Book SummaryThe Code Breaker, by Walter Isaacson

1-Page Summary1-Page Book Summary of The Code Breaker

How might the gene editing technology called CRISPR transform humanity? In his 2021 book The Code Breaker, Walter Isaacson discusses the advent and future of this groundbreaking scientific tool. He traces its development (focusing on the contributions of scientist and Nobel Prize winner Jennifer Doudna) and explores its significance as a victory for women in science. He also argues that CRISPR has the potential to change life as we know it and explains how, in some ways, it already has.

Isaacson is a journalist who served as the editor of Time magazine and CEO of CNN. He’s also a history professor at Tulane University and author of several popular...

The Code Breaker Summary Part 1: The Biological Process Known as CRISPR

CRISPR is short for “clustered regularly interspaced short palindromic repeats,” which refers to a repetitive pattern inside the DNA of some types of micro-organisms. It’s a natural biological feature that scientists discovered and used to facilitate gene editing. In this section, we’ll give some scientific background that will help you understand CRISPR. Then, we’ll explain how scientists discovered CRISPR in nature and figured out how it works.

Scientific Background

To help you understand CRISPR, Isaacson provides some scientific background information on three basic biological units: genes, DNA (deoxyribonucleic acid), and RNA (ribonucleic acid). Let’s explore those now.

Genes

Isaacson traces CRISPR’s development back to the proto-genetic theories of scientists Charles Darwin and Gregor Mendel in the mid-1800s. Darwin, who proposed the theory of evolution, argued that certain traits were passed down through generations via a process called natural selection. He thought reproduction occurred when tiny parts of both parents’ bodies migrated into the egg and sperm and then blended in the offspring, but this wasn’t quite correct. Mendel then showed that some_...

The Code Breaker Summary Part 2: Jennifer Doudna and the Scientists Behind CRISPR Technology

While many scientists played key roles in the development of the gene editing technology known as CRISPR, Isaacson focuses on Jennifer Doudna. (Shortform note: In an interview, Isaacson says that he chose to focus on Doudna because he was struck by her character and unique contributions to the field of biochemistry.)

In this section, we’ll explore how Doudna’s early life and career led her to help develop the CRISPR technology. We’ll also discuss the relative contributions of her colleagues and competitors. Finally, we’ll explain how CRISPR launched Doudna’s career.

Doudna’s Early Life and Career

Doudna was born in 1964 and spent the majority of her childhood in Hawaii. Because she was in the minority of white children there, she felt like an outsider, and she took refuge in Hawaiian nature. Isaacson explains that two adults in Doudna’s life nurtured her fascination with nature: A friend of her parents, who was a biologist, taught her some scientific basics during nature walks, and her father gave her a copy of _[The Double...

The Code Breaker Summary Part 3: CRISPR Presents Moral Quandaries

Now that you know what CRISPR is and how it came to be, let’s discuss what its advent means for society. First, we’ll discuss the moral quandaries CRISPR gene editing presents. Then, we’ll explain how scientists and policymakers have addressed them so far.

Germline Editing

Isaacson says that most people think it’s morally OK to edit somatic cells—non-reproductive cells that affect only an existing person’s bodily composition. But people disagree about whether it’s OK to edit germline cells, which include eggs and sperm. When you edit germline cells, you genetically modify potential future offspring, and the changes you make could be inherited by their offspring as well. Isaacson describes a few opinions on each side of the debate.

Some people who are against germline editing argue that it’s wrong because it’s heretical or unnatural—either God or nature (via evolution) designed our genes the way they are for a reason, so humans shouldn’t interfere. Isaacson says this argument may not be logical: If nature or God endowed us with the ability to develop and use CRISPR, then using it can’t be unnatural or heretical. He also notes that genes aren’t...

The Code Breaker Summary Part 4: CRISPR Applications

Regardless of the as-yet-unresolved moral quandaries that CRISPR presents, research involving CRISPR marches on full steam ahead. In this section, we’ll discuss CRISPR’s many applications—some that have already been realized and some that are yet to come.

Realized Applications of CRISPR

Isaacson describes many realized applications of CRISPR, but we’ll focus on three of the most momentous ones here.

First, in 2019, a Chinese scientist named He Jiankui created the first designer babies (modified humans created via germline gene editing). When the three babies were embryos, he edited a gene they had called CCR5, which makes you susceptible to HIV infection (but also protects you from West Nile Virus). The experiment was controversial because he blatantly disregarded the agreement science policymakers had made to pause germline editing. He faced international criticism and was convicted of criminal charges in China. His experiment led Doudna and other scientists to make a statement denouncing his actions and laying out guidelines for safer future experimentation with germline editing.

Second, CRISPR has been applied as a medical intervention in the form of **somatic...

Shortform Exercise: What’s Your Opinion on CRISPR Quandaries?

CRISPR is already changing the world in significant yet controversial ways. Reflect on what you make of the moral quandaries CRISPR presents.

Think back to the arguments Isaacson lists for and against germline editing. How do you think germline editing could transform the world? Do you view these transformations positively or negatively, and why?