Top: The ninespine stickleback, Pungitus pungitus, is typical of the saltwater form. Bottom: A freshwater form of stickleback with fewer bony plates and fewer spines. Image based on drawings from the ...

Parallel lines close parallel lines Lines which never meet and stay the same distance apart. Parallel lines are indicated by a pair of arrows. are two or more straight lines that remain the same ...

Convergent phenotypic evolution often results from similar genetic changes in independent species by a process known as parallel evolution. Sometimes, convergent evolution results from the evolution ...

Our brains are a mess. They evolved step by step, one function added to another in a million small steps that might help in one way, but that conflict with what another part of the brain is trying to ...