You are more Bacteria than Human

“The human we see in the mirror is made up of more microbes than human,” says Lita Proctor, leader of the Human Microbiome Project, which has shown that there are ten times more microbial cells in our body than cells that have our own DNA. Every part of us, from our skin to our stomachs, is composed of over 100 trillion cells from 500 different bacterial species, not to mention viruses and fungi. However, although the microbes vastly outnumber human cells, they’re much smaller and so they only make up between 1–3% of our body’s total mass. Finding out we’re walking petri dishes might make you squirm, but it’s actually a pretty great thing—microbes play a vital role in supporting and maintaining the human body. Among other functions, bacteria produce chemicals to help our digestive system process our food and thus harness energy and nutrients, and intestinal bacteria help keep our immune system primed to fight infections. The findings also show that the microbes provide more unique protein-coding genes than humans cells do—the human microbiome contributes 8 million, while the human genome only contributes 22,000. Basically, we’re all human-bacteria hybrids.

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