From Mandy Meikle, Woolfords, West Lothian, UK
Colin Barras reminds us that our 30 trillion human cells are outnumbered by 39 trillion microbes – a more accurate representation than Thomas Luckey’s 1970 estimate that microbes outnumber human cells 10 to one (13 April, p 28). But over 80 per cent of the human cells that make up our bodies are erythrocytes, also known as red blood cells. These contain no nucleus or organelles, they are simply packed with haemoglobin, the molecule that transports oxygen and carbon dioxide to and from our tissues. Some might say that they are not true cells at all.
But why would anyone care about the ratio of human to non-human cells in our bodies? Consider how many DNA-filled human cells, carrying our genes and presumably contributing to our sense of self, are replicating in our bodies compared with non-human cells: just under 7 per cent. In the end, does it matter?
