The mushroom networks of ‘The Last of Us’ exist in real life

In the second chapter of The Last of Us we see how the infected communicate with each other, so that if someone hurts one, all the others flock to the place of the attack, even if they are far away. It is said that, once they are infected by the Cordyceps fungus, they develop the ability to relate from a distance, as if they were linked by an invisible thread. And this is something that has its scientific basis, since fungal networks exist in reality.

However, while in The Last of Us we see them as something dangerous, in reality the mushroom networks are beneficial for the environment. At least some of them. Known as mycorrhizal networks, they act as highways that carry nutrients underground over large tracts of land. They exchange these nutrients among themselves, but also with the vegetation. In addition, they help to modify the soil, making it more fertile, and serve as a carbon store to clean the atmosphere.

At the other extreme we find some fungi that manage to grow and communicate underground, to spread their infection to points far away from where the rest of the fungus emerges. Therefore, these mushroom networks have their good and bad parts. In The Last of Us we have already seen the bad, now we have to wait and see if there is something good. They may surprise us.

Fungal structures that we should know

A fungus consists of several parts; but, to be able to talk about fungal networks, we must know only some of them.

To begin with, the fruiting body is what we sometimes know as the fungus or mushroom, since it is usually what emerges from the Earth and we can see with the naked eye. It is the reproductive part, since it has spore-forming structures, which vary from one species to another. It should be noted that the fruiting body does not always emerge from the Earth. In some species it can also be underground, although the functions are the same.

On the other hand, everything that is not the reproductive part of the fungus is known as the vegetative body. In it, there are two important and closely related structures. On the one hand, filaments originate from the spores, known as hyphae and made up of a network of elongated and cylindrical cells surrounded by a cell wall made of chitin. In turn, these hyphae clump together in masses similar to plant roots, known as mycelia. Both are important concepts, as they are closely related to the mushroom networks that are mentioned in The Last of Us.

The two faces of mushroom networks

In reality, contrary to what the epidemiologist interviewed in the first chapter of The Last of Us points out, no fungus seeks to control or kill anyone. They simply survive, like other living beings. Sometimes, to do this, they must parasitize others, while at other times, as a side effect of their own survival, they find them useful. We see that there are benefits and harms, but neither would it be appropriate to talk about good or bad mushroom networks.

To begin with, in mycorrhizal fungal networks, plant roots and fungal mycelia connect with each other, increasing efficiency in transporting both nutrients and water. In fact, it has been studied that in periods of drought, these underground roads are essential for plants to take advantage of the little water that reaches them and share it optimally. In addition, the fungus can exchange specific nutrients with plants. For example, it is known that provide 80% of the phosphorus to their host plants.

This makes them very beneficial. But it is not the only advantage. And it is that, since the fungi need carbon to build their networks under the ground, they are a sink of carbon dioxide that goes unnoticed. Much is made of the role of trees in sequestering carbon from the atmosphere. However, fungal networks also play a very important role in this regard.

Charlotte Roy (Wikimedia Commons)

The other side of the coin is that of other fungal networks that merely spread underground, without interacting with plants.

For example, they can carry nutrients to a fruiting body located miles away. Additionally, wood rotting fungi can use these communication pathways to find new places to grow. This makes it very difficult to remove them. For example, beyond the trunks of the trees, if we have a piece of furniture or a rotten wooden object, no matter how much we clean it, the network of fungi may have already spread under the ground and have looked for other wood to rot. For this reason, some fungi, such as Serpula lacrymans and Meruliporia incrassata, have become a serious problem in households in Europe and the United States, respectively.

An underground world to discover, beyond ‘The Last of Us’

Thanks to The Last of Us, many people have heard of mushroom networks for the first time. However, there are scientists who have been trying to raise awareness about its existence and its importance for a long time.

In fact, going back to mycorrhizal fungal networks, there is a project Promoted by the Society for the Protection of Underground Networks (SPUN) and advised by the conservationist Jane Goodall, whose objective is to map, understand and protect these underground highways. It involves scientists from the Netherlands, Canada, the United States, France, Germany and the United Kingdom. However, sampling for research is being carried out in other parts of the world. In fact, it started last year in Patagonia. There are still a few months left until it ends, since 18 months are scheduled from its beginning. At that time, soil samples must be taken to catalog these largely unknown fungal networks.

And it is that the mushroom networks are not only the Facebook of the infected of The Last of Us. Outside of fiction they have a multitude of virtues and defects. Real as life itself.

View Hide summary