Oat milk was discovered much more recently than you may have known. Like many now-familiar technologies, it was found by accident during the Apollo program when NASA learned what a zero-g environment does to goat milk.
to be clear you are fifteen thousand generations removed from the invention of stone tools. not from the end of stone tools. modern humans are still using stone tools.
Be afraid. I’ve put off answering this as long as I could, but I’m fresh back from a protistology conference [well, I was at the time I started writing this] and it’s time to put it right.
First of all, forget the classifications I’ve shown on other posts (Tree of Life, order of relation) – they’re already hopelessly obsolete.
A. What the hell is a protist, anyway?
We don’t really have a great definition of “protist”. They are certainly Eukaryotes, i.e. organisms whose cells have a nucleus and other systems of internal membranes, a cytoskeleton of protein filaments, and which have or had at some point mitochondria to “produce energy” (actually build gradients) by using oxygen to drive electron flow. Beyond that, the definition can only be negative: a “protist” is any eukaryote that is neither an animal, nor a plant, nor a fungus.
That leaves a lot. A liminal space of taxonomy, and a vast one.
(Lamża 2025, fig. 1. The region highlighted in blue at the bottom shows the locations where the root of the tree, corresponding to the deepest division, may fall: between Neozoa and Excavata, between Metamonada and Neozoa + Discoba, or between Discoba and Neozoa + Metamonada.)
You can find plants listed there as “Viridiplantae”, to distinguish them from red algae. Fungi and animals don’t even show up – they are lumped together as Opisthokonta!
If you want a quick and simple guide to the major groups of protists, then Grames-Webb, Boscaro, & Keeling 2025 (free ebook!) have you covered. To give a very non-exhaustive list of examples:
(all pics from the Keeling & Eglit linked afterward, or, failing that, Wiki)
Parabasalida. A group of protists that mostly lives inside animals. Since they have little access to oxygen, they have converted their mitochondria into hydrogenosomes (other protist groups have done the same). Some have a flagellum running under the membrane to create a sort of undulating wing, and a rigid “spine” called axostyle. Trichonympha and other genera live in the gut of termites, helping them digest wood.
Diplomonadida & Oxymonadida. Other two groups of oxygen-avoiding symbionts and parasites of animals. The mitochondria of Diplomonadida have lost all metabolic function, and those of Oxymonadida (wich also help termites with wood digestion) are gone altogether. Diplomonadida have a distinctive symmetry with two tufts of flagella and two nuclei.
Euglenozoa. Protists with an elongated body and only one large flagellum. Euglenida are photosynthetic, and have developed a little red eye from one of their chloroplasts; they have a vestigial second flagellum, though it’s tiny and almost invisible. Another group, Kinetoplastida, have brought their flagellum under the membrane forming a sort of wing with which they swim in a corkscrew motion; they include pathogens like Leishmania and Trypanosoma.
Heterolobosea. A group of protists that mostly switch between amoeboid and flagellate forms, except for one that forms slime molds with stalked fruit instead. They also include the infamous “brain-eating” Naegleria.
Jakobida. Bacterial feeders that build themselves stalked cradles, harvesting dense bacterial streams with one flagellum while the other lies along the cell body and generates a continuous water current.
Stramenopiles. A group defined by having ancestrally two flagella of which one is much larger and covered in “hairs” (mastigonemes) that increase its “pull” on water enough to allow a cell to crawl forward in its direction. It includes a vast diversity of organisms: many are photosynthetic, such as diatoms (Bacillariophyta, with their two-valved shell of silica), and the multicellular, plant-like brown algae (Phaeophyta, like kelp or bladderwrack), collectively forming the group Ochrophyta. There are also non-photosynthetic groups such as the stalked Bicosoecida, the ciliated Opalinea, and the very fungus-like Oomycota (which include the potato blight).
Apicomplexa. A group of parasites with very complex life cycles (see next part), which include Plasmodium (malaria) and Toxoplasma, as well as the enormous (>0.5 mm) Gregarinida found in insect guts. Their infectious stage is elongated, with a modified chloroplast called apicoplast at the anterior end, which is used to penetrate host cells.
Dinoflagellata. Protists with a cellulose theca and two flagella, one free for thrust, the other wrapped around like a belt, wiggling to steer. They are a major component of plankton – sometimes photosynthetic, sometimes cytoplasm-sucking predators, sometimes both – though sometimes they can bloom in toxic “red tides”. Some photosynthetic species, called zooxanthellae, live in symbiosis swith coral polyps, trading sugars for protection.
Ciliophora (♥). Also known as Ciliates, they don’t have just a few long flagella but a whole coat of short cilia beating in synchrony, though often the cilia are reduced to a few patches in strategic body areas. They have two kinds of nuclei: a macronucleus for everyday cell operations, and a micronucleus that remains inactive until it’s passed to the offspring, or exchanged with partners in the sex-like process of conjugation. This keeps a copy of the DNA safe from metabolic damage. Almost always heterotrophic, they have a huge diversity of shapes and lifestyles – see below.
Foraminifera & Radiolaria. Two famous planktonic groups, although sadly most people only ever know their shells. Admittedly the shells are pretty, extremely diverse, and important to paleontology, but it should be appreciated that they are predatory amoebae extruding thin pesudopodia through the shell pores to catch preys. The pseudopodia of Foraminifera resemble spiderwebs, while those of Radiolaria are straight needles. Some Radiolaria build their shells out of strontium sulfate to weigh themselves down and stay at a controlled depth, whereas Foraminifera use calcium carbonate, and their remains are a major component of biogenic limestone.
Cercozoa. A strange group that doesn’t share any obvious similarity in appearance apart from being amoebae of some kind. Some interesting members are Chlorarachniophyta (photosynthetic, with spiderweb-like pseudopodia), Vampyrellida (which famously pierce algal cells to suck out their content) and Euglyphida (with vase-like scaly shells).
Haptophyta & Cryptomonada. Two unrelated groups of biflagellate unicellular algae. In addition to their two flagella, Haptophyta have a flagellum-like strand called haptonema, which is used to collect food particles and spoon them into the cell mouth. Cryptomonada have a distinctive mouth-like cavity and ejectisomes that, when disturbed, shoot out coiled filaments to change direction by reaction.
“Heliozoa” used to be a group of protists with a spherical body and stiff radial pseudopodia, which turned out to be a bunch of groups that independently developed this shape. The core of the old group survives as Centrohelida.
Provora. Described only in 2022, a small group of predatory biflagellate protists with subcellular harpoons to attack their preys like microscopic whalers and a feeding groove reinforced into jaws (!).
Breviatea. Another tiny, recently described group. They lack mitochondria, and have simultaneously the usual two flagella and a shapeshifting amoeboid body.
Amoebozoa. A very diverse group of amoebae, most of which lack flagella altogether. The eponymous Amoeba with its finger-like pseudopodia (Lobosea) is here, as well as most groups of temporarily-multicellular “slime molds” and various unicellular armored species (e.g. Arcellinida).
Microsporidia. Very small spore-forming parasites that invade the cells of animals, or larger protists, by shooting them with a tube and pouring themselves through it. Their mitochondria no longer produce energy, and in fact they are forced to steal ATP from their host cells. They are close relatives of fungi, or sometimes classified as fungi themselves.
