30 September 2009

It’s the International Blasphemy Day!

God can never perceive. Perception and sensation are identical. Every sensation is accompanied by pleasure or pain. But God, if immutable, can neither be pleased nor pained. Every fresh sensation involves a change in mental and perhaps in physical condition. God, if immutable, can not change. Sensation is the source of all ideas, but it is only objects external to the mind which can be sensated. If God be infinite there can be no objects external to him, and therefore sensation must be to him impossible. Yet without perception where is intelligence?

Charles Bradlaugh. 1874. A few words about the devil, and other biographical sketches and essays.

International Blasphemy Day

29 September 2009

This all there is for tonight


We will start anew tomorrow.

28 September 2009

A 19th century painting of terrestrial gastropods


This is the plate of "Land Molluscs" from volume 6 of The Royal Natural History edited by Richard Lydekker, published in 1896 (available at The Internet Archive.

The snails with banded shells may be one of the 2 Cepaea species present in Great Britahn, perhaps C. hortensis; whereas the tall-shelled snail climbing up the log looks like either Cochlicella acuta or C. barbara.

Here is a detail from the bottom.


On the left are a couple of clausiliids. The snail in the middle with the aperture of its shell sealed with an operculum is Pomatias elegans. Near the top, a batch off eggs are visible. But life is not only about eating mushrooms and strawberries and laying eggs; there is also danger lurking in the shadows: on the right, a beetle, probably a carabid, is attacking an orange slug. Perhaps that is the slug that laid the eggs. Now it can die.

27 September 2009

Bipalium adventitium — Part 2

I wrote about the land planarian Bipalium adventitium in this post. That individual ended up in a vial of alcohol soon after that post was written. Last Friday, I found another one under a log in a park. There were also earthworms in the soil under the same log; they are the planarian's main, if not the sole, prey.

Here is a picture I took in the field; the planarian was still on the underside of the log.

It's hard to give dimensions for these animals, because their bodies are very stretchable. In this picture, the planarian was probably ~4 cm long.

I have also taken several video clips of it while it was crawling on a glass plate. Here is one of them. Excuse the quality; this is the best I can do with my current camera.


Notice how it moves its head from side to side as it crawls. That's the characteristic behavior of these planarians. The lateral movements of the head presumably enable the sensors on the head to pick up chemical clues from the environment.

The planarian hasn't eaten for at least about 50 hours. I have selected an unfortunate earthworm from the backyard and will be giving it to the planarian soon.

More will be in Part 3.

25 September 2009

Bivalves in the C&O Canal

A week ago I took a long walk on the towpath along the C&O Canal near Georgetown. At one point I descended into the canal itself to photograph some tracks (I will write about those some other time). These clams were extremely abundant in the mud at the bottom of the canal (there wasn't much water in the canal, obviously).


They are a Corbicula species, probably Corbicula fluminea, an invasive alien native to China.

The other bivalve species I noticed, which was much less abundant than Corbicula, was the following native unionid.


Tim Pearce identified it from the picture as either Elliptio dilatata or E. complanata.

I did not notice any live bivalves. But then again, I wasn't looking for them where there was water.

24 September 2009

Whole lotta scientific papers read

A paper in the 14 August issue of Science* reported that the average number of scientific papers read by scientists per year has increased more or less steadily since 1977. According to the following graph in the paper, in 2005, the last year for which data were available, the average was about 280 papers/year.

Modified from Fig. 2 in Renear & Palmer (2009).

If the trend has been continuing at the same rate, the annual average must have exceeded 300 papers by now.

I got curious and made a list of the papers I read during a 4-week period between 24 August and 20 September. Renear & Palmer do not explain how the numbers they cite had been obtained and how much of a paper one had to read to count it as "read". I counted a paper as read if I read about 2/3 or more of it.

My 4-week total was 21 papers. If I maintained the same pace throughout the year, that would add up to 273 papers. So I am slightly below the estimated average for 2009.

Of those 21 papers, 9, or ~43%, were about mollusks. Of course, many of the rest were indirectly related or applicable to my research with snails and slugs.

