DEE WILSON CONSULTING
Book Review:
Fascinating Story of Earth's Development
Becoming Earth: How Our Planet Came to Life
Ferris Jabr, 2024
This is one of the best books I read in 2024 on any subject. I initially found Becoming Earth through the local library. After reading it, I purchased the book and reread it, underlining as I read. Jabr's book is that good. It is packed with surprising information regarding the Earth's development and has a challenging, important theme, i.e., that life on Earth (in the aggregate), in dynamic interaction with geological processes, has transformed our planet's atmosphere, crust, soil, oceans and temperature, and in doing so, has shaped the world in which biological natural selection operates. Jabr tells this scientific story with admirable clarity and with frequent references to James Lovelock's Gaia hypothesis, which maintains that the Earth as a whole is a living organism that acts with intention to support life. Jabr disagrees with Lovelock's version of Gaia, e.g., he does not believe that Earth seeks an "optimal" state for life, or that Gaia acts with intention. However, after reading Jabr's detailed discussion of how life has shaped the Earth in multiple ways, I'm not clear how or that what has occurred in Earth's history rules out intentionality.
In Jabr's discussion of how Earth became a habitable world for current life forms, the most important early development was the oxygenation of the atmosphere. Jabr asserts: "When Life emerged several billion years ago it changed much more than the weather ... microbes initiated an aerial transformation ... bit by bit life altered the chemical composition of the entire atmosphere. Life created the air we breathe today." Prior to this transformation, "the atmosphere was most likely composed of carbon dioxide, nitrogen, water vapor, methane and trace amounts of ammonia, with almost no free oxygen (O2). To our eyes, the sky would probably have appeared a murky orange... Today, oxygen comprises 21 percent of the atmosphere. "The oxygenation of Earth was protracted, patchworked and pulsed -- an extended revolution that took nearly two billion years. .. Earth's oxygen rich atmosphere is inextricably linked to what is arguably the single most important evolutionary innovation in the history of our living planet: photosynthesis." ( p. 163) "At some point between 3.4 and 2.5 billion years ago, blue green microbes known as cyanobacteria developed a radical new version of photosynthesis, which took advantage of highly abundant resources, spinning sunlight, water and carbon dioxide into sugar and releasing oxygen as a by product" (p. 164), Jabr states. After hundreds of millions of years, some cyanobacteria were assimilated into mitochondria, "the so-called "powerhouse" of the cell. Bean-shaped, energy- generating mitochondria are found in the cells of all complex, multicellular creatures today," (p. 166).
The oxygenation of the atmosphere was a slow process. According to Jabr, "For about a billion years after the Great Oxygenation Event, the level of oxygen in the Earth's atmosphere and oceans remained a fraction of what it is today, i.e., 21%, a percentage that (due to unexplained causes) has remained stable for the past 55 million years. The oxygenation of the atmosphere led to the extinction of most organisms that could not tolerate high levels of oxygen, and greatly increased the metabolic efficiency of organisms adapted to an oxygen rich environment. Jabr states: " By adapting to breathe oxygen, organisms increased their metabolic efficiency by a factor of nearly eighteen, which may have increased the the development of more complex, energy-hungry cells, big bodies and all manner of corporeal embellishments." (p. 166)
In Jabr's account, the leading actor in Life's transformation of the Earth's atmosphere, crust, soil and oceans was microbes, tiny organisms that exist in inconceivably large quantities, some of which may live for millions or hundreds of millions of years. ( p. 11) Jabr states: "a tablespoon of healthy soil easily holds a population of organisms many times the number of humans alive today. A single gram of fertile soil may contain billions of microbes and viruses, millions of protozoans and algae ... " ( p. 62) A species of cyanobacteria, Prochlorococcus, " turned out to be the tiniest and most abundant photosynthetic creature on the planet. There are an estimated twenty thousand Prochlorococcus cells in a drop of seawater - and three octillion on Earth," (pp. 84-85), Jabr asserts. Trees' bark and animal skin and fur "teems with trillions of microbes." (p. 191)
Microbes are critical to the nitrogen cycle, the gas that comprises 78% of Earth's atmosphere. Jabr states: " Microbes are critical to this cycle: bacteria and other microbes are the only organisms that have evolved enzymes with the ability to cleave nitrogen and turn it into biologically useful molecules ... All complex life depends on the chemical wizardry of these nitrogen-manipulating microorganisms." ( p. 55)
Over hundreds of millions of years, microbes created plant friendly soil out of the Earth's crust: " When microbial life emerged, it undoubtedly began to alter the composition of the earth's first soils," ( p. 59) by chewing through rocks "to extract their mineral components, turned those minerals into new compounds and added carbon to the soil ..." (p. 59). In addition, "once microbes and fungi evolved the ability to digest tough plant tissues like cellulose and lignin, decomposing vegetation became one of the most important components of soil, reinvigorating it with essential nutrients, " ( p. 60) Jabr writes. Jabr also discusses the possibility that microbes played a role in the shaping of continents.
Given the astonishing effects of microbes on the transformation of Earth's atmosphere, the creation of top soil and life rich oceans, and possibly the terraforming of continents, it is disappointing that Jabr's book does not contain an in- depth discussion of the influence of microbes on gene development ( if not their creation) through gene transfer. Lynn Margulis was ridiculed decades ago for proposing that gene transfer, as well as reproduction, had an effect on the evolution of genes; but Margolis lived to have the last laugh. There is currently agreement that gene transfer between and among bacteria was a common factor in the early evolution of life. Bacteria are intelligent; they act in concert and their actions express intentions by any reasonable definition of intention.
Jabr's major theme is that " ... far from being passive, Earth and its constituent creatures are agents in their own evolution. Earth is a garden that sowed itself, nurtured itself, and through sentient life forms, eventually became aware of itself ..." (p. 74). Jabr acknowledges that life on Earth has experienced numerous catastrophes, some induced by humans. For example, Jabr asserts that early humans wiped out billions of megafauna ( very large animals) on multiple continents over a period of 30,000 years or more. He writes: "When humans populated the Americas between 15,000 and 7,000 years ago, more than eighty species weighing at least one hundred pounds each vanished." ( p. 28) There have been several extinctions of most biological species caused by global warming, though Jabr asserts there has never been a period in Earth's history when global warming occurred with the rapidity of what has happened since 1750. Prior extinctions due to global warming occurred over many thousands or millions of years, not a few hundred years.
Jabr acknowledges that humans are currently warming the planet in a way that threatens human survival and the survival of most other species, but believes that the worst case scenario will be avoided due to available technologies. Whatever the outcome of our civilization's reckless gamble with its survival and human disregard for the many thousands of species that have already been wiped out or threatened by the actions of humans, Jabr finds hope in the expectation that at least microbes will survive; and that after thousands or millions of years, Earth will be repopulated with other types of life. I find this cheerful thought cold comfort. Jabr makes clear that the self regulating capacities of Earth -- the Gaia hypothesis -- occur over millions of years. Gaia cannot save humans from self destruction, but I wonder if an intentional Gaia would go the trouble if it could, given humans' role in an ongoing sixth extinction of biological species.
Jabr asserts that James Lovelock believed that AI cyborgs will, in the foreseeable future, take over governance of the Earth, and will treat humans as pets! If so, perhaps the future of Earth will be decided by cyborgs and microbes, an interesting alliance, on a very hot planet.
Jabr lives in Portland, Oregon.
-- Dee Wilson