Choanoflagellata. The next of kin of animals, and in fact they are bizarrely similar to the flagellate feeding cells of sponges (choanocytes). Their one flagellum, beating to generate a water current, is surrounded by a funnel of adhesive microvilli, to which food particles get stuck.
The term “algae” is almost as vague. It can refer to any photosynthetic protist, or indeed any photosynthetic organism, whether unicellular or multicellular, that isn’t a proper plant (secondarily aquatic plants such as seagrasses aren’t considered “algae” in the same way that seals and whales aren’t considered “fish”). The taxonomic mess that is behind “fish” and “reptile” and “tree” and “worm” shall be left for another day.
By the way, Patrick Keeling and Yana Eglit (2023) have made an awesome and freely available collection of illustrations of major protists groups with a uniform color scheme, which I've been sampling above:
(Keeling & Eglit 2023 fig. 4, with names added by myself; download file S2 for full HD collection. Try to find the ones I mentioned! It's not quite the same list.)
In addition to the major and mid-sized groups, a host of tiny lineages, many consisting of just one genus or even one species, have been discovered since 2000 or so as sampling techniques improve: see Malawimonas (1999),Pseudophyllomitus (2002), Tsukubamonas (2011), Picomonas (2013), Provora (2022), Loeffela (2023)… These lineages do not belong to any of the major groups, though they can be useful to reconstruct the pattern of relations.
(j/k, these clades are actually unique and really interesting, and the people who described them are doing fantastic work)
B. Apicomplexa? I find them quite sim– uh, nevermind
Most protists are unicellular and microscopic, and certainly simpler in organization than plants or animals. However ☝️,
1. First, protists aren’t necessarily small. The largest Ciliates, Gregarina, and Lobosea are visible to the naked eye, and the multinucleate Foraminiferan Syringammina makes shells 20 cm wide. The giant kelp Macrocystis pyrifera (Stramenopiles), closer kin to microscopic diatoms than to plants, grows fronds over 40 meters long, forming vast undersea forests. And while most giant protists are multicellular or at least multinucleate, the green alga Acetabularia can grow several cm tall while being a single cell with a single nucleus.
(Left: Macrocystis forest off California, by bhodder via iNaturalist. Right: a grove of Acetabularia in Sardinia, each of them unicellular, by Tigerente via Wiki.)
2. But even at small size there is room for complexity. Ciliates have specialized themselves for a fantastic diversity of ecological roles by variations on their ciliary coating and cytoskeleton, becoming stalked filter-feeders (e.g. Vorticella) and polyp-like cell-suckers (e.g. Dendrosoma), grazing sediment-crawlers (e.g. Euplotes), worm-like sand burrowers (e.g.Spirostomum), roving armored omnivores (e.g. Coleps), or predators with a venomous sting (e.g. Lacrymaria). The stalk of Vorticella and the neck of Lacrymaria are caable of lightning-quick movement, and the filter-feeder species can sort particles of food with exquisite care.
This complexity extends to behavior: the ciliate Stentor is apparently capable of complex patterns of ciliary motion, detachment and swimming in response to chemical stimuli that suggest learning and habituation (Dexter &al 2019).
(The Ciliate Diversity Chart, Finlay & Esteban 2002. Stentor is the conical big guy on the right, in front of a grove of Vorticella.)
3. Many protist parasites have fantastically complex life cycles alternating sexual and asexual reproduction and mobile and immobile forms across multiple host species. Apicomplexa are especially impressive, with their multiple stages specialized for cell invasion, asexual multiplication, and fertilization. Others have conditional forms: when food is scarce, some Ciliates change into cannibal morphs with huge mouths (macrostome) to consume their kin.
The “slime molds” among Amoebozoa and Heterolobosea are also impressive, with isolated amoebae swarming and fusing together to form mobile “slugs” and then complex fungus-like fruiting bodies.
(Left: life cycle of the malaria pathogen Plasmodium, an Apicomplexan, from CDC; right: life cycle of a plasmodial slime mold such as Physarum, both through Wikipedia. Note that the word “plasmodium” is used with two completely different meanings!)
4. Many protists contain specialized structures you’d not expect to find inside a single cell: the proto-eyes of Euglenids, the internal skeleton of Parabasalids and Radiolarians, the jaws of Provora… Warnowiid Dinoflagellates have managed to develop ocelloids bizarrely similar to vertebrate eyes, complete with cornea, iris, lens, and retina, developed from modified mitochondria and chloroplasts.
For something less animal-like, see extrusomes, a collection of stuff-expelling organelles that is common among protists but is not found, generally, in animals (the urticating nematocysts of jellyfish are a rare animal exception). Ciliates make themselves harder to swallow with filament-emitting trichocysts and attack preys with venom-injecting toxicysts; Cryptomonads swim by reaction by shooting tubes out of ejectisomes; Provorans hunt with immobilizing harpoons called ancoracysts.
(Left: toxicysts of the predatory ciliate Didinium, from Hausmann 1978, fig. 35. (a) shows a lone Didinium, (b) a pack of Didinium devouring a hapless Paramecium, and (c-d) the toxicyst complex before and after firing.
Right: the ocelloid of the Dinoflagellate Nematodinium, from Gavelis &al 2015, fig. 1)
5. Some protists form really complex symbiotic multi-species associations that straddle the line between “small ecosystem” and “individual”. Such associations are called “holobionts” (see e.g. Lamża 2021). The Parabasalid Mixotricha paradoxa, for example – with many of its fellow termite-gut-dwellers – is covered in sockets in which Spirochaete bacteria are nestled. These bacteria, which are also specialized for attachment, beat as cilia to move their host. Other bacteria inside the cell help with metabolism. The back of the Ciliate Euplotidium is covered in bacteria that expel threads as defence against predation, and so on.
(The symbionts of Mixotricha, source)
On the subject of multicellularity, we might be tempted to give a new definition of “protists” as unicellular Eukaryotes (barring secondarily unicellular organisms, such as yeast). Wouldn’t this neatly exclude animals, plants, and fungi -- as well as some red algae, kelp, and arguably slime molds? -- restricting protists to a lower level of organization?
Eh. For one, “multicellularity” means rather different things to these groups (see Niklas & Newman 2020). The bodies of animals are built out of cells with dynamic surface attachments that can move past each other, and which use these surface interactions to build layers and internal cavities and secrete skeletons. Plants have rigid tissues with cells fixed in place, propped up by water turgor. Fungi are tangles of filaments that divide secondarily into cells as they grow. And slime molds, of course, form by aggregation of related cells in a communal liquid matrix, rather than growing from one.
Also, remember that evolution hates clarity. There isn’t really a sharp line between unicellularity and multicellularity. There’s a whole gradient from mundane single cells with a single nucleus, to cells with multiple nuclei that work together (e.g. Ciliates), to organisms with multiple nuclei that each control a separate region of cytoplasm, to organisms that actually divide their cytoplasm into multiple cells with various degrees of sharpness, to organisms with increasingly differentiated cell types. Protists are smeared all over this gradient.