*Allen H. Renear and Carole L. Palmer. 2009. Strategic Reading, Ontologies, and the Future of Scientific Publishing. Science 325:828-832. Abstract

23 September 2009

I am talking about group sex...by snails

In 2 previous posts (Rumina saharica and Oxyloma retusum), I had pictures of 2 pairs of snails mating simultaneously. I also speculated that mating snails may exude a pheromone-like chemical in their slimes that excites nearby snails, causing them to start mating also.

About a half an hour ago I was looking at the miscellaneous natural history pictures that my facebook friend David Cilia had recently uploaded on his page. One of them was the following shot of 2 pairs of mating Cantareus aspersus (Cornu aspersum, Helix aspersa) on Malta.

Photo by David P. Cilia. Used here with his permission.

The snails are in what is called the face-to-face position (as opposed to the shell-mounting position). The union of the genital openings, on the right side of each snail's head, is clearly visible in the lower pair. They are supposed to have shot darts into each other. The object I marked with a red arrow may be a dart stuck into the right-hand snail's side.

22 September 2009

We are going to freeze dry you all!

Pereira, T., & Lopes-Cendes, I. (2009). Cryptic anhydrobiotic potential in man: Implications in medicine Medical Hypotheses, 73 (4), 506-507 DOI: 10.1016/j.mehy.2009.06.012

The Elsevier journal Medical Hypotheses has been in publication since 1975. I am not familiar with the journal's requirements for manuscripts, but judging from this particular paper, they don't appear to be stringent at all. I get the impression that if you include in your manuscript some buzz words and phrases, such as, "human genome", "positive selection", "applications in medicine" and "promising research field", you can get just about anything accepted for publication.

The hypothesis in this paper is that it is possible that "mammals and humans have a cryptic anhydrobiotic ability which has not been discovered yet because of an unknown specific pre-conditioning stage [that] is necessary."

The authors base this claim on the well known fact several groups of multicellular animals, for example, bdelloid rotifers, tardigrades, nematodes and arthropods, have representatives that can survive extreme desiccation for long periods. This penomenon is known as anhydrobiosis, or life in the absence of water. Therefore, the authors conclude that, because anhydrobiosis confers on an animal an "unprecedent [sic] advantage for life in several extreme and hostile conditions it would be expected that such [a] trait would be positively selected and kept during evolution. Thus, it is possible that anhydrobiosis is a widespread phenomenon but that has been observed only in a few species that naturally undergo desiccation."

Of the top of my head, I can think of 2 problems with this reasoning. First, anhydrobiotic survival is advantageous only if a species lives in a habitat that is periodically desiccated and if the species has no other means of surviving the dry period. With a few exceptions, anhydrobiosis is normally seen in microscopic animals. Larger animals deal with the drying of their habitats either by migrating to a wetter habitat or by preventing water loss from their bodies. So, for example, during the long, dry Mediterranean summers, slugs migrate deep into the soil where there is still enough moisture for them to survive, while the snails become dormant in their shells conserving water. Neither group displays the ability to undergo anhydrobiosis.

The second problem with the authors' reasoning is that it is highly unlikely that the ability to survive anhydrobiosis will be retained if there is no need for it. If a trait becomes unnecessary, it may persist, be lost or become a vestige (see, Lahti et al., 2009). An unnecessary trait will be retained if the benefits it confers outweigh the maintenance costs. Why would evolution maintain the ability to survive extreme desiccation in humans when they can simply migrate to a wet enough habitat?

But these problems don't stop the authors from speculating on the potential applications of anhydrobiosis in humans (somehow assuming that their hypothesis has been proven correct). This includes the storage of tissues and organs in a desiccated state, protection to [from] radiation and heat and, are you ready for this?, whole body conservation. Freeze dried humans for rehydration in the future? I think we've stepped over the boundary into silly science fiction.

This paper came to my attention because it cites one of my old papers on bdelloid rotifers (Örstan, 1995). They cite my paper to support their claim that metabolism stops during anhydrobiosis. It probably does, but the funny thing is that my paper was not about that.

Medical Hypotheses also needs a better copy editor.

David C. Lahti, Norman A. Johnson, Beverly C. Ajie, Sarah P. Otto, Andrew P. Hendry, Daniel T. Blumstein, Richard G. Coss, Kathleen Donohue, Susan A. Foster. 2009. Relaxed selection in the wild. Trends in Ecology & Evolution 24:487-496.

