Bizarre creatures like the tiny tardigrade and the wondrous octopus have inspired some out-of-this-world origin theories… literally
They Came from Outer Space?! Bizarre creatures like the tiny tardigrade have inspired some out-of-this-world theories
Irecently came across a headline suggesting that octopuses were aliens. They do have eerie abilities, but aliens? Even more surprising, the idea was expressed in a scientific paper: “Cause of Cambrian Explosion — Terrestrial or Cosmic?” published in the journal Progress in Biophysics and Molecular Biology.
There’s a tangled tale here: for one thing, almost all the 30 authors cited often have made bold and controversial claims that challenge widely held scientific views. Other scientists ignore them, some debate them, but very few agree with them.
On the other hand, this article ties together so many intensely interesting pieces of science, from the origin of life, to the search for habitable planets in the galaxy, to some true biological puzzles. Two of these puzzles are animals that the authors of the paper assert have come from space: the tardigrade and the octopus.
Obviously, these are very different and barely related animals, but each provides a piece of an overall argument. Back in the 1980s, the late — and indeed great — astronomer Fred Hoyle teamed up with astrobiologist Chandra Wickramasinghe to make the heretical claim that life didn’t originate on Earth, but arrived onboard comet tails and meteoroids, showers and showers of them.
Such life would have been obliged to remain frozen and soaked in radiation in space for perhaps hundreds of millions of years. Tardigrades, barely visible eightlegged “micro-animals” that look like a caricature of a bear the size of the period at the end of this sentence, appear to have all the attributes necessary to do that. (See Alanna Mitchell’s column in Canadian Wildlife January/february 2016, reprinted online.) They’re resistant to temperatures as low as 0.5 degrees above absolute zero (for several hours) or as high as 150 Celsius, radiation doses equivalent to those in space, and crushing pressure six times that near the bottom of the Mariana Trench.
The authors of the journal paper ask why an Earth-dwelling animal would possess such unearthly equalities. What value would natural selection have seen in the ability to withstand temperatures or radiation rarely or never seen on Earth? The orthodox answer is that these little creatures have adapted to the variety of extreme environmental changes they experience in various habitats on Earth — they can be found practically everywhere. But for the scientists in this case, that’s just not enough. For them, tardigrades had to have come from an extreme environment somewhere in space. The question of the source of these adaptations is indeed worth asking, but only the most fervent believers in “panspermia” (life coming from outer space) would leap to that conclusion.
The more familiar octopus is also notable for its array of amazing features: arms that pretty much have their own nervous system and can behave independently of the octopus brain, the ability to match the colour and texture of its background, and amazing smarts that elevate it to the same intellectual league as primates. As in the case of the tardigrade, the history of these adaptations is mysterious, because the chambered nautilus, the most ancient of the octopus clan, shares none of these advanced features.
The octopus genome provides its own share of surprises and mysteries. In particular, it has the molecular machinery to edit the products of its genes without actually changing (or mutating) the genes themselves. In one sense then, its genome is very conservative and evolves slowly. But on the other hand, the animals can make substantial and relatively sudden changes to the array of proteins made by those genes.
This machinery is not unique to octopuses — we humans have it too — but in most other species, including humans, it’s a tiny piece of genomic production, whereas in the octopus it is central to their metabolism. And this editing is particularly active with genes responsible for the octopus nervous system.
How is it that in this regard they are so different from most forms of life? The authors of the paper suggest this genetic machinery came from space “most plausibly as an already coherent group of functioning genes within (say) cryopreserved and matrix-protected fertilized Octopus eggs.” That’s right: octopus eggs from space.
Having thrown two incredible claims at you, I admit I haven’t even tackled the main argument of the article: that an explosion of viruses more than 500 million years ago prompted what’s called the Cambrian explosion, the sudden appearance in the fossil record of most of the ancestors of modern life — the kind of fossils found in British Columbia’s Burgess Shale.
But I don’t have to; the tardigrade and the octopus are enough to remind us all that there is, and always will be, a persistent but tiny minority of scientists who think the orthodox view, that all life on Earth evolved right here, is just too parochial.
IN THE 1980S, TWO LEADING SPACE SCIENTISTS CLAIMED THAT LIFE DIDN’T ORIGINATE ON EARTH, BUT ARRIVED ONBOARD COMET TAILS AND METEOROIDS. NOW A LEADING JOURNAL TAKES UP THE CAUSE