By Lamża (2023)’s count, multicellularity of some sort arose at least 45 and probably more than a hundred times among Eukaryotes, and it did so through a number of different paths – by dividing daughter cells failing to separate (as in animals and kelp), by secondary division of multinucleate filaments (as in fungi and Oomycota), or by fusion of separate cells into a colony (as in slime molds and Chlorarachniophyta).
(Intermediates between uni- and multicellularity along various paths, Lamża 2023. Where does one cell become many?)
I can't believe I neglected to attach a video of Lacrymaria hunting in the previous part. Easy fix:
Anyway.
C. All creatures small and smaller
But the actual question was: how do we put order in all this mess?
In the beginning, of course, everything living was either a Plant or an Animal. Unicellular organisms were either animal-like “Protozoans” or plant-like “Protophytes” or “algae”. By the 19th century it was already clear how inadequate that division was, but it still survives in nomenclature: photosynthetic protists follow the rules of botany (families ending in -aceae), the rest those of zoology (families ending in -idae). I work in a zoology department.
Bütschli (1880) made a good effort dividing protists by mean of locomotion: Flagellata or Mastigophora that move with few long “hairs”, Ciliata that move with many short “hairs”, Sarcodina or amoebae which move by reshaping the cell, and Sporozoa that, uh, are mostly spore-forming parasites. (Note that eukaryotic cilia and flagella are basically the same structure varying only in size and number, unlike the bacterial flagellum which is completely different in structure and mechanism.)
This system was useful, and is still used in identification handbooks, but had little to do with actual affinities, no more than dividing animals into walkers/swimmers/flyers would. For that matter, switching between flagellate and amoeboid states in a life cycle is quite common; Breviatea and the Amoebozoan Mastigamoeba thoroughly queer the binary by being flagellate and amoeboid at the same time.
(A variant of Bütschli’s scheme used by Britannica. Ciliophora and Apicomplexa are solid groups, but “Sarcomastigophora” is an utter landfill of a term.)
In 1987, our friend Cavalier-Smith noticed that there were many strange groups of protists (among which Archaemoebae (a group of Amoebozoa), Diplomonadida, Oxymonadida, Parabasalida, and Microsporidia) appeared to lack mitochondria, and only lived in oxygen-poor environments. Many were internal symbionts or parasites of animals, such as the Diplomonad Giardia intestinalis and the Parabasalid Trichomonas vaginalis (you can probably guess where they were discovered).
It was natural enough to conclude that these “Archezoa” were primitive Eukaryotes that had developed a nucleus, but not yet acquired mitochondria like the more developed groups. Early molecular phylogenies did in fact show these groups clustering together, and breaking off from other Eukaryotes at a very early stage!
Alas, it was too convenient. Most of these groups were not primitive, but in fact highly derived.
Modified mitochondria, or at least genes of mitochondrial origin, were found in all these groups, and the fact that they clustered together at the base of early phylogenies was better explained by a phenomenon called “long branch attraction”. When two groups of loosely related organisms undergo great transformations (say, to adapt to oxygen-poor environments), they may end up sharing rare mutations simply because they both have so many, and so end up looking more related than they actually are, as well as being pulled away from all others. For example, the “archezoan” Microsporidia, which showed up in many trees as the deepest-branching lineage of eukaryotes, turned out to be ultraminimalist fungi!
(Left: Cavalier-Smith 2003, fig. 1; Heterokonta roughly corresponds to Stramenopiles. Right: ten examples of mostly biflagellate “excavates”, Simpson 2003, fig. 1)
In the 1990s and 2000s Cavalier-Smith remained one of the biggest names in protist taxonomy. Having abandoned the Archezoa, he made a neat distinction between Bikonta which frequently have two flagella, and Unikonta which have only one per cell or none. Bikonta is the most diverse group, including (1) plants sensu lato; (2) a group Rhizaria (Cercozoa + Radiolaria + Foraminifera), distinguished by feeding with thin pseudopods; (3) a group Chromista (Stramenopiles + Haptophyta + Cryptophyta) distinguished by having chloroplasts with four membranes (see below!); and (4) a group Excavata distinguished by a ventral feeding groove, including many of the old “Archezoa” but no longer at the base. Unikonta mainly includes fungi and animals (along with Choanoflagellata), grouped as Opisthokonta, plus Amoebozoa. Because of its ancestral photosynthesis, Cavalier-Smith gives Chromista the status of kingdom, apart from all mere Protista.
More recent phylogenomic work has been reworking many of these groups, while leaving the overall scheme recognizable. Chromista in particular is gone, and Excavata is on very thin ice.
You may have noticed from the list in part A that having two flagella is quite common in very disparate groups. Many of the new groups discovered since 2000 are grooved and biflagellate, and they’re a bit all over the place. It’s likely that the “excavate” condition is in fact not the hallmark of a particular line but the primitive condition of Eukaryotes, from which many lineages then evolved away. Stramenopiles and Jakobida specialized the two flagella for different purposes, Kinetoplastida and Choanoflagellata lost one, Ciliophora and Opalinea multiplied them into cilia, Fungi and most Amoebozoa lost them altogether, and so on.
(Keeling & Burki 2019, fig. 2. I recommend reading the whole paper for very important reflection on the nature of these groups and general methodological issues for protist taxonomy.)
The currently taught consensus – at least, the one I mark as correct in exams – is to divide eukaryotes in a number of “supergroups”, while remaining rather agnostic about most of the relationships between them:
The most diverse is called SAR, which in turn includes:
Stramenopiles;
Alveolata (Ciliophora, Dinoflagellata, Apicomplexa), united by a system of tough under-membrane pockets;
Rhizaria (Cercozoa, Radiolaria, Foraminifera), which all tend to have thin pseudopodia;
Opisthokonta (fungi including Microsporidia, animals + Choanoflagellata, and a few other small groups);
Amoebozoa, grouped together with Opisthokonta as Amorphea on account of their soft cell membranes;
Archaeplastida, which includes true plants as well as red and green algae;
Discoba (Jakobida + Heterolobosea + Euglenozoa, so almost half of the “Excavates”);
Metamonada (Oxymonadida + Diplomonadida + Parabasalida, almost the other half of “Excavates”);
Haptista (Haptophyta + Centrohelida);
Cryptista (Cryptomonada and other minor groups);
plus several recently discovered groups in awkward positions.
Here are the most recent complete phylogenies of protists I know of, along with the one by Lamża I showed at the beginning. There are of course disagreements, but large parts are compatible.
Most species fall either within soft-bodied Podiata (which are actually fairly similar to Unikonta with the addition of Breviatea and a few other minor groups), or within Diaphoretickes, which often have chloroplasts and some kind of hard envelope but from multiple independent origins. I’ll cover later evolutonary hypotheses on this split.
There are “excavates” on both sides of this division in Torruella’s tree; they still appear to cluster together in Lamża’s, but note that Lamża’s tree allows the root (i.e. the deepest division) to fall within Excavata.
SAR survives within Diaphoretickes. Haptista (or at least Haptophyta) is close to SAR, Cryptista to plants; Provora are near the base of Diaphoretickes or just outside. Discoba is close to Diaphoretickes (forming the greater clade Diphoda), and Metamonada might be basal to Eukaryotes after all. i think that covers all the major groups I described.
