A new study challenges the long-standing belief that intelligent life is an unlikely occurrence, suggesting that human-like evolution may be a natural outcome under the right planetary conditions. The research puts forward an alternative to the “hard steps” theory, which argues that the emergence of complex life is rare due to a series of improbable evolutionary leaps. Instead, the latest findings indicate that life evolves in response to planetary changes, making intelligent civilisations more probable than previously estimated. The study has been conducted by a team of experts, including astrophysicists and geobiologists, who assert that Earth’s environmental conditions played a crucial role in determining when complex life could emerge.

New Interpretation of Evolutionary Steps

According to a study published in Science Advances, the probability of intelligent life developing on other planets is higher than once believed. The research, led by Dan Mills, a postdoctoral researcher at The University of Munich, suggests that key evolutionary steps were not mere coincidences but rather responses to planetary changes. Mills explained that atmospheric oxygen levels, nutrient availability, and oceanic conditions dictated when complex organisms could thrive. He stated to Phys.org that Earth’s history was shaped by a sequence of “windows of habitability” that allowed life to advance in a systematic manner.

A Shift in Perspective

The widely accepted “hard steps” model, introduced by theoretical physicist Brandon Carter in 1983, argues that the emergence of intelligent beings is extremely rare. It is based on the premise that Earth’s evolutionary timeline was lengthy relative to the sun’s lifespan, making human-like intelligence an anomaly. However, the new research, co-authored by Jennifer Macalady, Professor of Geosciences at Pennsylvania State University, proposes that life progresses at a planetary timescale rather than an astrophysical one. Macalady told phys.org that rather than relying on astronomical predictions, geological factors should be considered to understand the evolution of life.

The findings suggest that if planetary conditions determine the timing of evolution, other planets may develop intelligent life at different rates. Jason Wright, Professor of Astronomy and Astrophysics at Pennsylvania State University and a co-author of the study, said that the framework increases the probability of detecting extraterrestrial life. He added that future research should focus on identifying biosignatures in exoplanetary atmospheres, such as oxygen and other life-supporting elements.

Future Research Directions

To assess the validity of this alternative model, researchers plan to examine whether previously assumed “hard steps” in evolution were truly rare occurrences. The study outlines proposals for experiments involving both unicellular and multicellular life forms under varying environmental conditions. The team suggests further investigation into whether certain evolutionary developments, such as oxygenic photosynthesis or the emergence of eukaryotic cells, have independently occurred multiple times throughout Earth’s history but were lost due to extinction events.

Massive structures buried deep within the Earth’s mantle have been found to be more than a billion years old, according to recent research. These continent-sized formations, referred to as large low-seismic-velocity provinces (LLSVPs), are believed to be both older and hotter than their surrounding mantle. Situated at the boundary between the mantle and the outer core, approximately 3,000 kilometres beneath the Earth’s surface, these formations have puzzled scientists for decades. Their nature and origin have remained unclear, with seismic waves slowing down significantly when passing through them, suggesting distinct physical and compositional properties.

Blobs Deep Beneath Earth’s Surface

According to the study published in Nature, seismic data from over 100 significant earthquakes were analysed to understand these structures. As reported by space.com, Arwen Deuss, a seismologist at Utrecht University in the Netherlands, told Live Science that the primary observation has been the reduction in speed of seismic waves passing through these regions. However, an unexpected result was the reduced energy loss of these waves compared to the surrounding mantle, suggesting that factors beyond temperature influence these massive formations.

Role of Crystal Size in LLSVPs

Computer models have indicated that the mineral composition of these formations may be responsible for the observed phenomena. It has been proposed that the size of crystalline minerals within the LLSVPs plays a significant role. The research suggests that seismic waves lose energy when encountering grain boundaries between crystals. Smaller crystals result in increased energy loss due to the presence of more boundaries, whereas larger crystals cause lesser resistance. Deuss explained to Live Science that the surrounding mantle is composed of older tectonic plates that have broken into smaller fragments over time, whereas the LLSVPs contain much larger crystals that have remained undisturbed for extensive periods.

Implications for Earth’s Mantle and Surface

It has been suggested that these deep mantle structures have played a role in shaping the Earth’s surface. LLSVPs are believed to contribute to volcanic activity, with mantle plumes originating from these regions, bringing deep material to the surface. The composition of volcanic rocks worldwide could potentially be linked to these mantle formations, according to the study.

The age of these structures has been a subject of speculation, but the study provides substantial evidence supporting their billion-year existence. Deuss stated to Live Science that confirmation of their age allows for further exploration of their origins, stability, and long-term impact on Earth’s geological processes. Additional studies are expected to investigate how these formations have influenced the movement of tectonic plates and the overall behaviour of the mantle.