Imagine a comet hurtling through the nothingness of space. It smashes into a planet, causing destruction — but also bringing life. That's because hitching a ride on the surface of the comet were tiny traces of organic material or even alien eggs, explaining how life could spread across the cosmos and arrive on our planet. Panspermia (meaning 'seeds everywhere') is the name of the theory that life on Earth may have cosmic origins, and it's been both debated by scientists and featured in works of science fiction.
Now, a group of nearly three dozen scientists from around the world are putting a tweak in the theory, suggesting not that Earth's earliest life has outer-space origins, but that panspermia may be responsible for the Cambrian explosion. That's a point in Earth's history approximately 541 million years ago when most major animal groups appear in the fossil record.
In the article "Cause of Cambrian Explosion — Terrestrial or Cosmic?" published in the August 2018 issue of the journal Progress in Biophysics and Molecular Biology, 33 scientists tie the rise of unique animals — tardigrades, octopuses, and the bevy of odd and unique animals that flourished at the time — to panspermia, suggesting that many of these relatively bizarre and never-before-seen creatures descend from organic alien material.
"It takes little imagination to consider that the pre-Cambrian mass extinction event(s) was correlated with the impact of a giant life-bearing comet (or comets), and the subsequent seeding of Earth with new cosmic-derived cellular organisms and viral genes," the authors write.
For those getting excited that a number of reputable scientists have cracked the mystery of life's origins, it's not so simple. This new paper isn't built on any new discoveries or research; it's a literature review that for the most part references the authors' own existing work. But that's by design, the authors acknowledge.
"We are acutely aware that mainstream thinking on the origin and further evolution of life on Earth is anchored ﬁrmly in the 'Terrestrial' paradigm," write the authors. "Our aim here is to facilitate further discussion in the biophysical, biomedical and evolutionary science communities."
Panspermia is at this point only a concept, but it dates back well before the last hundred years or so of modern science fiction. Way back at the turn of the 18th century, French diplomat and natural historian Benoit de Maillet proposed that life across the cosmos could have been "seeded" from space. And a few scholars even interpret ancient Greek philosopher Anaxagoras of Clazomenae's musings, who spoke vaguely of cosmic seeds 2,500 years ago, along the same lines.
The paper has already drawn skepticism. Astrobiologist Frances Westall, for instance, points out that while some forms of extremophile life have been observed surviving the vacuum of space for short periods of time, this new paper's suppositions would require eggs, embryos or other cells survive thousands of years, if not more, in space.
"Unfortunately it is all too easy to pull information out of the literature to support one's hypothesis," Westall told Newsweek when discussing the paper. "Nature is incredible, and I do not think it is necessary to call on extraterrestrials to explain it."