Book Review: Signatures of Life

Signatures of Life: Science Searches the Universeby Edward AshpolePrometheus Books, 2013After giving readers an exhaustive run-down of the latest scientific breakthroughs in the search for life on other planets, our author allows himself a little aria of hope: "The realization that life is probably universal, however thinly scattered throughout the universe, has meaning for all those who contemplate the cosmos and the mortality of man," he writes. "The conclusion that life exists across this vastness seems inescapable. We cannot yet be sure whether or not it lies within our reach, but in any case we are part of it all: we are not alone!"Impossible for readers not to feel that gust of optimism, to close Edward Ashpole's new book Signatures of Life: Science Searches the Universe with a renewed conviction that the known galaxies must teem with life, that humanity is right on the verge of making that most momentous discovery of all.Except that quote wasn't from Ashpole's book. It was from Walter Sullivan's We Are Not Alone, which likewise gave readers an exhaustive run-down on the latest scientific breakthroughs in the search for life on other planets. It was written in 1964.In that intervening 50 years, everything has changed: scientific technology has grown so manifold and sophisticated that it can detect atmospheric composition on unseen worlds hundreds of thousands of light-years distant from Earth. Probes unimagined in Sullivan's day have now done close fly-bys of virtually all the planets in Earth's solar system. The Curiosity rover has been sending back not only mind-boggling photos of the surface of Mars but also soil sample analyses like nothing the boys at Cape Canaveral could have foreseen. The various laboratories and compounds of SETI (Search for Extraterrestrial Intelligence) have grown enormously in sophistication, using the latest in radio telescope technology to scan the heavens.Well, almost everything has changed. One thing remains the same: no life. No life anywhere other than Earth. No trace of life anywhere but Earth. No hint of life anywhere but Earth. On Earth, life in astounding abundance. Life forming in one-day-old rain puddles. Life thriving in boiling magma-vents. Life squirming and striving and reproducing on the very doorstep of airless space, or inside rocks, or on the human eyelash. On Earth, life almost literally everywhere.Other than Earth, no life anywhere.It ought to be enough to render Sullivan's "life is probably universal" utterly unrepeatable flat-Earth nonsense, but there's Ashpole, a seasoned professional science writer, starting off Signatures of Life right on Page 1 with his "Grand Hypothesis," in bold letters: "that life and intelligence are universal phenomena."He doesn't want his readers' blind faith, oh no: he's come before them to talk about science:

So what about testing the Grand Hypothesis? Scientific hypotheses don't come any grander, but for many it will seem too grand, too far removed from practical scientific research, something speculative and remote that will not provide new knowledge. But in our time the hypotheses that life and intelligence are universal phenomenon is scientifically testable. We may not get any positive results, but if we don't test we certainly won't.

He writes a very enjoyable book. Even at a time when first-rate popular science writing has proliferated in the developed world (to a greater extent than any time in history, everybody lives every day in close, dependent contact with science fiction-style technology, all of which wants to be explained on some level or other), Ashpole is noticeably good at getting complex ideas across in clear, simple prose:

Viruses are the perfect parasite, but they need the right host to flourish - they are very specific parasites. So we might not have a problem with Martian viruses. Our viruses have to be able to enter the cells of their hosts and use the genetic system there to make copies of themselves. They don't reproduce themselves like other organisms in the biosphere. They get the host to do that for them. They are therefore entirely dependent on being able to enter the host's cells to used its genetic machinery to make more viruses. And to gain entry and do this the structure of the proteins on the virus must be able to key into the structure of the proteins on the host cells. This is the viral way of life, which is very finely tuned.

He tours his readers through the latest gadgets at SETI, and he takes an admirably even-handed look at the demimonde of UFO, um, enthusiasts. But he always comes back to his "testable" Grand Hypothesis, until a life-long Star Trek fan will just want to sit down and cry. Ashpole is perfectly happy to devote dozens of pages to microwave distribution curves of the intricacies of "twisted light," but he only ever just nervously glances in the direction of the infamous Anthropic Cosmological Principle; he's willing to plumb the squirrelly depths of ET-spotters, but he won't - he can't - confront the possibility that life - not just complex, civilization-building intelligent life, but any life, all life - might be a very local speciality, might even be confined to this one solitary planet. He looks at the incredible data the Cassini and Curiosity probes have sent back to Earth, data that confirms the existence of environments all throughout the solar system; he sees as clearly as his readers do that those environments, however rich, are utterly devoid of life ... but still he hopes:

So although the nature of extraterrestrial life remains open to speculation, we can hardly deny that "life as we know it" has been so successful on Earth that at least it looks like a universal phenomenon.

On the contrary, "life as we know it" looks - and always has looked - like the exact opposite of a universal phenomenon. But Ashpole's readers may prefer instead to hope right along with him. There's no harm in that - but there's no science in it either.