Researchers from Kyoto University have discovered an evolutionary legacy in human blood cells dating back 700 million years, and that the modern immune system is a direct descendant of the simplest single-celled organisms that inhabited the Earth long ago.
An in-depth genetic analysis conducted by researchers from Kyoto University has revealed a surprising link between modern humans and ancient single-celled organisms.
The researchers concluded that immune cells not only evolved over time, but also retained defense mechanisms that originated long before the first animals appeared on Earth.
Science previously possessed a detailed understanding of the structure and function of modern blood cells, but their historical origins remained a perplexing mystery. To trace this long evolutionary path, researchers adopted a new analytical approach that compares gene expression patterns in various animal and single-celled organism species.
According to the researchers, phagocytic cells—immune cells responsible for engulfing harmful bacteria and cellular debris—showed a striking resemblance to ancient microorganisms. Genetic analysis of key markers also confirmed that these cells originated around the same time period as the first multicellular life forms began to appear on Earth.
The study added that early animals formed their first blood cells by directly recycling the genetic material of their single-celled ancestors. In later stages, mast cells differentiated from phagocytic cells, which in turn later contributed to the emergence of red blood cells and T cells, leading to the formation of the complex modern immune system.
The researchers noted that constructing a detailed evolutionary tree spanning approximately 700 million years opens new horizons in modern medicine. The team also plans to use the developed analytical method to conduct in-depth studies on the origins of cancer, which could contribute to the development of more advanced and precise treatments.
The full study will be published in the journal PNAS.
