Vultures are renowned for burying themselves head deep in rotting carcasses, chowing down on what most other creatures would firmly decline. This lifestyle would ordinarily put most animals at risk of contracting diseases and infections from the bacteria incubating in the corpses, and yet vultures manage to resist this, and are even known to be able to eat anthrax and still survive. It turns out that some of the secrets as to how the birds achieve this might be hidden in their DNA.
After sequencing the entire genome of the cinereous vulture, or Eurasian black vulture, and comparing it to another bird of prey, the bald eagle, the researchers found certain genes that seem to allow the vultures to digest carcasses and others that protect them against infectious pathogens. In addition to that, they also discovered that the Eurasian black vulture, which is known as an “Old World” vulture along with all other vultures from Eurasia and Africa, probably evolved independently from the “New World” vultures found in the Americas.
The Eurasian black vulture is found through Europe and Asia, and is one of the largest birds of prey. Woon Kee Paek.
“This is the first Old World vulture genome that has been reported, and we can see that the cinereous vulture has genetic signatures for resisting infection from eating decaying flesh,” explains Jong Bhak, who co-authored the paper published in Genome Biology. “Understanding the genetic make-up of extreme life forms has potential for improving human health. The immune system genes we've identified could be useful targets in humans for protection against infection.”
When comparing the two birds of prey, they found variations in the genes associated with the regulation of gastric acid. According to the paper, this suggests that the acidic gastrointestinal tract of vultures acts in a way like a filter, sifting out the potentially dangerous microbes ingested from the decaying meat. This is complemented by changes seen in genes related to the vulture's immune system.
They found that there were key differences in a particular gene that codes for a protein called Alpha2-HS glycoprotein (AHSG), which promotes the process of endocytosis and possesses what’s called opsonic properties. This is where cells take in molecules, such as proteins, from pathogens and then use them to tag the said infectious microbe so that it can be more easily identified and subsequently consumed by other cells of the immune system. They also found another change in a specific gene that is known to accelerate programmed cell death, or apoptosis. It seems reasonable to suggest that these genes have been selected for to combat the pathogens the vultures encounter due to their diet.
That wasn’t all they found though. By comparing the genome of the Eurasian black vulture to the bald eagle, they found that the two species probably diverged around 18 million years ago, much more recently then when Old and New World vultures were thought to have split around 60 million years ago. This supports the theory that the two lines of vultures evolved independently, and developed their similar adaptations to scavenging through convergent evolution.