Around 80,000 to 100,000 years ago, humans made a giant migration between continents. This is mainly how humans discovered land, and how the aboriginals came to be in Australia. It's possible, and even probable, that, since all of these people were travelling by boat from mostly Africa (to my knowledge), that they stopped at papa new guinea, and other places like that, for extended periods of time. This type of behaviour is called 'island hopping' and it's believed to be the way that humans travelled thousands of years ago, across thousands of miles, long before the Vikings and Romans.

Probable, also, that island hopping would result in humans starting to domesticate animals like wolves, and animals similar to dogs and cats, for convenient hunting.

If I'm wrong about anything I said here, feel free to correct me