Category: microorganisms

Readers’ wildlife video

October 7, 2025 • 8:30 am

Today we have a 3-minute video taken by ecologist Adam Greer and showing fascinating and complex zooplankton.  The video is below, and I asked Adam to provide some additional information on this animal. Adam’s explanations are indented.

I am a zooplankton ecologist at University of Georgia. A major part of my research involves using camera systems to study the distribution and behavior of zooplankton. One zooplankton type we study is the appendicularians, which use mucous houses to feed on ocean microbes. They build and discard these houses several times per day, which can be a mechanism for moving carbon into the deep ocean. I recently put together a short video of this process, with the hope that it could help people see and appreciate that it is happening all over the world’s oceans. Appendicularians are quite fragile, and their houses are very difficult to see unless you use specialized optical techniques (the one we used in the video is called “shadowgraph imaging”).
I thought maybe this could be a variation on the wildlife photos, but obviously you may want to just show actual photos. Still, I think some of your readers might think it is interesting. I did my best to explain what is going on and use kind of informal language so everyone can understand.

The animal builds the (surprisingly intricate) house from a small mucous bubble then uses its tail to draw a current through the house. The water passes through a filter and then the particles get concentrated before being consumed (after going through the buccal tube). This diagram from Bochdansky and Deibel 1999 (below) is pretty helpful. The prey is very small relative to the size of the appendicularian – similar to the predator-prey size ratio of blue whales feeding on krill.

https://ars.els-cdn.com/content/image/1-s2.0-S0022098198001099-gr2.gif

The video does not go into these mechanics since you cannot really see that amount of detail, but I simply say in the video that they create a current through the house to capture their food. Then it shows the various stages of house building.

And Adam’s video (with music), which is indeed mesmerizing and clearly explained. Stuff like this is going on all the time, but we (or at least I) didn’t know about it.

Readers’ wildlife photos

May 31, 2025 • 8:30 am

Today we have a historical/natural history post by reader Lou Jost, who works as a naturalist and evolutionary biologist at a field station in Ecuador.

A diatom sample from the HMS Challenger expedition of 1872-76

The Challenger in 1873, painting by Swine

The HMS Challenger was a British naval ship equipped with both sail and steam power. At the urging of scientists, and riding the wave of popular curiosity about our then-poorly-known planet, the ship was converted by the Royal Society of London to become the world’s first specialized oceanographic vessel. It went on a mission from 1872 to 1876 to systematically explore the world’s oceans, especially the scientifically almost completely unknown Southern Ocean near Antarctica. This mission was the 19th century equivalent of a trip to the moon or to Mars (except that this  HMS Challenger mission had a much more interesting and diverse subject region!).

One of the navigators, Herbert Swine, made contemporaneous drawings and paintings on site, including the two HMS Challenger images I have shared here (though these were probably polished somewhat for publication). He also published his lively diaries of his time on the expedition, in two volumes, just before he died of old age. He was the last survivor of the crew.

A map of the expedition

The voyage of exploration went 80,000 miles, lasted 1250 days, and circumnavigated the globe. They made systematic chemical, temperature, and depth readings across the globe, taking biological specimens along the way. They discovered over 4000 new species, from vertebrates to phytoplankton, and lost several lives along the way. They were the first to systematically explore the mid-Atlantic Ridge, and by pure chance they also discovered the Marianas Trench,  the deepest part of the Pacific Ocean. In 1950-1951 a modern vessel, again bearing the name Challenger in a homage to the original, found the deepest part of any ocean, the “Challenger Deep”, just 50 miles from the HMS Challenger’s deepest depth record.

The Challenger at work

The immense number of samples obtained by the crew of the Challenger took 19 years to analyze and publish, in 50 volumes. Specimens were sent to many scientists of the time, and some of these still circulate today. Among the most interesting organisms they sampled are diatoms. Diatoms are single-celled organisms that make up much of the oceans’ phytoplankton, and their most notable features are the finely sculpted glass cases called “frustules” that enclose them. These glass frustules are often preserved intact for tens of millions of years, sometimes forming enormous deposits of pure frustules known as “diatomaceous earth” on the beds of ancient lakes and oceans. Some of these deposits are so big that millions of tons of diatom frustules thousands of years old are whipped up by the wind in dry parts of Africa every year, and then cross the Atlantic by air and rain down on the Amazon basin in South America.

