Review of "Why Fish Don't Exist"

Note: This was my entry for the 2023 Astral Codex Ten book review contest. It didn’t make it to the round of finalists, but hopefully De Novo subscribers will appreciate it more.

I. The Categories

In one of my all-time favorite Slate Star Codex posts, “The categories are made for man, not man for the categories”, Scott Alexander uses the example of whales and fish to show the futility of insisting on a single system of categorization in all contexts:

Suppose you travel back in time to ancient Israel and try to explain to King Solomon that whales are a kind of mammal and not a kind of fish. Your translator isn’t very good, so you pause to explain “fish” and “mammal” to Solomon. You tell him that fish is “the sort of thing herring, bass, and salmon are” and mammal is “the sort of thing cows, sheep, and pigs are”. Solomon tells you that your word “fish” is Hebrew dag and your word “mammal” is Hebrew behemah.

…

In fact, the only thing Solomon cares about is whether responsibilities for his kingdom’s production of blubber and whale oil should go under his Ministry of Dag or Ministry of Behemah. The Ministry of Dag is based on the coast and has a lot of people who work on ships. The Ministry of Behemah has a strong presence inland and lots of people who hunt on horseback. So please (he continues) keep going about how whales have little tiny hairs.

In this example, whales are not fish biologically, but it makes practical sense to consider them as fish. Categories can, and should, be re-interpreted to fit people’s needs in different contexts.

It’s a great example, so it’s such a shame that it’s wrong.

Why Fish Don’t Exist is a book about categorization and its flaws, so it is therefore fitting that the book itself defies categorization. The best I can say is that it’s partly a biography of David Starr Jordan (taxonomist of fishes and founding president of Stanford University), partly an overview of the history of taxonomy and eugenics, and partly an account of the author Lulu Miller’s personal journey as a science writer and human being. These themes are interleaved to tell a story about how we define categories, and how they can define us.

II. A Rising Starr

The story begins in media res: the life’s work of David Starr Jordan — his fish collection — has just been smashed by the Great San Francisco Earthquake of 1906. Although much was destroyed, Jordan remained undaunted. As he picked each fish up from the floor, he stitched a tag onto it to ensure that it would remain properly categorized, even if the chaos of the world again commingled it with the others.

On an orchard in upstate New York, a boy named David was born to farmers Hiram and Huldah Jordan in 1851. As a child, David Jordan displayed an early knack for learning the names of things: stars, countries, flowers. He chose his middle name, Starr, for himself after memorizing all the stars in the night sky. But in rural New York, there were few who cared for taxonomy – especially not his Puritan parents.¹

After studying at Cornell University from 1869–1872 (which the book glosses over in a single sentence), Jordan taught science at several Midwestern high schools and small colleges, but he was unsatisfied with this work. Thus, he eagerly took the opportunity to attend a training camp hosted by the renowned naturalist Louis Agassiz in the summer of 1873. The camp was on Penikese Island, off the coast of Massachusetts, and it was here that Jordan’s love for fishes began. Here too, Jordan fell in love with Susan Bowen, his first wife.²

Like Jordan, Louis Agassiz saw the importance of taxonomy. For him, taxonomy was not only a science, but a means of understanding God’s will: “hiding in nature was a divine hierarchy of God’s creations that, if gleaned, would provide moral instruction”. For example, lizards “score higher than fish because they bestow greater care upon their offspring”. The overall idea was basically to provide scientific proof for the Great Chain of Being, a concept from medieval philosophy that ranked God’s creations. Agassiz also strongly supported polygenism, the idea that different races of humans were created separately and existed in a fixed biological hierarchy. Notably, Agassiz never accepted Darwin’s theory of evolution, and when he died in December 1873, he was still an ardent creationist. As the truth of evolution became clearer, Agassiz fell out of favor with the scientific community.³ But at the time, he was as well-regarded as David Attenborough today.

