Cause of Cambrian Explosion - Terrestrial or Cosmic?

Area of Science:

• Astrobiology
• Panspermia
• Evolutionary Biology

Background:

• The Hoyle-Wickramasinghe (H-W) thesis posits that life on Earth originated from extraterrestrial sources, primarily comets.
• This theory suggests continuous seeding of life and genetic material throughout Earth's history.
• Recent evidence aligns with predictions of cometary impacts influencing evolutionary events.

Purpose of the Study:

• To review evidence supporting the H-W thesis of Cometary Biology.
• To examine the link between cometary impacts and major evolutionary transitions.
• To assess the role of extraterrestrial life delivery in terrestrial evolution.

Main Methods:

• Review of multifactorial physical and biological evidence.
• Analysis of retroviral emergence timing relative to the Cambrian Explosion.
• Examination of fossil microorganisms in meteorites and atmospheric particle detection.
• Assessment of cephalopod evolution and the emergence of the octopus.

Main Results:

• Complex retroviruses emerged around the time of the Cambrian Explosion (∼500 Ma), coinciding with predicted virus-bearing cometary impacts.
• Fossil microorganisms have been found in meteorites, and life-bearing particles detected in the upper atmosphere.
• The evolution of complex life, including intelligent cephalopods, is considered.
• The H-W theory predicts continuous delivery of diverse life forms from space.

Conclusions:

• Life was likely seeded on Earth by comets around 4.1 billion years ago.
• Ongoing delivery of space-hardy organisms (bacteria, viruses, cells, ova, seeds) from comets has driven terrestrial evolution and genetic diversity.
• The H-W thesis provides a plausible explanation for the origin and evolution of life on Earth, including the emergence of humans.