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What is this tiny, transparent creature found in my home?

What is this tiny, transparent creature found in my home?



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Found these in my bathroom, everything was literally crawling with them - there were thousands of those on walls, sink, bathtub… I have all surfaces were sprayed with chlorine spray and with bug repellent afterwards. Still these creatures came back same day, although in smaller numbers.

There's not many features I can use to describe this creature aside from:

  • Size: very tiny, below 1mm; (black strands are beard hair)
  • They are pale-yellowish and semi-transparent as it's seen on photos provided
  • Rather slow and they walk aimlessly on all kinds of surfaces
  • They seem to be coming from cupboard under the sink, where it's warm, moist, dark and there's access to sewage piping shaft

I'm aware photos could be much better, but they were taken with smartphone combined with a lens from a flashlight to enable macrophotography. Not a best tool for that purpose though.

EDIT: Added circles around creature. Please ignore zoom cursor on first image.


A Sunday with the Tardigrades

It was a wet and rainy day yesterday, and we have a dissecting microscope, so I decided to see if I could find some tardigrades.

I went outside and scraped a bit of moss and some lichens off of our deck. Then I put the lichens and moss in a dish. We don't have distilled water in our house, so I added a bit of cool some tap water to the dish. I squeezed the moss and lichens in the water. Then I took a pipette and transferred a bit of the stuff in the water to a plastic petri dish and looked for tardigrades.

Sure enough, I saw one climbing onto a raft of debris. The creature looked quite a bit like a transparent caterpillar.

It wasn't long before the other members of our household walked by and got interested. "What are you looking at?" "I want to see!"

I had to give up the microscope so everyone else could check out the tardigrades, protozoans, rotifers, and other mysterious creatures zipping around in the dish.

Which, of course, was part of my motive all along.

All about Tardigrades
Tardigrades are also known as "water bears." They're small, about 0.05-1.2 mm in length, and really cute. About 930 species belong to the Tardigrade phylum. This group of very small animals fits on the evolutionary scale between arthropods and nematodes. They look a bit similar to arthropods because they have eight legs.

Tardigrades also have an amazing ability to withstand drying out. They live in water, but if the water dries up, they go into an inactive state, and they can remain in that state, dried up, for years, until it gets wet and they're rehydrated.

William Miller explains more about this incredible property:

When the environment dehydrates in dry weather tardigrades desiccate into a reversible state of metabolic suspension called cryptobiosis. They shrivel to about one-third their former size into a wrinkled "tun." Individuals have been observed to come and go from the cryptobiotic state repeatedly and tardigrades have been reported to survive more than 100 years (Kinchin 1994).

Cryptobiosis is of great interest in the study of cryogenics and tardigrades have been subjected to laboratory experiments which verified their ability to survive. Tardigrades have tolerated temperatures below freezing at 0.05K (-272.95 C) for 20 hours and -200 C for 20 months. They have survived 120 C, pressures of 1000 atmospheres, and high vacuums. In the cryptobiotic state, tardigrades have shown resistance to hydrogen sulfide, carbon dioxide, ultraviolet light, and X-rays (Kinchin 1994). We could speculate that tardigrades could be transported through outer space in their existing form.


Doing science with Tardigrades

Part of the reason that I got interested in Tardigrades was because I found this interesting site from the Pathfinder Science Network. Opportunities for students to design and carry out their own experiments are kind of a holy grail for many science teachers. This virtual community has developed several experiments to meet that need. Their goal is to give students a chance to do science and not just repeat procedures. Pathfinder experiments cover a diverse set of topics ranging from global warming to the migration of humans, monarchs, and birds. Some students have even published their work on the Pathfinder site.

I can imagine all kinds of fun experiments that you can do with tardigrades. They have many great advantages. They're cheap, found just about anywhere (there are even tardigrades in the Antarctic!), and kind of cute. Plus, a great advantage (from my standpoint) is that there are a some Tardigrade DNA sequences in the database, so we can even do a bit of molecular phylogeny.

In the meantime, I've compiled a list of resources to help you get started.

Tardigrade web sites and references

2. The Tardigrade Newsletter banner
Background information, recent papers, news, people who study tardigrades. They have some great electron micrographs of tardigrades and their eggs that you can download and use as wallpaper on your computer.

3. www.tardigrades.com This site has images, video clips and a monthly magazine.

4. Taridigra in the Tree of Life Web Project. There are some nice drawings of tardigrades here, more links, and a long list of papers

5. Molecular resources about Tardigrada from the NCBI.

6. There is a a great movie at the Pathfinders site that's very helpful in getting started. The movie shows how to find tardigrades, how to transfer them to a slide, and some of the features you can see when you've got tardigrades swimming around in a dish. The PowerPoint presentation crashed my computer, so you might want to avoid that one.


What is the meaning behind Deuteronomy 32:8-10? [duplicate]

When the Most High gave the nations their inheritance, when He divided the sons of man, He set the boundaries of the peoples according to the number of the sons of God. But the LORD’s portion is His people, Jacob His allotted inheritance. He found him in a desert land, in a barren, howling wilderness He surrounded him, He instructed him, He guarded him as the apple of His eye

I've recently been doing quite a bit of bible study. One of the terms I've researched is "Sons of God" and its usage in the old testament. The general consensus appears to be that usually when this is used it is referring to spiritual beings - Angels in heaven. Such as its usage in Job 1, Job 2.

I've read multiple different versions of Deuteronomy 32:8 most of which include the term "sons of God" - others which include "sons of Israel". Some which even reference Caanite Gods. I can't make sense of the passage using "sons of Israel" My reading of it seems to make more sense if this was talking about "sons of God" as in spiritual beings working for the most high god (Angels). The passage would then mean: That God divided mankind into groups / tribes / countries . so that the number of groups equaled the number of angels in heaven. He then gave each Angel in heaven one of the groups of people as an inheritance they were assigned to watch over and protect. Abraham, Isaac, Jacobs blood line is then said to be the group that were given to Yahweh (the lord) as his inheritance.


The unique case of commensal caridean shrimp

Interestingly, some species of caridea live in commensal relationships with sponges and other invertebrates. Commensalism, although it’s common with marine shrimp species, is rare in freshwater species. So far, experts know of two species that live this way:

  • Limnocaridina iridinea, which lives in the mantle cavity of the unionida mussel from Lake Tanganyika, Central Africa. Unionidae is a family of bivalve mollusks.
  • The Caridina species, which live in symbiosis with freshwater sponges in Lake Towuit, Sulawesi, Indonesia.

Before Boarding, far from the shore..

Though Jonah’s ship was waiting for passengers at the far off shore, we could only catch a faint glimpse of it. We were inland. Laboring for the Lord…

He began his sermon with a song. The words of the hymn resonated through the church and quickly awakened the hearts of the listeners. The Spirit of the Lord engendered shouting of amens and hallelujahs. “Great is the Thy Faithfulness” was not a song that he sang because he liked to hear himself sing or enjoyed the compliments of the congregation. It was song that ministered to him. After the song, the Spirit guided him through a powerful message of hope. People responded to the message passionately. Hearts were softened. Some came to the altar for prayer, rededication or the greatest victory – accepting Christ. I was thankful that God was using him in such a mighty way. I was proud of him! I was astounded by how he humbly allowed God to use him.