Attending Agassiz’s camp marked a transition in Jordan’s life. Although he was still an itinerant science teacher, his new passion for fishes drove him to catalog the contents of local lakes and rivers everywhere he went. He soon gained the attention of the U.S. government and was asked to lead taxonomic surveys of the fishes of America. In 1879 Jordan became a professor at Indiana University, and rose to the rank of president in 1885, at the young age of 34. In 1891, Jordan was recruited by Leland and Jane Stanford as the founding president of Stanford University, which opened that year.

 III. The Author

Compared with David Starr Jordan, the author’s life is less interesting, but a few things are noteworthy. Her father, a biochemist, was her first philosophical influence. He explained the fundamentally uncaring nature of the universe: “as special as you might feel, you are no different than an ant. A bit bigger, maybe, but no more significant”. Although he believed that life lacks inherent meaning, he was nonetheless determined to make the most of it, and the author “strived [her] whole life to follow in his nihilistic, clown-shoed footsteps”.

However, she found such an outlook can be demoralizing, and that a small amount of “positive illusions” can work wonders for motivation.⁴ In Chapter 8, the author explores the delicate balance between realism and self-deception, noting that David Starr Jordan, always rational in his scientific writing, framed many of his failures as accomplishments in his memoirs. In her own life, the author tried to find this balance, acknowledging the indifference of the universe and its relentless slide towards entropy, while not giving up hope.

Finally, the author’s bisexuality shaped how she viewed categories as confining. After being lonely and depressed in high school (even to the point of attempting suicide), she fell in love with a man in college. However, she later cheated on him with a woman, which destroyed their relationship. After several years of soul-searching, she eventually came to terms with her sexuality and married a woman, who helped her to see “the world for what it is, a place of infinite possibility. All categories, imaginary.”

As the author sees it, categorization is an attempt to control the Chaos of the universe. Chaos, we all know, is the thing that will inevitably destroy everything and everyone we love. It strikes suddenly as an earthquake, or creeps slowly as a cancer. But for all the trouble Chaos causes, it is also a source of creativity, and sometimes even beauty. Categorization is beneficial when used to tame Chaos in limited contexts. Nonetheless, attempting to impose a perfect categorization on all the Chaos of the world is worse than futile, it’s a mistake.

IV. Jordan at Stanford

David Starr Jordan’s appointment as the first president of Stanford gave him great power to lead scientific advances, but also the temptation to abuse this power. Jordan’s first move was to hire his friends to fill out the faculty, order the construction of a marine research facility, and erect a statue of his hero Louis Agassiz above its entryway.

The statue was toppled by the earthquake of 1906, and its replacement was removed in 2020 following protests. 

He also took full advantage of the financial resources provided by the Stanfords, commissioning fish-finding expeditions across all the waters of the world. His research group would eventually catalog over 2500 species of fishes, making up a fifth of all known species at the time.

However, tension soon grew between him and Jane Stanford. He had a profound distaste for pseudoscience and criticized her interest in spiritualism. She thought he was wasting money chasing exotic fishes. In 1901, Jordan covered up an affair between a professor and a student by threatening the librarian who discovered it. However, the scandal was discovered by another professor, Julius Goebel, who reported it to Jane Stanford. Goebel also accused Jordan of nepotism, and of running the university like a gang. By 1904, Jane Stanford was preparing to replace Jordan, denouncing his “moral shortcomings” in a letter to the university trustees.

Conveniently for Jordan, Jane Stanford died under mysterious circumstances in early 1905 while on vacation in Hawaii. Although the coroner ruled that she was poisoned by strychnine (based on considerable evidence, including finding strychnine in her baking soda), Jordan fiercely promoted the alternate theory that she died of heart failure triggered by excessive food consumption at a picnic. Although Jordan may not have been behind the poisoning, he certainly did his best to cover it up. Shortly afterwards, Jordan fired Julius Goebel, the professor who had denounced him. This, however, was a step too far. The university trustees soon rescinded his power to fire faculty, and would later remove him from the position of president in 1913.

From the end of his Stanford presidency until his death in 1931, Jordan became one of America’s most fervent proponents of eugenics. He published books: The Human Harvest, The Blood of the Nation, Your Family Tree, and went on speaking tours. Jordan was also an ardent pacifist, because he believed that war killed the strongest men, leaving the less fit to reproduce.

