Nature
The nest temperature that decides a turtle's sex
In many reptiles — sea turtles, crocodilians and some lizards — sex isn't fixed by chromosomes but set by the temperature eggs experience during a critical window of incubation. A shift of just a degree or two around the pivotal temperature can flip a whole clutch from mostly male to mostly female. Rising sand temperatures from climate change are now skewing some sea turtle populations overwhelmingly female.