The expedition of the HMS Challenger launched the most systematic study of the 19th century on the diatoms of the Southern Ocean. They sampled at regular intervals during their voyage, and at multiple depths, including very deep water that had never before been studied, discovering new species of diatoms such as Asteromphalus challengerensis, named after the vessel (using bad Latin unfortunately). The samples were distributed to diatomists around the world, who carefully mounted them on microscope slides using special mountants of high-refractive-index liquid, designed to make the transparent diatom frustule more visible under standard microscopic illumination. Some of these Challenger diatom slides come up for sale periodically, and I could not resist buying one that appeared in eBay.

Increasing zooms of the diatoms on the slide:

This one slide, from 1873 during an Antarctic visit, has hundreds of individuals consisting of maybe a couple of dozen species. There are also many broken diatom fragments. Among the individuals, I was lucky enough to find several examples of what appear to be the aforementioned A. challengerensis. This is a rare species which is found only in water that is within 1 degree Centigrade of freezing. The taxonomy of this species and its relatives is in flux as we learn more about how the structures change with age.

Two slides of the species A. challengerensis:

Some of the taxonomic problems of these diatoms is caused by their weird way of replication. Diatoms can’t grow like a normal organism because they are in a glass case, so instead they shrink, each half of the frustule making a new matching half that is slightly smaller than the parent half-frustule, so that the two new halves each nest inside their parent half-frustule. Then they separate. Here is a nice illustration of this:

The population thus has a large spread of different sizes, and it appears that some frustule features may change as they get smaller, causing taxonomic confusions in the case of A. challengerensis and others.  By the way, eventually the smallest ones go through a sexual reproductive phase that builds a new full-sized frustule, so that the cycle can start over. This is really weird. Later I hope to write long post about the utterly astounding, almost unbelievable biology of diatoms.

Darwin published his theory of evolution just 13 years before this expedition, and evolution was on everyone’s mind, and the commander of the ship was an “early adopter” of the theory. At the time there was still not much clarity about the predictions of the theory. It was widely believed that the cold dark oceans would preserve “living fossils” similar to the earliest forms of life on earth. The expedition did not find this to be true, and so it actually was a slight setback for evolutionary theory. They unfortunately missed the hydrothermal vents which do indeed shed light on the origins of life.

I wrote at the beginning of this post that the HMS Challenger expedition was the 19th Century analogue of space exploration. So it was fitting that NASA decided to name one of the space shuttles “Challenger”, after the two scientific ships which carried that name. The photo above shows Challenger orbiting over the ocean 110 years after the original HMS Challenger sailed that same ocean. Unfortunately, as in the original Challenger expedition, people died on that space shuttle in the name of science, a reminder that exploration on the margins of what is known will always be risky, and the participants are real heroes of their age.

Living bacteria found in 2-billion-year-old rocks

October 20, 2024 • 9:30 am

Up to now, the oldest rocks known to contain living bacteria—microorganisms that were alive since the rock were formed—were sediments from about 100 million years ago.  Now, a group of researchers from South Africa, Japan, and Germany report finding living bacteria in rocks 20 times older than that: over two billion years ago.  And those bacteria were alive, and presumably dividing.

This finding, published in Microbial Ecology, suggests that if there was once life on Mars, one might be able to find its remnants by examining rock samples the way these researchers did.

The paper can be accessed by clicking on the screenshot below. You can also find a pdf here and a short New Scientist article about the discovery here.

The details: the researchers drilled into 2-billion-year old igneous “mafic rocks” in the Bushveld Igneous Complex of South Africa, described by Wikipedia as “the largest layered igneous intrusion within the Earth’s crust“.  Drilling down 15 meters using a special drilling fluid to lubricate and cool the drill bit, they extracted a 30-cm (about 12-inch) core of rock with a diameter of 8.5 cm (3.3 inches). They then carefully cut into this core, making sure not to contaminate it with modern bacteria.