Everything that isn’t an Eukaryote is a prokaryote, and there are two basic types of prokaryotes or “bacteria”: the true or Eubacteria and Archaea. Almost identical in appearance, they are biochemically different in many important ways, from the composition of the membrane to the way they translate genetic information into proteins. Eukaryotes are in some ways a mixture of the two: an Archaeal core of genes, translated into proteins the Archaeal way, but wrapped in an Eubacterial membrane, with Eubacteria-like energy-producing organelles (mitochondria to burn sugar with oxygen for a hypercharged metabolism, and chloroplasts to harvest the energy of sunlight for sugar production).
Did Eukaryotes arise as a hybrid of different types of prokaryotes?
(The endosymbiotic hypothesis of Eukaryote origins, Margulis 1970, frontispiece)
The endosymbiotic hypothesis was first proposed by Konstantin Mereschkowski as early as 1910, arguing that chloroplasts might be Cyanobacteria absorbed into a larger organism. Its current form is credited to Lynn Margulis (1967), who extended it to mitochondria (now accepted) and flagella (not as much). The idea is simple: we saw in Mixotricha, or for that matter the termites it inhabits, that organisms of multiple species can act together as one. Push the integration a bit further, and it might become nearly impossible to tease apart the sources.
An obvious piece of evidence is that mitochondria and chloroplasts have their own DNA, with their own ribosomes to translate it into proteins; DNA which matches closely to Alphaproteobacteria and Cyanobacteria respectively – although stripped down, with many of its genes transferred into the host’s nucleus. Nick Lane argued (The Vital Question, 2015) that the usefulness of this arrangement lay in giving the “energy-producing” organelles finer control over production, with their independent gene expression, while keeping most of the genome stored in the nucleus, safe from oxidative damage, much like you don’t want your kindergartens too close to your petrochemical plants.
The symbiotic origin of mitochondria and chloroplasts is now the consensus, though not so for flagella.
(Various hypotheses on the origin of nucleus (left) and mitochondria + chloroplasts (right), Martin &al 2015, fig. 1 & 2)
There is a bit of a chicken-and-egg issue here. Absorbing the mitochondrial ancestor for its oxygen-using skills would presumably require phagocytosis, and therefore a dynamic cytoskeleton; but cytoskeleton rearrangement is an expensive process that requires an oxygen-fueled metabolism in the first place!
A major breakthrough came in 2019 with the study of the Asgardarchaeota, a group of Archea that had been discovered a few years before in the Arctic hydrothermal system known as “Loki’s Castle”. Prometheoarchaeum (Imachi &al 2020) has the kind of long protrusions that could be used to envelop another cell without actual phagocytosis, and lives in metabolic symbiosis (syntrophy) with other Archaea or Bacteria. As it happens, phylogenomics showed it to be the closest living kin to Eukaryotes!
Later, the related Lokiarchaeum was found to have an Eukaryote-like cytoskeleton. This suggested a model in which something much like Prometheoarchaeum, living in a world that bacterial photosynthesis was increasingly polluting with oxygen, wrapped its arms around a bacterium that could use oxygen constructively, and eventually engulfed it as a proto-mitochondrion.
This probably happened between 2.5 and 2 billion years ago.
(Above: Prometheoarchaeum syntrophicum; below: a hypothesis of Eukaryote origin from a similar organism; Imachi &al 2020, fig. 3 & 5)
These metabolic interactions must have been many and complex, though, because our genome is replete with genes of Eubacterial origin, including many important metabolic pathways, and our cells are wrapped in membranes of Eubacterial style: possibly because membrane-making genes were imported into the nucleus from the mitochondria, or by yet another symbiont. While in some sense Archaea remain our chief ancestors, we are very much hybrid beings.
(Many waves of influx of bacterial genes into early Eukaryotes, Tobiasson &al 2026, fig. 4)
There isn’t much we can say about the earliest branches of the Eukaryote tree (or tangle); fossils from that time are sparse and hard to interpret. The oldest that clearly belongs to a recognizable group is the red alga Bangiomorpha pubescens, which is only one paltry billion years old. But we can say something about LECA, the Last Eukaryotic Common Ancestor, which was not the first Eukaryote but something much later. LECA very probably had an excavate-like groove to feed on bacteria, and swam with two flagella; look at the modern Malawimonas or Collodictyon for a decent approximation of its appearance.
(Lamża 2025, fig. 3)
The major division within Eukarya is explained as follows. The precursors of Podiata specialized as bacteria-eaters crawling on a solid substrate. They abandoned flagella, developed a soft membrane, and learned to reshape their cytoskeleton to move by pseudopodia, as amoebae, and to feed by phagocytosis (“swallowing” food with membrane vesicles). Those of Diaphoretickes/Diphoda, on the contrary, specialized as swimming predators of other protists. They invested in powerful flagella – some even multiplied them into cilia – and stiffened their body with thick pellicles, submembrane alveoli, internal axostyles, and even solid shells of calcite or silica. An arms race ensued, with such fierce hunters as Provora or Ciliophora on the prowl; Diaphoretickes, preying upon each others, became faster swimmers or hid under stronger armors, whereas slow-moving, soft-bodied Podiata sought safety in size or in number (eventually giving rise to massively multicellular slime molds, fungi, and animals).
Ironically, a sublineage of the predacious Diaphoretickes took the least predacious route. The patriarch of Archaeplastida repeated the trick of endosymbiosis, absorbing photosynthetic Cyanobacteria and turning them into the first chloroplasts. They made thick cellulose walls and often gave up movement. Out of this line red algae, green algae, and eventually true plants would arise.
(A summary of endosymbiotic events, Keeling 2013, fig. 2. Note that this reconstruction shows secondary endosymbiosis occuring once at the root of the SAR group, and then being lost in some of its branches; I’m told that now it seems more likely it occurred independently in different SAR lineages.)
The trick was too good to be confined to that line, and soon other Diaphoretickes also proceeded to envelop… unicellular Archaeplastida. Why do the work of taming a bacterium from scratch when you can start with an already tame one? Euglenids and some Cercozoans used green algae; Haptophytes, Cryptophytes, and Ochrophytes used red algae. This was secondary endosymbiosis, and it resulted in chloroplasts surrounded by as many as four redundant membranes (outer membrane of the cyanobacterium, inner and outer membrane of the alga, and inner membrane of the new host).
Since nothing in biology can ever be simple and sensible, Dinoflagellates upped the game with tertiary endosymbiosis, absorbing diatoms or other secondary “algae”, while the Cercozoan Paulinella started from scratch with independent primary endosymbiosis of a different kind of Cyanobacteria.
Some absorbed chloroplasts then went on to do very different things: in Apicomplexa like the malaria pathogen, modified chloroplasts are used to drill into host cells; in Warnowiid Dinoflagellates, as you’ll recall, they became a full lensed eye!
