Did Life on Earth Start Earlier Than We Believe?
Recent studies indicate that complex life on our planet emerged approximately 1.5 billion years sooner than formerly believed. Here we examine the leading hypotheses regarding the origins of life.
For hundreds of years, humans have pondered over the beginnings of life on Earth, our existence—essentially, our origins and destinies.
This query encompasses fundamental disciplines like chemistry, biology, and physics, as well as philosophy, psychology, and aspects of belief. Initially, early scholars were involved across various fields of inquiry. However, these core sciences are typically seen as more exact and straightforward to quantify compared to the others, which is why modern researchers often concentrate their efforts here.
During the 19th century, French chemist Louis Pasteur showed that life invariably arises from preexisting life. Whether they be plants, animals, or microorganisms, each reproduces within its own kind.
However, what about the initial living organism? If it emerged from non-living matter, when and how did this occur?
Life could potentially be far more ancient than our current understanding suggests.
A research conducted at Cardiff University in Wales, UK, indicates that complex life on our planet may have started approximately 1.5 billion years before what was initially believed. The team asserts they discovered indications within rock samples from Gabon suggesting favorable circumstances for life existed around 2.1 billion years ago.
Published in the journal Precambrian Research The research indicates that approximately over 2 billion years ago, the clash between two continental plates generated a fertile setting conducive to the development of intricate life forms.
This would have generated phosphorus and marine oxygen essential for the shift from unicellular organisms to more advanced forms of life.
However, their existence was brief — it seems these complex lifeforms were restricted to an inland sea and could not expand globally.
This study questions the long-held scientific agreement that complex animals first emerged 635 million years ago, proposing instead that there was an earlier, unsuccessful bid for more intricate forms of life on our planet.
What alternative theories are there regarding the emergence of life on Earth?
Several researchers have voiced skepticism regarding the recent discoveries and urged for additional studies.
However, this research has reignited discussions regarding how complex life developed on our planet.
Throughout the last hundred years, scientists have created several.
In this section, we examine several of the most common issues.
1. The Theory of Primeval Broth
A widely accepted hypothesis is the "primordial soup" theory, suggesting that life emerged from organic molecules in an early ocean.
British biologist Charles Darwin (1809-1882) was the pioneer who proposed that life might have originated in "a warm little pond."
It wasn’t until the 1950s that his hypothesis underwent experimentation. Harold Urey, an esteemed American chemist and Nobel laureate, along with Stanley Miller, a specialist in organic chemistry, replicated a primeval environment within a lab setting. Inside a sealed system, they combined water, methane, ammonia, and hydrogen gases, then initiated electrical discharges to mimic thunderstorms, thereby acting as a trigger for chemical reactions.
Following several days, amino acids, which are fundamental components of living organisms, had developed.
2. The concept of cosmic life
A fascinating theory suggests that life on Earth initially originated beyond our planet, specifically from outer space. This idea proposes that organisms, or at the very least, fundamental building blocks required for life, arrived on Earth from celestial sources.
This line of thinking does not pinpoint precisely where life began or in what shape it came to our planet. However, the prevailing notion suggests that it might have been delivered via a meteorite containing microorganisms that collided with Earth.
The initial supporters of this concept included British astrophysicists Fred Hoyle and Chandra Wickramasinghe. In the 1970s, their research indicated that comets could harbor sufficient organic material to potentially initiate life on planets like Earth.
3. The hypothesis of hydrothermal vents
The hypothesis of hydrothermal vents proposes that life on Earth might have originated at the bottom of the oceans near these vents. Hydrothermal vents are fissures in the seafloor from which geothermally heated water, rich in minerals, escapes.
Michael Russell, a British geologist affiliated with the NASA Astrobiology Institute, suggested that alkaline hydrothermal vents releasing hydrogen, hydrogen sulfide, and methane might have offered optimal circumstances for the creation of basic organic compounds.
Even though the surroundings of hydrothermal vents are deemed harsh—with temperatures reaching up to 400°C (752°F)—there are microbes that thrive in these settings through chemosynthesis.
Chemosynthesis is a biological process where microorganisms produce their sustenance. Instead of relying on light, they utilize energy derived from chemical reactions. This capability enables them to thrive in dim environments like the deep seabed.
4. The RNA world
The RNA world hypothesis suggests that prior to the presence of DNA and proteins, earthly life forms were centered around an adaptable molecule known as RNA (ribonucleic acid).
DNA (deoxyribonucleic acid) enables organisms to grow, endure, and replicate. These DNA sequences transform into messages or directives that facilitate the creation of proteins—complex molecules vital for nearly all functions within our bodies—and sustain life.
On the contrary, RNA fulfills these two vital roles for living organisms: it holds genetic data and serves as a catalyst for crucial chemical processes.
During the 1980s, chemists Thomas Cech and Sidney Altman uncovered ribozymes—RNA molecules possessing enzymatic capabilities—and as a result received a Nobel Prize.
Scientists have suggested that early life forms were likely based on RNA molecules capable of self-replicating and facilitating basic chemical reactions before giving way to contemporary organisms. Over time, proteins—which are more effective catalysts—supplanted these ancient RNA-based enzymes known as ribozymes.
Various hypotheses exist regarding the beginnings of life. However, these are the ones that have garnered the most focus within the scientific community.
Everyone—including the most recent findings from Cardiff University—emphasizes the intricacy of this question that still captivates and puzzles us in modern times.
Edited by: Zulfikar Abbany
Primary source:
A recent study from Cardiff University suggests that complex life on Earth emerged approximately 1.5 billion years sooner than previously believed, as reported on July 29, 2024. https://www.cardiff.ac.uk/news/view/2830233-complex-life-on-earth-began-around-1.5-billion-years-earlier-than-previously-thought,-new-study-claims
Author: Fernando Mateos Frühbeck