For those interested in inter-generational voyages and chemiosmotic coupling, here is a double review from Mr. AMB on Aurora (Science Fiction) and The Vital Question (Science Fact). They sound fascinating.
Aurora by Kim Stanley Robinson has racked up an impressive array of glowing reviews, including from The Guardian, NPR, and Scientific American. (This review from Book Smugglers is also good, but I think it has a bit too many spoilers to be read before the book–unless you’re into that sort of thing).
According to the publisher, “AURORA tells the incredible story of our first voyage beyond the solar system.” The ship is bound for a planetary system near Tau Ceti, which is so far away that the only way to get there is by way of an inter-generational voyage. We pick up the story near the end of the trip, long after the original crew (and their children) has already died. The characters have thus lived their entire lives on this mission and on this ship, which has been built with biospheres meant to mimic many of the environments on Earth.
Put simply, if Aurora sounds like the type of book you think you might like, then you should probably read it. My primary critique is that the first quarter of the book is too slow and would have been better clipped down to the first tenth or eighth of the book. That said, I agree with The Guardian that, “Where the novel really scores, though, is in the depth and truth of his human beings, both as individual characters and as communities. Indeed, it’s the way Robinson is able to combine individual and social perspectives into a seamless whole that really makes the book.”
One of the reasons I liked the book is because it made me think about real scientific issues; a science fiction book should make you think about the underlying science. So instead of reiterating what other reviews have said, let me jump to a scientific issue. In this video by Robinson (I’ve started it at the relevant point), he makes the point that an earth analogue planet is “either alive or dead.” That is, the planet either has some life of some sort or none at all, and if it has life, then “you’ve got a terrible problem because it is very possible that this alien lifeform will be not good for you and you not good for it.” A character in the book makes the same point.
To address this issue, let me recommend another book: Nick Lane’s The Vital Question: Energy, Evolution, and the Origins of Complex Life, which was one of Bill Gates’ best books of 2015.
The Vital Question attempts to answer one of the most perplexing questions in biology: how did life arise on Earth?
Lane is a Professor of Evolutionary Biochemistry at University College London. He would be the first to admit that his ideas are, for the moment, mostly untested hypotheses, but the arguments he makes are compelling. Lane argues that, given the basic principles of chemistry, “life” can only take on a certain number of forms, and all of them will be chemiosmotic cells that rely on using proton gradients to react hydrogen and carbon.
As Lane puts it:
In this book, I will argue that natural proton gradients drove the origin of life on earth in a very particular environment, but an environment that is almost certainly ubiquitous across the cosmos: the shopping list is just rock, water and CO2. I will argue that chemiosmotic coupling constrained the evolution of life on earth to the complexity of bacteria and archaea for billions of years. A singular event, in which one bacterium somehow got inside another one, overcame these endless energetic constraints on bacteria. That endosymbiosis gave rise to eukaryotes with genomes that swelled over orders of magnitude, the raw material for morphological complexity. The intimate relationship between the host cell and its endosymbionts (which went on to become mitochondria) was, I shall argue, behind many strange properties shared by eukaryotes. Evolution should tend to play out along similar lines, guided by similar constraints, elsewhere in the universe. If I am right (and I don’t for a moment think I will be in all the details, but I hope that the bigger picture is correct) then these are the beginnings of a more predictive biology. One day it may be possible to predict the properties of life anywhere in the universe from the chemical composition of the cosmos.
Kindle Locations 1315-1324. As he says, while explaining the long, difficult trip that “life” took from random chemicals in the ocean to the incredible last universal common ancestor of life, “these strict requirements can explain why all life on earth is chemiosmotic [i.e., the way that life is built upon the movement of ions across a selectively permeable membrane] – why this strange trait is as universal as the genetic code itself.” Kindle Locations 4575-4591.
With that background, an “alive” planet is not inherently problematic to human colonists. An “alive” planet could be filled to the brim with dangerous lifeforms that would could, for example, hijack our mitochondria or disrupt our immune systems — just like Earth-bound infectious diseases do today — but it’s highly likely that human explorers in the future would be able to discover and evaluate these lifeforms quickly upon their arrival. It’s also likely that, for many of these alien lifeforms, our immune systems would be able to mount a resistance, because you’re alive and reading this article precisely because you and your ancestors, going all the way back three billion years to LUCA, have been able to withstand a constant onslaught of attacks by other carbon-based, chemiosmotic lifeforms.
I should note here that The Vital Question doesn’t stop at that part of early evolution. The bulk of the book is really about the rise of eukaryotes, and Lane’s compelling argument that the constraints imposed by the symbiosis between eukaryotes and their mitochondria are responsible for our most complex traits, from sex differentiation to infertility to death.
The book is loaded with thought-provoking concepts, and fascinating hypotheses for why the “Tree of Life” you saw in high school is all wrong, why some animals are far more fertile than others, and why regular exercise makes people live longer while consuming too many antioxidants makes people to die sooner.