We think of all microbes as more or less the same species with some variations here and there, when in reality, it’s the oldest and most diverse subgroup of life on Earth. Their contribution to the ecosystem isn’t as apparent as other forms of life – as we can’t see them – though under the surface, microbial species are crucial for many processes that make life on Earth possible; from growing our food to keeping our gut functioning.
The process of memory formation and retrieval is one of the greatest mysteries in neuroscience, though we’ve certainly made some progress in the past few years. We now know that memory isn’t handled by a single region of the brain like many other functions, but by a network of neurons in different regions interacting with each other in a variety of ways. We also know that the interaction is handled by a protein called Arc, which allows neurons to interact with each other and encode information that could be retrieved later.
What we don’t quite understand, however, is how the Arc protein evolved to do that, or even where it came from. The only clue we have is retroviruses, as it’s almost identical to the Gag protein found in retroviruses like HIV. It uses the same mechanism to encode information in infected cells as Arc, leading some scientists to believe that memory is simply an accidental by-product of an ancient viral outbreak among our ancestors.
9. Hydrothermal Vents
Hydrothermal vents are openings found in the deepest parts of the ocean, often near volcanoes or other places with high tectonic activity. Much like hot springs on land, these vents continuously discharge hot water and a bunch of other minerals, except we know very little about them.
As there’s no sunlight at those depths, hydrothermal vents are home to a diverse, bizarre group of animals not found anywhere else on Earth. They rely on a class of microbes that can oxidize otherwise-harmful geothermal chemicals like hydrogen sulfide and turn them into consumable organic matter like sugars – a process known as chemosynthesis. These are some of the only organisms we know of that can stay alive at temperatures exceeding 80 degrees Celsius (or 176 Fahrenheit) – also called hyperthermophiles – though it’s unclear how, or even why, they evolved to do that.
8. The Neolithic Revolution
Epidemic outbreaks and infectious diseases have become such an inherent part of our civilization that it’s hard to think of a time when they were practically non-existent. Yet, for most of our history up until about 12,500 years ago – when the first farming settlements emerged – human beings survived without the scourge of devastating diseases like the Black Plague, HIV/AIDS, Ebola, malaria, and countless others.
This proliferation of diversity among harmful pathogens was a direct result of human beings settling down into farming societies, alongside what was arguably an entirely new type of life form in Earth’s history – livestock. As we started breeding and domesticating animals, many pathogens that were previously only found in the wild – including species of viruses, fungi, parasites, bacteria and other harmful microbes – could finally jump to humans, evolve, and multiply.
Many species of microbes live on the very edge of our understanding of mortality. While other theoretically-immortal species exist – like a jellyfish species that could theoretically reproduce forever – they usually succumb to disease or other signs of just being too old. The only species that have been observed to live so long that they could be considered immortal are actually microscopic, though they’re not counted because they’re not technically ‘alive’.
One bacteria species found in the South Pacific was found to have survived for over 100 million years, though in a dormant – or deactivated – state. The scientists were able to feed and reactivate them, though they couldn’t figure out how the microbes had managed to stay alive for so long, or even if they were really ‘alive’.
It’s especially surprising given the lack of nutrients in that particular region, completely redefining what we know about the evolution of microbes, and mortality. While other microbe species have been found to stay alive for mind-boggling periods of time, this is by far the oldest of them all.
6. The Secret World Of Soil
As anyone with even a passing interest in gardening would tell you, the soil is full of beneficial microbes that assist in plant growth in various ways. It’s one of the most diverse ecosystems we know of – one teaspoon of soil taken from the wild can be home to as many as 50,000 microbial species.
Identifying all of those species, however, is next to impossible. We know almost nothing about the origins of all the microbes that live in the soil, let alone how they interact with each other, or even what exactly all of them do. The biggest problem is that they’re difficult to study outside the environment – the microbes only grow in the specific conditions of real-life soil, and taking a sample out for study severs its connection to the ecosystem..
Archaea make up one of the three fundamental branches of life – along with bacteria and eukaryotes – though there’s still a lot we don’t know about them. They’re single-celled creatures without nuclei similar to bacteria – also called prokaryotes – though that’s really where the similarities end. Archaeal species are different from bacteria – or really every other species we know of – in almost every other way. According to one theory, it might even be the mysterious missing link between simple and complex creatures in the course of our evolution.
Archaea inhabit some of the most extreme environments on the planet, like acid lakes and deep-sea hydrothermal vents. Like the microbes found in soil, archaeal species don’t do too well in the lab, either, making studying them rather difficult. We still don’t know the cellular processes that drive their growth and reproduction, or even how many archaeal species there are out there.
4. Giant Viruses
When the first giant virus was discovered in Bradford, England back in 1992, local researchers mistook it for a class of bacteria due to its abnormally-large size. At 750 nanometers (nm), it’s larger than all other virus species we know of, as well as quite a few bacteria and archaea species. For comparison, the common cold virus is barely 30nm in size.
The discovery fundamentally changed how we thought about viruses, and since then, many other giant virus species have been found, including a 30,000-year-old specimen found in the Siberian permafrost. As we studied them, we realized that giant viruses aren’t just starkly different from other microbes, but also other virus species. Usually, viral infections rely on the host’s cellular translation infrastructure to replicate. Giant viruses, however, bring their own translational tools, making them more similar – at least in this specific aspect – to cellular creatures than viruses.
3. The Mysterious Microbes Inside Us
We know that our bodies are home to many different species of microbes – from tiny mites living on our eyelashes to the entire ecosystem of bacteria found inside our guts. According to one study, the ratio of microbial cells to human cells may be as high as 1.3 to 1, which means that there are more foreign organisms living inside us than, well, us.
More worryingly, we know absolutely nothing about most of them, or what they do. A team of researchers at Stanford found that the DNA of around 99% of all microbes found inside an average human body doesn’t match any other known life form in our genetic databases; they might as well be alien forms of life.
2. The Social Life Of Viruses
Most viruses that infect humans are simple creatures made up of genetic material encased inside a protein shell. Within that general definition, however, virus species come in all shapes and sizes, each with their own mechanisms of infecting their hosts. Viruses are neither alive nor dead, and completely rely on their hosts for activation and replication, as they lack any cellular infrastructure of their own.
Despite their seeming primitive nature, viruses are social creatures with sophisticated means of communication. In one study done on a class of viruses that infect bacteria, bacteriophages, researchers found that they’re not only capable of communicating with each other, but also tailoring their messages according to the situation in real-time. Whenever they infect a new cell, the phages release a specific protein that lets everyone else know that a cell has been taken. Once enough of those proteins are in the system, they can stop the infection and start focusing the ones they’ve already conquered.
In a report released in 2019, the WHO designated antimicrobial resistance as one of the top 10 public health crises facing the world today. While it’s by no means a new phenomenon – pathogen populations develop defenses against medicine almost as soon as they’re exposed – in recent years, many factors have come together to turn it into a major problem.
The biggest is over-prescription, as doctors around the world are increasingly using medicines for infections that are just not required. According to a Pew study, 1 out of 3 antibiotics prescribed to outpatients – or patients who don’t require overnight hospitalization – are unnecessary. Moreover, antibiotics are now increasingly manufactured in countries with lax industrial safety regulations, like India and China, making them laboratories for super-varieties of bacteria and viruses that are getting stronger and deadlier as we speak.
As a result, in the US alone, there are now more than two million cases of infections from resistant strains, and over 23,000 deaths. That number might be as high as 700,000 around the world, which is only a bit higher than the total number of HIV/AIDS-related deaths recorded in 2020.