As humans domesticated dogs over many thousands of years, the canine species evolved into hundreds of breeds designed to perform specific tasks such as pulling sleds and guarding sheep. Over time, as human civilization grew, the need for many breeds decreased. For example, as humans evolved from hunter-gatherers into farmers, they no longer needed hunting dogs. Later, as farming societies became industrialized, herd animals disappeared, and fewer shepherds meant fewer sheepdogs. But by this time humans had grown accustomed to dogs’ companionship, and breeding continued. Today, most owners keep dogs simply as companions, but some dogs still do the work they were intentionally bred for, such as following a scent, guarding a home, or leading the blind.