Örstan, A. 1995. Desiccation survival of the eggs of the rotifer
Adineta vaga (Davis, 1873). Hydrobiologia 313/314:373-375.

21 September 2009

The vagaries of field work

Taking advantage of the nice weather we had yesterday, I spent several hours in the field continuing with our ongoing Cepaea nemoralis survey. The purpose is to determine how far the species has dispersed around the point where we think the original introduction took place some time ago.

But, how does one decide if a species of interest is absent at a locality, say, a square roughly 30 m along one side? Philosophically speaking, how can one prove the negative? One really can't*. And we don't actually claim to prove that a species doesn't exist at a locality where we couldn't find it. We only say that we couldn't find it. The idea is to carry out searches at as many localities as possible and then hope that some sort of pattern will emerge after we put all of the localities on a map. For example, we may see a boundary beyond which Cepaea nemoralis seem to be absent. Or we may see an association with an environmental variable; for example, most of our localities where we found the species may be near a water body or in forested areas.

But, the act of finding a species at a locality where it actually exists could be daunting, especially if there aren't very many individuals and if the visibility is obscured by the plants and the debris on the ground.

So, to make this short story even longer, I will give an example from yesterday.

At one of my localities, a steep, wooded and rocky slope, I spent, literally hanging onto the bushes and tree branches to stop myself from sliding down to the river at the bottom, about 15 minutes searching for Cepaea nemoralis. I found no Cepaea, but I did find several snails shells that belonged to other species, which made me think that my search technique was otherwise effective. Finally I decided this was going to be one of the "open" circles on the map, a spot where Cepaea nemoralis did not exist. I started climbing up the slope while still keeping my eyes on the ground. I reached the edge of the forest and was about to exit into the sunny field beyond, and then I spotted one Cepaea shell.

The proof that Cepaea nemoralis was present at station FR-19. The spire of the shell was missing.

If I had happened to be looking at a different spot, or a plant had totally blocked the view, if I had happened to climb up a different path, I would have missed it. Or, maybe I would have found not one, but 2 shells.

During the 3-hour field trip I ended up searching 10 localities and found Cepaea at 3 of them. Was the species really absent at the other places?

I will never know. And it doesn't matter, because a pattern is starting to emerge.

*Within the limits of reason, of course. I did not see any elephants yesterday at any of the places I looked. And that does prove that elephants did not exist at those places, mainly because elephants are unlikely to have been present.

20 September 2009

Are we on a one-way street away from nature?

The other day I was watching segments of David Attenborough's speech during the opening of the Natural History Museum's Darwin Centre in London earlier this month. At one point, Attenborough said (my transcription):

...we are increasingly cut off from the natural world. It's a paradox, isn't it? That, we as mankind, know more about the natural world than we've ever done in history. And yet, at this particular moment, over 50% of the human race is urbanized to some degree.
This general idea is, of course, not new. I have in one of my old notebooks a quote attributed to Jacques Cousteau that I wrote down in the 1970s, which, after several translations, reads something like this: "We have grown so distant from nature that we've forgotten how to treat her."

Earlier this morning I read Danilo Mainardi's essay, The technological zoo, in the book Beasts and Bestiaries. And by coincidence, it turned out that he was thinking along the same lines when he wrote about his observations in New York City:
We are all aware that the minds of modern people (nowhere more than in the "Big Apple") are devoid of animals. Animals have no place in today's world, and they are portrayed less and less. When we go to the cinema, the ones that appear most alive and present are dinosaurs—which have been extinct for millions of years. And, of course, ecology fills our mouths with the word "biodiversity", which really means (but have we taken this in?) all the different species of plants and animals that share the planet with us.

Ecology, as fashion, therefore, not as real knowledge...
One result of our alienation from nature is that when we, especially our children, mix the fragments of information coming from the TV and the movies with the surviving bits of centuries old misconceptions about nature, the resulting "knowledge" could be quite distressing. That was the topic of this post.

For now, I have nothing else to add to these notions. Later today, I will be going out to be one with nature, however briefly that may last.

Over the hedge by by Michael Fry and T. Lewis.

