The subtitle of the book says “Mitochondria and the Meaning of Life” and the author tries very hard to match up to that high claim. The book promises to show us why mitochondria are the clandestine rulers of our world – the masters of power, sex, and suicide. In the end It does not quiet explain the meaning of life in the traditional terms but does put forward a very strong argument that life as we know it today owes a lot to those little symbiotes that inhabit every single cell in us. Yes, mitochondria has moulded and given direction to life on earth – from the first eukaryotic cell to the complex animals and finally to us. Without the mitochondria in us, we wouldn’t be here to be any the wiser.
Written in a lucid and conversational style, the book makes for very easy reading and even the hard concepts are put across in simple and sometimes quite entertaining style. The strength of the book is in how well planned and tied together it feels. The author knows which questions to ask when so as to lead us to the overall picture and he also knows how to deftly lead us on wrong routes so that when the real theory is revealed it has the whiff of truth to it and the pleasure of solving a detective puzzle.
Keeping with the ambition of the subtitle, the book grapples with some of the toughest questions known to evolutionary science – How did life originate on earth? How did organisms generate energy then? What conditions prevailed to make it possible? Can it be replicated in other parts of the universe? What was the nature of these first experiments in life? How did they evolve? How and when did life evolve beyond the bacterial stage? What was the crucial event that helped the first eukaryotic cell to evolve? Why were eukaryotes able to evolve into large and complex organisms in a fraction of the time that life existed on earth while bacteria remained stuck in an evolutionary rut? Why are bacteria immortals and eukaryotes mortal? How did sex originate for the first time among eukaryotes and why? Why are there two sexes in most known species, unicellular or multicellular? Why did eukaryotic cell come together to form colonies and eventually multicellular organisms? Why has evolution tended towards size and complexity ever since? Why did apoptosis or cell death evolve in multicellular organisms? How is the lifespan of organisms decided? Why do we age? Why do we die? Is there a way to extend our lifespans? Can we ever be truly immortal? Can the whole process be replicated in other parts of the universe? Can there be intelligent aliens?
Such are the wide variety of audacious questions asked and almost answered in this book and the astonishing thing for me was that it was not some five thousand pages longer with this sort of blindingly vast scope. And the answer to all these questions? As you might have guessed, it indeed is “Mitochondria”. How elegant that such a simple answer can be provided for such a variety of fundamental questions. One is almost tended to rekindle hope for the famous 42 now.
I had a full summary of the book prepared for this review which answered one by one all those questions I listed above, but now, as I am about to post it, I realize that I would be subtracting from the gradual suspense of the book that makes it such a joy to read by doing so. Instead, I would only like to point out a few of my issues with the book:
The author claims that the event of the fusion of the methanogens and the proteobacterium that gave rise to the first eukaryote is a very rare event and hence will not be replicated anywhere else in the universe, thus consigning most parts of the universe to a bacterial slime. The reason he advances for this is based on the fact that all eukaryotes derive from the same ancestor and this means that the the fusion that created this common ancestor happened only once in our entire evolutionary history. This is taken as proof concrete that the event of this eukaryotic creation/fusion is so statistically impossible that it has happened only once in the whole billions-of-years old history of the earth and that too only because it coincided with the oxygen enrichment of earth’s atmosphere at that time. This line of reasoning is then extended to argue that since this event is so rare and dependent on a number of steps one following the other, each of which are equally rare, the chances of complex life evolving anywhere else in the universe is next to zero.
This is a patently wrong argument in my view. The reason why the first eukaryotes were so successful was because they were able to/forced to move into the upper reaches of the ocean since all the competition was in the depths and their new chimeric nature allowed them to survive there. Since this was a blue ocean of no competition, they were able to exploit an entire new world of resources and grew and grew and grew and took it over. It was a literal gold rush for them. Now, imagine that in another billion years, another similar chimera was formed. The first chimera had a huge advantage that they were living in a vegetarian world where no one ate any other living being. But this new chimera, if it rises above to the oxygen rich world, which is now dominated by the carnivorous old chimeras and their monstrous descendants, would find a hostile world hard to survive in and will most probably also find itself someone’s easy dinner. The chances for any new chimera to survive is almost nil in this new dog-eat dog world. So on earth the first variety dominated and culled any new competition and this is the reason why another eukaryote never evolved. It is not because the event itself is statistically so unlikely. It is because the survival of such a chimera is statistically unlikely in a world already populated by other such eukaryotes capable of competing more effectively with a new eukaryote.
But, (and this is strangely overlooked by the author though it is firmly fixed in Darwinian principles) the fact that it did not happen a second time on earth in billions of years does not preclude the possibility that in another world where organisms are still primitive enough to be competing to eat external resources and not each other, a new chimera could evolve and move to uninhabited vastnesses where they would then use their eukaryotic nature to found another kingdom of life. It is entirely possible. So here is reassuring all alien buffs dejected by this book that universe has more to offer than mere bacterial slime on its menu.
- Minding Your Mitochondria (deeoconnor.wordpress.com)
- Sex born from hard rock and heavy metal (newscientist.com)
- Book Review: The Logic of Chance (books.slashdot.org)
- Mitiochondria Are Related to Ocean Bacteria, But Not to the Ones We Thought (blogs.scientificamerican.com)
- Oldest Human Ancestor Found in Lake Sludge (news.discovery.com)