1 00:00:02,080 --> 00:00:07,880 Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff, 2 00:00:07,920 --> 00:00:11,640 Speaker 1: it's Christian Sager here. So evolution takes time, but just 3 00:00:11,760 --> 00:00:14,920 Speaker 1: how much time it takes is the issue. How long, 4 00:00:15,000 --> 00:00:18,960 Speaker 1: for instance, did it take therapod dinosaurs to evolve into 5 00:00:19,000 --> 00:00:23,000 Speaker 1: modern birds tens, if not hundreds, of millions of years. 6 00:00:23,320 --> 00:00:25,720 Speaker 1: But since the turn of the last century, when American 7 00:00:25,760 --> 00:00:30,400 Speaker 1: biologist Herman Bumpust noticed that individual sparrows in a population 8 00:00:30,480 --> 00:00:35,120 Speaker 1: became larger as the result of one huge snowstorm, scientists 9 00:00:35,120 --> 00:00:40,239 Speaker 1: have been observing instances of short bursts of evolutionary progress 10 00:00:40,240 --> 00:00:45,320 Speaker 1: over a significantly brief period of time. Definitive instances of 11 00:00:45,479 --> 00:00:48,639 Speaker 1: rapid evolution are tough to come by, though, even in 12 00:00:48,680 --> 00:00:52,680 Speaker 1: these days of advanced genetic testing, but a recent study 13 00:00:52,800 --> 00:00:56,720 Speaker 1: published in the journal Science finds that over the course 14 00:00:56,760 --> 00:01:01,200 Speaker 1: of just a few months, green annully lizards living in 15 00:01:01,200 --> 00:01:05,319 Speaker 1: the area of the Mexico Texas border evolved a rapid 16 00:01:05,400 --> 00:01:10,039 Speaker 1: genetic tolerance to cold weather after an unusually frigid winter. 17 00:01:10,720 --> 00:01:15,160 Speaker 1: Green Annullies are warm weather reptiles that evolved on the 18 00:01:15,160 --> 00:01:18,640 Speaker 1: Caribbean island of Cuba. They found their way to the 19 00:01:18,720 --> 00:01:23,039 Speaker 1: mainland long ago, but a prolonged and extreme cold snap 20 00:01:23,160 --> 00:01:26,440 Speaker 1: can really put the hurt on a population of annuls 21 00:01:26,880 --> 00:01:32,480 Speaker 1: The winter of did just that before that year's famed 22 00:01:32,640 --> 00:01:37,480 Speaker 1: polar vortex hit. However, the research team collected annulis in 23 00:01:37,640 --> 00:01:41,040 Speaker 1: August to find out just how cold one of these 24 00:01:41,080 --> 00:01:45,600 Speaker 1: lizards could get before its motor function was compromised, specifically, 25 00:01:45,640 --> 00:01:48,440 Speaker 1: that is, when it couldn't right itself when it was 26 00:01:48,520 --> 00:01:53,280 Speaker 1: knocked over. They collected annuals from five different sites across 27 00:01:53,320 --> 00:01:57,080 Speaker 1: Texas and found that when gradually cooled in a chamber 28 00:01:57,120 --> 00:02:00,680 Speaker 1: in the lab, the individuals from the southernmost site became 29 00:02:00,920 --> 00:02:06,960 Speaker 1: uncoordinated at around fifty two degrees fahrenheit or eleven degrees celsius, 30 00:02:07,000 --> 00:02:11,799 Speaker 1: but the ones collected from the northernmost site became unable 31 00:02:11,840 --> 00:02:15,840 Speaker 1: to right themselves at around forty three degrees fahrenheit or 32 00:02:16,040 --> 00:02:21,280 Speaker 1: six degrees celsius. Because the scientists already had genetic samples 33 00:02:21,320 --> 00:02:24,480 Speaker 1: from the lizards in the first study, when a few 34 00:02:24,639 --> 00:02:28,640 Speaker 1: months later temperatures plummeted to lows that hadn't been seen 35 00:02:28,760 --> 00:02:32,960 Speaker 1: in fifteen years, the researchers went out and collected some 36 00:02:33,040 --> 00:02:37,360 Speaker 1: of the surviving lizards from all five sites. They placed 37 00:02:37,400 --> 00:02:41,320 Speaker 1: them in the same cooling chambers and found the southernmost 38 00:02:41,360 --> 00:02:45,799 Speaker 1: Annullies exhibited much more cold resistance than the ones that 39 00:02:45,880 --> 00:02:49,200 Speaker 1: had been collected back in the summer. They could now 40 00:02:49,280 --> 00:02:53,000 Speaker 1: stand strong in the face of forty three degrees fahrenheit 41 00:02:53,200 --> 00:02:58,080 Speaker 1: or six degrees celsius. RNA sequencing before and after the 42 00:02:58,080 --> 00:03:03,000 Speaker 1: cold front also revealed six significant differences between individuals from 43 00:03:03,000 --> 00:03:07,840 Speaker 1: the southern genomic regions before and after the weather event. 44 00:03:08,440 --> 00:03:11,560 Speaker 1: By the way, did you know that Annulli's living in 45 00:03:11,720 --> 00:03:16,359 Speaker 1: urban areas have stickier feet than their country cousins. Apparently 46 00:03:16,520 --> 00:03:20,360 Speaker 1: it's an evolutionary adaptation to having to cling to class 47 00:03:20,400 --> 00:03:22,519 Speaker 1: and metal. Now I want to be bitten by a 48 00:03:22,639 --> 00:03:30,079 Speaker 1: radioactive Annulli so I can crawl walls with him. Today's 49 00:03:30,120 --> 00:03:33,200 Speaker 1: episode was written by jess Lynn Shields and produced by 50 00:03:33,280 --> 00:03:36,800 Speaker 1: Dylan Fagan. For more on this and other topics, please 51 00:03:36,880 --> 00:03:49,680 Speaker 1: visit us at how stuff works dot com.