Global warming might make lizards super-intelligent

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Just when it seemed like we knew all the dangers of climate change, science has to go and throw us this curveball. Warmer temperatures make lizards' brains develop differently. Last thing we need is some newly super-intelligent lizards judging us.

That's the finding of researchers at the University of Sydney in Australia, who tested how rising temperatures affected the intelligence of the tiny lizard species known as the three-lined skinks. Over the last couple of decades, the average temperature of a skink nest has risen three degrees Fahrenheit, despite the females' attempts to dig deeper nests that will shield their young from the warmer temperatures. Those nest temperatures are likely to only get hotter as global temperatures continue to increase.


And while climate change often works to upset the fragile conditions that species need for reproductive success, hotter temperatures could be a positive boon for skinks, as eggs develop differently in response to warmer temperatures. First, eggs grown in hotter conditions tend to create a more equal gender balance — in cooler temperatures, more males are born because they are more likely to survive cold winters than females. But more importantly, the hotter skinks appear to be much smarter than their cooler counterparts, as Sydney researcher Joshua Amiel discovered with two sets of eggs he had incubated, one at 60 degrees and the other at 72.

Science explains what happened next:

When the skinks were a few weeks old and smaller than your pinkie finger, Amiel gave them a simple learning test. Each lizard was placed in a 24°C cage with two hiding places-overturned plastic flower-pot trays with entry holes cut in the sides. But one was a decoy, its opening blocked with Plexiglas. Clever lizards, after bumping the window a few times, should give up on the fake hiding place and go to only the good one, Amiel reasoned.

He tested each lizard 16 times over 4 days, touching its tail with a paintbrush to spook it into hiding. Amiel logged an "error" every time a lizard bumped its nose on the Plexiglas window and logged a successful "escape" if it found the real hiding place in 30 seconds. Lizards from warm nests and cool nests started out making a "relatively equal" number of errors, Amiel says. But the warm-incubated lizards improved, making on average one or two more escapes during the second 2 days than they had during the first 2 days. Cool-incubated lizards showed no such gains.


Yes, despite the skinks' natural preference for colder temperatures, heat actually unlocks learning centers of their brain that they never knew they had. And this cognitive advantage would likely prove successful in nature as well — after all, this sort of problem solving could prove extremely useful when cornered by predators, a situation that would end with the cooler, dumber skinks being eaten.

If this increased intelligence also occurs in other lizards, then we may suddenly have to contend with a whole bunch of newly smart species. And while an intelligent skink may not seem like much to worry about right now, I suspect that's much the same reaction the dinosaurs had to those first, ferret-like mammals, and look how that turned out.


There is a way to stop this, of course — if temperatures continue to rise, eventually it becomes too hot for the skinks and they lose their cognitive advantage. Of course, we wouldn't want to intentionally ruin our planet just to spite some newly smart lizards, right? Right!?

Biology Letters via ScienceNOW. Image by wwarby on Flickr.