18 September 2009

Concrete evidence

In this post, I presented rock solid data that showed a downward trend in the index of satisfaction (IS = optimism / happiness) over time.

Most recent data that became available today, however, indicate that IS has now stabilized and may be displaying only a slight downward trend. Either optimism and happiness are not changing at the moment or they are changing at roughly equal rates.


Next update.

17 September 2009

What's with the 4-fingered people in comic strips?

Moondog should be saying to Pilsner the Parrot, "Meet me at the card table in four". Monty by Jim Meddick.

Giving their human characters only 4 fingers seems to be a stupid tradition some cartoonists can't get away from. Another comic strip with 4-fingered humans is Foxtrot.

Comics strips with 5-fingered humans include Zits, Zippy and The Fusco Brothers.

16 September 2009

Beasts and Bestiaries: a book about how they used to illustrate animals

A couple of weeks ago, while reading a paper* on snail illustrations in old publications, I noticed a citation to a 2001 book called Beasts and bestiaries. The representation of animals from prehistory to the Renaissance by Francesco Mezzalira. It looked interesting, so I started searching for a copy. It turned out that the book was out of print, but I was able to locate, thru Amazon, an independent bookseller that had a new copy for a very reasonable price.

For some reason, I was expecting this to be a small book. So when it arrived today in a rather big box, I was surprised. The book turned out to be much larger than I had expected.


This is a handsome, lavishly illustrated production. The plates, many in color, are on glossy paper, which makes the pictures look nice, but the taking of photographs of them with a single flash is rendered difficult—there is always some glare.


It'll be a while before I find time to read the text; in the meantime I am enjoying the illustrations.

Of course, no book on this subject would be complete without a few pictures of our favorite animals. So, here is a quite realistic drawing of a slug from one of the books of the Italian naturalist Ulisse Aldrovandi from 1602. The caption reads: Limax nudus cinereus maculis albicantibus. I don't know which slug that would be in the present day taxonomy.


*Warren D. Allmon. 2007. The evolution of accuracy in natural history illustration: reversal of printed illustrations of snails and crabs in pre-Linnaean works suggests indifference to morphological detail. Archives of Natural History 34:174-191.

15 September 2009

The slimy secret to a long life

At the height of his career, Joseph-Guichard Duverney (1648-1730), a professor of anatomy at the Jardin du Roi in Paris and the “chief dissector” of the Paris Academy of Sciences, was famous for his public lectures and especially, dissections, not only of various animals, but also of humans that had sometimes been obtained by bribing the gravediggers.

Anita Guerrini’s short (but good enough) biography of him* includes the tidbit that after Duverney died at the age of 82, it was claimed that his health had been “undermined by long damp nights spent at the Jardin observing snails” (italics added).

Let’s stop for a moment and scrutinize that claim. According to the graph on this page, the life expectancy at birth in France in the early 1700s was below 30(!) years. Holy Cow! At 82, Duverney was >50 years beyond that.

If anything, long nights spent observing snails must have added years to Duverney’s life. I, for one, am following his example and hoping to even surpass in good health his 82 years.

*Anita Guerrini. 2009. Theatrical anatomy: Duverney in Paris, 1670–1720. Endeavour 33:7-11. pdf

14 September 2009

Hotel Drosophila: you can check out, but you can never leave

If you have a fruit fly infestation in your kitchen, like the one we've been having for the last several days, here's a way to get rid of them without insecticides.

Get a small plastic container, put some pieces of partially rotten fruit in it and then leave it with the lid off on a counter top where the fruit flies are loitering. Now leave the room for a while, say, 20 minutes. When you return, there will be a bunch of them Drosophila in the container. Pick up the lid and bring it very slowly to the container—the fruit flies seem to have good eye sight and/or are very sensitive to any movements around them—and when the lid is just about over the opening, bring it down quickly to seal the container. Take the container outside, open the lid and release the prisoners, then bring the container back in and repeat the process until the numbers of the flies come down to a tolerable level (you can't eliminate them all).

Here is my Drosophila Motel (patent pending, of course!) named after the famous Roach Motel. The suckers inside will soon be deported. The red-stained paper was from a raspberry box.

Yes, you may have to repeat the process several times, but, hey, would you rather spray your kitchen with an insecticide?

