Fashions have changed. Sixty years ago, the consensus among astronomers was that life on Earth was such an extremely unlikely occurrence that we may be alone in the universe. These days, very few astronomers believe that. The current groupthink is that the universe teems with life.
That’s why so many research organizations search for exo-planets, especially those with an Earthlike temperature that could allow liquid water. Others focus on exo-planets’ atmospheres. The free oxygen in our own air is only present because of plants. If we therefore detect free oxygen in the atmosphere of a distant exoplanet, we know that life is likely.
Nonetheless, the basic question remains: What is life? Perhaps surprisingly, scientists don’t agree on a definition. Are viruses alive? They have no metabolism; they don’t feed themselves; and many biologists regard them as inanimate. Yet they contain RNA coding that forces cells to make lots of viral copies.
And how did life begin? Through chemistry? If certain events cause life to arise from non-living components, it’s still mysterious. But whatever the process, we want to know if it happens readily. In other words, is life easy? Or does it require extremely unlikely events to unfold?
The main argument for “easy” is that earthly life began almost as soon as it was possible. After the molten early Earth sufficiently cooled, there came a long period of intense bombardment. Asteroids and comets kept pummeling our surface. This violence stopped about four billion years ago. And bingo, our earliest fossils date from 3.8 billion years ago. So life began within 200 million years of when it was first possible. That’s awfully quick.
A good counter-argument, for life being “hard,” is that life-creation or abiogenesis only happened once. All earthly life-forms are descendants of that first ancestral organism. We know this because all life, from elephants to bacteria, shares remarkable genetic similarities. They’re all made of the same kinds of amino acids and sugars. For example, many molecules have twists or spirals or asymmetries. Amino acids can be created with a left-handed or right-handed twist. But on Earth, all life only contains amino molecules with left-handed twists, and a right direction in all its sugars – and a right twist to its DNA, which is the same as a corkscrew.
Life didn’t have to be this way. And if life started a second time from scratch, it likely would show differences in such chirality. And maybe it wouldn’t solely store information in genetic material, as all earthly life does. Now, there are at least six million species of bacteria (even if only 100,000 of them have had their genomes sequenced). But every single microbe, plant and animal we have examined shows that it’s a descendant of the first life-creation. The point: Why didn’t life start a second time? And maybe a third? Or 100th? Nearly four billion years have passed, and yet life only originated once. This suggests that abiogenesis is not easy, but hard.
Well, which is it? Given its complexity, Fred Hoyle said, “Life as we know it is, among other things, dependent on at least 2,000 different enzymes. How could the blind forces of the primal sea manage to put together the correct chemical elements to build enzymes?” Later he famously described an accidental birth of life as akin to a tornado sweeping through a junkyard and randomly creating a jumbo jet. Supporting this, Francis Crick, the co-discoverer of DNA’s shape, described the origin of life as “almost a miracle, so many are the conditions which would have had to be satisfied to get it going.” If abiogenesis is really so unlikely, then even given the immense size of the cosmos, it’s possible that we are the only example.
Of course, all this assumes that abiogenesis only happens via accidental, random processes. But what if nature has an immense innate intelligence? I just saw an amazing 3-D nature documentary by David Attenborough, showing the first flying creature. It was the dragonfly, 320 million years ago. Its wings have the same shape as modern aircraft. That exact airfoil configuration is necessary for all flight, and requires a wing’s upper surface to have a convex curve. It’s hard to see how evolution could have created it. Unlike the evolution of giraffes’ necks, where any incremental increase in length would offer evolutionary advantages, a step-by-step process just wouldn’t work for a wing design. The wrong shape would be useless, and confer no advantage whatsoever. Thus, for flight, some 400,000 cells would all have to mutate simultaneously in just the right way to create a properly shaped wing. An evolutionary hypothesis cannot explain it.
Occam’s Razor would suggest that some overarching intelligence was at work. To me, the simplest explanation is that the universe or nature is innately smart, not dumb. We cannot visually see this intelligence, just as we cannot see neutrinos and electrical fields. And, yes, this viewpoint is utterly out of fashion. But if it’s the case, then maybe life’s complex genesis was not so impossibly unlikely, and the universe may indeed be pregnant with innumerable extraterrestrials.
It’s all guesswork. We know of life on only a single world – ours – so our sample size is one. And when you try to draw a line on a graph and you have just one data point…well, good luck.
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