 V. On Eugenics

Why Fish Don’t Exist presents eugenics as bad science and bad policy, and the eugenicists as thoroughly immoral. However, this view avoids answering an interesting question, one that is relevant even today. The eugenicists of the early 20^th century firmly believed they were doing the right thing, so what led them so far astray?

Certainly, they had a flawed understanding of human genetics. They incorrectly believed that undesirable traits could be explained by a few recessive Mendelian variants, and worse, they allowed racism to dominate science. Was the “feeblemindedness” of immigrants really genetic, or because they struggled in a culturally and linguistically unwelcoming educational system? However, over the past few decades, research has conclusively shown that many socially important traits, including intelligence, are indeed heritable to a large extent.⁵ Therefore, applying selection pressure with respect to these traits would shift their distribution in the population over time. A eugenicist would select humans in the same way dairy farmers have selected cattle for better milk production.

Source. Since the publication of that graph, even more progress has taken place.

Thus, I consider that the errors of the eugenicists were primarily ethical, rather than scientific. It is easy to speak of “applying selection pressure” while ignoring its human cost. For the record, I believe that any coercive interference with reproductive choice, such as involuntary sterilization, is morally abhorrent.⁶ It is wrong today, and it was wrong then.

But there’s no avoiding an ugly truth: I am quite confident that, had I lived 100 years ago, I would have supported the eugenics movement. Not only was it backed by the cutting-edge science of the time, it also promised to achieve a noble goal: the permanent improvement of humanity’s genetic heritage. It is only modern technology that offers a more humane way to reach this goal, without recourse to mass sterilizations.

Although I may have been uneasy about the means employed, I probably would have been convinced by the same arguments that convinced others, including top scientists and progressive politicians:

•  “These people don’t really want to have kids anyway, and couldn’t properly take care of them if they did.”

•  “A glorious future is worth a temporary sacrifice”

•  “Three generations of imbeciles is enough”

At best, I would have been like the famous geneticist T. H. Morgan, who initially supported the eugenics movement, but turned to criticize it after realizing its flaws.

Therefore, I cannot really blame David Starr Jordan for believing in, and advocating for, eugenics as a means to improve humanity. His main fault here was overlooking the tragic cost of forced sterilizations, which was easy to ignore once he categorized certain humans as “unfit”.

Why Fish Don’t Exist suggests that David Starr Jordan’s obsession with taxonomy was what led him to support eugenics. Classifying and ordering the natural world according to a scala naturae⁷ running from “lower” to “higher” organisms may have led Jordan to think in a similar way about people. In my opinion, this explanation is probably too simplistic – after all, many scientists who weren’t taxonomists supported eugenics. But I agree that categorization of humans into “fit” and “unfit”, one of the key concepts of the eugenics movement, was inspired by taxonomic categorization of the natural world. And as I mentioned above, once people were labeled “unfit”, it was much easier to justify sterilizing them.

To better understand the pain and injustice caused by forced sterilizations, the author visited the ruins of the notorious Virginia State Colony for Epileptics and Feebleminded, and interviewed two of its survivors, Anna and Mary. Anna was interned in 1955 at age seven, horrifically abused for the following twelve years, then sterilized and released at age nineteen. Mary also spent much of her childhood institutionalized alongside Anna, although she managed to avoid sterilization. Anna and Mary supported and protected each other as best they could, and even today remain close friends, living together in an apartment just a few miles from the old Colony. Although Anna’s dream of having children was stolen from her, she carries a doll, “Little Mary”, everywhere she goes. I get the impression that Anna and Mary, if ranked on a list of Contributors to Society, wouldn’t be near the top, but their lives are still very much worth living. In fact, their heartfelt friendship for each other should be an example for the rest of us.

VI. Giving up the fish

If categorization leads to injustice, then what is the alternative?

Trenton Merricks, a philosopher whom the author interviewed, rejects the concept of categories entirely. To him, for example, there’s no such thing as a “chair”, merely a set of atoms. But for most people, this is going too far. Even if no system of categorization can fully capture the chaotic complexity of the universe, categories are still powerful tools for thinking and communicating.