Then the Ediacaran and Cambrian Explosions happened, and plants and animals also did some interesting stuff, probably.
i think it's great how from the arrival of the first farmers in the region to the Magyars, you have a regular succession of peoples sweeping into the carpathian basin--mostly from the steppes to the east, not always--establishing a power base on the pannonian plain with an extended fringe of surrounding subject peoples, about 100-200 years of them being the major regional power, followed by somebody kicking their ass, their political power collapsing, and them getting demographically absorbed by the next population to conquer the basin. like we're playing a 5,000 year long game of King of the Hill.
frankly i can't believe people are content to let the hungarians run away with this one! come on, it's been a thousand years, time to shake things up!
The year is 1492. You are the Catholic Monarchs - both of them. Isabel and Fernando, tanto monta, monta tanto. You have just finished kicking all of the Muslim powers out of Iberia, and you’re feeling so pleased with yourselves that you expel the Jews about it. You have a problem, though - there’s this annoying Genoese moron named Christopher Columbus who keeps waving some bad math at you, insisting that the world is actually smaller than everyone thinks it is and he could totally sail to India by going west. He gets on your nerves so much that you just give him a couple of ships and send him off. He definitely won’t make it to India, but maybe he’ll find some little island and give all of your newly-unemployed hidalgos something to keep them busy. He’ll probably just starve to death in the middle of the ocean, and then he’s no longer your problem.
The year is 1519, and you are Hernán Cortés. You and all of your compatriots are stuck in the most effective way to make someone a bad person: put them in a situation where they must become incredibly wealthy and powerful incredibly fast or else they will die horribly. Transatlantic voyages are absurdly expensive. Anyone in the ‘New World’ who isn’t rich enough to afford their own army is deeply in debt, with no collateral but their own sword-arm. It is an environment that does not reward half-measures. It does not even reward full measures. It only rewards putting a brick on the gas pedal and crossing your fingers - if you kill one person then you’re a murderer, but if you kill hundreds of thousands of people then you're a paragon of glory and the Spanish crown will make statues of you.
The year is still 1519 and you are Moctezuma II, Huēyi Tlahtoāni (great ruler) of the ‘Aztec Empire,’ also known as the Triple Alliance, or the Mexica. You know a thing or two about half-measures not being rewarded, because you are in a process of rapidly expanding and consolidating a nascent Mesoamerican empire. You are quite good at your job - even before you ascended to the throne, you cultivated a reputation as a skilled warrior, a dedicated student, and a devout worshiper. Your name means something like ‘lord who frowns in anger.’ It’s a fitting name, because the process of ‘imperial expansion and consolidation’ generally involves killing lots of people. To make matters worse, some weird hairy white guys showed up out of nowhere and they keep demanding an audience with you. You try every trick in the diplomatic handbook - deferment, threats, flattery, bribes - but everything you do just seems to make them more single-mindedly focused on your destruction. Later, after you are dead, they will claim that you thought they were gods.
The year is 1545, and this whole ‘colonialism’ thing is starting to peter out. Trans-Atlantic voyages are still ruinously expensive, and the pickings are getting slimmer every day - it’s not like you can go loot Tenochtitlan a second time. You’re starting to wonder if it’s time for everyone to pack up, go home, and forget about… holy shit is that a mountain of silver? Is that an honest-to-god mountain with more silver in it than every other existing silver mine on the face of the earth combined? Yes. Some call it Potosí. Many will call it “the mountain that eats men.” In a single moment, colonialism goes from a plundering campaign for recently-unemployed soldiers to a permanent institution. The alchemists back in Prague and Vienna never learned how to turn lead into gold, but the mercenaries and taskmasters in Potosí found a much simpler equation to turn blood into silver.
The year is 1571, and the economy of the Ming dynasty doesn’t feel so good. Their experiment with paper money was a failure, to put it gently. The experiment with paper money failed horribly. It turns out when you try to have paper currency but you don’t have sophisticated counterfeit protections and there’s also a booming cottage industry of people making paper in their cottages, well, you can guess how that ends. So you’re trying to shift to a silver economy. But then you run into an even bigger problem: you don’t have enough silver. So if you start demanding taxes in silver, the price of silver will skyrocket, which means taxes will skyrocket when the economy is already ailing from the whole ‘paper money’ thing. Some hapless scholar-official in Guangdong is nervously watching a peasant sharpen his pitchfork when he gets word from a messenger: some gweilo just showed up at the part with literal shipfuls of silver and they want to buy silk, tea, spices, and porcelain at outrageous markups.
Within living memory, the world was still ‘medieval’ in many ways - slow, parochial, zero-sum, carefully arbitrated by tradition and precedent. Legible. And now Spanish sailors take Bolivian silver on ships guarded by West African mercenaries and Japanese ronin, sailing to their colony in the Philippines to rub shoulders with Chinese officials, Indian sultans, and Malay merchants. All because some dipshit from Genoa got his math wrong and wouldn’t shut up about it.
I enjoyed reading this piece for its adjacency to some of my own takes on the subject. It is a bit of a sloppy piece, so be a little cautious? For example, it notes that under the communists, "hundreds of thousands of small shrines that had structured Chinese folk religion were declared 'superstitious' and obliterated", but the majority of temple destruction in China actually dates to the Qing & Nationalist eras - something the article's own citation of this fact explains! This sloppiness is relevant, because it typically tilts in the direction of overstating what the CCP era achieved - the 20th century in general was an era of massive social upheaval for China. Still, the point stands that modern China engaged in intense capital formation & social reform that set the stage for future growth.
The pieces focuses on public health, education, and women's emancipation; I would add the "institutional" history of the CCP tearing down the old power structures of villages and provinces to build a much more unified governance structure & legal regime. India quite famously had straight-up internal tariffs on trade between provinces until the 1990's! And still does to a lesser extent today. Local regulations on firm size, lack of standardized property rights, and more all plague the Indian economy because these systems have only been piecemeal reformed since independence. The CCP in China built a national economic system with much more standardized rules and integrated trade (even if ofc they still have their local issues, every country does), and that was crucial for their economic success. And this process wasn't easy - it was the product of a violent social revolution involving the expulsion and murder of the previous local power brokers.
I think about all of this in relation to what I would describe as the "Garret Jones Critique" of China's modernization, that "China is the poorest Chinese country in the world". There are many Chinese diaspora communities; in Taiwan and Singapore they are the ethnic majority, and in places like Thailand or Indonesia they form rich, economy-driving minorities. Most of these countries or communities are richer than China today on a per capita basis. From that lens the CCP today is simply fumbling the ball less than they used to; the default state is that China as a "cultural unit" prospers economically, as long as stupid dumb-dumb communism doesn't get in the way.
A more historically grounded story complicates that narrative, which India vs China signifies well. The reality is that "a Chinese merchant diaspora city-state forming under the eye of the British Empire and away from all the traditional power brokers of Chinese society" just is not a one-to-one comparison to farmer-peasants in Anhui, right? Neither is Taiwan, a political "tabula rasa" of educated refugees taking over a vacated Japanese colony; even Chinese minority groups in Thailand prospered in no small part by being connected to China, the biggest economy in the region, and playing the trade markets. The reality is that if China was "naturally going to grow like this", it would have for the over the century in which it was exposed to western technology and markets and didn't (a feat Japan managed just fine).
