An article published in the journal “Nature Communications” describes a genetic research on the giraffe. An international team led by Professor Douglas Cavener of Penn State University sequenced the DNA of the giraffe and of the okapi, its closest living relative. A comparison extended to the genome of other mammals identified 70 genes linked to the giraffe’s evolutionary adaptations, including its long neck.

The unique characteristics of the giraffe have always fascinated people and have been a source of puzzlement to scientists. Their evolution was one of the mysteries that Charles Darwin already tried unsuccessfully to resolve because their neck also requires a heart with a particularly large left ventricle to pump blood up to the animal’s brain. The result is a blood pressure twice as high as other mammals.

Today DNA can provide solutions to these mysteries and for this reason the sequencing was also done to the okapi genome, a species that has a common ancestor with giraffes from which they began to diverge about 11 or 12 million years ago. It’s a rather short time in evolutionary terms for two species of mammals and yet the okapi looks more like another cousin, the zebra, also from the point of view of cardiovascular physiology.

The researchers sequenced the DNA of two specimens of Masai Giraffe, also known as the Kilimanjaro Giraffe, (Giraffa camelopardalis tippelskirchi) the largest giraffe subspecies, and the DNA from a specimen of okapi (Okapia johnstoni). The comparison between the genomes of the two species allowed to identify the genes that determined the giraffe’s unique characteristics.

These genomes were compared with those of more than forty other mammals to get a more precise understanding of the various evolutionary adaptations. In essence, this broader comparison allowed to make sure that certain mutations occurred in giraffes’ ancestors.

The result of these analyzes is that some genes that ahve characteristics different from those of other mammals are responsible for some big physical differences in giraffes. In particular, one known as FGFRL1 is a gene defined a regulator that has a huge influence in embryonic development because it contains a group of amino acids that regulate various processes, also in embryos.

There are also other genes that determine the unique characteristics in giraffes. Those are genes that determine the development of the body structure and in particular of  neck and legs and others that regulate various metabolic functions. In the end, there is a small group of genes that made the giraffe so unique showing how evolution can lead to big changes following some key mutations.