But which categorizations should we use?

Here we return to David Starr Jordan and the taxonomy of fishes. Jordan and his subordinates discovered over 2500 species of fish, and it was his life’s work to name and categorize them. Little did he know that taxonomically, fish don’t exist.

Taxonomy has progressed quite a long way since the days of Linnaeus and the scala naturae. Although taxonomists since Darwin had tried to group organisms by common descent, as molecular biology became more advanced, it was clear that many of the traditional groupings were incorrect. By the 1980s, biologists had settled on a rigorous definition of taxonomy in terms of clades, which are all the descendants of a single particular ancestor.

A phylogenetic tree of vertebrates (source) 

But, as shown in the phylogenetic tree above, “fish” are not a clade. Any valid clade that encompassed all “fish” would also have to include pigeons, wombats, and yes, whales.⁸ “Fish” is similar to “tree” in that the term describes a particular shape of organism, not a group descended from a common ancestor.

Why Fish Don’t Exist explains:

Still confused? Picture it another way. Imagine that for millennia we silly humans incorrectly believed that all creatures that lived on mountaintops were members of the same evolutionary group, called "mish." The fish of the mountain. Mish. Okay. So mish includes mountain goats, and mountain toads, and mountain eagles, and mountain men-burly and bearded and enjoying their whiskey. Now let's just pretend that, even though all these creatures are incredibly different from one another, they all happened to evolve a similar protective outerwear to survive at that altitude. Let's imagine that outerwear is not scales but plaid. They are all plaid. Plaid eagles. Plaid toads. Plaid men. Such that they appear, what with their habitat (mountaintop) and their skin type (plaid), to be the same kind of creature. They are mish. We falsely believed them to be all of a kind. We have done the same thing with fish — subjugated a world of nuance down into the word "fish."

In taxonomic terms, the category “fish” is paraphyletic, meaning that it’s missing some of its members. It’s possible to carve up “fish” into several valid clades, but grouping all fishes together is taxonomically incorrect. “Fish” might be a valid category for a fisherman or a government minister, but not for a scientist.

Why Fish Don’t Exist uses “giving up the fish” as a metaphor for looking beyond a comfortable categorization of the world and seeing its underlying complexity. Even though the category “fish” seems natural and reasonable, as the author puts it, “a category is at best a proxy; at worst, a shackle.” Although it’s inevitable for people to place the world into categories, trading an ill-fitting categorization for a better, more nuanced one can lead to important insights. 

“Giving up the fish” can mean different things for different people. For taxonomists, it led to new insights and a sense of purpose. For the author, it led to a better understanding of her own sexuality, as well as personal growth. For a certain psychiatrist, it led to a pragmatic treatment for a woman’s OCD.

So, what will you get when you give up the fish?

1. Jordan’s own score on the Puritan checklist is a respectable 27, by my count. +1 for upstate NY, +1 for four siblings, +2 for weird Biblical names in family, +3 for achievements in diverse fields, +3 Wrote a book about heterodox religious views, +3 for really weird books, +3 Social reformer, +3 Supported Prohibition, +3 Founded their own school (I’m going to count Stanford), +3 Ideals that were utopian yet racist, +1 Pacifist yet war supporter (though not “rabidly”, so doesn’t earn +3). +1 for moderately weird hair.

2.  She died of pneumonia in 1885; in 1887, Jordan re-married, to a 21-year old student at Indiana University.

3. And today there’s a strong push to remove Agassiz’s name from things, for example from a neighborhood in Cambridge MA.

4. Crucially, a small amount. Here, the author takes some humorous jabs at Angela Duckworth’s concept that “grit” and self-esteem can overcome anything.

5. For a good review of the science and its social implications, see The Genetic Lottery, a recent book by Kathryn Paige Harden.

6. The same applies for restrictions on abortion, which are today’s controversial topic in reproduction.

7. Latin: “ladder of nature”. Is the Tierzoo Youtube channel, which I have greatly enjoyed, a slippery slope towards eugenics?

8. But not bees. Sorry, California.