5 books that changed our understanding of the origin of life

Before starting kindergarten, most children are already asking where babies come from. The question comes naturally to children, courtesy of their innate curiosity about the world and themselves. As such, is it any wonder that humanity has collectively wondered about the origins of life itself for millennia?

The traditional answer held by many religions is that life requires a divine spark to get going. These takes often argue that life was created fully formed — as is, with no need for change over time — and a creator handcrafted each creature. Conversely, spontaneous generation, the idea that life just happened to happen, dates back to Anaximander, a pre-Socratic Greek philosopher who lived in the 6th century B.C. He and a few other Greek philosophers even accepted that life could change over time in response to outside forces.

Debate over where life came from and where it’s going, if anywhere, continues to this day. Many thinkers have provided possible solutions, each landing between meticulously planned creation and blind randomness. However, only in the last few hundred years have scientists built an empirical case for the origins of life on Earth.

Here, we’ll examine five books that moved the debate forward by deepening our understanding of where life comes from and where it may go.

Theory of the Earth by James Hutton (1788)

The question of why the Earth has its current form has been popular historically. Creation myths are a feature of nearly every culture. Early science and philosophy also focused on this problem. Thales, the first philosopher, famously attempted to find the first principle of the material world. As such, before understanding the origins of life, scientists needed to understand the planet we live on.

Modern geology truly begins with the work of James Hutton, a Scottish polymath working in the 18th century. At the time, the leading geological theories in the West assumed that the Earth was young — a few thousand years old or so — and geological features were explained by catastrophism. This theory claimed that for changes to occur, catastrophes occasionally reshaped the face of the Earth and caused some species to go extinct.

In his publications, particularly Theory of the Earth, Hutton goes the other way. He argued that observed geological features could be better explained by assuming the Earth was ancient and that its surface changed gradually over time. Years of empirical observation, he spent 25 writing the book, backed these arguments.

One of the more significant ideas he argued for was uniformitarianism, the then not-fully-established notion that natural laws are the same everywhere and have always existed. Uniformitarianism proved key to his idea that gradual changes drive geological features (rather than sudden catastrophic shocks). He also mused on the evolution of life and even proposed an early version of the mechanism of natural selection.

Unfortunately, the book’s reception was hampered by Hutton’s laborious prose. Its central ideas were not widely considered for several decades when other geologists reworked them into their own, much easier to grasp, models. Even then, the concept of natural selection didn’t make it into these later works. Today, the scientific community takes many of these ideas for granted. Uniformitarianism, in particular, is no longer seriously debated.

On the Origin of Species by Charles Darwin (1859)

Hutton gave us a sense of how the planet changes, but what about life? While ideas about life evolving date back to Aristotle, they didn’t catch on until the 19th century. Erasmus Darwin, grandfather of the Darwin you know, argued for a version of evolution. Jean-Baptiste Lamarck famously advocated for an evolutionary model that bears his name today. However, these ideas were stalled by the lack of empirical evidence and the inability of these early models to adequately explain the endless forms of life that are most beautiful and wonderful in the world.

It was not until 1859 that a scientist delivered the best explanation of evolution in one of the most famous books ever published. Today, On the Origin of Species is not only the foundation of evolutionary biology. The ideas presented in the book have shaped all of modern biology.

Its author, Charles Darwin, traveled on the HMS Beagle in 1831 as a scientist during its five-year voyage. Initially brought on for his expertise in geology, he also collected countless specimens, fossils, and notes for further analysis in England. The sights and events of the voyage convinced him of the accuracy of geological models postulating change over time. Charles Lyell’s Principles of Geology, which argued for uniformitarianism, influenced Darwin greatly.

Darwin spent the better part of the next twenty years writing On the Origin of Species, working on the book between other projects and planning for it to be airtight upon release. He only published when another scientist, Alfred Russell Wallace, was on the verge of releasing a similar work. They agreed to present what they had immediately as a joint publication, and shortly after, Darwin released what text he had as one of a series of books on evolutionary biology.

On the Origin of Species introduces several foundational ideas to biology. He argues that the main drivers of evolution are natural selection — the tendency of a species with traits best suited for a given environment to survive and pass those traits on — and sexual selection — the role of mate choice in determining which traits get passed on. As most creatures have more offspring than can survive and reproduce, these two mechanisms explain how individuals succeed in a competitive environment. The book is also the origin point for the idea of a common ancestor from which all subsequent species evolve. Given Darwin’s extensive data collection efforts and superb reasoning skills, this version of evolutionary theory took off where its predecessors did not.

Written in an accessible style, On the Origin of Species has been widely read since its release. It has also proved controversial to those with beliefs challenged by Darwin’s findings. While he avoided much of the debate surrounding the book, partly due to his enduring and mysterious illness, it has been alternatively praised, banned, celebrated, and condemned over the past 150 years.

While briefly eclipsed by other notions of evolution and adjusted over time to integrate with new findings, modern biology now rests on Darwin’s foundations and the laws of natural selection.