You just can't opt out of politics, which is both contextual and typically harder at larger scales. It was not trivial for the CCP to build modernity on top of traditionalism; India as a country did not manage it for a long time. Would the KMT have done it in China, if they had won the Civil War? Maybe! As mentioned, they were already doing some of that work, I definitely don't have a decided opinion on the question; I certainly think they could have. I don't consider it some "default state", though. The history of the KMT itself is rife with examples of traditional norms & local institutions triumphing over the modernizing center - who knows how long that could have gone on. Being India was "in the cards" for China, just like being Taiwan.
Be afraid. I’ve put off answering this as long as I could, but I’m fresh back from a protistology conference [well, I was at the time I started writing this] and it’s time to put it right.
First of all, forget the classifications I’ve shown on other posts (Tree of Life, order of relation) – they’re already hopelessly obsolete.
A. What the hell is a protist, anyway?
We don’t really have a great definition of “protist”. They are certainly Eukaryotes, i.e. organisms whose cells have a nucleus and other systems of internal membranes, a cytoskeleton of protein filaments, and which have or had at some point mitochondria to “produce energy” (actually build gradients) by using oxygen to drive electron flow. Beyond that, the definition can only be negative: a “protist” is any eukaryote that is neither an animal, nor a plant, nor a fungus.
That leaves a lot. A liminal space of taxonomy, and a vast one.
(Lamża 2025, fig. 1. The region highlighted in blue at the bottom shows the locations where the root of the tree, corresponding to the deepest division, may fall: between Neozoa and Excavata, between Metamonada and Neozoa + Discoba, or between Discoba and Neozoa + Metamonada.)
You can find plants listed there as “Viridiplantae”, to distinguish them from red algae. Fungi and animals don’t even show up – they are lumped together as Opisthokonta!
If you want a quick and simple guide to the major groups of protists, then Grames-Webb, Boscaro, & Keeling 2025 (free ebook!) have you covered. To give a very non-exhaustive list of examples:
(all pics from the Keeling & Eglit linked afterward, or, failing that, Wiki)
Parabasalida. A group of protists that mostly lives inside animals. Since they have little access to oxygen, they have converted their mitochondria into hydrogenosomes (other protist groups have done the same). Some have a flagellum running under the membrane to create a sort of undulating wing, and a rigid “spine” called axostyle. Trichonympha and other genera live in the gut of termites, helping them digest wood.
Diplomonadida & Oxymonadida. Other two groups of oxygen-avoiding symbionts and parasites of animals. The mitochondria of Diplomonadida have lost all metabolic function, and those of Oxymonadida (wich also help termites with wood digestion) are gone altogether. Diplomonadida have a distinctive symmetry with two tufts of flagella and two nuclei.
Euglenozoa. Protists with an elongated body and only one large flagellum. Euglenida are photosynthetic, and have developed a little red eye from one of their chloroplasts; they have a vestigial second flagellum, though it’s tiny and almost invisible. Another group, Kinetoplastida, have brought their flagellum under the membrane forming a sort of wing with which they swim in a corkscrew motion; they include pathogens like Leishmania and Trypanosoma.
Heterolobosea. A group of protists that mostly switch between amoeboid and flagellate forms, except for one that forms slime molds with stalked fruit instead. They also include the infamous “brain-eating” Naegleria.
Jakobida. Bacterial feeders that build themselves stalked cradles, harvesting dense bacterial streams with one flagellum while the other lies along the cell body and generates a continuous water current.
Stramenopiles. A group defined by having ancestrally two flagella of which one is much larger and covered in “hairs” (mastigonemes) that increase its “pull” on water enough to allow a cell to crawl forward in its direction. It includes a vast diversity of organisms: many are photosynthetic, such as diatoms (Bacillariophyta, with their two-valved shell of silica), and the multicellular, plant-like brown algae (Phaeophyta, like kelp or bladderwrack), collectively forming the group Ochrophyta. There are also non-photosynthetic groups such as the stalked Bicosoecida, the ciliated Opalinea, and the very fungus-like Oomycota (which include the potato blight).
Apicomplexa. A group of parasites with very complex life cycles (see next part), which include Plasmodium (malaria) and Toxoplasma, as well as the enormous (>0.5 mm) Gregarinida found in insect guts. Their infectious stage is elongated, with a modified chloroplast called apicoplast at the anterior end, which is used to penetrate host cells.
Dinoflagellata. Protists with a cellulose theca and two flagella, one free for thrust, the other wrapped around like a belt, wiggling to steer. They are a major component of plankton – sometimes photosynthetic, sometimes cytoplasm-sucking predators, sometimes both – though sometimes they can bloom in toxic “red tides”. Some photosynthetic species, called zooxanthellae, live in symbiosis swith coral polyps, trading sugars for protection.
Ciliophora (♥). Also known as Ciliates, they don’t have just a few long flagella but a whole coat of short cilia beating in synchrony, though often the cilia are reduced to a few patches in strategic body areas. They have two kinds of nuclei: a macronucleus for everyday cell operations, and a micronucleus that remains inactive until it’s passed to the offspring, or exchanged with partners in the sex-like process of conjugation. This keeps a copy of the DNA safe from metabolic damage. Almost always heterotrophic, they have a huge diversity of shapes and lifestyles – see below.
Foraminifera & Radiolaria. Two famous planktonic groups, although sadly most people only ever know their shells. Admittedly the shells are pretty, extremely diverse, and important to paleontology, but it should be appreciated that they are predatory amoebae extruding thin pesudopodia through the shell pores to catch preys. The pseudopodia of Foraminifera resemble spiderwebs, while those of Radiolaria are straight needles. Some Radiolaria build their shells out of strontium sulfate to weigh themselves down and stay at a controlled depth, whereas Foraminifera use calcium carbonate, and their remains are a major component of biogenic limestone.
Cercozoa. A strange group that doesn’t share any obvious similarity in appearance apart from being amoebae of some kind. Some interesting members are Chlorarachniophyta (photosynthetic, with spiderweb-like pseudopodia), Vampyrellida (which famously pierce algal cells to suck out their content) and Euglyphida (with vase-like scaly shells).
Haptophyta & Cryptomonada. Two unrelated groups of biflagellate unicellular algae. In addition to their two flagella, Haptophyta have a flagellum-like strand called haptonema, which is used to collect food particles and spoon them into the cell mouth. Cryptomonada have a distinctive mouth-like cavity and ejectisomes that, when disturbed, shoot out coiled filaments to change direction by reaction.
“Heliozoa” used to be a group of protists with a spherical body and stiff radial pseudopodia, which turned out to be a bunch of groups that independently developed this shape. The core of the old group survives as Centrohelida.
Provora. Described only in 2022, a small group of predatory biflagellate protists with subcellular harpoons to attack their preys like microscopic whalers and a feeding groove reinforced into jaws (!).
Breviatea. Another tiny, recently described group. They lack mitochondria, and have simultaneously the usual two flagella and a shapeshifting amoeboid body.
Amoebozoa. A very diverse group of amoebae, most of which lack flagella altogether. The eponymous Amoeba with its finger-like pseudopodia (Lobosea) is here, as well as most groups of temporarily-multicellular “slime molds” and various unicellular armored species (e.g. Arcellinida).
