchers have revealed those characteristics may be the result of unique genes that affect the skeleton, heart and nervous system.

Yep, scientists now have the genetic instruction book that contains all the secrets of the animal. And mapping the giraffe’s genetic code, or genome, has highlighted a host of DNA sequences that make the animal so special.

giraffes
“Ooh, yummy” (Nellie Doneva/AP)

Professor Douglas Cavener, from Pennsylvania State University in the US, who led the study, said: “The evolutionary changes required to build the giraffe’s imposing structure and to equip it with the necessary modifications for its high-speed sprinting and powerful cardiovascular functions have remained a source of scientific mystery since the 1800s, when Charles Darwin first puzzled over the giraffe’s evolutionary origins.”

The animal’s heart, built to pump blood vertically a distance of two metres (6.5ft) to its brain, has an unusually large left ventricle chamber.

Taking a giraffe’s blood pressure would show a reading twice as high as that of other mammals.

giraffe
That is one long neck… (Kamran Jebreili/AP)

Oh, and we’re not done with the giraffe facts yet – did you know they can sprint at speeds of up to 37 mph on their long spindly legs? Also, despite appearances, its neck also contains the same number of bones as the necks of other mammals – including humans. The big difference is that both the giraffe’s leg and neck bones are greatly extended.

“At least two genes are required – one gene to specify the region of the skeleton to grow more and another gene to stimulate increased growth,” said Prof Cavener.

The scientists pinpointed unique regions of the genome by comparing it with that of the giraffe’s close relative, the okapi.

Both animals have a common ancestor but they branched off in separate directions along the evolutionary path around 11 to 12 million years ago. The okapi has similar gene sequences to the giraffe, but it’s not, well, as lanky. Plus, they look more like zebras…

okapi
Okapis have similar genes to giraffes but they’re definitely not as lanky (Jens Meyer/AP)

Tests comparing the two animals uncovered 70 giraffe genes that showed multiple signs of adaptation.

Several genes controlled both heart and artery and skeletal development – this intrigued scientists. It raises the possibility that the giraffe’s stature and cardiovascular system were modified together through changes to a small group of multi-purpose genes.

Now, let’s just take a moment to appreciate how cute giraffes can be…

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…because numbers of them in the wild are dwindling, but publication of the genome in the journal Nature Communications could raise awareness.

Prof Cavener added: “While the plight of the elephant – giraffe’s shorter companion in the African savannah – has received the lion’s share of attention, giraffe populations have declined by 40% over the past 15 years due to poaching and habitat loss.

“At this rate of decline, the number of giraffes in the wild will fall below 10,000 by the end of this century. Some giraffe subspecies already are teetering on the edge of extinction.”