Animals exist today because Earth had an issue 500 million years ago

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The Ediacaran Period, spanning from about 635 to 541 million years ago, marked a transformative era in the history of life on Earth. It was during this pivotal time that complex, multicellular organisms emerged, setting the stage for the explosion of life that would follow.

According to a captivating study led by John Tarduno, the William Kenan, Jr. Professor in the Department of Earth and Environmental Sciences at the University of Rochester, Earth's magnetic field was in a highly unusual state when the macroscopic animals of the Ediacaran Period diversified and thrived.

The research raises the question of whether these fluctuations in Earth's ancient magnetic field led to shifts in oxygen levels that may have been crucial to the proliferation of life forms millions of years ago.

Ediacaran fauna were Earth's first complex lifeforms

One of the most remarkable life forms during the Ediacaran Period was the Ediacaran fauna. As Tarduno explains, "They were notable for their resemblance to early animals — some even reached more than a meter (three feet) in size and were mobile, indicating they probably needed more oxygen compared to earlier life forms."

The close timing between the appearance of the Ediacaran fauna and the ultra-low geomagnetic field motivated the researchers to revisit environmental factors, particularly atmospheric and ocean oxygenation, as potential drivers for the emergence of these complex life forms.

Earth's protective magnetic field

About 1,800 miles below us, liquid iron churns in Earth's outer core, creating the planet's protective magnetic field. This invisible shield is essential for life on Earth, as it protects the planet from harmful radiation from the sun.

Deflecting solar wind and cosmic rays

The magnetic field's primary role is to deflect the high-energy charged particles that make up solar wind. Without this protection, these particles would strip away the Earth's atmosphere, exposing life on the surface to the full force of the sun's radiation.

The magnetosphere also shields the planet from cosmic rays, which are high-energy particles originating from outside our solar system that can cause genetic mutations and damage to living organisms.

Preserving Earth's atmosphere and water

By deflecting harmful solar radiation and cosmic rays, Earth's magnetic field helps to preserve the planet's atmosphere and water.

The atmosphere, in turn, shields life on Earth from the sun's ultraviolet radiation and helps to maintain a stable climate.

The magnetic field also prevents the atmosphere from being stripped away by solar wind, which would lead to a gradual loss of water vapor and other essential gases.

Protecting Earth's ozone layer

The magnetic field also plays a crucial role in protecting Earth's ozone layer, which filters out harmful ultraviolet radiation from the sun.

Without the magnetic field, the ozone layer would be depleted by the constant bombardment of charged particles, exposing life on Earth to dangerous levels of UV radiation that can cause skin cancer and other health problems.

Earth's magnetic field is a vital component of the complex system that sustains life on our planet. However, Earth's magnetic field wasn't always as strong as it is today.

Link between magnetic field strength and animal life

Researchers have proposed that an unusually low magnetic field might have contributed to the rise of animal life. However, examining this link has been challenging due to limited data about the strength of the magnetic field during the Ediacaran Period.

Tarduno and his team employed innovative strategies and techniques to study the strength of the magnetic field by examining magnetism locked in ancient feldspar and pyroxene crystals from the rock anorthosite. By dating the rocks, researchers can construct a timeline of the development of Earth's magnetic field.

Using cutting-edge tools, including a CO2 laser and the lab's superconducting quantum interference device (SQUID) magnetometer, the team analyzed the crystals and the magnetism locked within with precision.

Their data indicates that Earth's magnetic field at times during the Ediacaran Period was the weakest field known to date — up to 30 times weaker than the magnetic field today — and that the ultra-low field strength lasted for at least 26 million years.

Ediacaran oxygen boom may have triggered life expansion

A weak magnetic field makes it easier for charged particles from the sun to strip away lightweight atoms such as hydrogen from the atmosphere, causing them to escape into space.

If hydrogen loss is significant, more oxygen may remain in the atmosphere instead of reacting with hydrogen to form water vapor. These reactions can lead to a buildup of oxygen over time.

Tarduno and his team's research suggests that during the Ediacaran Period, the ultraweak magnetic field caused a loss of hydrogen over at least tens of millions of years. This loss may have led to increased oxygenation of the atmosphere and surface ocean, enabling more advanced life forms to emerge.

Cambrian explosion saw Earth's magnetic field recover

Tarduno and his research team previously discovered that the geomagnetic field recovered in strength during the subsequent Cambrian Period, when most animal groups begin to appear in the fossil record. The reestablishment of the protective magnetic field allowed life to thrive.

As Tarduno notes, "If the extraordinarily weak field had remained after the Ediacaran, Earth might look very different from the water-rich planet it is today: water loss might have gradually dried Earth."

Ediacaran magnetic fields and life beyond Earth

The work suggests that understanding planetary interiors is crucial in contemplating the potential of life beyond Earth.

"It's fascinating to think that processes in Earth's core could be linked ultimately to evolution," Tarduno says. "As we think about the possibility of life elsewhere, we also need to consider how the interiors of planets form and develop."

In summary, the study by John Tarduno and his team uncovers a fascinating link between Earth's magnetic field and the rise of complex life during the enigmatic Ediacaran Period.

Their research deepens our understanding of the intricate interplay between our planet's core processes and the evolution of life while raising intriguing questions about the potential for life on other planets.

As we continue to explore the mysteries of our own planet's history and search for signs of life beyond Earth, studies like this remind us of the complex and interconnected nature of the universe, urging us to consider the crucial role that planetary interiors play in the development and sustenance of life.

The full study was published in the journal Communications Earth & Environment.

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