Like Jonah, my husband is a church boy. The epitome of a child who practically grew up living at the church. The son of a truly great, godly man who founded a small church. My late father in law pastored for forty-five years. He gave my husband the kind of example that one would expect from a pastor. He consistently sought the Lord as his GPS for raising his seven children. He showed my husband how to be a good husband, and a good father. Growing up in the Word, my husband knows the Bible’s life principles. At a young age he showed a gift to minister in song. His anointing shone brilliantly when he sang solos. Many people told him he’d be a minister but he would not let their accolades determine his walk. Though he felt the tugging to the preaching ministry, he prayed and waited for a confirmation God.

If your spouse, fiancee, boyfriend or girlfriend is seeking this confirmation, run! No, I am kidding. Pray! Pray for the message to be clear. Pray for a shield of protection around them because piercing arrows of discouragement are soon to come. Pray for strength to know how to support him as the one true confidant. The one who can listen, encourage and love hard in the midst of the rarely mentioned ugly moments of church leadership.



Lit 2 Go

Atwater, Emily Paret. "Chapter 5." How Sammy Went to Coral-Land. Lit2Go Edition. 1920. Web. https://etc.usf.edu/lit2go/106/how-sammy-went-to-coral-land/1877/chapter-5/ >. June 27, 2021.

Emily Paret Atwater, "Chapter 5," How Sammy Went to Coral-Land, Lit2Go Edition, (1920), accessed June 27, 2021, https://etc.usf.edu/lit2go/106/how-sammy-went-to-coral-land/1877/chapter-5/ .

Oh! do you know
Where the sea-flowers blow,
Down deep in the ocean&rsquos bed?
Where the shy plants hide
&lsquoNeath the swelling tide,
And the Anemone lifts its head?
Where the Nautilus frail,
To set his sail,
Creeps forth from the silver sand?
Then come with me,
And you will see
The wonders of Coral-Land.


&ldquoSo this is Coral-Land!&rdquo exclaimed Sammy, wonderingly. &ldquoWhat a beautiful place it is!&rdquo

He and his companion had soon recovered from the fright caused by their recent unpleasant experience, and now, filled with a comforting sense of tranquility, they swam leisurely along in the placid water. The dangers and privations of the journey were over, they had made an excellent meal on some delicious tidbits found among the weeds, and nothing now remained but to enjoy to the full the delights of their new home.

It was truly a charming place, being in reality a good sized lagoon, or lake, shut off from the outside world by the protecting coral-reefs which encircled it like a large ring.

There are many such lagoons, and this one, called by the fish-world, &ldquoCoral-Land,&rdquo because of the beautiful coral within its depths, was only one of many coral-lands, for coral-islands, and coral-reefs are found everywhere in tropical seas. Sometimes these coral-reefs are found near the shores of large islands, or continents, and then they are called Shore-Reefs. There are also Barrier-Reefs, usually enclosing an island in the deep sea, and Lagoon Islands or Atolls, which enclose a lagoon, or lake, such as the one where Sammy now was.

Near the centre of this Lagoon arose another ring of coral-reef, like a small circle within a larger circle, and in the centre of the second little lake so formed, was a tiny coral-island, dotted here and there with gay flowers, and waving palm-trees.

Outside the reefs the white-topped breakers thundered on unceasingly, but the calm waters of the Lagoon were undisturbed by their fury. Far above and below towered the magnificent rocks, forming so complete a barricade that sharks and very large fish found it difficult to gain an entrance to the Lagoon, and could never penetrate to the inner lake, where the inhabitants of Coral-Land sometimes took refuge.

As for the smaller fish, the reefs were punctured with innumerable little passages and caverns through which they could easily gain access to the outside ocean, if they wished, but most of them preferred the quiet and security of the Lagoon. Many had been born there and knew no other life, and many, like the Sun-Fish had grown so fat with good living that it would have been almost impossible for them to squeeze through the largest opening.

In fact the Lagoon was like a large aquarium of curious and beautiful fish. Floating lazily along was a round, prickly Globe-Fish, and close behind him drifted a cross looking Porcupine-Fish, an odd, countrified sort of creature, with his gaping mouth, the sharp spines on his ugly body raised in preparation for a possible attack from the strangers. Away off among the distant rocks some dazzling Gold-Fish chased each other merrily hither and thither a brilliant blue fish darted out from a near-by thicket, and a company of scarlet fish swam past, making a beautiful picture, with the clear, blue waters of the Lagoon as a setting.

Far down below myriads of gorgeous shells lay scattered about on the white sand like gay figures in a carpet, every color showing plainly through the wonderfully transparent water. Here a tree of coral rose up from the depths, its branches covered with lovely star-shaped flowers farther below a bed of shrubbery sprang from hidden rocks, and close at hand a colony of beautiful Sea-Anemones lifted their proud heads, and swayed gracefully in the water. Some of these flowers were shaped like chrysanthemums with rows of fringed petals, some were shorter and stouter, like dahlias, and all formed a mass of brilliant color, pink, purple, orange, blood-red, and sea-blue, striped with pink.

Never had Sammy seen such a sight as this bed of Anemones, and, struck with admiration, he stopped to examine them more closely. But the experienced Pilot warned him to be careful.

&ldquoThey look very fine,&rdquo said he, &ldquobut they are not to be trusted.&rdquo You know, of course, that the Sea-Anemones, like almost all flowers and plants which grow in the ocean, are living animals, polyps, we call them. The Anemones are polyps, and the coral big and little, living and dead is being made, or has been made by polyps.

&ldquoYou see that bed of pink flowers over there, and those green rushes, and those fern-like plants? Well, they are all living polyps, or colonies of polyps, some kinds of which leave coral when they die, like the coral polyps proper.

&ldquoAs for the Anemones those innocent looking flowers really possess powerful weapons in the shape of tiny lassos, which are concealed in lasso-cells. These lasso-cells, which are very small, are carefully hidden in the walls of those petal-like tentacles, or feelers of the Anemone. Still other lasso-cells are hidden in the mouth of the Anemone, and inside its stomach. In the cells the long, slender, thread-like lassos lie coiled up ready for use. The lassos escape from the cells by turning themselves inside out with lightning-like swiftness, and woe to the crab, or small water animal that comes in contact with this lovely flower! It is immediately pierced by the lassos, and poisoned by the deadly fluid hidden in the cells. Even big fish have been known to die in great agony when touched by the Sea-Anemone.

&ldquoThe Anemone frequently swallows a whole crab (if it is a good size itself) and is particularly fond of gulping down its food in this manner, keeping it for awhile in its stomach to squeeze out the juice after which what is left is thrown out through its mouth.

&ldquoAll Anemones have mouths and stomachs, and some have rows of eyes like a necklace around the body. The mouth is a small opening in the centre of the disk, or head of the Anemone, and this leads into the stomach below.