Microsporidia. Very small spore-forming parasites that invade the cells of animals, or larger protists, by shooting them with a tube and pouring themselves through it. Their mitochondria no longer produce energy, and in fact they are forced to steal ATP from their host cells. They are close relatives of fungi, or sometimes classified as fungi themselves.
Choanoflagellata. The next of kin of animals, and in fact they are bizarrely similar to the flagellate feeding cells of sponges (choanocytes). Their one flagellum, beating to generate a water current, is surrounded by a funnel of adhesive microvilli, to which food particles get stuck.
The term “algae” is almost as vague. It can refer to any photosynthetic protist, or indeed any photosynthetic organism, whether unicellular or multicellular, that isn’t a proper plant (secondarily aquatic plants such as seagrasses aren’t considered “algae” in the same way that seals and whales aren’t considered “fish”). The taxonomic mess that is behind “fish” and “reptile” and “tree” and “worm” shall be left for another day.
By the way, Patrick Keeling and Yana Eglit (2023) have made an awesome and freely available collection of illustrations of major protists groups with a uniform color scheme, which I've been sampling above:
(Keeling & Eglit 2023 fig. 4, with names added by myself; download file S2 for full HD collection. Try to find the ones I mentioned! It's not quite the same list.)
In addition to the major and mid-sized groups, a host of tiny lineages, many consisting of just one genus or even one species, have been discovered since 2000 or so as sampling techniques improve: see Malawimonas (1999),Pseudophyllomitus (2002), Tsukubamonas (2011), Picomonas (2013), Provora (2022), Loeffela (2023)… These lineages do not belong to any of the major groups, though they can be useful to reconstruct the pattern of relations.
(j/k, these clades are actually unique and really interesting, and the people who described them are doing fantastic work)
B. Apicomplexa? I find them quite sim– uh, nevermind
Most protists are unicellular and microscopic, and certainly simpler in organization than plants or animals. However ☝️,
1. First, protists aren’t necessarily small. The largest Ciliates, Gregarina, and Lobosea are visible to the naked eye, and the multinucleate Foraminiferan Syringammina makes shells 20 cm wide. The giant kelp Macrocystis pyrifera (Stramenopiles), closer kin to microscopic diatoms than to plants, grows fronds over 40 meters long, forming vast undersea forests. And while most giant protists are multicellular or at least multinucleate, the green alga Acetabularia can grow several cm tall while being a single cell with a single nucleus.
(Left: Macrocystis forest off California, by bhodder via iNaturalist. Right: a grove of Acetabularia in Sardinia, each of them unicellular, by Tigerente via Wiki.)
2. But even at small size there is room for complexity. Ciliates have specialized themselves for a fantastic diversity of ecological roles by variations on their ciliary coating and cytoskeleton, becoming stalked filter-feeders (e.g. Vorticella) and polyp-like cell-suckers (e.g. Dendrosoma), grazing sediment-crawlers (e.g. Euplotes), worm-like sand burrowers (e.g.Spirostomum), roving armored omnivores (e.g. Coleps), or predators with a venomous sting (e.g. Lacrymaria). The stalk of Vorticella and the neck of Lacrymaria are caable of lightning-quick movement, and the filter-feeder species can sort particles of food with exquisite care.
This complexity extends to behavior: the ciliate Stentor is apparently capable of complex patterns of ciliary motion, detachment and swimming in response to chemical stimuli that suggest learning and habituation (Dexter &al 2019).
(The Ciliate Diversity Chart, Finlay & Esteban 2002. Stentor is the conical big guy on the right, in front of a grove of Vorticella.)
3. Many protist parasites have fantastically complex life cycles alternating sexual and asexual reproduction and mobile and immobile forms across multiple host species. Apicomplexa are especially impressive, with their multiple stages specialized for cell invasion, asexual multiplication, and fertilization. Others have conditional forms: when food is scarce, some Ciliates change into cannibal morphs with huge mouths (macrostome) to consume their kin.
The “slime molds” among Amoebozoa and Heterolobosea are also impressive, with isolated amoebae swarming and fusing together to form mobile “slugs” and then complex fungus-like fruiting bodies.
(Left: life cycle of the malaria pathogen Plasmodium, an Apicomplexan, from CDC; right: life cycle of a plasmodial slime mold such as Physarum, both through Wikipedia. Note that the word “plasmodium” is used with two completely different meanings!)
4. Many protists contain specialized structures you’d not expect to find inside a single cell: the proto-eyes of Euglenids, the internal skeleton of Parabasalids and Radiolarians, the jaws of Provora… Warnowiid Dinoflagellates have managed to develop ocelloids bizarrely similar to vertebrate eyes, complete with cornea, iris, lens, and retina, developed from modified mitochondria and chloroplasts.
For something less animal-like, see extrusomes, a collection of stuff-expelling organelles that is common among protists but is not found, generally, in animals (the urticating nematocysts of jellyfish are a rare animal exception). Ciliates make themselves harder to swallow with filament-emitting trichocysts and attack preys with venom-injecting toxicysts; Cryptomonads swim by reaction by shooting tubes out of ejectisomes; Provorans hunt with immobilizing harpoons called ancoracysts.
(Left: toxicysts of the predatory ciliate Didinium, from Hausmann 1978, fig. 35. (a) shows a lone Didinium, (b) a pack of Didinium devouring a hapless Paramecium, and (c-d) the toxicyst complex before and after firing.
Right: the ocelloid of the Dinoflagellate Nematodinium, from Gavelis &al 2015, fig. 1)
5. Some protists form really complex symbiotic multi-species associations that straddle the line between “small ecosystem” and “individual”. Such associations are called “holobionts” (see e.g. Lamża 2021). The Parabasalid Mixotricha paradoxa, for example – with many of its fellow termite-gut-dwellers – is covered in sockets in which Spirochaete bacteria are nestled. These bacteria, which are also specialized for attachment, beat as cilia to move their host. Other bacteria inside the cell help with metabolism. The back of the Ciliate Euplotidium is covered in bacteria that expel threads as defence against predation, and so on.
(The symbionts of Mixotricha, source)
On the subject of multicellularity, we might be tempted to give a new definition of “protists” as unicellular Eukaryotes (barring secondarily unicellular organisms, such as yeast). Wouldn’t this neatly exclude animals, plants, and fungi -- as well as some red algae, kelp, and arguably slime molds? -- restricting protists to a lower level of organization?
Eh. For one, “multicellularity” means rather different things to these groups (see Niklas & Newman 2020). The bodies of animals are built out of cells with dynamic surface attachments that can move past each other, and which use these surface interactions to build layers and internal cavities and secrete skeletons. Plants have rigid tissues with cells fixed in place, propped up by water turgor. Fungi are tangles of filaments that divide secondarily into cells as they grow. And slime molds, of course, form by aggregation of related cells in a communal liquid matrix, rather than growing from one.
