Comparing with apes, why are we more vulnerable to pathogens?

Many diseases occurring in human beings don't exist in apes, such as typhoid fever, cholera, mumps, whooping cough,  and gonorrhea. why is that the case? Is mankind's immune system less developed?

Image Credit: Sapiens.org

A team of scientists from University of California San Diego led by  pathologist Ajit Varki has just reveled the secret behind the long evolution history of our immune system.  By analyzing modern human genomes and ancient DNA from our extinct cousins, the Neanderthals and Denisovans, the researchers detected a burst of evolution in our immune cells that occurred in an ancestor of all three types of human by at least 600,000 years ago and concluded that innate immune interactions with pathogens markedly altered hominin Siglec biology between 0.6 and 2 Ma, potentially affecting human evolution.

This research was published recently in the current issue of Genome Biology and Evolution. It is common knowledge that human beings are much advanced than microbes. And our ancestors developed sugar molecules called sialic acids as a defense against microbial pathogens. However, this created new vulnerabilities for the pathogens to evolve to exploit sialic acids and many microbes have taken this advantage including coronaviruses. Most coronaviruses infect cells in two steps—first by recognizing abundant sialic acids as binding sites to gain a foothold, and then seeking out the higher affinity protein receptors like ACE2,” Ajit Varki says. “Think of it like an initial handshake or introduction that is required before one can ask for a date.” The novel coronavirus, SARS-CoV-2, has also been reported to dock with sialic acids before binding with the ACE2 receptor to pierce human cells

Reference

Khan, Naazneen, et al. "Multiple Genomic Events Altering Hominin SIGLEC Biology and Innate Immunity Predated the Common Ancestor of Humans and Archaic Hominins." Genome biology and evolution 12.7 (2020): 1040-1050.


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