“Experiments on Plant Hybridization” by Gregor Mendel (1865)

Accepting the theory of evolution by natural selection had some early problems. One was the question of how exactly the inheritance of traits worked. While selecting favorable features in plants and animals is an ancient practice, the laws of inheritance emerged only recently. For these, the world needed the services of a botanist monk and his thousands of pea plants.

Gregor Mendel was an Austrian monk and botanist working in the middle of the 19th century. Over seven years of experimentation, Mendel worked out the patterns that governed the inheritance of certain traits in pea plants. Through careful observation of seven pairs of traits over successive generations of plants, he discovered what is now known as Mendelian inheritance. Concepts like dominant and recessive traits can be traced back to his experiments.

These laws addressed a problem inherent to the early version of Darwinian evolution. Darwin proposed something called “blending inheritance,” where children’s traits are a mix of their parents. For example, a tall man and a short woman would be expected to have kids of average height. However, this isn’t what we see in real life — the children would tend to be tall instead. This break from observation constituted a real problem, as some critiques of Darwin pointed out that blending inheritance would mean any evolutionary advantages would be averaged out with negative traits after a few short generations.

Mendelian inheritance presumes that traits do not blend. Instead, they are particulate. A creature either has the trait of being red, or it does not. Mendel presented his findings in 1865 and published them shortly after. While technically a paper rather than a book, the importance of “Experiments on Plant Hybridization” cannot be overstated.

However, his findings were initially given little thought. The paper earned only three citations in the first few decades after publication, and Darwin was likely never aware of it. Only after the dawn of the 20th century did the paper receive the attention it deserved, and the science of classical genetics took off.

What Is Life? The Physical Aspect of the Living Cell by Erwin Schrödinger (1944)

Even Mendel’s findings didn’t fully resolve the problem. While they give structure to how traits perpetuate, they still don’t explain how this happens. Even if we understand that mixing a white and a purple flower will give us seeds that grow into purple flowers, his findings don’t reveal how that process works inside the plant. The first person to accurately propose what this mechanism ended up being was the noted physicist Erwin Schrödinger.

Schrödinger was already quite famous for his work in quantum physics. In addition to the equation that bears his name, he had already identified possible problems with the Copenhagen interpretation of quantum physics with a thought experiment involving a rather (un)lucky cat. In 1938, the Austrian Schrödinger fled to Ireland in response to the Anschluss and gave a series of lectures at Trinity College, Dublin, in 1943. These were later reworked into a book, What Is Life? The Physical Aspect of the Living Cell.

The book explores how heredity information could work within the bounds of physics and biology. Schrödinger begins by discussing how ordered natural laws are often the result of chaotic action at the microscopic level. Notably, he looks at how classical physics could not entirely provide some requirements for the “hereditary mechanism.”

Subsequent chapters examine how it would be possible to have an enduring molecule that is stable enough to hold genetic information and small enough to fit into the cell. Schrödinger then examines the potential problems of this model by comparing it with the known facts and concludes that it could work. Later chapters turn philosophical and fully displayed Schrödinger’s interest in Hinduism.

While DNA was known to exist at the time, its importance, function, and shape were not. Only in the subsequent decades did scientists like Rosalind Franklin, James D. Watson, Francis Crick, and Maurice Wilkins illuminate the molecule’s significance. Controversially, Watson, Crick, and Wilkins were the only ones to win a Nobel Prize for the discovery. They would all acknowledge the influence of Schrödinger’s ideas in their work.

Cosmos by Carl Sagan

Uniquely among the books on this list, Cosmos is not a book describing a discovery. It is a popular science book accompanying Carl Sagan’s well-regarded television program of the same name. However, this does not mean that it is unimportant.

Sagan was an American astronomer, professor, and science communicator. Holding a post at Cornell University (among other institutions), he found the time to put together the Voyager Golden Record, brief the Apollo astronauts, and correctly propose that Venus’ extreme climate resulted from a greenhouse effect run amuck.

He is best known as a science communicator and public figure due to the extreme popularity of his writings and television appearances. Of these, none compare to Cosmos.

Sagan was asked to co-write and present Cosmos: A Personal Voyage, and he simultaneously wrote the companion book. The book has 13 chapters, each corresponding to an episode of the show. These chapters focus on topics such as cosmology, evolution, civilization, and the nature of science. Each chapter (and, for that matter, TV episode) is presented accessibly while still providing a deep dive into the subject matter.

While it may not have pushed human knowledge further into the unknown, it certainly changed how millions of people viewed the world around them. It does so without needing other books as filters, as was the case for James Hutton. Its accessibility and mass appeal sent it to the top of the best-seller lists. It was the top-selling popular science book of all time until it was surpassed by Stephen Hawking’s A Brief History of Time (though more people may probably finished reading Cosmos.)

All prominent science communicators in the United States, including Sagan’s students Bill Nye and Neil deGrasse Tyson, owe a debt to Cosmos. For anyone first getting into science, this book can shape their understanding of the origin of life and their place in the world.