&ldquoSometimes the Anemone uses the tentacles around the disk to help feed itself, and it also uses the mouth, lips and disk for the same purpose. When the Anemone is at rest it expands its disk and draws in the sea water, and when it is disturbed it contracts, and throws out the water from its mouth. The Anemones are very sensitive to touch, and will shrink up like a sensitive plant. They are of all sizes too that little blue one over there is only about one-eighth of an inch, and that big purple fellow stands over a foot from its base.

&ldquoYou see that the body of the Anemone is shaped like a column, the flat head, or disk, being at the top, with rows of tentacles, like petals, fringing the edge. The bottom of the Anemone is also flat, and with this flat base it holds fast to the rocks to which it attaches itself. The Sea-Anemones are able to move about from rock to rock, and in that they differ from their first cousins, the Coral Polyps, for they are always stationary.

&ldquoThe Anemone has several curious ways of reproducing itself. Sometimes one animal will divide itself and become two individuals, and sometimes pieces from the bottom of the Anemone will become separate Anemones. Another strange way is by throwing out the young through the mouth, and it doesn&rsquot seem to make much difference whether they come out in the shape of eggs, or whether they are fully formed, as is frequently the case.

&ldquoStill another process of reproduction is by budding. A small lump appears on the parent Anemone this keeps on growing and growing until it soon has a mouth, disk and tentacles like the mother after which it separates, and starts out in life for itself. Whole colonies of Anemones are formed in this way.

&ldquoBut come,&rdquo said the Pilot. &ldquoHere we have spent all this time talking about the Anemones, and the coral is far more interesting and beautiful. Suppose we take a look at this large tree,&rdquo he went on in his most school-master manner. &ldquoSee how lovely it is with its trunk and branches covered with little star-shaped flowers! Those flowers are the polyps, and they, or rather their ancestors, made the tree. You know that the most important of the coral polyps live in groups, or colonies. They usually reproduce themselves by budding in very much the same way as do the Anemones, but the Coral Polyp does not separate from the parent when it gets its growth it stays fastened to the mother, and soon imitates her example by producing a bud which becomes a coral flower. And so it goes on until there is a whole colony of animals, each one having a separate mouth and stomach for his support, and yet continuing as a part of the family.

&ldquoI told you that the Anemones and Coral Polyps were first cousins, and so they are, for almost the only difference between them is that the Anemones have no coral in their make-up. Then too, the Coral Polyps cannot move about like the Anemones, and they are somewhat different in appearance, being more like lovely daisies, or stars, than chrysanthemums.

&ldquoThe coral is made from the lime of which the water of the ocean contains a large quantity, and is hidden in the sides and lower part of the polyp, there being none in the stomach and disk. When the polyp dies the fleshy part decays, and the coral, which is the skeleton of the polyp, is left. It is very hard, being composed of carbonate of lime, and will last for ages. The inside of this tree that we are looking at is all dead coral, or corallum, while the flowers that are on the outside of the trunk and branches are the living animals.

&ldquoSome kinds of coral polyps bud and extend in different directions, and that accounts for the many wonderful shapes in which coral grows. Some species divide in two, like the Anemones, but the majority live in families, or colonies. There are coral reefs and coral trees, domes and balls of coral, graceful vases, and all sorts and kinds of different plants and odd growths.

&ldquoYou know that living coral cannot exist above the surface of the ocean, for exposure to the sun and air kills the polyps yet it is always growing upward and outward, the living animals making their homes upon the tombs of their ancestors, so to speak, until they in their turn perish and add their skeletons to the growing structure.

&ldquoThe most wonderful of all coral is that found in the coral reefs, which are so old that the most ancient fish in all fishdom, or his great-grandfather before him, could not tell when they were begun and so hard and enduring that the storms of centuries have never been able to destroy them. But strong as they are, the mighty ocean, (both friend and foe to the coral), is still stronger, and in time the constant washing and beating of the tides wear away portions of the hard rock, changes the formation of the reefs, and helps in a large measure in the making of the lovely coral islands. But still the coral goes on growing, the living polyps protecting the dead coral below and beneath, and then dying to make way for the next generation. And so the coral holds its own in spite of the fury of the sea, and the many little boring water animals that strive to penetrate the dead coral, and crumble the rock into ruins. But the coral has its friends, as well as enemies, and the most useful of the first are various weeds and plants which grow on the reefs, and beside protecting the upper parts from exposure, help in their formation by leaving a kind of coral behind them when they die.

&ldquoIf you will look about you,&rdquo went on the Pilot, &ldquoyou will see what beautiful colors some of the coral has. See that big piece over there like a large red toadstool, and this curious vase all covered on the outside with tiny polyps like purple stars! You will find it in many lovely colors, and still more fantastic shapes. I have heard that some varieties of pink and red coral are very highly valued for jewelry by the two-legged land race.&rdquo

In this manner the learned Pilot discoursed to his pupil, being only too glad to have an excuse for showing off his superior knowledge and Sammy drank it all in, having in mind the time when he should return to his far-away home and brag of his adventures to the simple fresh-water fish.

Beside acting as guide, and explaining to his companion the mysteries of Coral-Land, the Pilot kindly introduced Sammy to some of his acquaintances and friends. One of these was a very large odd-looking Sun-Fish, a curious creature, all head and no body. This fish, being very haughty in his manners, and exclusive in his tastes, was considered very aristocratic: and having spent the greater part of his life in the Lagoon, was acknowledged as the great social leader of Coral-Land.

The Sun-Fish presented Sammy to the Trunk-Fish, (so named from his curious shape), and the Trunk-Fish in turn introduced him to the Globe-Fish and the Porcupine-Fish, and they made him acquainted with the family of scarlet fish, and some handsome gold-fish. Two of the gold-fish, called respectively Gay and Gilt, were particularly friendly to Sammy, who soon found them much more entertaining than the worthy, but somewhat prosy Pilot.

So, as the days went on, our hero spent more and more of his time in the company of his new friends, while the Pilot was content, now that his duty was done, to gossip with the Sun-Fish, or betake himself to some particularly good feeding ground of which he knew. Coral-Land abounded in quantities of good things such as fishes love, and Sammy soon grew fat, for Gay and Gilt were much less greedy than the Pilot, and always shared their meals evenly with their friend. It did not take him long to learn what to enjoy and what to avoid, both in the way of food and acquaintances, and he found it a most useful form of knowledge.

Thus he learned to beware of the graceful jelly-fishes who were constantly to be met floating about, their long tentacles streaming behind, and their umbrella-shaped disks expanding and contracting as they swam, for he knew that the Jelly-Fish was a cousin of the Sea-Anemone, and that its tentacles could sting most unpleasantly. So he admired them from a distance, and very beautiful they were, especially at night, when their gleaming phosphorescent bodies lighted up the darkness of the sleeping Lagoon.

Sammy learned that the affectionate embrace of the many-armed Octopus was not to be desired and that a thicket of seaweed is a good hiding-place from a chance enemy, and is apt to contain many delicious tidbits in the way of fish food. He knew the manners and habits of the many brilliant-hued fish who live in Coral-Land and he knew that the floor of the Lagoon had as many curious and beautiful inhabitants as its waters. There the Star-Fish sprawled on the sand, the Sea-Cucumber crawled along, expanding and contracting its worm-like body there the Sea-Urchin hid himself in the rock, and shells large and small, pink, blue, red and all the colors of the rainbow lay scattered about on the sand and rocks.

