Jan. 26, 1999
Gold finds our deep hot biosphere teeming with life - and controversy
The ideas come crowding in: Deep within the Earth's crust is a vast ecosystem of primitive bacteria nurtured by a reservoir of hydrocarbons of unimaginable size, much of it untapped. Even more: The microbes predate all of the planet's other life forms, existing even before photosynthesis became the preferred life-giving form.
In a new book, The Deep Hot Biosphere (Copernicus/Springer-Verlag, $27), Cornell professor emeritus of astronomy Thomas Gold argues that subterranean bugs are us -- or at least they started the whole evolutionary process, and that there's no looming energy shortage because oil reserves are far greater than predicted.
In the hands of anyone other than Gold, the reaction to all this might be a skeptical raised eyebrow. But Gold, as ever the Cornellian gadfly, makes his argument with erudition and conviction. Founder and director of Cornell's Center for Radiophysics and Space Research for two decades, Gold is hardly a stranger to sticking his neck out. He has been proven right in such diverse realms as a theory of hearing, the interpretation of pulsars and a theory of the Earth's axis of rotation.
But Gold's most controversial idea, as physicist Freeman Dyson notes in the book's forward, is that of the nonbiological origin of natural gas and oil, which he first proposed more than 20 years ago. These hydrocarbons, Gold postulated, come from deep reservoirs and are composed of the material from which the Earth condensed. The idea that hydrocarbons coalesced from organic material is, he says, quite wrong. The biological molecules found in oil, he avers, show only that the oil is contaminated by microbes, not that it was produced by them.
Some researchers, and in particular petroleum geologists, have taken issue with Gold's proposal. They are likely to be even more put out by his new book, which says that these microbes populate the Earth's interior down to a depth of several miles and that everything we see living on the planet's surface is only a small part of the biosphere. The greater part, and the ancient part, is very deep and very hot.
Indeed, Gold shows irritation at a scientific community that "has typically sought only surface life in the heavens." Scientists, he writes, "have been hindered by a sort of 'surface chauvinism.'"
Absolutely, says Gold. "Spectroscopic evidence is very strong for many planetary bodies. The prime example is Titan [a moon of Saturn], which has clouds of ethane and methane. They interchange with the surface, so there must be lakes or oceans of liquid ethane or methane. Once you know that, it's clear they came outside from the body within."
Thus, he writes, life on many other planetary bodies seems probable, even though their surfaces are either too hot or too cold to support life. "Subsurface life, however, is another matter. Mars, the satellites of the major planets, many asteroids and even our own moon should be regarded as real prospects for harboring extraterrestrial life of this kind," he writes.
On Earth, says Gold, there is clear evidence that subsurface microbial life still exists; for example, in the discovery of primitive microbes in hot ocean vents. "We pulled up bugs from five kilometers down in the granite in Sweden. They were perfectly alive and probably the earliest life form on the planet," he says. The primitive microbes, he notes, are thermophiles and hyperthermophiles, heat-loving archaebacteria.
Photosynthesis, his book argues, "developed in offshoots of subterranean life that had progressed toward the surface and then evolved a way to use photons to supply even more chemical energy." When surface conditions such as temperature and liquid water became favorable to life, surface life was able to blossom.
In the eons since, the deep world of microbes has had to rely on chemical energy, the oxidation of hydrocarbons, ranging from methane to petroleum, as the organisms emerge upwards from deep reservoirs below. "Every oil-bearing region in the world must have large amounts of microbiology," he says.
Writes Gold: "In my view, hydrocarbons are not biology reworked by geology (as the traditional view would hold) but rather geology reworked by biology. In other words, hydrocarbons are primordial, but as they upwell into Earth's outer crust microbial life invades."
Reviewing the book, Publishers Weekly noted that "if Gold is right, the planet's oil reserves are far larger than policy-makers expect... moreover, astronomers hoping for extraterrestrial contacts might want to stop seeking life on other planets and inquire about life in them."