Study claims human immune system may have evolved from ancient ‘Asgard’ microbes

A new study suggests that the immune system found in humans and all other complex life forms may have evolved from an ancient microbial species known as Asgard Archaea. These microbes, thought to have emerged about 2 billion years ago, have provided insights into the origins of key proteins that help organisms fight off viruses. The speculated discovery explains how our immune system evolved, according to the study led by microbiologists Pedro Lopez-León of Radboud University and Brett Baker, an associate professor at the University of Texas at Austin.

The role of Asgard archaea

The basic evolution of life is divided into three main domains: Bacteria, Eukaryotes, and Archaea. Bacteria are simple cells without a nucleus, whereas eukaryotes are more complex, house DNA in a nucleus, and have specialized organelles. Archaea, on the other hand, do not have a nucleus but share the same energy-processing properties as eukaryotes.

Among archaea, the Asgard superfamily, discovered in 2015, plays a key role in bridging the evolutionary gap between bacteria and eukaryotes, according to Live Science. ReportThese archaea were named after the realm of the gods in Norse mythology because they were discovered near a hydrothermal vent in the Arctic known as “Loki’s Castle.”

An immune protein with ancient origins

of study They looked at thousands of genomes from a wide variety of life forms and identified tens of thousands of virus defense systems. The researchers focused on two proteins present in all domains of life: viperin and argonaute. Viperin is part of the human innate immune system and fights viruses by preventing them from replicating inside infected cells. Argonaute, originally found in plants, stops viruses from replicating by breaking down their genetic material.

The genes for these proteins are surprisingly similar between archaea and eukaryotes, suggesting they arose from a common Asgardian ancestor, according to the findings published in Nature Communications. Critical catalytic sites in these proteins have remained largely unchanged for over two billion years, indicating they could be effective in defending against viral threats.