All these shells had, of course, their living inhabitants, for a shell is always the home of some water animal, and when the owner dies the shell is left as a monument, and very beautiful monuments most of them are.

The Sea-Snail, the Cockle, the Razor-shell and many others have each a good-sized foot which helps them in crawling along, or in boring holes for themselves in the rocks.

Sammy had taken some pains to become acquainted with the Nautilus and his family, whose beautiful little boats he had often seen sailing gaily along on the surface of the Lagoon, especially after a storm when the water was calm.

The Nautilus has a beautiful spiral mother-of-pearl shell, and when on a voyage it uses part of its body as a sail, and the long tentacles about its mouth help it in swimming. It spends a good deal of its time on the bottom of the ocean near the coral reefs, and can creep along very quickly, supporting itself with its head and tentacles. The head is flat and muscular and acts as a defense to the opening of the shell, and the Nautilus also possesses very strong jaws which it makes good use of in crushing crabs and other shell-fish on which it feeds.

Sammy found it rather difficult at first to come to a friendly understanding with the Nautilus, for the gallant little mariner was somewhat shy of strangers, and would frequently show his distrust by suddenly drawing in his tentacles, upsetting his shell, and dropping to the bottom of the Lagoon, thus effectually cutting short any conversation. But this was only his way of protecting himself after a time he grew bolder, and being a true sailor spun many a wonderful yarn about his voyages.

To the Nautilus Sammy was indebted for a most important piece of information. It happened in this wise. He had now spent several weeks in Coral-Land. He knew the Lagoon thoroughly from end to end, the best feeding and hiding-places, the delightful caverns and caves in the reefs, and was on friendly terms with almost all its inhabitants. But a fish is a restless creature, and, strange to say, Sammy was daily growing more and more weary of this peaceful Lagoon. It was all very wonderful to be sure, the beautiful coral in its lovely colors and fantastic shapes, the gay flowers and plants, the strange shells, and the brilliant, sparkling fish but then the warm water was certainly enervating, and the mountain stream that he called home had many charms, now that he was no longer there.

The Pilot-Fish had long since departed for other scenes, and Sammy wished that he had consented to accompany him. Now it was too late, and the only thing to do was to wait and hope for some way of beating a retreat. Not caring to confide his weakness to his two friends, who would not understand it, he kept his secret to himself, longing more and more for that quiet mountain stream so very far away.

One fine day as Sammy was swimming sadly along, and alone, near the outer reef of the Lagoon, his friend, the Nautilus approached him in great excitement.

&ldquoI&rsquove seen such a strange sight,&rdquo he exclaimed eagerly, sailing close up to the salmon in his haste. &ldquoThis morning I thought I would have a little adventure, for it&rsquos very tiresome spending so much time in the Lagoon, so I found my way, through a passage known only to myself, out to the ocean, and such fun as I had sailing up and down! To be sure I had to keep a pretty sharp outlook, for it is a dangerous place out there. However, nothing of any consequence happened, and I was beginning to feel a little disappointed, when suddenly, only a short distance away, I saw a school of large, pink fish, very much like you in appearance, and all swimming north. Never before in all my experience have I known a school of fish of that kind in our neighborhood! It will be the talk of Coral-Land for a week. Excuse me, but I really must go and tell my family,&rdquo and abruptly upsetting his shell the Nautilus disappeared at once from view.

For a moment Sammy hesitated. Gay and Gilt, with his other friends, were far away. Should he try to find them and say good-bye? No, it would take too much time, and they would be sure to protest against his going, and then the school would be out of sight. One swift glance about him, and away he dashed another moment and he was at the reef, a passageway out was found, and darting through the breakers, he rose to the surface and looked forth once more on the broad ocean. Behind him lay all the wonders and beauties of Coral-Land, and there, far away towards the north, a mass of moving fish darkened the surface of the water. Could he reach them before they disappeared, or before some hideous monster saw and intercepted his flight? Away he darted, faster, faster, and still faster. Now the school was getting larger, he was surely gaining still nearer, and he could see the sun gleam on countless scales nearer still, one final effort, and the school of salmon opened to receive him, and then swept on northward and homeward.

There was a pause. Grandma dropped her work, and leaning idly back in her rocking-chair, gazed dreamily out over the ocean, sparkling in its sunset glory.

&ldquoIs that all?&rdquo inquired Eleanor. &ldquoDidn&rsquot Sammy really get home?&rdquo

&ldquoThat is all,&rdquo said grandma. &ldquoWhat became of our hero after he joined the school of salmon I never knew. In all likelihood he never left his companions. But whether he guided them to the pleasant waters of that mountain stream, or whether they took him with them to some lake or inland river, I cannot tell.&rdquo

As for Gay and Gilt, they long mourned the mysterious disappearance of their playfellow, and often now when the sun shines brightly on the blue waters of the Lagoon, when the Nautilus sails forth on his voyage, and the sea-flowers sway and nod in their deep beds, the two gold-fish swim sadly about amid the depths of Coral-Land and tell stories to the passing stranger of the merry young salmon who came from the north, so long ago.

This collection of children's literature is a part of the Educational Technology Clearinghouse and is funded by various grants.


What is this tiny, transparent creature found in my home? - Biology

I know this is Project Puffin, but oh, the terns..

I was there from the beginning, to witness mom and dad in the throes of courtship, wings drooped, tail erect, sharp bill pointed skyward as they strut in circles around each other on the rocks in early spring. They acted out elaborate rituals of presenting fish, sometimes playing coy as the other begged like a hungry tern chick. This soon led to the awkward act of, male standing unsteadily on the back of the female, trying to balance and maneuver so as to achieve an assumedley successful copulation. Then came the act of digging shallow nest scrapes, breasts pushed against the ground as their feet dug out the earth beneath them. In the early season, there’d be new cups every day, appearing on the edges of the flat rocks and vegetation. And suddenly, magically, they’d be graced with an perfect, delicately speckled egg. So fragile against the heavy weight of the world.

For the next three weeks, mother and father take turns incubating the eggs. Whoever is
not on the nest brings back fish for the other stalwart parent, sometimes begging to take over duties with murmurs and a few gentle shoves. It seemed as if the birds were quite drawn, perhaps instinctively, to incubate, even if their mate already was on the eggs. Perhaps it’s just nice to have an excuse to sit and take in the sights for several hours.

The first sign that the living chick inside is ready to enter the world is made apparent by the materialization on a small section of the egg shell of what we call “starring”. Almost

See the pip through the starring?

imperceptible, these hairline cracks appear in a circular, star-like pattern, telling us that this little creature is just beginning its journey to the outside world. Soon, a tiny fleck of egg is pushed out from underneath, now classifying this as a “pipping” egg. Close inspection of the pinhole may reveal an eggtooth at the tip of a tiny tern chick bill, pushing out of the dark. The tooth is pointed and white with a black tip and is a perfect temporary tool for breaking free of this calcium enclosure. It is
a long and arduous process for this weak, wet, naked little bird and it takes many breaks, breathing, resting, and then at it again. When you get a close look at a bird emerging from the only home it has ever known, you get an idea of how cramped it is in there. These little creatures are doubled over, their heads between their legs with hardly any room for their wings. It’s incredible. They’re almost like a spring, wound up and ready to burst forth, which is basically what happens, but all in very slow motion.