Here’s a photo of part of the Bushveld intrusion showing the igneous rock (see caption for details:

(From Wikipedia): Chromitite (black) and anorthosite (light grey) layered igneous rocks in Critical Zone UG1 of the Bushveld Igneous Complex at the Mononono River outcrop, near Steelpoort Photo: kevinzim / Kevin Walsh, CC BY 2.0, via Wikimedia Commons

Remember that igneous rock is formed when other rock is melted by extreme heat and then cooled.  As this rock cooled, there were cracks in it that were filled with clay during the process, and, when the rock was solid, the clay was impervious to further intrusions. In other words, the clay in the rock cracks were 2 billion years old. But was the clay and its inhabitant bacteria that old? (See below.)

What they found.  To test whether what they saw in the cracks (bacteria!) were really original, 2-billion-year-old bacteria rather than organisms that had entered the rock after formation or were contaminants during the drilling or handling, the authors dissolved tiny fluorescent microspheres in the drilling fluid, spheres smaller than bacteria. Tests showed that although the microspheres were visible in the fluid sample, they were not seen within the rock (of course the researchers took great care to not contaminate the rock either during extraction or when it was cut and examined).  Here is their schematic of how the cores were extracted and handled (figure from the paper). Note the flaming to kill anything living on the outside of the core (click all figures and photos to enlarge them):

Here is a fluorescent sample of drilling fluid (on the left), showing many microspheres, and a sample of the rock showing DNA-stained bacteria on the right, which appear as green rods. The scale is the same, so you can see that the microspheres are smaller than the bacteria:

(from paper): Microscopic inspection of the drill fluid sample. A 1000-fold magnification images of fluorescent microspheres and (B) microbial cells stained by SYBR Green I

The presence of living organisms (at one time) in the cracks was also confirmed by finding “amides I and II,” which, say the authors “are diagnostic for proteins in microbial cells.”  The New Scientist paper adds that the cell walls of the bacteria (if they are indeed “bacteria”!) were intact, which, says author Chen Ly, is “a sign that the cells were alive and active”.

What did the bacteria eat? The paper’s authors say that “indigenous microbes are immobile and survive in the veins by metabolizing inorganic and/or organic energy available around clay minerals.” They do add that there is doubt about the ages of the clay cracks, as they might actually have been formed much more recently than two billion years. Both the paper and the NS blurb are careful not to say that the bacteria have actually been in the rocks for two billion years, but that seems to be the tacit assumption.

Here are two photos from the paper of one of the bacteria-containing cracks. The color indicates, say the authors, spectra from silicate minerals and microbial cells

The upshot and implications: These are by far the oldest rocks even seen to contain indigenous (rather than externally-derived) living organisms, presumably bacteria. It’s not 100% clear that the organisms are themselves 2 billion years old, but the assumption here is that they are. New Scientist floats the idea that we should do this kind of analysis to look for life on other planets, most notably Mars:

This discovery may also have important implications for the search for life on other planets. “The rocks in the Bushveld Igneous Complex are very similar to Martian rocks, especially in terms of age,” says Suzuki, so it is possible that microorganisms could be persisting beneath the surface of Mars. He believes that applying the same technique to differentiate between contaminant and indigenous microbes in Martian rock samples could help detect life on the Red Planet.

But they quote one critic who asks the same questions I do above, and insists that the bacteria aren’t as old as the rocks. (For one thing, bacteria couldn’t survive in an igneous rock when it was very hot during formation.)

“This study adds to the view that the deep subsurface is an important environment for microbial life,” says Manuel Reinhardt at the University of Göttingen, Germany. “But the microorganisms themselves are not 2 billion years old. They colonised the rocks after formation of cracks; the timing still needs to be investigated.”

Questions that remain:

1.) Are the bacteria themselves two billion years old? I’m not sure how they would investigate this if the clay could have entered the rock and then been sealed into the cracks a long time after the igneous rock was formed.

