A team at Kyoto University developed a new method to compare gene expression profiles across cell lineages and species, including unicellular organisms.
Macrophages showed the most similarity to unicellular organisms, suggesting early blood cells were macrophage-like.
The gene FOS, common in blood cells across species, was traced to a single-celled ancestor 700 million years ago, implying blood cells emerged with multicellular animals.
The analysis reconstructed a family tree: mast cells branched from macrophages, then T cells and red blood cells from mast cells, and B cells from macrophages after mast cell segregation.
Researchers state that vertebrate blood cell differentiation pathways reflect 700 million years of evolutionary history.
The method may help uncover evolutionary origins of diseases like cancer, aiding understanding and treatment development.