Think back to the last time you took a stroll through a dense, overgrown forest? You probably saw all different varieties of plant life – vines, bushes, moss, trees, and a healthy number of fallen logs. A forest is one of the best places to see the circle of life at its most beautiful, which means life balanced with death.
When things die in nature, they begin to break down and decompose, which is where fungi come into play. Fungi belong to a kingdom all their own, just like animals, plants, monera (bacteria), and protista (algae). Fungus are eukaryotic organisms that absorb nutrients from other organic matter. Therefore, when a tree falls or an animal dies, fungi are typically the first on the scene to begin the natural process of decomposition.
Upon seeing a mushroom, most people would immediately see it as a vegetative organism, closely related to plants. However, as recent research has shown, mushroom are in fact more closely related to humans that plants!
The Strange History of Life
Humans have always been fascinated with life in all its forms, but thousands of years ago, we only classified life on Earth into two categories – plants and animals. We can thank Aristotle for that, and he further divided animals into those with and without blood, as well as those in the land, sea, and air. That rudimentary system remained in place until the 1600s. In the 18th century, Carolus Linnaeus divided life into the kingdoms of animals and plants, and then further began dividing those into different genera and species, which is why we have the two-part naming system in science (Homo sapiens, for example; Homo is the genus and sapiens is the species.
It wasn’t until the middle of the 19th century that single-celled organisms were finally given their due as a separate kingdom of life (Protista). Seventy years later, single-celled organisms were divided into eukaryotes and prokaryotes, so bacteria became the 4th kingdom of life. Although fungi had been recognized as a unique part of the animal kingdom, it was not separated into its own kingdom until 1969. This five-kingdom system remains the most widely accepted format for classifying life on Earth.
All classifications of life until recently, including the expansion from two kingdoms to five, were based on physical observations of how things looked, even under a microscope. This is how the closeness and relationships between species, genera, classes, orders and kingdoms were decided. Given that fact, it comes as no surprise that most people classified fungi as plants for so long. The similarity in appearance is pretty clear, like little red and white trees…
However, thanks to modern technology, the analysis of genetic relationships between species and organisms is now possible, and it shows something very interesting. By examining the genes of different species, both animal and fungi, the mutational changes can be observed, and genealogical relationships can be determined that go back millions of years.
As it turns out, animals and fungi share a common ancestor, and branched away from plants at some point about 1.1 billion years ago. It was only later that animals and fungi separated on the genealogical tree of life, making mushrooms more closely related to humans than plants. Most likely, this common ancestor was a single-celled organism that had sperm-like characteristics (like an animal) and then a later developmental stage with a stronger cell wall (fungi).
The Connection Between Mushrooms and Men
Haven’t you ever noticed that eating a perfectly cooked portobello mushroom is closer to eating meat than a salad? Well, that isn’t exactly a scientific explanation of the connection, but this new revelation of our link to fungi does shed some light on the trouble we have with fungal infections in the body. It is notoriously difficult to treat fungal infections, rather than viral and bacterial pathogens, and this close genetic link may explain why.
Fungi and animals are both eukaryotes, with nuclei and other complex structures inside their cell membranes, whereas bacteria are much simpler – composed of just genetic material and a cell wall. Therefore, when we try to fight a bacterial infection, the body is able to easily differentiate and neutralize the threat. Unfortunately, with fungal infections, the body sometimes thinks that the infection is…. us. Drugs that are synthesized to fight the cells of fungal infections may also attack healthy human cells, as there is very little structural difference.
This is certainly a problem for medical treatment, but it’s also a fascinating bit of news about our common ancestors. Next time you ask for mushrooms on your pizza, remember that it’s slightly closer to cannibalism than just ordering onions!