Why did the Wildlife Biologist Step on Poisonous Snakes, Thousands of Times?

A researcher in Brazil investigated why some snakes bite humans and others don’t using a very unusual– not to say totally nuts  – methodology: he stepped on them, thousands of times. João Miguel Alves-Nunes of the Butantan Institute published the results of his experiment in Scientific Reports.

The principal subject of the experiment was the jararacas (Bothrops jararaca) — one of South America’s most venomous and dangerous snakes. Popular wisdom has it that the jararaca would only bite if you touched or stepped on it, so Alves-Nunes donned special protective boots and stepped on more than 100 of the vipers, again and again, totaling 40,480 steps.

Turns out the folk wisdom is wrong because the scientist learned (the hard way) that many of the snakes struck when he got close to them; that they were more aggressive during the day, in warmer temperatures; and that smaller specimens, especially younger females, were most likely to sink their fangs into an intruding boot.

“The best way to do this research is to put snakes and a human together,” Alves-Nunes tells the journal Science in an interview. “In this case, the human was me.” The human took special care not to harm the snakes by treading lightly.

The trials were going along just fine until Alves-Nunes did a side experiment with another snake species. “I felt 100% safe, and the jararaca bites never punctured [the boots]. However, when I was doing simulations with a rattlesnake, one punctured the boot, and I was bitten.”

It was then that Alves-Nunes learned that he was not only allergic to snake toxins, he was allergic to antivenom as well. He lived, but had to interrupt his experiment for a 15-day medical leave.

His tribulations are for a good cause. The findings – along with other studies showing snake distribution – can help hospitals prepare for bite victims with antivenom supplies. “We can identify the places where the animals are more likely to be aggressive. For example, warmer places with a higher female snake population should be a priority for antivenom distribution.”

Does the researcher have any regrets? “When I was bitten by the rattlesnake during the simulation, I recorded it with a camera. And what was the first thing I did? I called my mother right there. Now I have this embarrassing moment on video: me crying to my mother.”

Photo credit: João Miguel Alves-Nunes via Science