13 September 2009

Evil thoughts for a Sunday morning

The existence of evil is then a terrible stumbling-block to the Theist. Pain, misery, crime, poverty, confront the advocate of eternal goodness, and challenge with unanswerable potency his declaration of Deity as all-good, all-wise, and all-powerful. Evil is either caused by God, or exists independently; but it cannot be caused by God, as in that case he would not be all-good; nor can it exist independently, as in that case he would not be all-powerful. Evil must either have had a beginning or it must have been eternal; but, according to the Theist, it cannot be eternal, because God alone is eternal. Nor can it have had a beginning, for if it had it must either have originated in God, or outside God; but, according to the Theist, it cannot have: originated in God, for he is all-good, and out of all-goodness evil can not originate; nor can evil have originated outside God, for, according to the Theist, God is infinite, and it is impossible to go outside of or beyond infinity.

To the Atheist this question of evil assumes an entirely different aspect. He declares that each evil is a result, but not a result from God or Devil. He affirms that by conduct founded on knowledge of the laws of existence it is possible to ameliorate and avoid present evil, and, as our knowledge increases, to prevent its future recurrence.

Charles Bradlaugh. 1874. A few words about the devil: and other biographical sketches and essays.

11 September 2009

One problem with Google Maps

I've been preparing a map of a relatively small area of Montreal, Canada for a manuscript I am writing. This is, of course, about some snails I collected back in August when I was there. As my base map, I downloaded a suitably scaled map from Google Maps and then started adding my own layers to it using Photoshop. When I noticed some discrepancies between my field notes, how I remembered the roads were and the Google map, I went back and compared the map with the actual image in Google Earth. That's when I noticed this peculiarity of Google Maps.

Here is a portion of the map. It shows that the Autoroute Décarie crosses over the 4 diagonal roads, Rue Sherbrooke, Boulevard de Maisonneuve, Chemin Upper Lachine and Rue Saint Jacques and the railroad. Right?

Wrong. Note what happens when I increase the scale: those roads, including the railroad, suddenly shift up and cross over the autoroute.

That's the correct spatial relation of all of those roads with respect to each other, as you can see in the Google Earth image. There is still another error, though. Chemin Upper Lachine is supposed to under, not over, the railroad. Even at the highest scale, Google Maps doesn't fix that error.

This isn't some quirky behavior that happens to be specific to the map of Montreal. I have noticed it happen even in Maryland. I don't know what the underlying rationale is and if this is a standard practice in cartography. In any case, this could create one heck of a confusion if one is driving in an unfamiliar area using a map printed out from Google Maps. It happened to me once.

10 September 2009

What were the first scientific journal and the first paper on mollusks ever published?

There are apparently 2 contenders to the title of being the 1st scientific journal. The Royal Society claims that their Philosophical Transactions, the 1st issue of which came out on 6 March 1665, is "the world's oldest scientific journal in continuous publication". The very 1st scientific journal may, however, have been the French Journal des Sçavans; its 1st issue was published only 2 months earlier on January 5, 1665. The time was certainly ripe for regular and serial publications of scientific ideas.

According to this brief Wikipedia article, the Journal des Sçavans was published with interruptions until 1816 when it "became more of a literary journal, and ceased to carry significant scientific material". Hence, PT's claim to be the oldest continuously published scientific journal.

Although the Royal Society won't let you read PT unless you pay them a sum enough to ransom a kidnapped queen, the Google Books has fortunately scanned the very 1st volume of PT and has it available for free here (do you hear that Royal Society?). Here is the title page of volume 1:


This brings us to the 2nd question: What was the first scientific paper ever published on mollusks? Now, I don't know if the very 1st numbers of JS are available on the Internet, but, even if they were, I wouldn't be able to decipher that peculiar language the French use. So, I will instead look for an answer to our question in PT.

Going down the table of contents of volume 1 of PT, I come to a paper titled "An Extract of a Letter, Written from Holland, about Preserving of Ships from Being Worm-Eaten" that was published on p. 190. (Curiously, PT didn't give the authors' names with their letters until near the end of the 1st volume.)

