When you see an ant crawling around your kitchen, you probably don’t give much thought as to whether it’s an organism or not. It’s got six legs, two little antennae, and a body. Of course it’s an organism, right?
While ants are still considered organisms all on their own, the highly intricate social systems within an ant colony have led some scientists to believe that the ants actually behave like parts of a single organism rather than individual actors. This type of specialized and highly synergetic social structure has become known as a “superorganism”. The exact definition of this term has been widely debated, though, with some thinkers expanding its definition to include human beings as well as the entire biosphere of the planet Earth.
Ants, on the other hand, are the species most widely believed to constitute a superorganism, and the behaviors that they exhibit blur the lines between what is and what is not an individual. By examining the behaviors of ants and ant colonies, we can gain greater insight into what is meant by the term “superorganism” and the ways in which living things interact in general.
What Is a Superorganism?
The term “superorganism” is typically used to describe a unit of eusocial animals that behave in highly specialized ways and cannot survive on their own for extended periods of time. A eusocial animal is a type of animal that has a single reproductive female, or small reproductive group, and the non-reproductive members of the group all play a part in caring for the young. Some examples of eusocial animals are bees, ants, and wasps. In all three of these insects, you have a queen who gives birth to the young, and groups of soldiers and workers who are responsible for protecting and providing food for the colony.
Eusociality does not only exist among insects, however. There are several species of parasitic shrimp that live inside sponges and exhibit eusocial behavior. Several kinds of naked mole-rat could also be considered to be eusocial, as they will help raise young birthed by a single reproductive queen if resources get scarce. It has also been argued that humans are eusocial, since we often help each other raise young that are not directly ours.
This method of caring for young is not the only defining characteristic of a superorganism, though. High division of labor is another important feature. Individuals within a superorganism will often have highly specialized jobs that are aimed at forwarding the goals of the colony as a whole. Worker ants, for instance, will spend their entire lives caring for the young of the colony, when none of those young are actually theirs.
Some have argued that human beings are superorganisms due to the fact that we have other organisms living within our bodies. For example, there are a massive number of microbes living in your digestive tract that aid in digestion. Since that could be considered a specialized division of labor that furthers the greater good of the entire human being, a human might be considered a superorganism.
It has also been argued that the entire biosphere of the planet Earth could be considered a superorganism, since all living things interact in complex and specialized ways, and all rely on other living things for survival. Others have argued, however, that a planet is not the result of evolution, and so cannot be considered a superorganism.
How Are Ants Superorganisms?
While disputes about the exact definition of a superorganism persist, most scientists are in agreement that an ant colony is just about the best example of a superorganism out there. Beyond their eusociality and their highly specialized labor, ants exhibit some behaviors that show just how connected they really are to one another, and how committed they are to the survival of their colony.
First of all, the fact that there are “neuter” castes of an ant colony, groups of individuals that do not reproduce, presents a real problem for Darwin’s theory of evolution. The fact that ant workers are willing to care for young that are not their own, with no chance of being able to reproduce themselves, implies that natural selection happens on a colony level rather than just an individual level.
Ants, however, exhibit certain behaviors that make them seem more similar to cells in a single organism than individual actors. First of all, scientists believe that around 90% of ant communication is chemical-based. They release pheromones from exocrine glands located on different parts of their bodies to communicate certain messages, which is very similar to the way that cells secrete and absorb chemicals to communicate with one another.
For example, fire ants will send out “recruitment trails” when they find a large source of food that they cannot carry alone. The ant who found the food will send out a pheromone signal to the next ant in line, and this signal will be passed down the line until enough ants have been recruited to carry the food. This is also basically the way that all ants know where to walk, they simply follow the pheromone trail of the ant in front of them.
Ants will also use vibrations to communicate certain information to one another, but this is mostly to augment the pheromone signals and is not used as a primary method of communication.
Another great example of ants working as a single organism using pheromone signals is the way in which a colony will react to being attacked. In a study from 2015, researchers simulated attacks on 30 different ant colonies to see how they’d react. They found that ant colonies will often send scouts out to the periphery of the colony. When the researchers picked off some of these scouts, it seemed as if a chemical distress signal was sent out to the entire colony, and the whole colony recoiled into a tight, defensive position very quickly. However, when the researchers instead began taking out ants at the center of the colony, the ants would scatter away from the center and seek a safer location.
The results of these experiments suggest that an ant colony reacts to danger in a similar way to a human nervous system. When the ants recoiled from the threat from the outside, it was almost like a human pulling their hand off a hot surface and toward their body. When the ants scattered away from the center, it was almost like a human running out of a burning building.
These results suggest that ants have a high level of interconnectivity, and they support the superorganism view. These survival strategies, exhibited by every member of the colony at once, seem to be more like the knee-jerk reactions of a single organism than a group of individuals reacting on their own.
There’s no way that a scout on the one side of the colony could have known that a scout on the opposite side had been taken out without chemical signals moving throughout the entire colony rapidly. Similarly, there’s no way that you could realize that you burnt your hand if chemical signals did not move rapidly through the cells in your body. In this way, ant colonies behave more like single organisms than groups of individuals.
Are Human Societies Superorganisms?
Perhaps after learning about why ant colonies are considered superorganisms, you might be wondering if human societies could be considered superorganisms as well. After all, humans also communicate with one another with pheromones, could be considered eusocial, and have highly specialized jobs.
As our understanding of pheromone communication in humans advances, the case for human societies being considered superorganisms grows stronger and stronger. However, there still seem to be distinctions between the way humans interact with each other in a group versus how ant colonies work together.
Humans seem to operate in far more individualistic ways than ants do. Very seldom will you see conflict within an ant colony. For instance, you won’t often see an ant break away from a line in search of a new direction. Humans will often have dissenting opinions, and so it’s pretty clear that we don’t always act in the best interest of the “colony” but rather in our own individual self-interest.
Pheromone communication among humans also does not seem to be as important to humans as it is to ants. While we do partake in pheromone communication, other forms of communication seem to be more important to human beings, such as language and physiological expressions.
While human societies are not typically considered to be superorganisms, the definition of what exactly constitutes a superorganism is up for debate, as was stated at the beginning of this article. Do human societies exhibit some of the characteristics associated with superorganisms? Certainly. The line is blurry.