Single-celled organisms like bacteria did (and still do) really well for two and a half billion years with very little change in form. Why did some bacteria then make the jump to complexity on just one occasion in four billion years? Why did some bacteria become endosymbionts of archaea? Vital Question: Energy, Evolution, and the Origins of Complex Life by Nick Lane seeks to answer these questions. The book reads like one-long hypothesis in which Lane makes the case that the answers to these important questions had to do with energy. The whole book argues that energy is connected to evolution.
The following are many “sub” questions about eukaryotic cells that Lane attempts to answer throughout the book:
- Where did all the “parts” of a typical eukaryotic cell come from?
- How and why did the nucleus evolve?
- Why do just about all eukaryotes have two sexes?
- Where did the extravagant internal membranes come from?
- How did the cytoskeleton become so dynamic and flexible?
- Why does sexual cell division, or meiosis, halve the chromosome numbers by first doubling them up?
Lane initially explains to the reader what constitutes life. He then goes through the origin of life and how energy was involved in a detailed manner. Finally, Lane discusses the idea of cell complexity and some of his predictions. In this journey of a book, the reader accumulates lots of interesting information, some of which are included in the following:
- A single cell consumes around 10 million molecules of ATP every second!
- As far as energy output, life is more like a rocket launcher that a candle.
- All life is driven by redox chemistry.
- One mitochondrion contains tens of thousands of copies of each respiratory complex. If you took the combined surface area of all the mitochondria in your body, it would cover 4 football fields!
- Energetically speaking, enzymes are not powerful because they speed up reactions, but because they channel their force and maximize the output.
- Different genes in the same eukaryotic organism do not all share the same common ancestor.
- Eukaryotes have close to 200,000 times more energy per gene than prokaryotes.
- The benefits of sex are greatest when the mutation rate is high, selection pressure is strong, and there is a lot of variation in a population.
Lane shows that the simplest possible scenario for the origin of eukaryotic cells/organisms was a single chimeric event between a host cell (archaea) and an endosymbiont (bacteria). Even though the reading is technical, this book is very much worth it to work through.