On the Science and Mathematics blog, the rhythms of life.
This article was published on the Science and Mathematics blog of the newspaper O Globo, coordinated by the deputy director of IMPA, Claudio Landim.
Mathematics and the Rhythms of Life
Tiago Pereira da Silva, member of the Brazilian Academy of Sciences and professor at the University of São Paulo.
At dusk in Southeast Asia, travelers can witness a completely free spectacle. "Na faixa," in São Paulo slang. Thousands of fireflies light up and extinguish their tiny lights together, forming a truly marvelous concert.
Well, actually, it's a bit like São Paulo samba: a few fireflies are out of sync, but the fact that thousands of them blink together seems like magic. This phenomenon is quite well-known, and for over 300 years it has attracted travelers from all over the world.
But why on earth do these insects start blinking together if, when separated, each one has its own blinking rhythm?
Interestingly, for a long time the explanation for this phenomenon was that this synchronicity between fireflies doesn't exist. Somehow our brain wants to see order where there is none. When we blink our eyes, we create the sensation of synchronicity. This was indeed the explanation of the phenomenon offered by Philippe Laurent in 1917 in the journal Science.
I was commenting to a good friend of mine in the Netherlands that it took about 50 years for people to really understand what was happening. Poor guy, it was 10 PM here in São Paulo, 3 AM in Amsterdam. And he was still full of energy and said he preferred to work late into the night. Our conversation then shifted to different work rhythms. But little did he know that the subject remained the same. How so? I imagine you must be wondering what the conversation about fireflies has to do with people's rhythms and their sleeping and waking cycles.
Let's go. Our basic rhythm of waking and sleeping is called the circadian rhythm. For example: we wake up at 6 am, have lunch at noon, have dinner at 7 pm (although the French and Spanish disagree), and around 10 pm we count sheep. The next day, voilà, everything repeats itself.
Well, sort of. Maybe you sleep a little longer because of a beer the night before. Still, why is our circadian rhythm so robust?