The human body: a microscopic marvel or a borrowed vessel? Prepare to be amazed as we delve into the captivating world of microbes and their profound impact on our existence. But first, a bold statement: we are not alone in our bodies! And no, we're not talking about alien invasions.
Around 1683, Antonie van Leeuwenhoek, a Dutch scientist, made a groundbreaking discovery. He scraped plaque from his teeth and, through a homemade microscope, observed a bustling world of 'animalcules'—what we now know as bacteria. This marked the first recorded observation of bacteria by humanity.
Van Leeuwenhoek's fascination with the miniature realm led him to repeat this experiment on his family and friends, revealing a thriving microbial community in the oral cavities of those with questionable oral hygiene. But here's where it gets controversial—these microbes weren't just living on us; they were living in us!
Fast forward to the 20th century, and scientist Thomas Luckey estimated the ratio of bacterial cells to human cells in the colon as 10:1. This figure was widely accepted for decades until a 2016 study revised it to a more realistic 1.3:1. But even this reduced estimate shows that, on average, we are outnumbered by microbial cells in our bodies.
So, are these microbes just hitchhikers? Not quite. Associate Professor Andrea Stringer highlights their crucial role in training our immune system, aiding digestion, and synthesizing essential vitamins. Functionally, they are indeed part of us.
This interdependence extends to all animal life, as demonstrated by 'germ-free' animals raised in sterile environments, which often suffer from poor health. Moreover, the connection between microbes and mental health is becoming increasingly apparent, with studies showing a link between the gut microbiome and psychiatric conditions like anxiety and depression.
But how human is our DNA? Well, we share a staggering 98-99% of our DNA with other primates, and around 80-90% with most other mammals. Even more surprisingly, we share a significant portion of our DNA with non-animals, such as plants and yeast. Some of our genes may even have been acquired from microbes through horizontal gene transfer.
As we explore the sub-atomic realm, the boundaries between human and non-human blur even further. The average human cell contains trillions of atoms, each with a nucleus that accounts for over 99% of its mass. But the true nature of atoms is far more complex, with electrons occupying a 'cloud' of potential locations, making the concept of 'empty space' within atoms a matter of debate.
So, what makes us, us? It's a question that delves into the heart of our identity. As geneticist Dr. Vicki Jackson points out, while our genes are important, we are far more than just our DNA. Our health, behavior, and personality are shaped by the interplay of genes, environment, lifestyle, and experiences. Consciousness, that elusive essence of 'us', remains a mystery, arising from the intricate electrical transmission between neurons in the brain.
In the end, the human body is a complex tapestry of microscopic life, genetic code, and sub-atomic particles. It's a borrowed vessel, a temporary home for a multitude of organisms, each playing its part in the grand symphony of life. And perhaps, in this intricate dance, the boundaries between self and other are not so clear after all.
