Recent studies indicate that complex life on our planet emerged approximately 1.5 billion years sooner than initially believed. Here, we examine the leading hypotheses regarding the origins of life.
For hundreds of years, humans have pondered over the beginning of life on Earth, our existence—essentially, our origins and our future direction.
This query encompasses fundamental disciplines such as chemistry, biology, and physics, along with philosophy, psychology, and aspects of belief. Initially, early scholars were involved in various fields of inquiry. However, these primary sciences are typically seen as more exact and straightforward to quantify compared to the others, which is why contemporary researchers often concentrate their efforts on them.
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.
And what about the initial living organism? If it emerged from non-living material, at what point and through which processes did this occur?
Life could potentially be far more ancient than our previous understanding.
A research conducted at Cardiff University in Wales, UK, indicates that complex life on our planet may have started approximately 1.5 billion years sooner than was initially believed. The team of researchers asserts they discovered indications within the rock samples from Gabon suggesting favorable circumstances for life existed around 2.1 billion years back.
Published in the journal
Precambrian Research
The research indicates that approximately over 2 billion years ago, the clash between two continental plates 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 bid for multicellular organisms 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 originated 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 environment.
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. The renowned American chemist and Nobel laureate, Harold Urey, along with the biochemistry scientist Stanley Miller, constructed an early Earth-like environment within a lab setting. Inside this sealed system, they combined water, methane, ammonia, and hydrogen gases, then initiated electrical discharges 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 theory suggests that life on Earth initially originated beyond our planet, from outer space. This idea proposes that organisms or the fundamental building blocks needed for life journeyed here and eventually landed 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 suggests that it might have been delivered via a meteorite containing microorganisms colliding with Earth.
The initial advocates for this concept included British astrophysicists Fred Hoyle and Chandra Wickramasinghe. During the 1970s, their research indicated that comets hold sufficient organic material to potentially initiate life on planets like Earth.
3. The hypothesis of hydrothermal vents as origins
The hydrothermal vent hypothesis proposes that life on Earth may have originated at the bottom of the oceans near these hydrothermal vents. These vents are fissures in the seafloor from which geothermally heated, nutrient-laden water gushes out.
Michael Russell, a British geologist associated with the NASA Astrobiology Institute, suggested that alkaline hydrothermal vents releasing hydrogen, hydrogen sulfide, and methane might have offered optimal circumstances for generating basic organic compounds.
Even though the surroundings of hydrothermal vents are deemed harsh — with temperatures soaring up to 400°C (752°F) — certain microorganisms thrive here 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 environments devoid of light, like the deep-sea bed.
4. The RNA world
The RNA world hypothesis suggests that prior to the presence of DNA and proteins, earthly life was centered around an adaptable molecule called 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—complex molecules essential for 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 as a result received a Nobel Prize.
Researchers have suggested that RNA molecules with the ability to self-replicate and facilitate basic chemical reactions came before today’s organisms. Over time, proteins—which are better at catalysis—took over roles previously played by 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 issue 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 formerly 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