Suddenly they’re out in the real world, wet, matted and vulnerable in the middle of a raucous tern colony. They could emerge on a warm, sunny morning or midnight in the pouring rain. Not much larger than a silver dollar, these vulnerable, shivering, brand new little birds
need to dry under the protection of their parents. They stay warm under mom or dad’s brood patch, the bare underbelly of the adults, naked during the breeding season to provide heat through skin on skin contact. Any disruption to the colony, either a peregrine, gull or wayfaring stranger, will put the birds up and suddenly the chicks are exposed to the elements and possible depredation. When you’re this small and brand new, there’s no defending yourself in the harsh world of nature.

But soon, the chicks are dry and suddenly very hungry and the role of the adults change from quietly lounging around on the nest to constantly flying out to sea, catching fish and hurrying home to feed frantically begging chicks, again and again and again. For the chicks, the name of the game is hurry up and wait. They’re inert little blobs, either on the rocks or tucked under the vegetation until they somehow can discern their fish-bearing parent out of the constant din of the entire colony. Suddenly they’re up and running, the chicks pitter-patter back and forth on their tiptoes, necks stretched, eyes wide, mouths agape, begging for the imminently incoming meal.

This goes on for a while and we spend much of the summer following the action by carrying out feeding studies from the blinds, monitoring the food that the birds are bringing in for the young. We spend three-hour stints watching around six, previously-marked nests and write down every feeding that occurs at each one, including what the food item was, how large, which adult provided it, which chick received it and the time of arrival and departure of the provider. It all happens in a flurry and, when you have many nests feeding at one time, you’re really scrambling to get down all the data. And those fish go down quick, with the chicks scrambling madly to win the prize and swallow it down before a sibling or unwanted intruder nabs it. This constant influx of food make for quickly growing little bodies, sometimes gaining as much as 15 grams in just a day or two.

And, indeed, it’s only about a month later and I’m looking down upon my feeding study nests and watching eager flapping as the tern chicks prepare their muscles for flight. My charges here are common terns, whereas many of the arctic terns have already fledged (they nest a little earlier than COTEs). Everywhere you look, there are chicks popping up like popcorn off the rocks and out of the grass, taking flappy-jumpy hops that progressively get a little lither, a bit more buoyant, until suddenly a small gust of wind catches hold and surprises them into flight. Their stubby tail feathers haven’t grown all the way in at this point, so they’re a bit awkward at first but grace takes over as they wheel around the colony for an entirely new view of a world I can only imagine. But reality strikes when an impatient adult divebombs from above, sending it careening into the grass, wings splayed, landbound once again..until it gathers up the courage for another attempt.


Philosophical Explanations of Cancer, Biology, Science and Biodiversity

'I do think advocates of the “naturalistic” approach to disease sometimes downplay the role of values in these difficult cases of line-drawing in medicine, with respect to diagnosis, prognosis, and choice of markers of risk. If we wish to respect patient autonomy, however, we should make these risk-benefit trade-offs transparent to them.'

'Sober argued that there are certain claims of science that are both “causal” and “a priori” - this sounds counterintuitive, because we tend to think of causal claims as empirical ones.'

'The short answer is that cancer is a very complex disease we should not expect a science that investigates this complex disease to come up with a simple, unified theory or model that explains all there is to explain. Cancer is massively heterogeneous - both in its causes and dynamics, as well as in responses to therapy, progression, etc. This is illuminated by the fact that when I tell cancer scientists that I wrote a book on cancer, they typically ask me which kind of cancer (e.g., breast, bone, lung, etc.). No cancer scientist thinks that one should (or could) write a single book on cancer (in general).'

'The issue is not “who” should get screened, but “when,” and “how” or “how often" one should get screened. For instance, routine mammography screening of women starting at age 40 is likely to lead to a lot of false positives, unnecessary follow up, expense, and overdiagnosis and overtreatment.'

'Little boys are at higher risk of cancer than little girls so there is likely to be some greater vulnerability associated with sex. That said, sex is not just about chromosomes, and gender is not just sex assigned at birth. '

Anya Plutynski has written on the history and philosophy of evolutionary biology and genetics, the role of modeling in science, and scientific explanation. Here she discusses science and natural kinds and cancer, ‘line drawing’, ‘inductive risk’ and ‘underdeterminism’, normativity and naturalism, genetics, context and causality, causal information vs accuracy, values and objectivity, Sober and causal modelling, Rosenberg and Lange, Kuhn and Lakatos, pluralism and pragmatics, whether it's sensible to ask why someone gets cancer, cancer screening issues, gender and sex, and biodiversity.


3:16: What made you become a philosopher?

Anya Plutynski: On the one hand, I suppose it was a series of accidents. On the other hand, I was always interested in philosophy, though I did not recognize my interests as philosophical, initially. In high school, I was drawn to authors like Hesse, Dostoevsky, Tolstoy, and Huxley. In retrospect, what drew me to these authors were how they engaged with philosophical questions about freedom, morality, and the relationship between science and society. I developed a love for history and philosophy of science at University of Chicago, taking classes with J.Z. Smith, Dan Garber, Howard Stein, and Bob Richards. I went to Penn for graduate school initially intending to work on Kant, though I developed doubts about whether I had the motivation to continue, and I took some classes in biology, thinking I might leave philosophy and go to medical school.

However, I started finding my classes in biology philosophically interesting, especially an independent study with Neil Shubin. He and I worked through several important texts in the modern synthesis, just as I was taking a history of biology seminar with Mark Adams in the HSS program, and hearing these issues discussed from the biologist’s perspective, alongside that of a historian like Mark, brought into focus for me how the questions these scientists were debating were not only empirical, but often methodological, and conceptual. I shifted from Kant to history and philosophy of biology. Gary Hatfield supervised my dissertation and supported my pursuing a master’s degree in biology alongside my Ph.D. in philosophy. Gary was a fantastic advisor he was able to help me synthesize my interests in history, biology, and philosophy of science, and guided me toward communities like ISHPSSB (the International Society for the History, Philosophy and Social Studies of Biology). At my first ISH conference, I felt like I found my academic home.

3:16: So you’re interested in issues of the philosophy of science . Interestingly you have expertise in cancer and use this knowledge as a source of many of your ideas regarding these philosophical ideas. So one of the general issues discussed by philosophers of science regards the nature and existence of natural kinds. So you ask this question regarding cancer – you wonder whether cancer counts as one natural kind, or many? You look at two responses: Khalidi thinks it is a natural kind, Lange thinks it is a Kludge! So to start, can you sketch what they argue and where the big disagreement lies and what it tells us about what we mean when we say something is natural and scientific?

