Scientists Discover ‘Obelisks’: A New Class of Life Forms in the Human Microbiome

The Discovery of Obelisks: A New Class of Life Found in the Human Microbiome

In a finding that has redefined the boundaries of biological classification, scientists have identified a novel group of genetic elements residing within the human microbiome. Dubbed Obelisks, these simple, self-replicating RNA structures are so distinct from known life forms—including viruses and viroids—that researchers have described the discovery as ‘insane’ in its implications.

This groundbreaking research, which leveraged advanced metagenomic sequencing of global human health data, reveals that Obelisks are widespread, thriving primarily within the bacteria that colonize our mouths and guts. Their existence underscores how much remains unknown about the complex biological ecosystem we carry within us.

What Are Obelisks? Defining the Novel RNA Elements

For decades, the biological world has been broadly categorized into cellular life (bacteria, eukaryotes) and non-cellular life (viruses and viroids). Obelisks appear to occupy a unique space, challenging established definitions.

Obelisks are circular RNA elements that are significantly more complex than viroids but lack the protective protein shell (capsid) characteristic of viruses. They are extremely small, typically composed of around 1,000 nucleotides.

Key Characteristics of Obelisks:

• RNA-Based: They use RNA, not DNA, as their genetic material, forming a closed, circular loop.
• Self-Replicating: They possess the necessary genetic information to force their host cell (a bacterium) to replicate them.
• Novel Proteins: Crucially, Obelisks encode novel proteins, which the researchers named obulins. This feature distinguishes them from viroids, which do not encode any proteins.
• Host Dependency: They rely entirely on the machinery of their host bacteria for replication and survival.

This combination of features—being circular RNA, encoding proteins, and lacking a viral capsid—makes Obelisks a unique biological entity, potentially representing a new fundamental class of life or genetic element.

Prevalence and Location in the Human Body

The discovery was made by analyzing vast public datasets of genetic sequences derived from human gut and oral samples. This metagenomic sequencing allowed researchers to look beyond known organisms and identify previously overlooked genetic material.

The findings indicate that Obelisks are not rare curiosities but common inhabitants of the human ecosystem. Their prevalence varies significantly depending on the location:

• Oral Samples: Obelisks were detected in approximately 50% of the human oral samples analyzed globally.
• Gut Samples: They were found in roughly 7% of human gut samples.

Researchers noted that Obelisks are often found inside specific types of bacteria, such as Streptococcus sanguinis, a common bacterium found in the mouth. This suggests a highly specific relationship between the Obelisk and its bacterial host, where the Obelisk uses the bacterial cell as its factory.

“The sheer number of these things is mind-boggling. It’s a whole new kingdom of life that we didn’t know existed, right under our noses,” remarked one of the lead researchers, highlighting the surprise within the scientific community regarding their high prevalence.

Implications for Human Health and Future Research

As of 2025, the precise impact of Obelisks on human health remains unknown. Since they primarily infect bacteria, their effects are likely mediated through changes to the host microbe, which could, in turn, affect human physiology.

Potential Areas of Impact:

1. Microbiome Function: By hijacking bacterial machinery, Obelisks could alter the metabolism or function of key microbial species in the gut and mouth. Since the microbiome is crucial for digestion, immunity, and even neurological health, any disruption could be significant.
2. Disease Association: The presence of Obelisks in high concentrations in certain bacterial species warrants investigation into whether they are associated with specific diseases, particularly those related to oral health (like periodontal disease) or gut inflammation.
3. Evolutionary Biology: Obelisks offer a window into the earliest forms of life and genetic material, potentially shedding light on the evolutionary steps that led to complex viruses and cellular organisms.

This discovery reinforces the complexity of the human virome (the collection of viruses and virus-like elements in the body). Scientists are now focused on culturing the host bacteria to study the Obelisks in a controlled environment, which is the necessary next step to determine if they are pathogenic, symbiotic, or neutral to the human host.

Key Takeaways

This finding represents a major step in microbiology, revealing a previously hidden layer of complexity within the human body:

• New Entity: Obelisks are novel, circular RNA elements distinct from both viruses and viroids.
• Widespread: They are highly prevalent, found in up to 50% of oral samples globally.
• Bacterial Hosts: They infect and replicate within common bacteria found in the human mouth and gut.
• Unknown Impact: Their specific effects on human health are currently under investigation, but they likely influence the function of the host bacteria.

What’s Next

Future research will focus on isolating the obulins—the proteins encoded by Obelisks—to understand their function. Determining how these proteins interact with the bacterial host and, indirectly, with human cells is critical. The scientific community anticipates a rapid expansion of studies aimed at mapping the full diversity and distribution of Obelisks across different human populations and environments in the coming years.