Your Blood May Carry a 700-Million-Year-Old Secret

Kyoto University researchers say blood and immune cells may trace back about 700 million years to early multicellular life.

Comparing gene activity across species, they found macrophage-like cells were likely the earliest blood-cell type.

The study links the ancient FOS gene to that lineage, with later evolution producing mast cells, T cells, B cells, and red blood cells.

The findings suggest modern vertebrate blood still preserves genetic traces from single-celled ancestors.