This is funny because one of the bears with the most attacks on humans (perhaps even the most dangerous bear, depending on who you ask*) isn't even on the list mentioned by the original ask.
Sloth bears are not the biggest bears. They primarily eat ants and termites. They do not see us as food. Hardly a contender for most dangerous bear, right?
First of all, sloth bears evolved alongside tigers and leopards and the saber-toothed cat Megantereon. And they still are routinely hunted by tigers. As a result, they've adapted to fight back as aggressively as possible, and in fact are aggressive towards all large mammals (Servheen et al., 1999). In addition, their long, curved claws, adapted for tearing into anthills and termite mounds, prevent them from climbing trees to escape, and their snuffly rooting behavior means they often don't notice tigers until they're too close to make a run for it (Sharp et al., 2024).
When faced with a threat like a tiger, sloth bears rear up and charge, slashing away with their claws. In a study on 43 filmed encounters, 86% of the time this scared the tiger off. 9% of the time the tiger won and killed the bear anyway (Sharp et al., 2024). Humans are notably squishier than tigers.
The sloth bear defense in action. From Sharp et al. (2024).
And second, sloth bears live in a historically densely populated area with rural communities dependent on the forest and farming. So the heightened chance of running into an (unarmed) human, coupled with their hair-trigger aggressiveness, makes them far more likely to go on the offensive and maul intruders. Most attacks involve the bear charging rapidly into the human before they even knew what happened.
I was following two of my companions and saw a black form lying at the foot of a clump bushes, about 10 m from me. I called out to my companions. Before I knew it, the impact of the charging bear knocked me off my feet. It happened so fast, I didn’t see the bear coming… just dust, flying leaves, and the screams and roars of the bear. (Ratnayeke et al., 2014, p. 476)
In one region in Chhattisgarh, 137 attacks (of which 11 deaths) were recorded over a 2-year period (1998-200) alone (Ratnayeke et al., 2014). In Sri Lanka only rogue elephants are more feared than sloth bears (Servheen et al., 1999). But of course, those numbers pale in comparison to the sloth bears killed in retaliation or harvested for their gallbladders.
Yes, polar bears are top predators and yes they do see us as prey, and you should absolutely be as careful around them as any other unpredictable large animal. But their remote habitat means they rarely have the chance to do so, and the few people they do encounter are - as you can tell from the above posts - well-armed and expecting trouble. A 20-year study in Canada, for instance, recorded 6 human deaths and 14 injuries; conversely, 251 polar bears were shot and killed in self-defense (Floyd, 1999). And while they can kill and eat people, they have been described as "largely indifferent to humans and often demonstrate behavior that is more curious than aggressive" (Floyd, 1999, p. 79). A much larger study of verifiable recorded attacks, covering the polar bear's entire range (Canada, Greenland, Norway, Russia, US) and spanning 1870 to 2014, found 20 deaths and 63 injuries caused by polar bears during that time. Despite their reputation, polar bears were found to have a 24% fatality rate (20 of 84 deaths), compared to a 42% fatality rate for black bears. And 88% of polar bear attacks were predatory compared to 87% of black bear attacks (grizzly bear attacks tended to be defensive, females with cubs and so on) (Wilder et al., 2017). In conclusion, "to date polar bears have been no more likely to actively hunt and kill people than black bears" (Wilder et al., p. 9).
This thing is as predatory as a polar bear. Despite being less capable of inflicting damage than grizzly and polar bears, and far easier to scare off, black bears usually attack with intent to devour. Chalk that one up for this humble ursine.
*Wikipedia says the sloth bear is the bear that has attacked the most people... but the source they cite states plainly that that distinction goes to the brown bear.
Bargali, H. S., Akhtar, N., & Chauhan, N. P. S. (2005). Characteristics of sloth bear attacks and human casualties in North Bilaspur Forest Division, Chhattisgarh, India. Ursus, 16(2), 263-267.
Floyd, T. (1999) Bear-inflicted human injury and fatality. Wilderness & Environmental Medicine, 10(2), 75-87.
Ratnayeke, S., Van Manen, F. T., Pieris, R., & Pragash, V. S. (2014). Challenges of large carnivore conservation: sloth bear attacks in Sri Lanka. Human Ecology, 42(3), 467-479.
Servheen, C., Herrero, S., & Peyton, B. eds. (1999) Bears: Status survey and conservation action plan. IUCN/SSC Bear Specialist Group.
Sharp, T. R., Garshelis, D. L., & Larson, W. (2024) A most aggressive bear: Safari videos document sloth bear defense against tiger predation. Ecology and Evolution, 14(7), 1-22.
Wilder, J. M., Vongraven, D., Atwood, T., Hansen, B., Jessen, A., Kochnev, A., York, G., Vallender, R., Hedman, D., & Gibbons, M. (2017). Polar bear attacks on humans: Implications of a changing climate. Wildlife Society Bulletin, 41(3), 537−547.
