Bacteria Colonizes Asteroid Sample, Life's Left-Handed Mystery, and Zipf's Law in Languages
08:30 Share

Welcome to Discover Daily by Perplexity, an AI-generated show on tech, science and culture. I'm Alex. And I'm Sienna. Today we're exploring how language follows fascinating mathematical patterns that could tell us something fundamental about how our brains work. But first, let's look at some developments in space science and molecular biology that have scientists rethinking some basic assumptions.

Earth bacteria rapidly colonized samples from the asteroid Ryugu, surprising scientists who had implemented rigorous containment measures. The contamination occurred after the Japanese Hayabusa-2 spacecraft brought the samples back to Earth, despite using vacuum rooms and nitrogen-filled canisters for protection.

Within just weeks of atmospheric exposure, the bacterial population grew from 11 to 147 microbes, demonstrating the remarkable adaptability of Earth's organisms to extraterrestrial material. The colonization process was documented through careful observation.

Scientists discovered rod-shaped and filamentous structures characteristic of common soil bacteria, with the microbes showing a generation time of 5.2 days. These organisms, likely belonging to the Bacillus family, appeared on the rock surface, spread over time, and eventually died off.

What makes this particularly noteworthy is how Earth-based organisms managed to colonize material from an asteroid that's 4.5 billion years old.

While this presented challenges for studying the pristine samples, it demonstrated the remarkable ability of terrestrial microbes to adapt to and colonize extraterrestrial materials, even under strict contamination control measures. The research team's nano-X-ray scans confirmed the samples were initially microbe-free, showing the contamination occurred only after Earth's atmospheric exposure.

This rapid bacterial growth poses a challenge for scientists studying pristine space samples, as even the most rigorous containment protocols may not be enough to prevent microbial colonization. The findings also highlight the importance of developing more advanced containment methods for future missions, especially those aimed at detecting potential biological signatures on other worlds.

In other news that's making scientists reconsider some fundamental assumptions, a NASA-funded study has found that RNA shows no consistent preference for left- or right-handed amino acids. This discovery challenges what we thought we knew about how life developed its distinct molecular handedness.

You see, life on Earth exclusively uses left-handed amino acids to build proteins. Scientists long wondered if this preference came from RNA's chemical properties in life's earliest days.

But when researchers tested 15 different ribozyme combinations under conditions simulating early Earth, they found something unexpected. While individual ribozymes could show preferences for either left- or right-handed building blocks, there was no universal bias toward either form. This finding suggests that life's preference for left-handed molecules likely emerged through evolution rather than chemical predetermination.

It's particularly relevant for how we search for life beyond Earth, as we might need to broaden our criteria for what chemical signatures could indicate biological activity. Sienna, speaking of patterns in nature, I understand you've been looking into some fascinating mathematical regularities in language?

That's right, Alex. Scientists have found that human languages follow a remarkably precise mathematical pattern known as Zipf's Law. While it's often simplified as a single relationship, research shows that word frequencies actually follow a more complex three-segment structure, though generally the most frequent words appear more often than less frequent ones, following a power law distribution.

This pattern appears consistently across vastly different languages, from German to Russian, French to Italian. When plotted on a graph, it creates a distinctive curve that's similar, though not identical, across languages. What's particularly interesting is how this might reflect the way our brains process information. The consistency of this pattern suggests it's tied to fundamental aspects of human cognition.

Scientists think it emerges from a balance between two competing needs. Speakers want to use fewer, common words to communicate efficiently, while listeners need enough specific words to understand the message clearly.

This balancing act appears to be universal, transcending cultural and linguistic boundaries. Recent research has shown that this pattern isn't just about words either. Similar distributions show up in other complex systems, from the sizes of cities to the brightness of stars.

The dual processing theory in cognitive science helps explain this phenomenon. Our brains employ two distinct systems for language: a fast, intuitive system for common words and a slower, more deliberate system for less frequent ones. This cognitive architecture may explain why word frequencies follow such a consistent mathematical pattern across languages.

What makes this especially relevant now is how it's helping develop more natural language processing systems. By understanding these underlying patterns, developers can create AI systems that better mirror human communication patterns. For instance, chatbots and translation tools that account for Zipf's "law" tend to produce more natural-sounding language. The discovery also raises interesting questions about language evolution.

Did this pattern emerge because it's optimal for human cognition? Or did our brains adapt to process language in this way? Researchers are now investigating how the three-segment structure of word frequencies might reflect different aspects of language processing and evolution. These questions are driving new research in cognitive science and linguistics.

That's it for today. Thanks for tuning in and don't forget to subscribe on your favorite platform. For more info on anything we covered today, check out the links in our episode description. And don't forget, you can now access Perplexity's AI-powered knowledge base on the go with the mobile app, available for both Android and iOS. We also just released the Perplexity desktop app for macOS.

In other Perplexity news, we're excited to announce that Perplexity now offers a comprehensive one-stop shopping solution where you can both research and purchase products. The platform now features Buy with Pro, a first-of-its-kind AI commerce experience offering one-click checkout and free shipping for Pro users in the U.S.,

There's also an innovative snap to shop feature that lets you find products by simply taking a photo and an AI-powered discovery system that provides unbiased product recommendations with clear visual product cards. The platform integrates with Shopify to access up-to-date product information from businesses across the US, making online shopping easier and more efficient than ever.

We'll be back with more stories that matter. Until then, stay curious.