2.) If the bacteria that old, were they dividing during that period? I don’t see any mention of seeing dividing cells, and the authors say that the cells were effectively trapped in the clay. If so, could they still divide, or are we seeing the original bacteria, perhaps two billion years old and still kicking? This raises another question:

3.) Were the bacteria “alive” during this period? If they were really metabolizing over this period, then yes, they were alive. But if their metabolism was completely shut down, what do we mean by saying they were alive? The NS piece says that the presence of cell walls means that the bacteria were “alive and active”, but is that really true?

4.) Finally, if these things had stainable DNA, can it be sequenced? It would be interesting to get the DNA sequences of these bacteria, which they’d presumably have to do by culturing them. Although we now have methods to get the DNA sequence of a single bacterium by sequencing its RNA transcripts (see this report), you’d have to pry the bacteria out of the clay to do that. And if you can get the sequence, does it resemble that of any living bacteria, or are these ancient forms very different from today’s microbes?  (If they do resemble modern bacteria—for evolution would be very slow when cell division takes millions of years—then perhaps we could culture them.)

The biggest question, of course, is #1 above. I’m hoping that these things really are two billion years old, for what we’d then have is a very, very ancient bacterial culture. But I’m very dubious that we’ll find bacteria in Martian rocks.

 

h/t: Matthew Cobb, for alerting me to the relevant. tweet

 

Indigenous knowledge and the microbiome

February 9, 2023 • 9:45 am

The paper below was sent to me by a New Zealander who told me that it was an exemplar of how “indigenous knowledge” is touted as a way of advancing modern science by contributing new ideas and perspectives.  It wasn’t that the sender endorsed it, but rather questioned its assertions.  When I saw the title implying that indigenous knowledge could, by connecting with “colonized Western science”, improve scientific understanding of the microbiome. I was dubious, too. After all, the discovery of microbes is an achievement of “colonial science”, for indigenous peoples, be they Inuit, Native American, or, in this case, Māori, simply didn’t know about microbes and had no way to visualize them—ergo no way to study them. How, then, could indigenous knowledge of the microbiome contribute anything to modern science?

The answer, if you read the paper and some of the papers it cites, is that it can’t. What I’m NOT saying is not that indigenous people can’t contribute to scientific understanding in this area, for they can, simply by collaborating with “modern” scientists and also, perhaps, by calling attention to some phenomena that will lead science into new areas of microbial research.  But even there the accomplishments are thin so far, though there are some Māori working in microbial science and collaborating with non-Māori scientists in projects involving microbes.

But that’s not what the authors, two of whom are of Māori ancestry, maintain. Their claim is given in this part of abstract of this paper from Environmental Microbiology (click on screenshot below to read, pdf here):

Indigenous Peoples have a rich and long-standing connection with the environments that they descend from—a connection that has informed a deep and multifaceted understanding of the relationship between human well-being and the environment. Through cultural narratives and practices, much of this knowledge has endured despite the ongoing effects that colonization has had on many Indigenous peoples across the world. These narratives and practices, based on observation, experimentation, and practical application over many generations, have the potential to make compelling contributions to our understanding of the environmental microbiome and its relationship to health.

This is the claim that indigenous knowledge, in this case Mātauranga Māori or Māori “ways of knowing” , will give us insights into the microbiome that we wouldn’t have had otherwise. But how can that be since MM has nothing in it about microorganisms? It turns out those insights don’t seem to exist, but they bury their claim in a number of assertions (some of which are true) about the Māori.

First, what do the authors mean by “microbiome”? There are two construals: the microbial fauna associated with the environment in general, and then the microbial fauna associated with us: in our skin and in our gut. They go back and forth between these two interpretations.

