Many Melanesians living in Papua New Guinea have quite strong naturally curly hair, don't they.
Literal
Papua-New-Guinea [at-に] living Melanesian-people [possessive-の] many [topic-は], considerably strong natural-perm is [agreement-ね].
天然パーマ (natural perm) is a common Japanese term for naturally curly hair — borrowing パーマ from English 'permanent (wave)' and prefixing 天然 (natural). の多く (many of) partitions a group. The relative clause パプアニューギニアに住む modifies メラネシア人.