WWhen he has time, Jan Mees works to correct mistakes in science.
A marine biologist, Mees leads the Flanders Marine Institute in Belgium and also works with a group of volunteer scientists on building a World Register of Marine Species, a database fact-checking scientific names for aquatic life. Surprisingly, instead of adding to the register, they end up removing a lot of entries.
After examining 418,850 species, the project has eliminated 190,400 of them—more than 45 percent—as redundant. The species felis and Triakis semifasciataand the leopard shark are actually the same. Octopus rooseveltiiwas named in 1941 as a tribute to then-president Franklin Delano Roosevelt, but it already existed as Octopus oculifer, named in 1909. Previous generations of marine biologists may have unknowingly studied the same species under different names.
Ultimately, 24 to 31 percent of all current species names will eventually be discarded as redundant.
In the 19th century, biologist Louis Agassiz named North American species without strong evidence or scientific rigor, creating many over-classifications.
Agassiz declared three new genera of fish based on fossilized teeth, which were later found to belong to the same individual fish. Many of Agassiz’s species identifications have been abandoned for similar reasons.
The shore-dwelling sea snail known as Litteronia saxatilishas been mistakenly identified and named as a separate species or subspecies 112 times since 1792. The World Registry of Marine Species has corrected these errors and updated the scientific literature.
The rough periwinkle, or Litteronia saxatilis has been extensively misidentified due to the emphasis on appearance and the difficulty of reviewing scientific literature before digitization and database searches.
Why are there so many duplications?
Most duplications are due to minor physical variations being seen as novel species, obscured discoveries, or overzealous imaginations seeking recognition.
John Alroy, a paleobiologist at Macquarie University, has developed a new way to estimate the number of mistakenly labeled species on land and underwater. He uses a “flux ratio” to predict that eventually, 24 to 31 percent of all current species names will be discarded as duplicates.
We have also been under a different kind of illusion: seeing one species when there are actually several.
Genomic analysis in 2021 revealed a surprising result about giraffes. It turns out that the giraffe, thought to be a single species since Linnaeus named it Giraffa camelopardelis in 1758, is actually four distinct species, genetically different for at least a million years. This has surprised zoologists, who are now rushing to reevaluate what they thought they knew about this familiar animal. “To put our results into perspective, the genetic differences between the distinct giraffe species are similar to those between polar and brown bears,” says Axel Janke, a geneticist at Goethe University in Frankfurt, Germany. “We’ve clearly completely forgotten what a giraffe is.”
This discovery has also energized conservationists. As a single species, giraffes were already classified as “vulnerable,” but now as separate species and therefore separate populations, at least three of the four meet the criteria for reclassification as “endangered” or “critically endangered.”
As we've come to understand, there are an astonishing number of species.. Even after removing duplicate or imaginary species, we have to confront the fact that we have barely begun to count life’s diversity. Advances in genetics now indicate that the number of existing species—as defined by genetically distinct reproductive populations—is much greater than previously thought.
How much greater?
The estimate keeps increasing. In 2011, a comprehensive survey of biodiversity estimated 8.7 million species, of which only 1.2 million had been documented. This indicated that 86 percent of all land-dwelling species, and 91 percent of all aquatic species, remained undiscovered.
However, these numbers were overshadowed by a preliminary report from the National Science Foundation five years later. The Dimensions of Biodiversity project, using gene sequencing, predicts that the total number of species on Earth is more than 20 orders of magnitude greater than previously understood, although it will take years for full results to emerge.
“Until now, we haven’t known whether aspects of biodiversity scale with something as simple as the abundance of organisms,” says Kenneth J. Locey, a postdoctorate fellow at Indiana University and a Dimensions of Biodiversity researcher. “As it turns out, the relationships are not only simple but powerful, resulting in the estimate of upward of 1 trillion species.”
One trillion species. This would indicate that we have only identified and documented a very tiny fraction of all potential life forms.
WAs gene sequencing technology becomes faster and cheaper, it also creates family connections that challenge our understanding of the bigger picture.
In classical classification, birds are currently in Linnaeus’s original group of Aves. In the distinct Linnean category of Reptilia, alligators and crocodiles are part of the group Crocodylia, while lizards and snakes are currently in the group Squamata. From a standpoint based on physical structure, this makes perfect sense: Crocodiles, lizards, and snakes are more similar to each other than any of them are to birds.
The giraffe, believed to be a single species since 1758, is in fact four distinct species.
But cladistics follows the evolutionary path from a common ancestor. Despite their looks, Crocodylia are the closest living relatives of Aves, both arising from the group Pseudosuchia around 250 million years ago. An alligator is more closely related to a peacock than to a Komodo dragon. The Komodo dragon is more closely related to you.
Some confusing findings of cladistic classification are aquatic. The group of Cancer, or crab, is now known to be a diverse collection of genetically distant species—not a group at all. The benefits of evolving a crab-like body are such that multiple evolutionary lines developed a similar body shape, creating close similarities despite very different origins.
And while Linnaeus revised the group Pisces, or fish, to not include whales and other cetaceans, many evolutionary paths have adapted to a life in the ocean that Pisces has now been completely removed. What we informally call fish actually represent over a dozen different evolutionary lines, so genetically diverse that, as some biologists have pointed out, “fish” do not truly exist. If one were to draw a broad enough cladistic circle to encompass all fish, it would also include humans.
