Alfred Russel Wallace, an English naturalist, explorer and co-founder of the theory of evolution through natural selection with Charles Darwin, spent significant time on the Aru Islands, located in the province of Maluku in Eastern Indonesia. These islands, consisting of low, swampy terrain surrounded by shallow seas, teem with diverse flora and fauna.

Wallace arrived on the Aru Islands in 1857 during his eight-year expedition around the Malay Archipelago. His main intention for visiting was to collect natural history specimens, particularly birds. During his stay, he lived among the indigenous people of Aru, the Aru Islanders, who helped him learn more about varieties of birds, insects, and other animals living there.

One of the most significant discoveries that Wallace made on the Aru Islands was the bird species Semioptera wallacii, now commonly called Wallace's Standardwing. This bird of paradise, known for its extravagant mating dance, played a crucial role in his groundbreaking studies on the theory of evolution.

He also discovered several other species, such as the golden birdwing butterfly and the Wallace's long-billed cuckoo. In his letters and writings, he documented the diversity of life he encountered on the islands and even noted the differences between wildlife on the western and eastern sides of the island chain. His observations marked the delineation known as the Wallace Line, a boundary that separates the eco-zones of Asia and Wallacea.

Wallace's exploration of the Aru Islands contributed significantly to his ideas on evolution. He observed the adaptation, variety, and distribution of species across the islands. His experiences led him to form a theory of natural selection independently of Charles Darwin. It was during his time on the islands and other parts of the Malay Archipelago that he developed his biogeographical theory "The Wallace Line" which distinguishes Indonesian fauna and flora in terms of the continental regions of Asia and Australia.

His experiences and observations during his time on the Aru Islands and throughout the Malay Archipelago are recorded in his book, "The Malay Archipelago", published in 1869.

In all, Wallace's time on the Aru Islands marked a significant period in the development of his understanding of natural selection and biogeography, and his discoveries continue to have considerable influence in the field of biology.
