Researchers recently confirmed the discovery of microscopic fossils dating back to 3.5 billion years ago. These are the oldest traces of life on Earth ever found. 

There are many hypotheses that try to explain how life appeared on Earth. Some scientists think life has emerged thanks to the primitive atmosphere conditions of Earth in its early life while others argue that microbial forms of life could have been transported between worlds by streams of cosmic dust.

If we have yet to reach a common understanding on the origins of terrestrial life, the date at which it has begun is an even deeper mystery that scientists cannot agree on.

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When Did Life on Earth First Arise?

In the beginning, Earth was a massive ball of molten lava with a harsh atmosphere made of water vapor and toxic gases.

As temperatures cooled, the planet’s surface solidified into a crust and water vapor gradually condensed into oceans in which first life forms (bacteria) developed.

Cooperation, and not competition, led groups of these single-celled bacteria living in symbiosis to specialize and assemble into more complex living organisms.

However, you’d be hard-pressed to put firm dates on any of these distant events.

Up until the 1950s, life was thought to be just 540 million years old, but a number of scientific discoveries have been consistently pushing that date back further and further.

In 1953, Stanley Tyler, a geologist at the University of Wisconsin-Madison, discovered ring-shaped microscopic fossils in Precambrian rocks in Minnesota and Ontario that were 1.9 billion years old.

Today, current estimates of the original date of life on Earth vary between 3.8 billion and 4.3 billion years old. However, a recent study by researchers at the University of Tokyo challenged these estimates, deeming them “highly controversial”, and suggested that life on Earth existed from as early as 3.95 gigayears (billion years) ago.

Now, in yet another study, researchers believe they have found the earliest traces of life ever found that have been dated to around 3.5 billion years ago.

3.5 Billion-Year-Old Microfossils Hint at an Earlier Development of Life

An example of one of the microbial fossils found on-site in Western Australia

Researchers at UCLA and the University of Wisconsin–Madison have unearthed 3.5 billion-year-old microfossils in Western Australia using a new spectrometry technology.

According to researchers, these fossilized rock samples, “are the oldest fossils ever found and indeed the earliest direct evidence of life on Earth.”

UCLA paleobiologist J. William Schopf and UW–Madison geoscientist John W. Valley, who led the research team, found the chemical signatures of 11 microbial specimens that belong to five species, some now extinct and others resembling still-existing microbial species.

It’s worth noting that these filamentous microbial specimens were first identified by professor Schopf in 1993, but his findings were long disputed by other scientists who thought the microfossils to be nothing but oddly-shaped mineral formations.

Now, thanks to the Secondary Ion Mass Spectrometer Lab developed at the UW–Madison WiscSIMS lab, Schopf put doubts to rest and proved that the 10 micrometer wide specimens are indeed of biological origin.

“Studies such as this one, indicate life could be common throughout the universe,” said Schopf. “But importantly, here on Earth, because several different types of microbes were shown to be already present by 3.5 billion years ago, it tells us that life had to have begun substantially earlier — nobody knows how much earlier.”

How old do you think life on Earth is? Do you think it even matters whether we know the exact age of life on our planet? Let us know your thoughts in the comments section below. 

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