YYet humans need “fish,” or something very similar to the concept of “fish,” to understand the world.
Words are not just units of speech; they are units of thought. The choices we make in organizing the world tend to disappear once we’ve made them, but they are inevitably embedded in language.
Take colors, for example. Among English speakers, we identify pink as a distinct color from red. In the Malaysian language (Bahasa Malay), however, there is no separate term for pink. There is only merah, red. You can try to convey the idea of pink by describing it as “light red,” but even then you’d be imprecise: The closest term in everyday use is merah muda, which means literally “young red,” and it can refer to a bright red as well as a light one. You can express the notion of pink by mentioning a pink object, such as merah jambu, or “red like a guava.” The only issue is that you’re now describing not a range of shades but one shade in particular: the pink of a guava skin. Speaking Malaysian, of course, does not mean color-blindness, but to an English speaker such indefinite language can appear like an awkward and inaccurate approach to color. Why not just create a word for “pink” and be done with it?
As language-bound human beings, we still require the semantic construct of agreed-upon labels.
However, English does the same thing. We don't have a word like pink for the blue part of the spectrum. If you don't like saying “light blue,” then you have to be very specific—like saying “robin’s-egg blue.” So, there's a gap in our language just like in Malaysian. But if you're a native English speaker, you probably never realized it.
On the other hand, Russian speakers learning English notice this right away: Their language splits our “blue” into two colors, the lighter goluboy and the darker siniy. What's interesting is that these differences are not just technicalities. They become wired into our brains. Scientists found that native Russian speakers are faster than native English speakers at telling dark-blue shades from lighter ones, likely because, to them, the difference between goluboy and siniy is clear.
As humans bound by language, trying to understand life's complexities, we still need agreed-upon labels. Biologists Francine Pleijel and George Rouse suggested the LITU, or “least-inclusive taxonomic unit,” to replace the concept of species. This would be temporary identities, described as “statements about the current state of knowledge (or lack thereof )”—snapshots rather than static points, documented assuming they might change as more genetic information becomes available.
This would get rid of lectotypes, allotypes, and other type specimens, a change Pleijel and Rouse strongly support. They believe that existing codes of nomenclature make scientists label organisms as species even though they generally don't know much about what's happening in nature.
Physarum polycephalum challenges the fundamental ideas of Linnean thought. It's a common tree slime in European and North American forests, classified in 1822 but ignored until 1970. Then a teaching assistant at Iowa State University found a surprising characteristic: The slime not only had an external immune system but one that functioned externally instead of internally.
A sample of polycephalum, taken from a rotting elm log, kept infections at bay by secreting an antiviral substance so strong that when sprayed on crops it was 100 percent effective in getting rid of tobacco mosaic, a virus that affected tobacco plants, tomatoes, peppers, and cucumbers.
Over the past five decades, more extraordinary aspects of the organism have been discovered. It's not an animal, a plant, or a fungus. It can hibernate for years. It has no musculature, yet it can move at 1.6 inches an hour. Somehow, it's a single-celled organism. (The Guinness Book of World Records says it's the largest cell on the planet.) If separated, segments can function independently, then come back together. They can even merge seamlessly with different specimens from different places. It seems like individual existence is optional.
Its apparent simplicity hides an extremely complex sex life. Instead of just two genders, male and female, Physarum polycephalum has 720 different forms of mating pairs, methods of creating genetic variety that are essentially equivalent to genders. Sexuality and reproduction, as we’ve come to understand, involve a variety of themes and variations.
Physarum polycephalum is also able to learn. In order to efficiently find food sources, it expands and self-corrects its pattern until it covers the maximum amount of territory with the least amount of resources. By this measure, it can be considered intelligent: The highly efficient networks it creates can find the quickest path out of a labyrinth or the shortest routes to connect multiple locations. In one experiment, it was presented with multiple food sources (in this case, oat flakes) arranged to replicate the geographic locations of Tokyo and 36 surrounding towns. The slime mold reached out to all food sources with pathways that nearly replicated the Japanese rail system connecting those locations—a system carefully designed by humans to operate as efficiently as possible.
Despite lacking a central nervous system, let alone a brain, it’s also capable of remembering. Somehow, it manages to retain what it’s learned. If placed in the same labyrinth weeks apart, it will recognize the maze and reconstruct its previous escape route. Even a small piece of the original will do the same.
We don’t completely understand polycephalum's intelligence, but that’s not stopping us from collaborating with it. In fact, we’ve recently enlisted it to help us explore the cosmos.
How to point the instruments in the right direction? By predicting where these streams will be. To do that, astrophysicists have turned to polycephalum, using the same efficiency it uses to solve mazes and reconstruct the Tokyo metropolitan train system. Using an artificial intelligence program designed to imitate the spore as closely as possible, they’ve been feeding it galactic maps and asking it to make connections.
So far, the project has traced the connections between more than 37,000 galaxies. It’s just getting started, but it’s already demonstrated the power of shifting our perception of the living, approaching nature not as static objects to be inventoried, but as dynamic, interdependent manifestations of a greater whole.
To live is to exist together. To exist is to have a conversation.
In the words of pioneering 18th-century French naturalist Georges-Louis de Buffon: “Nature is not a tangible object, because this object would encompass everything.”
Excerpted from Every Living Thing: The Great and Deadly Race to Know All Life © Jason Roberts, reprinted with permission of Random House.
Lead image: CreativeAngela / Shutterstock