Here is an extract from that letter*:


What were those wood-eating "worms" that the writer wrote about? Why, they were mollusks, of course; specifically, bivalves of the family Teredinidae that are commonly known as shipworms. And the funny thing about this report is that, according to its author, it was an extract of an article that had come out in the 15 February 1666 issue of the Journal des Sçavans!

Although the article was more about how to prevent the infestations of ships with shipworms than about the animals themselves, I will argue that it was probably the 1st article about mollusks published in a scientific journal.

*The articles published in PT back then were actually "letters" sent to the editor.

09 September 2009

A fine example of the self-destructive stupidity of humans

In a 2-page article, the New Scientist gleefully reports that cheap in vitro fertilization will soon be available in Africa. Oh Joy! What they certainly need in Africa is more people. Most of the article is actually about making IVF cheaper not just in Africa, but everywhere else too. Let's hope they will make it so cheap that many more people will use it to have many more babies. The more the better. Yes!

What is really bizarre is that the editors of the New Scientist appear to be very enthusiastic about the prospects of adding even more people to the already-over-the-limit world population. They wrote: "Now that we know it is possible, no-frills IVF should be a priority for clinics everywhere, not just in Africa."

When there are so many procreators around, who needs enemies?

08 September 2009

Scenes from the C&O Canal in Georgetown

Last Friday's hike along the C&O Canal thru Georgetown in Washington, D.C. started near a sign revealing the area's polluted past.


The bygone industries included a tannery, a soap factory and several water mills. In addition, there must have been docks for the canal boats and the goods they carried, including, coal, wood and grain.

Most of those buildings are probably gone now, but some surviving and undoubtedly renovated ones bear the traces of their former lives. The said sign explained:
Evidence of water outlets, bricked up chutes, smokestacks, and block and tackle still remain on many buildings.


These bricked over former openings may once have been windows or entrances providing direct access to the canal in the foreground, which is now a muddy shallow depression with only puddles of shallow water.

I thought the most interesting structure along the canal was this old, irregular stone wall that had been built right on top of the bedrock.


The present Georgetown seems to be occupying a level way above its past ground.

07 September 2009

Happy Laboratory Day!

Distillation of wine to make cognac from The principles of chemistry, illustrated by simple experiments by Stöckhardt & Peirce (1861).

Chemistry classes were definitely more fun back in the 1860s.

06 September 2009

It's been a slow weekend

Fusco Brothers by J.C. Duffy

04 September 2009

Mysterious tracks in the C&O Canal

Today I was by the C&O Canal in Georgetown, Washington, D.C. where the canal begins (or ends, depending on which way one is traveling). Here is a view of the canal from M Street.


Notice the abundant tracks in the mud in the canal.


I suspect they are turtle tracks. I couldn't get closer to them to take a better look, but this particular track on partially dried mud had what appeared to be feet marks on each side.


I can't think of any other animal that would have left a track like that. Curiously, even though I walked along the canal for more than an hour towards Georgetown, I didn't see any turtles.

Part 2

03 September 2009

Snakes in the minds of Turkish students

Ekoloji is a journal of environmental studies published in Turkey since 1991. For the past several years, the journal has been an open-access online publication with papers either in English or Turkish.

One of the recent papers is about the results of a survey concerning snakes done in several elementary schools in Turkey (Oluk, 2009). The study subjects were 7th grade—in the Turkish educational system 13-year old—students. There were 423 of them, composed of approximately equal numbers of boys and girls.

The participants were asked to reply to several questions about both biological and cultural aspects of snakes. The paper presents the questions and the summary responses in several tables. I have selected the ones I thought were especially interesting and am giving them here in one table. The answers are in percentages.

QuestionYesNoDon't know
All snakes are poisonous85.64.79.5
Snakes inject venom with their tongues43.044.412.5
Snakes can swallow frogs67.615.416.8
Snakes eat grass7.677.115.4
Snakes in Turkey can swallow a person15.458.425.8
Snakes are invertebrates652213
Snakes are reptiles83.212.34.5
Earthworms are small snakes41.44018.7
Angry snakes may run after people53.426.619.9
A snake may enter a sleeping person's mouth and settle in the stomach29.644.426.0
A snake may hold a grudge against a person who has killed its mate37.834.827.4

Although most kids' knowledge of snakes' diet was accurate, when it came to the classification of snakes, many were confused. A part of the problem may be the Turkish word for reptile, sürüngen, which literally means something that crawls. Thus, it is perhaps not too surprising that since most invertebrates, like earthworms, crawl on their bellies, they are as a group confused with snakes, or snakes are confused with them.

