If you want to find out whether humans are considered to be unicellular or multicellular organisms then you’ve come to the right article.
As, in this article, I’ll share the answer to this question with you, and also after you’ve read the answer to the main question then I’ll also cover the answers to a few more closely related questions.
I hope you receive some new knowledge from this article!
Are Humans Unicellular Or Multicellular Organisms?
Humans are multicellular organisms just like all other animals and plants on earth.
To be multicellular is to consist of more than a single cell and have clusters of specialized cells dedicated to performing specific functions.
For instance, mammals have specialized brains, muscles, skin, blood, and nerve cells.
Virtually all multicellular organisms are eukaryotes.
This means every cell possesses its own clearly defined nucleus and a nuclear membrane for protecting the cell’s chromosomes.
Unicellular organisms include bacteria, protozoa, and some species of fungi and algae.
Unicellular prokaryotes do not have a distinct nucleus and lack the membrane-enveloped organelles (specialized cell structures) responsible for performing specific jobs inside cells.
Check out the informative video below if you want to see a video explanation of why humans are multicellular.
Why Are Humans Not Unicellular Organisms?
Humans are multicellular organisms containing between 37 and 40 trillion different cells.
However, it wasn’t always this way.
The first multicellular organisms appeared about 1 billion years ago but the earliest humans date back a mere 15 million years.
Just as homo sapiens evolved from the first multicellular organisms, the first multicellular organisms evolved from the first unicellular organisms.
So you could say that ‘humans’ have been both unicellular and multicellular just at different points in our evolution.
There are still unanswered questions about why and how human beings evolved to contain so many cells.
But Darwin’s Theory of Evolution gives us a convincing explanation.
Naturally occurring cellular mutations became more or less common depending on how beneficial they were to an organism’s continued survival.
Over many millions of years, mutations capable of facilitating multicellular development were the most useful and became the most common.
Environmental pressures favored the more complex organisms.
So humans continued to become more and more complex until they eventually developed groups of highly specialized cellular tissues (like, for example, a heart, stomach, and brain).
Why Are Humans Considered Multicellular Organisms?
Humans are considered multicellular organisms because they are an extremely complex species made up of many trillions of cells.
This is different from a unicellular organism which contains just one cell.
Human cells have evolved to become highly specialized and groups of similar cells cluster together to perform specific functions.
It’s why our brain cells are different from the cells in our lungs which are, themselves, different from the cells in our stomach and heart.
Can a Human Survive As a Single Cell?
Human beings have evolved so far beyond the unicellular origins that we now have little in common with those early ancestors.
Many of our cells have developed into interdependent tissues and can no longer function individually.
After millions of years of genetic development, we’re now far too complex for a unicellular existence.
In a unicellular organism, a single cell performs all necessary functions.
But multicellular humans have trillions of different cells organized into ‘task’ groups to ensure specialization at every level.
All of these groups are interconnected and damaging one can have serious consequences for the others.
How Are Unicellular Organisms Helpful to Humans?
Not all bacteria cause sickness or disease.
Some types of unicellular bacteria actively benefit humans.
These so-called “good bacteria” exist in large numbers inside our bodies helping to perform essential functions like digestion, immune system defense, and maintaining skin and eyebrow health.
But the human stomach is where these unicellular organisms make the biggest impact.
Unicellular gut bacteria has been with us a long time and may even have influenced our evolution.
Today, these gut bacteria are locked in a symbiotic relationship with the human body, using our stomach’s warmth and moisture to propagate and, in return, helping us digest a greater variety of foods, regulating our blood ammonia levels, strengthening our immune responses and fighting off everything from yeast infections to cancers.
Yeast is one of the most commonly encountered examples of unicellular fungi.
It’s used by brewers to convert sugars into alcohol and by bakers to produce the carbon dioxide needed to raise bread.
How Are Unicellular Organisms Harmful to Humans?
Humans may have developed a mutually beneficial relationship with our gut bacteria but this doesn’t mean all unicellular organisms are harmless.
Environmental bacteria picked up from outside our bodies can cause serious sickness if it isn’t neutralized via processes like hand washing, cooking meat thoroughly, and using antibiotics correctly.
Some unicellular bacteria cause digestive dysfunction and discomfort.
Others lead to strep throat, acne, or much more serious bacterial infections like tuberculosis, tetanus, anthrax, or cholera.
It depends on the specific genetic makeup of the unicellular organism in question.
What Are the Differences between Unicellular and Multicellular Organisms?
Below I’ll cover the obvious differences between unicellular and multicellular organisms.
The differences are:
- Unicellular organisms are made up of just one cell but multicellular organisms are made up of many cells.
- The functions of a unicellular organism are carried out by a single cell spread across many different tasks. However, multicellular organisms form clusters of highly specialized tissue (cell groups) to perform many different functions.
- Unicellular organisms are entirely exposed to their environment but multicellular organisms can create outward-facing tissues (like the skin) with strong defensive capabilities to protect vulnerable cells.
- While not impossible, it is extremely rare for multicellular organisms to also be prokaryotes. Virtually all multicellular organisms are eukaryotes (with a handful of exceptions). Unicellular organisms may be eukaryotic or prokaryotic depending on the species.
- Unicellular organisms tend to have very short lives, especially in comparison with multicellular organisms that can live for many years.
- Damage to a unicellular organism is almost always fatal. Multicellular organisms can damage and lose many cells before the organism reaches a critical condition. Given enough time, a multicellular organism can repair or replace most damaged cells.
- Unicellular organisms are not limited to a static or stable shape like, for example, a wriggly, pulsating shape of an amoeba. Multicellular organisms, on the other hand, have a fixed body shape with a protective barrier on the outside.
- Unicellular organisms are necessary simply because they don’t have the capacity for complexity. But multicellular organisms have access to trillions of cells and can apply them in endless combinations and configurations.
Check out the video below if you want to see a video explanation of the differences between unicellular and multicellular organisms.
