National Geographic - Puppies reach “peak cuteness” between six and eight weeks old, which could provide some insight into how dogs evolved alongside people.There are roughly (or, if you prefer, ruffly) a billion dogs on the planet. Although dogs and humans have been existing alongside one another for tens of thousands of years, experts say 85 percent of the world's dogs are feral. Roaming streets and villages, these canines aren't domesticated pets but still hang out around human habitats.
When pups are between two and three months old, their mothers will abandon them for any number of reasons. With no mother to watch out for them, infant mortality of pups under one year skyrockets to around 90 percent. So, only about 10 percent of motherless, homeless pups survive.