Zoologist: Every domesticated large mammal species now in existence was domesticated thousands of years ago  Since those days, people undoubtedly tried innumerable times to domesticate each of the wild large mammal species that seemed worth domesticating
Clearly, ttherefore, most wild large mammal species in existence today either would be difficult to domesticate or would not be worth domesticating
it is not much easier today to domesticate wild large mammal species than it was in the past