Read for yourself:

Here are the claims that, say the authors, support their assertion:

a.) Māori “ways of knowing” give unique perspectives on life that can further research on the microbiome. Here are two of them:

Inherent in the ancestral interactions with nature came the creation of kōrero tuku iho (traditional teachings and wisdom that is passed down through subsequent generations). These traditional teachings contained and still carry meaningful sources of mātauranga (knowledge) or messages about the structures of nature and how to successfully navigate them. Indigenous narratives are replete with examples connecting the health of individuals and communities with the natural environment. For example, Inyang refers to a proverb from the Ibibio of Kenya—“ke owo aba nte nkankuk omo”—which suggests that a person’s life is “replicated” in their environment (38). Luther Standing Bear of the Sicangu and Oglala Lakota once noted that “we are of the soil and the soil is of us” (39). Whakataukī (Māori proverbs) often refer to the environment as the source of wellbeing.

and (my bolding)

The ability for Indigenous scientists and researchers to articulate, explain, and understand scientific phenomena through their own cultural lens is an important pathway for Indigenous and non-Indigenous success in any field (54). In addition, the success of Indigenous scientists and researchers creates pathways for people from their own culture to relate and aspire to those roles themselves. Instead of assuming that Indigenous approaches weaken the validity of robust science (55), we argue that Indigenous ontologies, epistemologies, and methodologies provide an increased depth to understand the environment-microbiome-health nexus. Indigenous Peoples have long been able to explain the complexities of natural phenomena through stories and narratives where features of the environment are personified or codified. These uniquely Indigenous mechanisms of understanding and explaining the natural world, including the microbiome and its connection to health and the wider ecosystem—mechanisms underpinned by observation, experimentation, and practical application—have enabled Indigenous Peoples to survive and thrive for generations.

This is simply re-interpreting legends and stories to apply to the microbiome, a phenomenon unknown to the creators of those stories. What we have here are analogies that may be interesting, but useless in further understanding of the microbiome. In fact, the authors admit this:

Indigenous narratives may not refer directly to the microbiome, but there are many references to an unseen connection between people and the environment. For example, Indigenous Peoples may talk of the environment “speaking to us,” and similar language is a part of other traditions, including within the many major religious texts.

But statements about the environment “speaking to us”, even under the most liberal interpretation, don’t forge a connection between modern science and indigenous knowledge.  Here’s one more:

Indigenous epistemologies and frames of knowing repeatedly recognize the influence of unseen (or microscopic) forces upon health. Studies of the microbiome can be viewed similarly, as a way of coming to understand those unseen entities that are essential to good health. Some non-Indigenous scientists may be uncomfortable with the “spiritual” connotations associated with Indigenous knowledge systems of the unseen, but for Indigenous peoples, the spiritual and physical worlds are intertwined so that they cannot be fully understood separately (40). Because of this, Indigenous ways of understanding the unseen could provide a culturally relevant framework for the study of the microbiome.

This again is an analogy, and while it may help explain to people steeped in legends that those “unseen forces” are tiny microorganisms connected with health and disease, wouldn’t it just be better to dispense with the numinous stuff? And to what extent do we really nee a “culturally relevant framework” to study microbiomes? Perhaps we need it to communicate with indigenous people, but that’s communication, not scientific research.

Then come are several claims about the Māori that, while the claims deal with people interacting with the environment (including microbes), involve microbiomes only tangentially—and again don’t open a path to deeper understanding of the phenomenon.

b.) By being forced via colonization away from nature into the cities, the Māori have become more prone to “diseases of civilization,” have been removed from the healthy microbes in the natural environment, and have adopted unhealthy diets that foster non-optimal internal microbes.

In addition to suffering from inequities in access to health services, healthy foods, and adequate housing (5–7), it is also likely that Indigenous Peoples have reduced access and exposure to health-promoting microbiota. As a result of urban drift and the impacts of urbanization on the environmental microbiome (8, 9), many Indigenous People now live in cities that are far from their ancestral lands and the diversity of potentially beneficial exposures they possess (10). What’s more, Indigenous Peoples, like many minority groups, are more likely to have reduced access to high quality and/or biodiverse green and blue spaces in urban areas due to their greater representation in lower socioeconomic neighborhoods (11, 12) and the general impacts of urbanization on ecosystem integrity and biodiversity (9). On the other hand, eating more traditional diets is associated with increased diet quality (13) and improved cardiovascular health (14) among Indigenous Peoples and a traditional Indigenous lifestyle has been associated with more diverse and abundant commensal microbiota (15).

