A newborn giraffe calf stands in its enclosure at the San Francisco Zoo on August 29, 2014 in San Francisco, California. (Photo : Getty Images/Justin Sullivan)
The genome of the world's tallest land animals, giraffes, has been sequenced by a group of researchers at the Pennsylvania State University. The team has discovered a set of evolutionary mutations, which enable the creatures to have such a remarkable physical characteristics, including long necks.
A typical giraffe can be as high as 19 feet. Their unique physiology has fascinated humans for times immemorial. These creatures have extraordinarily large left ventricle and a blood pressure that is twice as high as other members of the animal kingdom.
In addition, giraffes are swift runners and are highly capable of digesting food items, including acacia leaves, that are otherwise considered poisonous for other animals. While different theories, including Darwinism and Lamarckian evolution suggest "why" giraffes have long legs and neck, the researchers have always wondered "how" this would have happened.
Moreover, giraffes do not bear any resemblance to its closest living relatives, okapi, who look more like a zebra. Therefore, there are no "intermediate" species in between the two animals.
To understand the genetics behind giraffe's characteristic features, the team of researchers sequenced their entire genome. The study findings, published in the journal Nature Communications, depict how the giraffe's unique body evolved over the period of a thousand years.
During the study, the researchers compared the gene-coding sequences of giraffe and okapi with 40 other animals. At the end, they figured out only 70 genes that they believe are responsible for giraffe's incredible adaptive features.
By studying okapi's genome, the researchers were specifically able to identify the genes that make giraffes what they actually are. The team used okapi as a genetic filter since there are only a few differences between the genomes of an okapi and a giraffe.
An analysis of the 70 genes revealed that almost 46 of them controlled the development of nervous, cardiovascular or skeletal system in giraffes. This accounts for the specialized changes nerves, heart and blood vessels that giraffe requires to compensate for their great height.
In addition, several of these genes showed mutations signifying control of more than one system. For example, some of the identified genes regulated both skeletal and cardiovascular development.
"To achieve their extraordinary length, giraffe cervical vertebrae and leg bones have evolved to be greatly extended," research Douglas Cavener said, in a press statement. "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."
The following video is a detailed documentary on giraffes:
