Picture this: an advanced race of aliens come across a human being for the very first time. What would they see? How would they describe us?
No doubt they would study not just our physical appearance but also our genetic makeup to see what’s makes us tick.
They would observe a hybrid organism that is a combination of mammal fused together with ancient microbes in symbiosis.
They would see that the mammalian genes have leveraged the power of ancient microbes to become far more sophisticated than would have been possible alone.
They might even call us a ‘superorganism’…
A massive shift in our understanding of human biology began to happen around the turn of the 21st century. Scientists were able for the first time to map the entire human genome.
Our genome is made up of DNA, our genetic material, which is essentially the programming for how our bodies are put together and function from moment to moment.
Scientists can now see that there is more than just human DNA in the mix, there is also microbial DNA.
Before this big shift we were aware of microbes living on our skin and inside us. However, the surprise was the sheer quantity and variety.
But how do you measure the quantity and relative importance of human versus microbe within this superorganism? If you do it by weight or physical size, the human part is much bigger and clearly dominates.
However if you measure by number of cells and genetic material, the microbe part is much bigger and appears to dominate. Current estimates are that microbe genes outnumber human genes by 3:1 or as much as 10:1. Remember that genes are what make an organism tick.
Could it be that humans and microbes just happen to exist next to each other, neighbours but not exactly friends? How do we know the relationship is any closer than that?
Surely humans and microbes aren’t fused together in some kind of sinister Frankenstein creation?
As we learned more from scientific studies over the last decade, it gradually became clear that these microbes are not just passengers hitching a ride, but that they are fundamental to how our body functions. (By the way, we’re not unique, this is also applies to many other organisms on Earth.)
We are the result of millions of years of evolving together in symbiosis with microbes. It appears that we don’t actually have enough human DNA to perform all the functions our body performs, but are dependent on the microbial genes.
In other words we human beings are incomplete without microbes!
Breastfeeding is great illustration of this. One of the principal ingredients in human breast milk are HMO’s (human milk oligosaccharides). The interesting thing about HMO’s is that our babies cannot actually digest them. Instead they are food for the baby’s microbes!
A human baby picks up friendly microbes from its mother while passing through the vagina during delivery. These microbes are fundamental to how the baby develops during it’s all-important first few years.
So to support the microbes, mother’s milk contains large amounts of food just for them. It’s a sophisticated mix of the right food to support the right bacteria and to fend off harmful bacteria from the vulnerable little newborn.
Mother’s breast milk also contains even more friendly bacteria to top up the ones just seeded into the baby by the vaginal delivery.
The alien race observing us would see that microbes are so fundamental to the human superorganism that they are built into our reproductive process. Friendly bacteria are planted into the baby and then carefully looked after, from the very first moment we’re born into this world.
There’s no question that this is a big change in how we look at the human species. The worldwide scientific community is still getting their collective heads around it. The medical community is a way behind, as they have to wait for things to be carefully established in scientific studies before adopting new medical practices.
It’s also clear that this new perspective challenges some dearly-held beliefs, for example:
Old Belief: We are a single independent organism, a human.
Truth: We are actually a hybrid, a holobiont, a superorganism.
Old Belief: Bacteria and other microbes should be wiped out as they make us ill.
Truth: Many bacteria can make us ill, and horribly so, but many – if not more – are helpful and necessary to us.
It also raises some important questions:
-What exactly are we, as humans?
-What happens if we remove the ancient microbes from our bodies, in the pursuit of cleanliness?
During the 20th century we waged war on bacteria. Those of us in the West can now enjoy life without many of the nastiest infectious diseases that plagued our ancestors, like leprosy, smallpox, syphilis, cholera, polio and tuberculosis.
However infectious diseases have been replaced by a ton of new ‘non-communicable diseases’ (NCD’s). Instead of killing us horribly and quickly like infectious diseases used to do, they kill us horribly and slowly. Here’s just a few of the most common NCD’s:
What’s the connection between our microbiome and these NCD’s? We now know that our old friends, the bacteria, play a fundamental role in how our immune system – and indeed our whole body – works.
If we don’t have enough of our old friends, we get sick and fat, and our brains malfunction.
What is my microbiome: it’s the name for the microscopic organisms (and their DNA) that live inside us.
Why does it matter? The old assumption was that microbes inside us were just passengers and, at most, helped to keep our poo smooth!
But now we know they are actually fundamental to how our bodies work. Without them, our bodies break down and life is miserable!