AP: Khalidi argues that cancer seems to qualify as a homeostatic property cluster kind, because the “hallmarks of cancer” (or, hallmark features of cancer cells) suggest that there are common “homeostatic mechanisms” that cause cancer cells to cluster, as a kind. Lange argues that diseases are not natural kinds, and so, of course, cancer is a not a natural kind, and not even a unified type of disease. As we are learning more about cancer, it has become clearer that each cancer is the product of a suite of distinctive functional disruptions. I agree with Khalidi that in principle the “hallmarks” are all strongly associated with the behavior of cancer cells, but I also agree with Lange that cancers are not one kind of dysfunctional state, but a motley collection. I think both make good points, and in the book I use the two stances as foils to propose my own view. The philosophical picture of natural kinds - even the modest forms like Boyd’s homeostatic property cluster view - are not well-suited to the aims of medicine and disease classification. It turns out that we can cross-classify different cancers, for different purposes.

By way of a simple example, we can classify all “end stage” cancers as (in a sense) of a kind, in that they all are likely to lead to death in the near future, but each such cancer has a distinctive etiology, and might have arisen in different tissues, organs, etc.. We can also cross classify cancers that arise in different tissues and organs as of a ‘kind’ insofar as they similarly respond to a specific targeted drug. Disease classification in medicine, in other words, is pragmatic, and concerned largely with diagnostic, prognostic, and treatment matters. These are “natural” categories in a sense, because there are empirical (predictive, explanatory) relationships that they track, but there’s not one kind of outcome we’re interested in, in medicine, and different causal pathways are predictive and explanatory of these different outcomes (disease initiation, progression, metastasis, death, response to drugs, etc.). Prioritizing one as the “true” way to carve up disease categories is a choice we make, and not a choice that’s determined by the natural world.

3:16: What are the issues of ‘line drawing’, ‘inductive risk’ and ‘underdeterminism’ involved in trying to understand a disease as a disease?

AP: Early diagnosis saves lives, but not all cancers progress uniformly to metastasis and death. Some remain indolent (or, regress). Cancer screening thus carries a risk of not only false positives, but also, overdiagnosis and overtreatment (the diagnosis and treatment of a condition that would never have led to symptoms or mortality in the lifetime of the patient). Diagnosing cancer thus involves a judgment that risks error and so carries “inductive risk”. (There’s a good deal of uncertainty about how many patients are overdiagnosed and overtreated for cancer - estimates range from less than 1% to as high as 20% for some cancers (prostate, thyroid).)

Diagnosis of cancer also involves "drawing a line" between invasive disease and indolent or slow growing conditions that may or may not lead to invasive cancer. Assessing how and where to draw these lines involves choices, which have various risk-benefit trade-offs. Inductive risk also is at play in assessing the benefits and harms of different screening regimens – whether in choice of modality or choice of cut-off for various biomarkers of disease.

3:16: Are normative judgments inevitably involved in making scientific distinctions and do you think the focus on being naturalistic unhelpful because it encourages value judgments to be less than transparent and distorts the picture of what science is?

AP: In medicine, many distinctions do require a fine balance of risk and benefit, which require value judgments about risk tolerance. This is especially apparent when diagnostic categories are vague or open ended, or the chance of progression of illness given some pathophysiological state is uncertain. The obvious cases are psychiatric diagnoses whether to call someone’s psychological state a disorder or simply ordinary suffering has been a long standing matter of controversy in some cases. I don’t think being “naturalistic” is unhelpful, if you mean simply attending to empirical evidence! Attention to the total evidence is always ideal in scientific judgment, and in medicine! As long as you are also transparent about the role of values in such judgment, when it comes to patient’s decision making about treatment, then “naturalism” per se is not a problem. However, I do think advocates of the “naturalistic” approach to disease sometimes downplay the role of values in these difficult cases of line-drawing in medicine, with respect to diagnosis, prognosis, and choice of markers of risk. If we wish to respect patient autonomy, however, we should make these risk-benefit trade-offs transparent to them.

3:16: How does your thinking about the role of genetic factors in causing cancer illustrate the role of ‘context dependency’, locality and instability in assigning causal roles to entities in science and help us understand the ‘causal selection’ problem?

AP: This won’t be news to most philosophers of biology (or, for that matter, most cancer scientists!), but one of the central upshots of what I found when looking at the role of genes in cancer is that the effect of a mutation is highly context-dependent. As you might expect (from an evolutionary perspective), there are lots of “back up” mechanisms in place to prevent changes to genes during somatic cell division from yielding disease. So, for instance, we shed skin all the time that carries many “cancer mutations,” but these mutations never yield disease. Whether a mutation acquired during cell division yields disease depends on where and when it comes about, the cell and tissue or organ of origin, factors in the tissue microenvironment, like presence of a blood supply, immune response, age and sex of the patient, and a host of other factors. So, I think that for complex diseases like cancer - the causal selection problem is more often than not a pragmatic matter of sorting out where and how we are likely to effectively intervene. In many cases of complex, multifactorial disease, there may at best be pragmatic reasons to focus on one or another specific cause, causal pathway, or mode of intervention.

3:16: In setting standards for what we should be using as evidence for a scientific theory, should we care more about what the causal information is for rather than with accuracy – and is this what actually happens?

AP: When we talk about biomedicine, what count as “theories” is a broad swath of things: mere hypotheses, versus robust families of models that can be used to make precise predictions, or yield “how likely” (or “how possibly”) explanations. In other words, these “theories” are built for different purposes, and so they can have be said to have different virtues, insofar as the meet or fail to meet those purposes. Consider classical population genetics: I tend to think of this “theory” as a family of models that are useful (if simplified) ways of representing the causal dynamics of evolutionary change in populations. Likewise for much of the mathematical modeling in cancer: many of these are simplified, idealized models that help us investigate very general questions about cancer’s dynamics. Though in some cases they can be used to make accurate predictions, often they provide at best how “possibly” explanations.

So, questions of “accuracy” are not so central to these theoretical parts of biology and medicine. When it comes to hypotheses like whether this or that drug works (and how well) to reduce mortality in this or that cancer, then of course, predictive accuracy is important, but so too is causal information about how the drug works or is likely to work. So, I tend to think that the answer to this question depends on the kind of “scientific theory” at issue. Modelers often have to make choices that trade off these virtues - causal information v. predictive accuracy - in different ways in different contexts.

3:16: Why don’t you think values that keep coming in to these judgments compromise objectivity?

AP: Helen Longino pointed out that there are different kinds of values in science - what she calls “social” and “epistemic” values. Whether or to what extent such values compromise objectivity depends on how and when they play a role in a scientific inquiry. For instance, trading off generality for accuracy in theoretical modeling is not (necessarily) to compromise “objectivity” – at least objective judgments about likely general patterns or processes, e.g., governing cancer’s dynamics. But, the desire for profits in developing and expanding the application of cancer drugs can certainly compromise objectivity, and lead to poor quality research. Values play a role in establishing methodological standards or setting thresholds for efficacy of drugs. Such values can compromise the quality of research and the likely benefit to cancer patients.

3:16: You’ve looked in the field of cancer studies to illustrate examples of Sober’s ideas regarding causal modeling. First, what are the views regarding ‘causal modelling’ that Sober defends?

AP: Sober has written so many articles and books on causal modeling that I feel unprepared to summarize them! But, I expect you’re thinking of his 2011 paper on “a priori causal truths”, which I discuss in the book?

