Panspermia: Seeds Everywhere

Each new research project in astrochemistry makes less controversial the proposal that organic molecules from space contributed to the origin of Earthly life.

Researchers keep finding more varieties of organic molecules in outer space, including hydrocarbons and amino acids, DNA nucleobases and even vitamins. The abundance of organic molecules and macromolecules in space and proposed mechanisms to produce that abundance should open the skies to the prospect of life itself having originated in space. But scientists tend to be squeamish about such prospects (with exceptions).

No matter the extent to which scientists welcome organic building blocks of extraterrestrial origin to the terrestrial "broth" from which life is presumed to have arisen, that broth remains unchallenged as the womb of the first living cells. A nascent geocentrism lurks in the minds of men. But new research in astrochemistry challenges the need for a terrestrial broth. The job of championing the heresy of an extraterrestrial, not Earthly, origin of life fell to the eminent British astronomer Sir Fred Hoyle.

During the last decades of his life, Hoyle presented the case in a number of books and articles that biology cannot be native to Earth, but must have arrived from space. Hoyle did not originate this idea, called panspermia, and he acknowledged its long history. But, with new research data in hand, Hoyle waved the dust off this old idea and, in collaboration with astrochemist Chandra Wickramasinghe, labored to bring it to public attention. Wickramasinghe and colleagues continue the project today.

Hoyle's campaign met with resistance from most of the scientific community, and to the extent that his evidence and arguments were not overtly attacked or dismissed, they were ignored. But ongoing research continues to expand the catalog of organic molecules identified in interstellar space, and in comets, a catalog that now includes everything from alcohols to amino acids (and HERE). And increasingly complex organics continue to be found. In 2011, Researcher Sun Kwok of the University of Hong Kong analyzed spectral data from the European Space Agency's Infrared Space Observatory and NASA's Spitzer Space Telescope and found evidence of unsuspected organic complexity. "We know that these organics are being made in the circumstellar environment," Kwok said. According to an article on physorg.com, "The team's discovery suggests that complex organic compounds can be synthesized in space even when no life forms are present." "Our work has shown that stars have no problem making complex organic compounds under near-vacuum conditions," says Kwok. "Theoretically, this is impossible, but observationally we can see it happening."

Cosmic-scale organic chemistry was not predicted by any scientific theory. It was an empirical surprise.

Lecture by Sir Fred Hoyle to the Sri Lanka Institute of Fundamental Studies, December 1982, "From Virus to Cosmology", on the theory of cometary panspermia

Hoyle and Wickramasinghe insisted that infalling organic material from space consisted of bacterial cells and viruses and that biology took root from those extraterrestrial seeds. They insisted moreover that the rain continues and that epidemic diseases sometimes are the result of "genetic storms"—of exceptionally active episodes of infall. And the heresy went even further to propose that evolution itself was largely the result of genetic infall from outer space.

The evolutionary angle has been bolstered by the growing body of evidence for horizontal gene transfer as a significant evolutionary mechanism. Researchers have demonstrated that when viruses insert their genes into host organisms—the normal mode of infection—the viral genes can infect germ cells and appear in the next generation of hosts. In this way, the genome of a species can be augmented with new genes. Scientists increasingly invoke this process of gene transfer in their explanations of evolutionary change. But in whatever ways scientists might concede that genes get shuffled among organisms, few of them look to outer space for novel genetic material.

As for the means by which interstellar bacteria and viruses might make their way to planets, Hoyle identified comets as the likeliest delivery vehicles. Comets originate in, and during their eccentric orbits travel through, clouds of organic dust. Hoyle contended that as organic material evaporates from comets when they round their host stars—a well-documented phenomenon in the case of our own solar system—that the freed material, including whole cells and viruses—the controversial part—makes its way through planetary atmospheres to the planets below.

In short, Hoyle proposed that comets harbor microscopic life and disperse it across the orbital paths of planets. Whether life "takes" or not on a particular planet will be influenced by various contingencies idiosyncratic to that planet. Such contingencies include whether the planet is positioned within a "habitable zone" surrounding its star. The idea is that only planets at the proper distance from their stars will provide suitable conditions for complex ecosystems to evolve. Habitable zones have been proposed for entire galaxies, as well, being defined as the space at a given distance from galactic center that includes stars of certain types, namely those that form from "enriched" starter material, which includes the assortment of elements produced by previous stars and includes the necessary building material for making planets.

A research team of which Wickramasinghe was a member found evidence early in 2013 that a meteorite that broke up over Sri Lanka in December 2012 contained fossilized microbes. The evidence has been disputed, but earned coverage in MIT Technology Review's blog. The growing body of evidence for panspermia theory is archived and updated regularly by advocate Brig Klyce at www.panspermia.org.

The star larvae hypothesis extends the model of Hoyle and Wickramasinghe by positioning evolution within an overarching developmental cycle, on- and off-planet, and in the process adding a teleological dimension to evolutionary theory.

Hoyle conceived of planets as functioning like petri dishes in which bacteria flourish and then rejoin the life suspended in the interstellar medium when the planets they inhabit meet their ultimate fates. This aspect of his thinking seems to be Hoyle’s least satisfying conjecture. Panspermia is a one-way street in his model, with no apparent role for complex, multicellular life other than to host bacteria and viruses. As outside of mainstream thinking as Hoyle’s proposals were, and to a significant degree still are, they nonetheless were highly conventional in their nihilistic view of evolution. His is another theory of evolutionary purposelessness.

The star larvae hypothesis, in contrast, proposes that biology plays an essential role in the natural evolution of the cosmos. The hypothesis incorporates panspermia, which it takes to be the critical process in the stellar life cycle that delivers biological building blocks—bacteria and viruses—to planets. Beyond that it proposes that the stellar life cycle includes a "return trip," the graduation of biological life to the adulthood of extraterrestrial civilization and ultimately stardom.

That graduation bridges the divide that separates the organic from the inorganic. It involves the metamorphosis of biological metabolism into nuclear metabolism. The technological dimension of the process culminates in a replenishing of the universe's essential building blocks, protons.

Tiny animals called Tardigrades survive the vacuum of outer space and extremes of radiation, pressure and temperature, even though these conditions have had no opportunity to exert selection pressures on the creatures so as to shape their evolution—if in fact these odd critters are natives of Earth.

NEXT > The Proton Crisis and the Heat Death of the Universe

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