Scientists played recordings of people talking normally through speakers hidden at water holes in the Kruger National Park.
About 95% of animals were extremely frightened and quickly ran away.
In contrast, recordings of snarling and growling lions elicited significantly less alarm.
The human speech they chose to play included local languages commonly spoken in the country.
During the experiment they noted that some elephants, in response to the big cat calls, even attempted to confront the sourc of the sound.
The study’s findings suggest that the animals, which included antelopes, elephants, giraffes, leopards and warthogs, have learnt that contact with humans is extremely dangerous, due to hunting, gun use and the use of dogs to catch them.
The fear exhibited goes beyond the Kruger National Park, as a global pattern shows wildlife tend to fear humans more than any other predator, according to the study.
The authors note that this poses a challenge for areas which rely on wildlife tourism, because the human visitors they want to attract are inadvertently scaring off the animals they have come to see.
One of the authors, Dr Liana Zanette, told the BBC that their research focuses on the “ecology of fear” – a concept that refers to the impact of predator-prey interactions on their environments.
“Predators kill prey and that obviously reduces prey numbers, but what we’ve demonstrated in other work is that the fear predators inspire can itself reduce prey numbers,” she said.
“Measuring, mitigating and manipulating the fear we [humans] inspire in wildlife presents challenges and opportunities which we suggest ought to now be considered integral components of conservation planning and protected-areas management.”
The findings also open up the potential to protect vulnerable species in these ecosystems. Human sounds, when used appropriately, could help protect against illegal poaching.
“We are also collaborating in experiments testing whether we can deter rhinos from poaching hotspots,” she added.