Also, remember that evolution hates clarity. There isn’t really a sharp line between unicellularity and multicellularity. There’s a whole gradient from mundane single cells with a single nucleus, to cells with multiple nuclei that work together (e.g. Ciliates), to organisms with multiple nuclei that each control a separate region of cytoplasm, to organisms that actually divide their cytoplasm into multiple cells with various degrees of sharpness, to organisms with increasingly differentiated cell types. Protists are smeared all over this gradient.
By Lamża (2023)’s count, multicellularity of some sort arose at least 45 and probably more than a hundred times among Eukaryotes, and it did so through a number of different paths – by dividing daughter cells failing to separate (as in animals and kelp), by secondary division of multinucleate filaments (as in fungi and Oomycota), or by fusion of separate cells into a colony (as in slime molds and Chlorarachniophyta).
(Intermediates between uni- and multicellularity along various paths, Lamża 2023. Where does one cell become many?)
I was gonna write a longer piece about this but it didn't really come together, so to at least get the thought out:
In "social media vs education" discourse, there is a tension between the macro data not really showing any large declines in student learning & minimal benefits from things like cell phone bans, and the more anecdotal/smaller survey data of people telling you the kids in the classroom have really changed. I don't actually think you should toss out the personal experiences, that is being naive, while I think "oh the test scores are all corrupted by declining standards" narrative is equally naive - so what is the story?
The squaring of this circle is that when people talk about their student learning changing, it is almost always about books. They aren't unable to understand instructions, they can do math fine (again mild declines sure), people are taking calculus and chemistry and playing piano just like they always did. What has shifted is that people's attention span for reading books is vanishing, to the point where school districts are giving up on even assigning summer reading and shifting assessments to short form reading assignments. This cycle is just extremely hard to break because books are the one thing you can't "internalize" into the classroom - you can't ask them to sit in the room and read a book during an exam - and cheating the assignment is universal and free. Kids always wanted to skim their summer reading, but skimming, Cliff Notes, "asking a friend", those were all work and sometimes just an approximation of doing the reading anyway.
Now you just google/claude the answer to any of your homework questions about a book, you don't need even crack the (pdf's) spine. And of course the entire backdrop culture has shifted to either short form text or fully audiovisual content, so you don't care much about the object-level skill anyway. The bottom has dropped out on the incentives & value for many students.
But the rub is that this hasn't impacted learning all that much. The Kids Can't Read Bleak House, yes, but they were never great at that and it wasn't that related to other skills. "The mind needs books like a sword needs a whetstone" concept was just too limited; there are a lot of different whetstones out there. The test scores are doing fine, people's skills in the workforce are holding up, none of the "breakpoints" of someone's personal trajectory are flashing red. And of course many people do still read books! We have no shortage of historians because they were always a particular type of person anyway. Books aren't going away; their market share of global attention is just shrinking.
Are there consequences for this beyond the personal, though? Yes, individuals can still learn to be nurse practitioners and marketing analysts just fine, but is the ~body politic of the nation~ or whatever suffering from an endemic shallowness in its comprehension of itself? Maybe! I don't think that idea is crazy, actually, though it is a much more complicated story with many moving parts. But it is one that sits primarily outside the education system; school was never a particularly effective vaccine against "disenlightenment", and if the internet has done anything it has neutered the power of formal institutions to be that force.
This doesn't mean that the education system isn't facing challenges of course (AI & cheating is a big one), or that there aren't nuances to this whole story. I only wrote the quick-and-dirty version here after all. I just do think this tension is endemic to so much discourse from teachers, parents, students, etc - they are observing a mismatch between what they want students to be, and what students need to be to pass though the system.
I mean, test scores are down. Whether that's a "large" decline is perhaps a matter of definition: I don't think breathless stories about illiterate kids are reasonable (and I'm a known Bleak House truther), but I would argue they're large by the standard of how much the test scores move historically.
Yes, I mention that they are down, but I don't think these results being "small" is very subjective? Your own results have them at borderline significance declines, a few percentage points of the scoring distribution. Results like PISA - which Freddie deBoer wrote up recently - have US reading scores actually going up since the pandemic, and the math declines being nearly equivalent to student levels in 2015. These are ~10 point range reductions on tests that have score distributions in that span like ~300 point. Many metrics (like Harvard's Education Scorecard - you can look at Page 7) put their 2024 results as something like "we are at the same performance level as 2005". 2005 was just not a learning apocalypse year, right?
It is sad that we aren't making progress, that learning isn't really improving and is actually getting worse. We both A: thought we were gonna keep better at this, and B: there definitely was some bogus pedagogy movements in this era causing damage. But these are changes that are within the normal range. If you compare what these test say, to the tone of pieces like "The Elite College Students Who Can't Read Books", I think the claim "there is a gap here in understanding between the two sides" holds up well. And that is the gap I am talking about - if you want to just talk about the test scores in isolation from the narrative, then it can be a different conversation.
I am also a bit of a Bleak House truther, as I believe we discussed! Not to your level I don't think, but on the level of that book just being very hard and average students pretty much never being able to read it well. My favourite part of that story is that we all randomly started talking about that study in like 2024? So it was a big part of the "covid loss" or "social media brainrot" narrative? But the study was from 2015! And on college freshman. People who, yeah okay they got phones a few years ago, but for whom the impact of the internet was still pretty nascent, those kids grew up without phones. Most people just didn't really notice the date of the study. Though this was all a while ago, I may be misremembering the details here!
off the cuff ratings of various elements of human anatomy and physiology:
eyes: very nifty design only a little undercut by the viscera horror of something terrible happening to them. 8/10
nose: a lil goofy ngl but it works in context. 6/10
ears: also goofy, don’t like them, why do they produce wax and get infected. but the core concept is fine. 4/10
brain: very cool, does lots of neat stuff without having to gurgle, ooze, or twitch. 10/10
liver: like most good organs it is a calm, steady machine. a tranquil filterer of the blood. don’t like the whole oozing bile thing though. 6/10
kidneys: piss is actually slightly less gross than bile. 7/10
bladder, gall bladder: i strongly feel organs should not grow random rocks in them. 4/10
bones: very aesthetic. functional in sort of a primitive mechanical way but they give us an extremely useful set of imagery for death and time. 8/10
skin: terrifically design, though it does sometimes flake. 7/10
tongue, lips: crudely mechanical but in kind of a cool way. 7/10
digestive tract: why does it gurgle and ooze?? why must it engage in peristalsis and jerk and shudder? it’s not even the products of digestion I object to—it’s that so many organ systems in the body are at least on a macroscopic level serene and still and almost plantlike, quietly performing their function without calling any attention to themselves. and then we have the system that farts and burps and generally reminds you you are trapped in a prison of wet red meat. 1/10, only because eating is often pleasant.
heart, lungs: for such crucial organs the fact they have to continuously move feels so… primitive. we should respire by like passively absorbing air through our skin. our blood should be whisked around our body by millions of tiny invisible cilia in our veins. what is this rube goldberg shit, with an extremely vulnerable single point of failure? 3/10
hair: almost completely unnecessary. mostly functions as a way to further customize our flesh-prisons. that’s actually pretty neat. 8/10
are you perchance a single-cell organism? Because those are the only people who actually like using cillia for fluid transport. Even plants don't do that.
pixelskylines
romaincrisis
