Our bodies are crawling with bacteria -- in your gut, mouth, skin, literally everywhere -- and in 2016, we learned it's incredibly beneficial.
Everyone's individual collection of bacteria is called their 'microbiome' and researchers are rapidly discovering how this bacteria is actually influencing everything from sleep to digestion to migraines and moods.
Pretty good for an organism that doesn't have a brain, huh?
The microbiome has been called the next big frontier in medicine and here's a summary of what we've learned this year alone.
It's related to weight loss
Obese people have less diverse microbiomes than healthy people and King's College London professor of Genetic Epidemiology Tim Spector told The Huffington Post Australia we were only beginning to understand why.
"This idea of 'eat less fatty foods, exercise more and you'll be fine' has failed," Spector told The Huffington Post Australia.
"Studies have clearly shown if you take microbes from fat people and put them into skinny mice, you can make them fatter. In a way, it's an infectious cause of obesity."
Bacteria could be used to alleviate psychiatric conditions
Research from scientists with New York City's Icahn School of Medicine at Mount Sinai found that altering the gut bacteria in a sick person might help alleviate psychiatric conditions.
"We're sort of like a walking vessel for these bacteria," MIT biological engineer Timothy Lu told HuffPost.
"There's a symbiotic relationship between the two sides, human and bacteria."
The study showed that when gut bacteria from depressed mice were transferred into healthy mice, there were changes to the myelin sheath in the brains of the healthy mice -- which affects the way nerves work. And they began to engage in social avoidance behaviours characteristic of depression.
It could be the reason why you get migraines
A study by the University of California San Diego Health Sciences found people who got migraines had significantly more microbes with the ability to break down nitrates in their mouth than the rest of the population.
Nitrates, which are found in cured meats, leafy vegetables and some cheeses, can have the effect of relaxing blood vessels, so those with more specific microbes can convert more quickly, creating a rush of blood vessel changes which in turn causes a migraine.
It probably affects sleep and jet lag
A Central Queensland University study is currently seeking to create a bacteria pill to treat jet lag, after a correlation was shown between gut health and sleep.
Research associate Dr Amy Reynolds told HuffPost Australia sleep was mysteriously linked to diabetes, obesity and other chronic health conditions and answers could be found in the microbiome.
"We're certainly hoping that if it does eventually show there is a relationship between sleep deprivation and the microbiome, it does open a new avenue to create clinical treatments for people who don't get enough sleep like shift workers or people who travel a lot."
Early use of antibiotics can affect the microbiome permenantly
A University of Helsinki study found early use of antibiotics in children could alter the natural population of microbes in a way that left them at higher risk of weight gain and asthma later in childhood.
Neurologist and author Dr David Perlmutter told HuffPost the correlation was concerning.
"Exposure to antibiotics dramatically changes the microbiome and is likely the reason we see increased risk of obesity in children in perfect correlation with the number of antibiotics they've had as children," Perlmutter said.
Bacteria could be used to make medicine
Biologists and medical engineers at the Massachusetts Institute of Technology are reprogramming gut bacteria to act as "living therapeutics" that can correct the metabolic dysfunctions underlying certain ailments.
"It's become really clear that the bacteria living in us and on us affect our bodies in a variety of different ways -- in ways that we never imagined," Dr Timothy Lu, a biological engineer at MIT, told The Huffington Post.
"The old idea that people are just people and that everything that happens in our bodies is dictated by human cells and DNA is probably not the complete picture."
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