The responses to the culturally oriented questions probably represent ancient misconceptions that have been passed on by word of mouth. They are often accepted without questioning, because an adult or one's peers may have said so.

The responses to the question regarding the information sources of the students help explain the origin of some of their misinformation. The category "TV, movies, cartoons" was the source for 88.5% of the students, while 39.8% specified documentaries. Encyclopedias were used only by 19.7% and magazines by 16.9%. Curiously, Internet was not one of the choices. The paper doesn't state when the survey was done; it's possible that it dates to a period before the Internet became a major source of information at least for those with access to it.

The author blames the overall unsatisfactory performance of the students in the survey partly on the inadequate school programs and their text books. I can think of one other possible underlying factor. Many of these kids, especially if they have spent their lives in urban areas, may have never seen a live snake, especially in the wild. Besides, there aren't very many zoos in Turkey. To many of the students, snakes are somewhat mythical creatures that they learn about mostly in non-educational settings.

OLUK, S. 2009. İlköğretim 7. Sınıf Öğrencilerinde Yılanlarla İlgili Alternatif Kavramlar ve Yaygın İnanışlar / Alternative Concepts and Widespread Beliefs Among 7th Grade Students Related to Snakes. Ekoloji 70: 47-56. [Turkish with English abstract] pdf

02 September 2009

"I saw a slug that was bigger than my SUV," recalls one terrified camper

I have discovered a treasure trove on Google Books: the entire archive of the defunct U.S. tabloid Weekly World News.

Now we can learn about the dinosaurs on Mars...


and the diver who was attacked by "horribly ugly" mermaids.


Then there was the obituary of Elvis Presley who died in 1993 at age 58.


If you have been suspecting that the Bible is full of hogwash, suspect no more. Here is the proof it is all true! (Yes, the Earthly Paradise was in Colorado.)


And finally, a dire warning to all of us: watch out for the monster slugs!


01 September 2009

A new unit of humidity?

Science Daily, the site that just recently gave us the news of the discovery of “Turkish Tablets” in a 2,700 year old “Turkish Temple” in Turkey, now seems to have invented a new unit of humidity. In a news item that came out today, they report that U.S. and Australian astronomers are thinking of building an observatory at a 4000-m high place called Ridge A on the mountains of Antarctica. Despite the extreme cold, the place appears to be quite suitable for a telescope, because there is no light pollution and the air is very still and dry. In fact, Science Daily reports that "the water content of the entire atmosphere there is sometimes less than the thickness of a human hair".

I am having difficulty understanding how one measures the humidity of air in terms of the "thickness of a human hair" or a linear dimension. I know that rainfall is normally measured using a linear dimension. So I suspect they mean that if all the water in the atmosphere above Ridge A (is that the "entire atmosphere"?) condensed and fell to the ground and stayed there, the depth of the water would be less than the thickness of a human hair. If that's indeed what they mean, that's a bizarre way of explaining it. Since most people are used to the expression of the atmospheric humidity as a percent of saturation, it would make more sense to simply express the air humidity at Ridge A the same way. 1%, or 0.1%, or whatever.

Revision added 2 September 2009: Here is the paper by Saunders et al. that was the basis for the Science Daily item. Science Daily's citation of the journal's title, "Publications of the Astronomical Society" is incomplete; the full title is Publications of the Astronomical Society of the Pacific.

If you take a look at the paper you will see that they are indeed talking about "precipitable water vapour". So my interpretation is correct. The annual mean PWW for Ridge A is given as 210 µm, that would indeed be negligible precipitation.

I don't quite see the conceptual difference, if there is any, between "precipitable water vapour" in the atmosphere (let's say, in millimeters) and absolute humidity, which is the total amount water present in a particular volume of water (grams/cubic meter).

And I still say that the Science Daily's "explanation" of the amount of atmospheric water above Ridge A is utterly confusing for the uninitiated.