Much of this is surely true, but you can see that they throw in the microbiome as something associated with the deleterious effects of past bigotry and colonization. What we see here is the result of poverty, and one’s gut biota is among the least important of all those problems mentioned. Here’s another tangential connection:

In New Zealand, Māori are disproportionately affected by non-communicable diseases (NCDs) such as cancers, diabetes, metabolic illness, and heart disease, like many Indigenous Peoples globally (18). Interestingly, recent research has shown that many NCDs are associated with and influenced by the microbiome (19–22). For example, dysbiosis of gut microbiota was present in stroke and transient ischemic attack patients, compared with controls (23), and reduced diversity of the gut microbiome was associated with obesity and insulin resistance (24).

Again, this shows the effect of a genome unaccustomed to foreign environments suffering from their effects. Although cancer and heart disease are more frequent among Māori than among descendants of colonists, that’s not a connection between indigenous knowledge and microbes, nor a way to help understand the microbiomes. These facts are of course important in public health considerations, but they don’t speak to the paper’s main point.

Below the paper again brings up traditional knowledge and sayings, but to no scientific use:

Inherent in the ancestral interactions with nature came the creation of kōrero tuku iho (traditional teachings and wisdom that is passed down through subsequent generations). These traditional teachings contained and still carry meaningful sources of mātauranga (knowledge) or messages about the structures of nature and how to successfully navigate them. Indigenous narratives are replete with examples connecting the health of individuals and communities with the natural environment. For example, Inyang refers to a proverb from the Ibibio of Kenya—“ke owo aba nte nkankuk omo”—which suggests that a person’s life is “replicated” in their environment (38) Luther Standing Bear of the Sicangu and Oglala Lakota once noted that “we are of the soil and the soil is of us” (39)

References to the environment, which are surely part of every indigenous culture, don’t point an obvious way forward in microbial research, even if they do say “we are of the soil and the soil is of us.” Again, we have a proverb that doesn’t help either science or the health of the Māori. It is merely an analogy that has been snuck into a discussion of scientific research.

c.) Māori are more susceptible to global warming because many have been forced into cities. The connection to the “microbiome”, I suppose is that the Māori have been forced away from their environment, part of which includes microbes:

Indigenous Peoples are particularly vulnerable to climate change, and the climate crisis will likely compound health inequities experienced by Indigenous People (31, 32). Contemporary climate change is also directly impacting the ability of Indigenous People to interact with ancestral lands. For example, Maldonado et al. (33) highlighted the case of the Isle de Jean Charles in Louisiana, where intense coastal erosion has reduced the island that has been a home and refuge to Grand Caillou/Dulac Band of Biloxi-Chitimacha-Choctaw since they were forced to relocate there by early settlers. Accordingly, microbiota also respond directly to changes in climate but also indirectly via the degrading effect of climate change on ecosystems (34)

This is what’s called a “stretch”.  The problem here is one of people living in unhealthy environments because of bigotry in the past, and you don’t need to know much about microbiomes to deal with that issue.

d.) Māori are underrepresented in microbiological research. This is true of nearly all indigenous people, who show “inequity” of representation in science. I do think that casting as wide a net as possible is the best way to beef up the talent pool in science, so the more people competing for positions and slots in graduate school, the better.  Surely indigenous people should be given equal opportunity to study science and become scientists! But this has nothing to do with the different “perspectives” that different groups bring to science, for, as we have seen, Māori “ways of knowing” offer little to understanding microbiomes. I’ve always been deeply dubious about the claim that different identity groups will have different ways of producing scientific knowledge, for I haven’t seen many examples. (One I sometimes cite is that women evolutionists have promoted more research into female preference in the study of sexual selection, but that’s the only one I’ve thought of.)

e). It’s essential to collaborate with Indigenous people if you’re doing science that affects them or their environments.  On this I wholly agree, for you can’t just go imposing environmental or medical changes on people without their assent and collaboration. One example is the collaboration between Māori and non-Māori scientists in helping save the famous endemic kauri trees of New Zealand, magnificent trees that require protection from logging and from “kauri dieback” a serious microbial disease. In this case, scientists identified the causal organism and are testing different treatments (without much luck), and the Māori sequester the endangered trees and their environs, for incursions by tourists and strangers help spread the disease.