3:16: That's the one yes.

AP: Ok, well then, in 2011, Sober argued that there are certain claims of science that are both “causal” and “a priori” - this sounds counterintuitive, because we tend to think of causal claims as empirical ones. But, here’s a vivid example from Sober’s paper, an example from theoretical population genetics (the part of evolutionary theory that gives mathematical representations of evolutionary dynamics, of the sort I mentioned above: i.e., “if-then” claims about the causal factors at work in evolving populations): "If A is fitter than B in a population in which no other evolutionary causes are at work, and the traits are perfectly heritable, then A will, in expectation, increase in frequency.” Sober claims that this truth is causal, because it’s about the role of natural selection in a population. However, it is also “a priori” in the following sense: it's not defeasible by empirical observation. Nonetheless, it takes work to demonstrate – he’s not claiming that we know such a thing from birth, or that it’s “obvious” or somehow “true by definition,” but that it’s “necessarily” true, as an “if-then” claim, about any population that meets these (idealized) conditions.

3:16: So why do you think that arguments against this sort of modeling from Rosenberg and Lange don’t work?

AP: To some extent, I think that what’s happening in this dispute is Rosenberg and Lange and Sober are talking past one another. Sober argues that there are true, general claims about causal relationships in ideal conditions, and he gives examples, such as the one above. In the book, I consider several similar claims from cancer researchers, such as this one: “If stem cell renewal were the only driver of cancer incidence, then there should be a linear relationship between stem cell renewal and rate of incidence across different tissues.” Theoretical claims such as this abound in ecology, economics, and evolutionary biology there’s even a popular jokes about this kind of approach to science: the "imagine a spherical cow” meme. Scientists propose and offer theoretical demonstrations "causal truths” about spherical cows and other imagined states of affairs, because they’re interested in such “if-then” generalizations: generalizations about what would follow, if certain extreme or idealized conditions held. Building fictional models can enable scientists to derive informative truths about both ideal systems, and the real world.

Such truths may be informative not only “despite” their lack of fit to the world, but indeed, exactly because of their lack of fit, as folks like Sober, Wimsatt, and more recently, Sober’s student, Angela Potochnik, have argued. Rosenberg and Lange (2011) argue against Sober that it is absurd to suggest that we can meaningfully speak of such claims as both “a priori” and “causal”. My argument was that denying this would make much of scientific reasoning – modeling and mathematical arguments, yielding scientific understanding, prediction, and explanation – opaque. I suggest that several examples of theoretical explanations in cancer look much like the cases that Sober describes: e.g. “for any system that meets these conditions, it would follow that…” This derivation of general “causal a priori” truths is part of what modelers in science do.

3:16: Kuhn and Lakatos were central to debates in philosophy of science at the end of last century and I see that you are still drawing on them so presumably they still have currency in contemporary philosophy of science debates? Can you sketch for us how their approaches are currently understood, perhaps through looking at the role of ‘puzzles’ within cancer research, as opposed to 'theories', and how this distinction helps frame Lakatosean ‘research programs’?

AP: I first read Kuhn and Lakatos in classes with Stein at Chicago, and I’ve always found them fruitful to return to. Both engaged more directly with scientific practice than many of their contemporaries, in ways still relevant today. Both recognized that science is not simply a matter of theory development or hypothesis testing, but a dynamic interplay between theory, experiment: iterated puzzle solving. Both saw that theoretical commitments are one of several factors driving science practical limitations and interests shape the questions we ask, and the answers we give. I used Kuhn to frame my last chapter, because he mentions almost in passing that there is no one “solution” to the puzzle of cancer.

I liked this way of thinking of cancer because it seemed more in keeping with how scientists themselves think. Scientists that study cancer do not by and large see cancer as one, unified problem, but as a set of very different puzzles to be solved. I argue in the book that many cancer scientists don’t see their work as advancing and testing “theories,” so much as solving puzzles. I was led to this way of thinking about cancer research also by Joan Fujimura, as well as M. Morange. Both of their work on the history of 20th Century cancer research suggested to me that what launched the focus on cancer genes were specific puzzles that scientists happened to have the right tools to solve.

3:16: Your approach defends a pluarlist and pragmatic approach to scientific research in biomedical research. Could you summarise the key points, what are its advantages and limitations and then say whether you think this sort of approach is relevant only to this area of scientific research or whether in fact this notion of having partial and overlapping models is something that applies in other fields of science as well?

AP: The short answer is that cancer is a very complex disease we should not expect a science that investigates this complex disease to come up with a simple, unified theory or model that explains all there is to explain. Cancer is massively heterogeneous - both in its causes and dynamics, as well as in responses to therapy, progression, etc. This is illuminated by the fact that when I tell cancer scientists that I wrote a book on cancer, they typically ask me which kind of cancer (e.g., breast, bone, lung, etc.). No cancer scientist thinks that one should (or could) write a single book on cancer (in general). While there are simple theoretical models that help us get a partial picture of cancer, they often represent only a small part of the picture – representing one specific dynamic, causal pathway, or one temporal and spatial scale. So, having a variety of different models and modes of investigation of diseases like cancer - from the molecular on up to the epidemiological - is incredibly important, if we wish to explain the many different patterns, processes, and outcomes involved.

3:16: Given your approach, is it really sensible to ask why a person gets cancer?

AP: You and I both have had cancer so it’s a case of a philosophical question that has a directly personal interest. If you mean, are there some factors that increase the risk of cancer (and, you grant that identifying such risk factors is a satisfactory answer to the “why” question), then yes. In some cases, it is sensible to ask why a person gets cancer. Indeed, I think we can and should assign causal responsibility, whenever someone knowingly exposes people to high doses of carcinogens (e.g., radiation, polluted waterways or air). Licking paint brushes with paint containing radium was “the” cause of mouth and jaw cancers, in the case of the “Radium girls.” Inherited mutations to genes, such as BRCA 1 and 2, increase one’s lifelong risk of developing cancers of the breast and ovaries (and, some other cancers). So, it is possible in some cases to identify a strongly predisposing cause, known to be associated with specific cancers. However, in the vast majority of cases, it’s very difficult to identify a major causal factor most cancers are due to many indirect causal factors that accumulate over a lifetime. As for the “existential” why question that many of us cancer survivors face, it’s hard to give a satisfying answer. There is a sense in which cancer is a matter of “chance."

3:16: What are the implications for deciding who should get cancer screening from your thinking here? As you ask: In what ways does inductive risk, broadly conceived, come into play in the science behind cancer screening, and mammography screening in particular?

AP: The issue is not “who” should get screened, but “when,” and “how” or “how often" one should get screened. For instance, routine mammography screening of women starting at age 40 is likely to lead to a lot of false positives, unnecessary follow up, expense, and overdiagnosis and overtreatment. This is why the USPSTF argued in 2009 (and again in 2016) that for the vast majority of women, screening starting at 40 was unnecessary. The evidence they reviewed from mammography trials suggested that the largest benefit was to women starting screening at 50 (provided they did not have any family history or known risk factors). Likewise, PSA (prostate specific antigen) tests offered to a lot of men during the 1990s- early 2000s probably led to a lot of overdiagnosis and overtreatment for prostate cancer. Nowadays, the USPSTF recommends starting screening later, and watching to see if PSA numbers rise, rather than routinely treating patients at a certain PSA number cut-off. Of course, this is a decision one should make in consultation with a physician, in light of one’s own risk preferences.

