"Humans attempt to create new species , such as breeding donkey with horses to get mules and lions with tigers to get ligers , but these `` NEW `` species are almost always born sterile and unable to perpetuate themselves ."
"Actually , breeding horses and donkeys is n't an effort to create a new species . Where did you get such a thoughtless idea . And neither is interbreeding lions and tigers . However , you do n't seem to be aware that neither ligers or tigons are sterile . They are capable of breeding with each other or with either of the parent species . And then there are polar bears and brown bears , which can and will interbreed if given the opportunity . And the offspring are perfectly fertile ."
"new species donkey horses lions tigers these `` NEW `` species are almost always born sterile"
"Actually , breeding horses and donkeys is n't an effort to create a new species . interbreeding lions and tigers neither ligers or tigons are sterile"