Superstitions evolved to help us survive according to this New Scientist article.
Darwin never warned against crossing black cats, walking under ladders or stepping on cracks in the pavement, but his theory of natural selection explains why people believe in such nonsense.
The tendency to falsely link cause to effect – a superstition – is occasionally beneficial, says Kevin Foster, an evolutionary biologist at Harvard University.
For instance, a prehistoric human might associate rustling grass with the approach of a predator and hide. Most of the time, the wind will have caused the sound, but “if a group of lions is coming there’s a huge benefit to not being around,” Foster says.
Foster and colleague Hanna Kokko, of the University of Helsinki, Finland, sought to determine exactly when such potentially false connections pay off.
Rather than author just-so stories for every possible superstition – from lucky rabbit’s feet to Mayan numerology – Foster and Kokko worked with mathematical language and a simple definition for superstition that includes animals and even bacteria.
The pair modelled the situations in which superstition is adaptive. As long as the cost of believing a superstition is less than the cost of missing a real association, superstitious beliefs will be favoured.
Read the full article.
Tubelite argues that Intelligent Design (i.e. the creationists arguments against Darwinian evolution) is neither designed, nor intelligent with the following argument:
Years ago, my father told me of an industrial accident he had witnessed. Someone had climbed into a reaction chamber for routine inspection during a plant shutdown, when, unknown to him, a hidden hand opened a valve which flooded the chamber with nitrogen. He collapsed after a few minutes, unconscious. Another person climbed in to see what was wrong, tried to revive the unconscious engineer and himself collapsed. Both died for lack of oxygen soon after.
I remember being extremely surprised and somewhat skeptical – surely they would have felt the same rising panic we feel when holding our breath? There would be enough time and strength left over for a mad dash to the exit, even if it involved a climb… something didn’t add up.
Recently, I heard of a few more such accidents, and remembering the old story, dug around a bit. Turns out that the urge to breathe – air hunger – is triggered, not by low blood oxygen levels, but high carbon dioxide levels! Wikipedia continues: In mammals (with the notable exception of seals and some burrowing mammals), the breathing reflex is triggered by excess of carbon dioxide rather than lack of oxygen, so asphyxiation progresses in oxygen-deprived environments, such as storage vessels purged with nitrogen or helium balloons, without the victim experiencing air hunger. There are other interesting links about using nitrogen asphyxiation as a painless, humane method of killing animals including humans.
He points out that this is such pathetic design that the entire Intelligent Design argument falls flat on its face. Not that it will matter to the creationists, as can be seen from the following flowchart (click on image for full-size):
Do you remember the distinctive smell of the earth when it rains for the first time. (Marathi readers will be reminded of the song aala aala ga sugandh maaticha.) Ever wondered what causes it? Ever wondered what this smell is called? Obviously not.
But, by now you should know that if there is one thing I enjoy, it is to take a poetic concept and kill it by introducing the prosody of science.
Anyway, the smell is called geosmin. And, in the spirit of scientific enquiry, here are the gory details, from howstuffworks.com:
As it turns out, the smells people associate with rainstorms can be caused by a number of things. One of the more pleasant rain smells, the one we often notice in the woods, is actually caused by bacteria! Actinomycetes, a type of filamentous bacteria, grow in soil when conditions are damp and warm. When the soil dries out, the bacteria produces spores in the soil. The wetness and force of rainfall kick these tiny spores up into the air where the moisture after a rain acts as an aerosol (just like an aerosol air freshener). The moist air easily carries the spores to us so we breathe them in. These spores have a distinctive, earthy smell we often associate with rainfall. The bacteria is extremely common and can be found in areas all over the world, which accounts for the universality of this sweet “after-the-rain” smell. Since the bacteria thrives in moist soil but releases the spores once the soil dries out, the smell is most acute after a rain that follows a dry spell, although you’ll notice it to some degree after most rainstorms.