3:16: There’s currently much debate around gender and sex roles: I note that you have written about how fundamental aspects of sex determination can impact the biology of brain tumors and what will need to be done to accommodate this discovery. I wonder whether you think these sorts of consideration need to be considered when we consider how to deflate the importance of gender difference which for some means erasing sex difference as well?

AP: Sex (in terms of not only the sex assigned at birth, but having predominantly XX or XY sex chromosomes, for those born with binary chromosomal compliments) can (and does) influence the relative risk of some cancers. XY folks are more likely, on average, to develop some cancers, not only the obvious ones (prostate cancer), but also bone, brain, and many other cancers, and not only as a matter of higher levels of exposure to risk factors, since the risk is elevated even in children. Little boys are at higher risk of cancer than little girls so there is likely to be some greater vulnerability associated with sex. That said, sex is not just about chromosomes, and gender is not just sex assigned at birth.

I don’t think gender differences should be deflated or erased altogether. Gender identity can be incredibly important to defining how one sees themselves and their relationships to others. If you mean by “deflate the importance of gender difference,” eliminating gendered differences in salary, leadership roles, or social roles, then, I don’t think the biology has much to do with this. Equitable access to education, employment, and participation in government or leadership roles in society is a matter of justice. Leadership roles, income, or education, for instance, should not be allocated on the basis of either sex or gender. That there is some association of sex with cancer risk does not (at least not obviously) have any direct implications for access to leadership and education among the diversity of genders. There may be one exception: perhaps we should encourage men to retire earlier than women, since they die on average younger than women.

3:16: And of course biodiversity is another area of great significance currently. We’re apparently going through an extinction phase and again causality is a big issue for us as we try and decide what to do. Do your views regarding causality help us understand better this predicament – and perhaps others like climate change?

AP: These are great questions, but I’ve not really thought about how my views on cancer causation shape my thinking about extinction or climate change. In the context of biodiversity conservation, one insight I gained from reading a lot about the history and current practice of efforts at conservation is that attention to local context is incredibly important. Conservation planning cannot occur successfully when done in isolation from the people and places which one is seeking to conserve. I suppose that this echoes my thinking in cancer, about how, in cases where a multiplicity of causal factors are at play, operating at a variety of temporal and spatial scales, we need to attend to this diversity of causal pathways.

3:16: And finally for the readers here at 3:16, are there five books you could recommend other than your own that will take us further into your philosophical world?

AP: Great question!

If they’re interested in questions that come up in my book, I think I’d recommend Stegenga’s Medical Nihilism


Snail Tales

Up the mountain from an old-growth tulip poplar grove in southwestern North Carolina, shortly after the sun rose, a feasting snail at a tiny scale caught my eye. Amongst the leaf litter, reflecting a warm glow in the morning sun, the snail devoured a miniature orange mushroom. And then another. And another.

This snail may have been Fumonelix cherohalaensis, a new species catalogued by scientist Daniel Dourson in 2012. Dourson, an independent biologist, found several new snail species in the southern Appalachians that are endemic, meaning only found in a specific range, to certain mountains or counties. Dourson spotted this particular shell-spiraling species only at elevations above 4,500 feet along Cherohala Skyway of North Carolina — a ridgetop road beginning just a few miles away from where I found a snail munching its meal that morning.

Two small antennae feelers just below their eye antennae lead snails — like this Appalachian tigersnail — to their food. Photo by Bill Frank, courtesy of jaxshells.org

Appalachia has an ancient heritage of diversity given the mountains’ resilience to ice ages. Through the eons, the mountains nurtured pockets of life that hosted plant and animal species during their centuries-long migrations away from glaciers. While small and slow, land snails managed this feat.

This region hosts up to 264 snail species — more than anywhere else in North America — and the most endemic species, according to Taylor Ricketts, a biology professor at the University of Vermont. The forests of the Blue Ridge Mountains alone foster 122 endemic land snail species.

Since snails are mostly nocturnal, they are most likely to be seen grazing in the early morning hours. A snail’s crawl is lubricated by a slimy mucus produced just below the mouth in humid air, usually during darkness or fog. Slugs, who also slime crawl, are considered their close cousins — a snail without a shell. Snails have a heightened sense of smell that will lead them to eat just about anything, from plants to animals to mushrooms to soil and rock particles, depending on their species and habitat.

This Fumonelix cherohalaensis was found on Huckleberry Knob on the Cherohala Parkway. Photo courtesy of The Field Museum, 2017

Snail populations, and the species that depend on them, are affected by changes in the environment that deplete calcium from the soil, a 2002 study published in the Southeastern Naturalist indicates. Timber harvesting and acid rain cause calcium loss in the soil, hurting snail populations, sending ripples through the ecosystem. For instance, ground-foraging birds that feed on snails lose their source of calcium and then birth weaker eggshells, a 1994 study from the Netherlands found.

These terrestrial snails can provide important clues about land-use impacts in old-growth forests, such as Joyce Kilmer Memorial Forest in North Carolina — close to where I found my small snail munching its mushroom. Since slow-moving snails stick close to home, they are vulnerable to human-caused forest disturbances, according to Daniel Douglas, a scientist at Eastern Kentucky University. In a 2011 study, he found more snail species in old-growth forests than in second-growth forests and hypothesized that snails could be regional indicators of ecological conditions.

Although it is an eternal source of wonder why snails’ shells spiral, a group of Japanese scientists found that the spiral emerges during the embryonic stage of growth when the snail consists of only eight cells. To make baby snails, some mollusks don’t even need another spiral partner — most have both male and female reproductive organs. Science aside, these miniature creatures are enamouring with their petite spiral charm and have even inspired legends with their mystery.

The Snail and the Salamander

Bessie Bird of the Echota Cherokee tribe in Alabama told this story to her grandson Tali Shaffer as a child. Shaffer, now a tribal storyteller, has published this story and others on the Echota Cherokee website at echotacherokeetribe.homestead.com

“Back in the long ago time before men, Salamander was a tiny snake and had no legs. He slithered about in creeks, under stones and in leaves that cover the forest floor.

One day he met snail, who at this time had legs, at the edge of a salt lick. Salamander knew what the lick was and laid on the edge watching other animals come and consume the salt. Snail had never been here before and had no idea what salt was.

Salamander looked at Snail’s nice legs and thought to himself how much he would like to have those for himself so he thought up a plan to kill slow-witted Snail and have those legs for himself. “Snail,” said Salamander,” look over there at that beautiful leaf across the clearing, bet it sure tastes good?” Tempted, Snail started walking across the salt, which began to immediately burn his soft body and burn holes in him. In moments the Snail laid dying and his legs fell off. As he was dying, he cursed Salamander as Salamander grabbed his legs and slithered away with them. “As long as you wear my legs, your body will be wet and soft just like mine and you will never lay in the sun again.” To this day, Salamander cannot sun himself but must hide in the damp darkness.”