Thanks to a generous gift, National University of Singapore study traced historical shipping records and vindicated Darwin from accusations of deceit.

For the past four decades, Charles Darwin had been accused of keeping the essay of fellow naturalist Alfred Russel Wallace for a fortnight, thereby enabling him to revise elements of his theory of evolution, before jointly announcing the theory of evolution by natural selection in July 1858. Just recently, two researchers from the National University of Singapore (NUS), supported by a private donation, reconstructed the route taken by Wallace's letter to Darwin from Ternate and provided evidence that Wallace sent the letter a month later than historians had always assumed, thus clearing Darwin of the accusations against him.

Dr John van Wyhe, a historian of science and Senior Lecturer in the Departments of Biological Sciences & History at NUS and his collaborator Dr Kees Rookmaaker, published their study, titled "A new theory to explain the receipt of Wallace's Ternate Essay by Darwin in 1848", in the Biological Journal of the Linnean Society in December 2011. This study was supported by a generous private donation to the Darwin Online-Wallace Online projects.

The controversy

Alfred Russel Wallace, the naturalist who spent eight years in Singapore and South East Asia between 1854 and 1862, discovered evolution by natural selection independently of Charles Darwin. Wallace had a dramatic eureka moment while living on the island of Ternate in the Moluccas (now Indonesia). He wrote up his ideas in an essay which he sent in 1858, to Charles Darwin, for him to pass on to noted geologist Charles Lyell. Darwins accusers claim that he waited two weeks to do so, lying about the date of receipt to give himself time to revise his own ideas in the light of Wallaces.

Wallaces essay was published together with an essay by Darwin in 1858 and marks the first publication of the theory of evolution which then resulted in one of the greatest revolutions in the history of science.

How the mystery began

In 1972 a researcher found another letter from Wallace to a friend named Bates that was sent on the March 1858 steamer from the island of Ternate in modern Indonesia. The letter still bore postmarks from Singapore and London which showed that it arrived in London on 3 June 1858 - two weeks before Darwin said he received the essay from Wallace. Thus began the mystery - how could two letters from Wallace leave Ternate on the same steamer and travel along the same mail route back to London but Darwin received his two weeks later than Bates did? This mystery has led to numerous conspiracy theories. For example, several writers have claimed that Darwin stole ideas from Wallaces essay during the time he kept the letter secret. But most other evidence suggests that Darwin received the letter when he said he did.

So did Darwin receive the letter when he said he did, or not?

I initially assumed that it was impossible to solve since so many historians had examined it before. But it occurred to me that we really have no contemporary evidence of when Wallace sent the essay to Darwin, only his much later recollection that he sent it by the next post after writing it in February. That suggested that the essay was sent in March 1858. But this recollection from years later seemed to me not very reliable as evidence of what really happened at the time. The other evidence that Darwin received it on 18 June 1858 seemed more likely. All of his correspondence changed dramatically after that date for example. Since that side of the correspondence was all one really had to go on, it occurred to me to trace the letter from Darwins end, rather than Wallaces, said Dr van Wyhe.

If Darwin really received it on 18 June- how could it get there? It had come to his house in the countryside from London the day before, the 17th.

Dr van Wyhe then found that a steamer arrived in England the day before, the 16th with mail from India and South East Asia. This was surely not a coincidence - Wallaces letter must have been on that ship. Dr van Wyhe then had to trace back the remainder of the 9,240 miles of the journey from England, through the Mediterranean, across Egypt, to Sri Lanka, Penang, Singapore, Jakarta and so on. His assistant on the Wallace Online project, Dr Kees Rookmaaker, who speaks Dutch, was an invaluable help as he was able to check the ship arrival and departure times in the Dutch newspapers and sources for the Dutch East Indies, while Dr van Wyhe went through the English newspapers. It was an exciting detective story tracing the connections that mail batch took from London to South East Asia.

Eventually our mail itinerary was completed all the way back to Ternate and we were astonished to find that there was an unbroken series of mail connections to Ternate - not in March as all other writers before had assumed, but in April 1858! My further research has clarified why Wallace mailed it later than we assumed and many other parts of this famous, but misunderstood chapter in the history of science, added Dr van Wyhe.

First of all, we now know that Wallace was replying to an early letter from Darwin- and that letter from Darwin arrived in Ternate on the March steamer. We have assembled the first complete collection of all the surviving Wallace correspondence from Ternate and nearby islands. These reveal that he never replied to a letter on the same steamer which delivered it. Apparently the turn over time was too short. Therefore this is an additional reason to doubt that Wallace could have sent the famous letter to Darwin in March as so long assumed, said Dr van Wyhe.

Dr van Wyhe is currently completing a major new book on Wallace in South East Asia which aims to radically revise the traditional story of Wallace and his famous independent discovery of evolution.

Dr van Wyhe is the Director of the research project in Singapore - Wallace Online, a website which aims to be the definitive and reliable source of Wallaces work. It will contain all of Wallaces books and article, as well as a complete collection of his specimens collected from South-east Asia, and much more, such as a revised itinerary of his whereabouts during these years and his notebooks edited for the first time to modern scholarly standards. The website will be launched in 2013, the centenary of the death of Wallace.

Provided by National University of Singapore