Have you ever sat and wondered what animal is actually the most dangerous one on Earth?
I know there is probably a short list in most people’s heads – hippos, big cats, alligators, sharks – but it turns out that scientists have a handy-dandy tool called the Crespo scale that takes all of the guesswork out of the answer.
The scale ranks animals based on their population size (PS) and mortality rate (MR). The former accounts for the likelihood of encountering said animal in a specific country, and the latter is created by dividing the global population by the maximum estimated number of fatalities caused by a species per year.
Author David Duarte Crespo is the one who came up with it, and explained his thought process in the paper.
“The Crespo is a scale that ranks the ‘danger’ of an animal species based on how much of a threat it presents toward a random individual in a given country. I chose to just use two factors for the scale because they’re universal – they can be applied to pretty much any animal species – and they’re measurable. You can measure (or at least estimate) things like how many people a species k***s or how many of them are; you can’t measure how aggressive or territorial it is.”
He and his team did exclude domesticated animals from the study due to how prevalent they are living around humans.
“These are animals that we spend the most amount of time with and they’re some of the ones most likely to unalive you, especially if you live in a western country. So to avoid this bias, I didn’t include them. I also didn’t include human beings themselves for obvious reasons.”
Crespo divides or multiplies the PS and MR numbers by five points called Degrees of Danger (DoDs). One DoD is “Very Unlikely” and five DoDs are “Very Likely.”
The numbers are then multiplied together to get the total. The maximum number of DoDs is 25, and this will determine into which category an animal is put.
The scale puts animals in a 1-5 system, with 5 being Very High Danger and 1 is Low Danger. Anything above a 3 is considered a significant threat.
Only animals with enough annual data were included, and the most dangerous animals were consistently found in low- and middle-income countries. The ones that posed the largest threat to people are those that carry disease or parasites.
“Since there’s a lot of data lacking, it meant I could only include species that I found enough data for. Even still, there are a few holes. An example is not knowing which African country is facing the most attacks and deaths by Nile crocodiles.”
One interesting aspect of the scale is that an animal could be more dangerous in one country than in another.
“Even though most of the results were roughly as expected, there were a few surprises that caught my attention. One that springs to mind is the Asian giant hornet being much lower on the scale, only being classed as a category one. I was expecting it to be ranked higher given the fact that it has a huge population as a colony insect and is native to many densely populated countries like Japan. It’s also ended up becoming an invasive species in recent years.”
The most dangerous threat in the natural world, based on this scale?
Mosquitoes.
They are closely followed by Russell’s viper, blood flukes, and feral dogs, but the sliding scale will depend on where you live.
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