Here’s one more example of how cultural sensitivity is important in cases involving microbiology, but again, this has nothing to do with indigenous knowledge advancing the microbiome. In fact, in this case modern science can help both indigenous and non-indigenous people:

There are also ethical and cultural challenges unique to microbiology that require Indigenous perspectives and leadership (49). Treatment or experimental procedures, such as fecal transplant, may have significant “health” benefits (57), but acceptance and uptake of such procedures among Indigenous Peoples will likely be low without significant Indigenous input. In Māori cultural practice there already exist concepts that govern societal, practical, and hygienic practices. The concept of tapu (state of restriction), for example, provides a uniquely Indigenous way of thinking about cross contamination, and restrictions relating to human waste and food (58). Māori have also developed contemporary ethical guidelines based on cultural values (tikanga), as in Te Ara Tika, a set of guidelines for conducting ethical research with Māori (59); and Te Mata Ira, Guidelines for Genomic Research with Māori, developed to ensure that Māori perspectives and values are reflected in genetic/genomic research.

Of course one has to recognize cultural sensitivities and strictures, and perhaps even incorporate then in doing research affecting indigenous people, but again, this is a matter of cross-cultural understanding, not cross-cultural scientific fertilization.

I’ve written way too much, I see, but I hope you’ve gotten the point that the authors are stretching like Gumby to try to show how indigenous (especially Māori) knowledge can advance our knowledge of the human and environmental microbiome. In the case of microbial studies, that possibility is especially unlikely because indigenous knowledge has nothing to say about microbes, except by analogy to legend and traditions. That doesn’t mean that indigenous researchers can’t make contributions to understanding microbiomes—only that they will have to do so by digging into the toolkit of modern science.

It’s ironic that the one solid finding about microbiomes mentioned in the entire paper comes not from indigenous knowledge, but from studies in Finland using the methods of modern science:

Being outdoors also increases exposure to (28) and transfer of environmental microbiomes onto the skin (29), via the aerobiome (30), the respiratory tract (29) and into the gut (19). For example, a placebo-controlled double-blinded study in Finland showed that the intervention group that engaged with microbially rich soil brought into playground sand experienced colonization of these microbiota to the skin with subsequent promotion of immunomodulation (interleukin-10 and T cell frequencies) (19).

 

ZeFrank on the slime mold

August 6, 2022 • 1:45 pm

UPDATE:  I called a dicty worker and got this answer.

The solution to the “altruism” problem requires two things. First, stalks and spores are formed only when there’s a shortage of food (bacteria, usually). That means that all the genes in all of the individuals in the area will not leave copies if there’s no way to disperse those genes away from the locale of famine.

Second, dicty individuals that are more related to each other are more likely to get into the spore-forming top, but if you share ANY genes for this behavior with other individuals in the spore body, you’re still better off being part of the stalk than simply dying, for there’s still a chance that some of your genes will be in slightly related individuals that form the spores. Better to take that chance that ensure that you leave no descendants.

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ZeFrank has another biology video, this time on the slime mold (one with an amoeba life stage) Dictyostelium discoideum.  This is a strange microorganism that usually reproduces asexually, but can do so sexually. In one stage of the asexual reproduction, the cells aggregate into a slug which then turns into a stalk that produces spores that disperses genes. Some of the cells that aggregate, however, don’t get to reproduce as they form the stalk instead of the reproductive top of the stalk. It seems, in other words, like a form of altruism.

I used to know the answer to this conundrum, because a cell certainly doesn’t want to help other cells reproduce at the cost of its own reproduction.. (If they were  genetically identical it wouldn’t matter, but I don’t think they are.)  And I don’t think ZeFrank gives the solution.

I know some readers here work on “Dicty”, as they call it, so we’ll have an answer soon.