Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff,
Speaker 1: it's Christian Sager here. So evolution takes time, but just
Speaker 1: how much time it takes is the issue. How long,
Speaker 1: for instance, did it take therapod dinosaurs to evolve into
Speaker 1: modern birds tens, if not hundreds, of millions of years.
Speaker 1: But since the turn of the last century, when American
Speaker 1: biologist Herman Bumpust noticed that individual sparrows in a population
Speaker 1: became larger as the result of one huge snowstorm, scientists
Speaker 1: have been observing instances of short bursts of evolutionary progress
Speaker 1: over a significantly brief period of time. Definitive instances of
Speaker 1: rapid evolution are tough to come by, though, even in
Speaker 1: these days of advanced genetic testing, but a recent study
Speaker 1: published in the journal Science finds that over the course
Speaker 1: of just a few months, green annully lizards living in
Speaker 1: the area of the Mexico Texas border evolved a rapid
Speaker 1: genetic tolerance to cold weather after an unusually frigid winter.
Speaker 1: Green Annullies are warm weather reptiles that evolved on the
Speaker 1: Caribbean island of Cuba. They found their way to the
Speaker 1: mainland long ago, but a prolonged and extreme cold snap
Speaker 1: can really put the hurt on a population of annuls
Speaker 1: The winter of did just that before that year's famed
Speaker 1: polar vortex hit. However, the research team collected annulis in
Speaker 1: August to find out just how cold one of these
Speaker 1: lizards could get before its motor function was compromised, specifically,
Speaker 1: that is, when it couldn't right itself when it was
Speaker 1: knocked over. They collected annuals from five different sites across
Speaker 1: Texas and found that when gradually cooled in a chamber
Speaker 1: in the lab, the individuals from the southernmost site became
Speaker 1: uncoordinated at around fifty two degrees fahrenheit or eleven degrees celsius,
Speaker 1: but the ones collected from the northernmost site became unable
Speaker 1: to right themselves at around forty three degrees fahrenheit or
Speaker 1: six degrees celsius. Because the scientists already had genetic samples
Speaker 1: from the lizards in the first study, when a few
Speaker 1: months later temperatures plummeted to lows that hadn't been seen
Speaker 1: in fifteen years, the researchers went out and collected some
Speaker 1: of the surviving lizards from all five sites. They placed
Speaker 1: them in the same cooling chambers and found the southernmost
Speaker 1: Annullies exhibited much more cold resistance than the ones that
Speaker 1: had been collected back in the summer. They could now
Speaker 1: stand strong in the face of forty three degrees fahrenheit
Speaker 1: or six degrees celsius. RNA sequencing before and after the
Speaker 1: cold front also revealed six significant differences between individuals from
Speaker 1: the southern genomic regions before and after the weather event.
Speaker 1: By the way, did you know that Annulli's living in
Speaker 1: urban areas have stickier feet than their country cousins. Apparently
Speaker 1: it's an evolutionary adaptation to having to cling to class
Speaker 1: and metal. Now I want to be bitten by a
Speaker 1: radioactive Annulli so I can crawl walls with him. Today's
Speaker 1: episode was written by jess Lynn Shields and produced by
Speaker 1: Dylan Fagan. For more on this and other topics, please
Speaker 1: visit us at how stuff works dot com.