The History of Viruses
Viruses: What Are They, and Where Did They Come From?
What Are Viruses? Are They Alive?
Virology evolved later than bacteriology and around the 19th century huge strides were made in the study of microbes (germs). The latin word virus mean “poisonous fluid” and this is just was they seemed to the first virologists in the beginning. Viruses are microscopic infectious agents that can only live and replicate inside the cells of a living host. ” They infect all types of living organisms, including plants, animals (yes, humans ), and many other life forms. Viruses are highly diverse, and even today, virologists and biologists struggle to classify them within the basic tree of life. They can cause various diseases, such as influenza (the flu) and human immunodeficiency virus (HIV).
Viruses are not considered living organisms because, even though they can grow and reproduce, they lack key cellular structures. For example, they don’t have mitochondria the famous "powerhouse of the cell" that helps produce energy for biological processes. They also don’t have enzymes that catalyze (kickstart) ATP production. ATP is an energy molecule that acts like a battery, storing and providing power when your body needs it most. Since viruses lack these essential parts, they are not like us they are simply genetic material hijacking cells to survive in other words Viruses don’t have metabolic processes, which is a big reason why they’re not considered alive. Living things (like humans, plants, and bacteria) break down food or chemicals to produce energy and build new materials that's metabolism. Viruses, on the other hand, don’t do any of that. They just sit around until they find a host cell to hijack. Instead of making their own energy or materials, they steal everything from the cell they infect.
Viruses Are Constantly Evolving But They Don't "Want" to Hurt Us
Viruses aren’t out to get us. They don’t "want" to kill their host they just want to survive and replicate. In fact, a virus that kills its host too quickly isn’t very successful because it loses the chance to spread.
Just like every other living thing (or in this case, near-living thing, viruses follow one simple rule:
Evolve or die.
As humans evolve, so do viruses. They constantly mutate, adapt, and find new ways to spread. It’s not personal—it’s just survival. Some viruses, like the flu, change so rapidly that new vaccines are needed every year. Others, like the common cold, have evolved to infect us but not kill us, allowing them to spread more effectively.
Evolution isn’t just part of viruses it’s part of all life. Everything that exists today, from bacteria to humans, has survived because it adapted. Viruses are no different.
Where Did Viruses Come From?
Virologists don’t have a clear, 100% proven answer to where these tiny invaders originated (we’re still figuring that out!), but there are some solid theories.
1. "The Escape Hypothesis" Did Viruses Start as Runaway Genes (Instructions)?
This theory suggests that viruses started as pieces of DNA or RNA that "escaped" from cells and learned how to infect others.
Imagine that inside your cells, there are tiny bits of genetic material that move around like puzzle pieces. Over time, some of these pieces figured out how to leave one cell and enter another, eventually evolving into viruses.
A good example is HIV:
It starts as a small piece of genetic material (RNA).
When it enters a host cell, it transforms into DNA so it can sneak into the cell’s instructions.
The host cell accidentally makes more copies of the virus, which then spread to other cells.
Scientists noticed that viruses like HIV act a lot like "jumping genes"pieces of DNA in our bodies that naturally move around. About 42% of human DNA comes from these jumping genes! If some of these genes gained extra abilities, they could have evolved into viruses.
In simple terms: Viruses may have started as "runaway" pieces of DNA or RNA that figured out how to jump from cell to cell and became infectious. (Bastard)
2."The Shrunken Cell Hypothesis" Did Viruses Get Lazy?
This theory suggests that viruses might have started as living organisms but became smaller and simpler over time because they started relying on other cells to do the work for them.
Imagine a person who once lived alone, cooked their own food, and handled everything themselves. Then, they move in with someone who takes care of them cooking, cleaning, and handling daily tasks. Over time, they forget how to be independent because they don’t need to anymore. Eventually, they become completely dependent on the other person to survive.
Viruses may have done the same thing:
A long time ago, they might have been fully independent organisms.
Over time, they started living off other cells and slowly lost the parts they didn’t need.
Now, they can’t survive or reproduce on their own—they must infect a host cell to make more viruses.
Some giant viruses, like Mimivirus, which are so big that scientists at first thought it was a tiny germ instead of a virus. Most viruses are super tiny, but this one is almost as big as bacteria and has way more instructions (genes) inside it.
Even though it's big and kinda special, it still can’t do anything on its own. It has to sneak into a living cell (like an amoeba) and take over to make more copies of itself. Basically, it's just a really big, lazy virus that might have traces of their old, complex selves, suggesting they might have been more like living organisms in the past before they "downsized" into viruses.
In simple terms: Viruses used to be independent, but they got smaller and lazier over time, relying completely on host cells to survive kind of like a once-independent person who now needs constant help. This is truly my least favorite hypothesis because I believe that life does not devolve.
3. "The Virus-First Hypothesis" Did Viruses Come Before Everything Else?
This theory suggests that viruses may have existed before any living cells and were the first things to copy themselves.
Imagine a time before life existed just tiny pieces of genetic material floating around. Some of these pieces figured out how to copy themselves, and over time, they got more advanced. Eventually, they helped create the first real cells by developing protective membranes and walls. (evolving)
Some scientists believe:
Viruses may have come before bacteria, animals, and plants.
The first life may have started with RNA, not DNA, because RNA can copy itself and help chemical reactions happen.
Some early RNA viruses might be the ancestors of today’s viruses.
Another interesting idea is that some big viruses may have helped create the first complex cells (like the ones in humans and animals). Some scientists think the nucleus in our cells (which holds DNA) might have actually started as an ancient virus that became part of the first cells instead of infecting them.
In simple terms: Viruses may not have come from cells at all they might have been the first replicating entities and even helped shape life as we know it!
Final Thoughts
Viruses are constantly evolving alongside us. They aren’t evil, they just follow the same rule of life as everything else: evolve or die. Some viruses are deadly, while others live in us harmlessly or even help us yes, there are helpful viruses too.
While scientists haven’t figured out exactly where they came from, the three main theories suggest that they either escaped from cells, shrunk down from bigger organisms, or existed before everything else.
One thing is for sure: Viruses are ancient, always changing, and they aren’t going anywhere anytime soon.! Evolve or die and remember to wash your hands. !
Citations ( So I do not get fined.)
Medical News Today. (n.d.). What are viruses? Medical News Today. Retrieved from https://www.medicalnewstoday.com/articles/158179
Annotation:
This article provides an overview of viruses, explaining their structure, reproduction, and effects on human health. It compares viruses to bacteria, discusses how they spread, and highlights different types of viral infections. Written for a general audience, the article is accessible and informative but lacks in-depth scientific analysis. It is a useful source for readers looking for a basic understanding of viruses without technical jargon.
Saylor Academy. (n.d.). The origins of viruses. Retrieved from https://iiab.me/modules/en-learnsaylor/course/theoriginsofviruses14398218.pdf
Annotation:
This document explores various hypotheses about the origins of viruses, including the progressive, regressive, and virus-first hypotheses. It provides a scientific perspective on how viruses may have evolved from genetic material or cellular ancestors. The resource is more detailed and research-oriented compared to general health articles. It is particularly useful for students and researchers interested in virology and evolutionary biology. However, because it is a course document, it may require prior knowledge of basic biology concepts to fully understand.