By Shane Rodgers
If you trace your ancestry back far enough, you may find relatives that are single-cell organisms.
They may not be the life of the barbeque, but these early lifeforms are believed to have played a big role in building human immunology.
Scientists at Kyoto University released a study this week showing evidence that human blood cells originated from single-celled ancestors that lived 700 million years ago.
In a statement, the university said the lineage and components of blood cells varied widely between species.
This was linked to the way animals evolved to protect themselves from infectious diseases.
“Thanks to advances in hematology and immunology, we now have detailed knowledge of the components and functions of both human and mouse blood cells,” the researchers said.
“However, their evolutionary history has remained largely unknown. This inspired a team of researchers at Kyoto University to investigate when and how blood cells originated, and how they diversified.”
The team developed a new analytic method to compare gene expression profiles across various cell lineages and animal species.
This allowed them to construct “phylogenetic trees” of cell lineages and estimate the evolutionary history of these lineages in animals.
From that they tracked a particular gene back to a single-celled ancestor that lived 700 million years ago.
This suggested that the first blood cells emerged around the same time as the onset of multicellular animals.
“This finding implies that early animals generated the first blood cells by repurposing genetic material inherited from single-celled progenitors,” the research report said.
“Ultimately, the scientists were able to reconstruct the family tree of blood cells over the 700-million-year span, revealing that evolutionary history has been imprinted in our bodies as differentiation pathways of these cells.
“This work illustrates that the blood and immune cells circulating in our bodies can be considered a successful extension of the legacy left to us by our single-celled predecessors.”
The researchers say the methods developed in this study could help unravel the evolutionary origins of diseases such as cancer, potentially leading to better treatments.
The findings are published in the latest Proceedings of the National Academy of Sciences of the United States of America journal.
The full report is here.
