In 1858, while collecting thousands of animal specimens in the islands of the Malay Archipelago, his observations, combined with an attack of malaria, gave rise to what he would call "an intuition".
This brilliant autodidact understands how species evolve.
Faced with limited resources in a given territory, only the individuals most adapted to their environment survive and reproduce, transmitting their superior characteristics to their offspring.
An idea - to the tunes of a "stroke of genius" for Cyril Langlois from the Ecole Normale Supérieure in Lyon - which he shared with his compatriot Charles Darwin by sending him his article.
The latter finds there the essence of his own theory - which he has been refining for 20 years without ever having published anything - "and is deeply upset by it", says the associate professor.
French entomologist Jean-Marc Sor shows the photos he took in Indonesia of an Ornithoptera croesus croesus, a giant butterfly discovered in 1859 by British naturalist Alfred Russel Wallace, November 3, 2013 in Muret (Haute-Garonne) © REMY GABALDA / AFP/Archives
In the process, a co-presentation and co-publication of their work on natural selection is organized in London.
The two men are absent, Wallace does not even know anything about it, but the two names are well affixed.
Evening readings and classes
Before becoming an explorer, collector, naturalist, geographer, anthropologist... Alfred Russel Wallace was born on January 8, 1823 in Wales into a poor family.
He is the eighth and penultimate child of a jurist who has never practiced, keen on literature, quickly ruined annuitant.
Forced to stop school at the age of 14, the young Wallace drinks up evening classes and specialized readings which will lead him to embark at the age of 25 for the Amazon.
Objective: map, collect butterflies, insects or birds.
Wallace's bee © Jonathan WALTER / AFP
He goes up the Rio Negro in a canoe, further than any other European, curious about everything, collecting mysterious specimens and filling in dozens of notebooks.
But back in England in 1852, his boat caught fire and sank.
Despite the loss of his collection, Wallace would publish two books from his expeditions and set off again in 1854, this time for Asia, which he traveled meticulously for eight years.
At the other end of the globe, pressed for time (and by Wallace's mail) Charles Darwin published "On the Origin of Species" in 1859, a real revolution.
The first print run (1,250 copies) sold out the same day, as did the second.
Darwin eclipses Wallace but the two men have mutual respect.
Wallace becomes one of the greatest defenders of Darwinism.
Even if he will oppose sexual selection (linked to the struggle for reproduction) and will refuse - he is a follower of spiritualism - to see Man as the product of natural selection alone.
"Thinking that the spirits could have an influence on man, he refused the idea that man is an animal like the others", convinced that "human evolution was progressive", explains Cyril Langlois.
Visionary
He would nonetheless remain one of the most renowned British scientists of his time.
In particular for his work on the Malay Archipelago, from which he reported in 1862 more than 125,000 specimens of insects, birds, mammals... mostly unknown in Europe.
He was also one of the founders of biogeography - a discipline that tries to understand the geographical distribution of species - and highlighted the existence of a border (known as the "Wallace line") between the animal and plant species of the islands. from Bali and Lombok yet very close.
If his enthusiasm for spiritualism or his opposition to vaccination for all were sources of controversy, "Wallace was a visionary on many subjects", underlines Laurence Talairach, co-director of the translation of Wallace's story "The Malay Archipelago, cradle of the orangutan and the bird of paradise".
Undated photomontage transmitted by Global Wildlife Conservation on February 21, 2019 showing a Wallace's giant bee (Megachile pluto, D) discovered in Indoénsia and about four times larger than a European bee © CLAY BOLT / Global Wildlife Conservation / AFP / Archives
Supporter of greater social justice, defender of the right to vote for women, he warned of the excesses of capitalism and the consumer society or the impact of colonization on the regions he visited.
And even if one ended up eclipsing the other, it is indeed a "Darwin-Wallace" medal that still rewards researchers today who advance the biology of evolution.
(Sources: Encyclopedia Universalis and Larousse, Natural History Museum)
© 2023 AFP