Why does the continent of Australia have a culture similar to that of Europe while the island of New Guinea, nearby and settled by the same ancestors, has culture unique to the island; what happened to when Europeans encountered the area and why?
The reason for that similarity is that Europeans (British) colonized Australia after they arrived at Botany Bay in 1788. The British empire made Australia its colony to send prisoners to a distant place. Most prisoners spoke English and related to European culture. Then, in the 1850s, a gold rush started and more and more Europeans arrived at the continent. During the decades of years of coexistence with local inhabitants, a modern Australian culture formed.