A whole lot of mating garter snakes seeer/Imazins/Getty Images
Birds do it, a few bees get to do it – but how did sexual reproduction evolve in the first place? An evolutionary model suggests that it could have started as a way for two cells to pool their resources when favourable environments turn harsh.
“The idea is when times get hard, you fuse with another cell,” says at the University of York, UK. “Then you’ve got this big cell which has more chance of surviving.”



