This line would prove to be one of the most impactful outcomes of Wallace‘s research in Indonesia. Most wildlife on the islands follows this line – even birds and some plants such as certain species of Eucalyptus. The animals found on each side of the line can be shown to have an evolutionary connection to either Asia (to the West of the Wallace line) or Australasia (to the East). To account for the phenomenon, Wallace proposed an imaginary line to divide the region into two parts. These two islands are only 22 miles apart – about the distance between York and Leeds – and yet not even birds travel between them. He found that islands as close together as Bali and Lombok had completely different animals on them. He had travelled for more than 14,000 miles all over the closely-grouped archipelago and noticed that “between these corresponding groups of islands, …, there is the greatest possible contrast in the animal productions.” (Wallace, 1863, p. It’s here that Wallace came upon a curious pattern.
Together they collected ~125,660 natural history specimens. Recent estimates put the number of the staff helping him at one time or another to at least 1,200 people (Wyhe, 2018, p. At just 31 years old, he travelled around the country for 8 years (1854–1862) collecting animals and plant samples there in collaboration with a veritable army of (mostly) local helpers, guides, and research assistants.
