Did Life on Earth Start Earlier Than We Believe?
Recent studies indicate that complex life on our planet started about 1.5 billion years sooner than earlier estimates suggested. Here we examine some leading hypotheses regarding the emergence of life.
For hundreds of years, humans have pondered over the beginnings of life on our planet, as well as the nature of existence itself—questioning primarily our origins and our future direction.
This query encompasses fundamental fields such as chemistry, biology, and physics, along with philosophy, psychology, and aspects of belief. Initially, early scholars were involved in various realms of inquiry. However, these foundational sciences are typically seen as more exact and straightforward to quantify compared to the others, which is why researchers often concentrate their efforts on them nowadays.
During the 19th century, French chemist Louis Pasteur showed that life invariably arises from pre-existing life. Whether they be plants, animals, or microorganisms, each reproduces within its own species.
And 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 rocks from Gabon suggesting that environmental conditions were conducive to life around 2.1 billion years ago.
Published in the journal
Precambrian Research
The research indicates that approximately over 2 billion years ago, the impact of two continental plates colliding generated a nutrient-abundant setting conducive to the development of complex 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 effort towards developing intricate life forms on our planet.
What alternative theories are there regarding the emergence of life on Earth?
Certain researchers have voiced skepticism regarding the recent discoveries and have demanded additional studies.
However, this research has reignited discussions regarding how complex life originated on our planet.
Throughout the last hundred years, scientists have created several dozen.
In this section, we examine several of the most common ones.
1. The Theory of Primeval Broth
The most prevalent 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 experimental validation. Harold Urey, an esteemed American chemist and Nobel laureate, along with Stanley Miller, a specialist in chemical evolution, constructed a rudimentary atmospheric environment within a lab setting. Inside this sealed apparatus, they combined water, methane, ammonia, and hydrogen gases and then sparked these mixtures using electrical discharges meant to mimic lightning’s role as an energy source.
Following several days, amino acids, which are the fundamental components of life, had developed.
2. The concept of cosmic life
A fascinating idea suggests that life on Earth initially originated beyond our planet, coming from outer space. This concept proposes that living organisms or essential building blocks required for life were transported here and took root on Earth.
This train of thought does not pinpoint precisely where life began or in what shape it came to our planet. However, the predominant notion is that life might have been delivered via a meteorite bearing microorganisms that struck Earth.
The initial advocates for this hypothesis included British astrophysicists Fred Hoyle and Chandra Wickramasinghe. During the 1970s, their research indicated that comets held sufficient organic material to potentially initiate life on planets like Earth.
3. The hypothesis of hydrothermal vents
The hydrothermal vent hypothesis proposes that life on Earth might have originated at the bottom of the oceans near these hydrothermal vents. Such vents are fissures in the seafloor from which emanate heated water saturated with minerals.
Michael Russell, a British geologist associated with the NASA Astrobiology Institute, suggested that alkaline hydrothermal vents emitting hydrogen, hydrogen sulfide, and methane might have offered suitable circumstances for the creation of basic organic compounds.
Even though the surroundings of hydrothermal vents are deemed harsh—with temperatures soaring up to 400°C (752°F)—there exist microorganisms 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 emergence of DNA and proteins, early life forms on Earth relied on 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 guidelines that facilitate the creation of proteins—these intricate molecules play a crucial role in nearly all functions within our bodies—and sustain life.
On the contrary, RNA fulfills these two crucial roles for living organisms: It holds genetic data and serves as a catalyst for vital chemical processes.
During the 1980s, chemists Thomas Cech and Sidney Altman uncovered ribozymes—RNA molecules possessing catalytic capabilities—and received a Nobel Prize for their discovery.
Scientists have suggested that early RNA molecules could self-replicate and facilitate basic chemical reactions before modern life forms emerged. Over time, these were supplanted by proteins, which serve as superior catalysts.
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 was originally believed. This finding was announced 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