I’ve been reading up on Australia, and it seems to me that there’s a lot of very toxic critters living there. Why is that, as opposed to, say Mongolia?
Australia is more isolated and most of their animals evolved separately from the rest of the world.
But why would that make them more lethal, if in fact they are more lethal?
If anything, one would expect that to make them less lethal, not more.
Correct. It did.
With the crocodilian exception of diving into a waterhole in northern Australia (without local knowledge - some are quite safe) I would have little reservation about wandering off into the wilderness anywhere on the continent (other issues like water and GPS aside). There are a few little pieces of knowledge that can help (like standing stock still if you see a snake), but for the most part, our toxic critters are more scared of you than you are of them.
On the other hand, other continents may not have the poisonous things, but they have large animals that would happily tear your head off with their fangs. I’d be very, very scared of bears in the US, for example.
Do we have the most toxic creatures? Probably yes.
The most dangerous to humans? At an educated guess, I’d say no.
I answered this question once before but it was buried in a mostly unrelated thread. Anyway I’m lazy so I’ll simply re-post the same answer
Why does Australia have so many poisonous creatures? That’s a complicated question, but broadly speaking it’s because Australia is an ecological hellhole. No offence meant, that’s a statement of fact. 
Seriously, Australia is a terribly impoverished continent and a tough place for any species to make a living. The soils are extremely old and thus extremely infertile. The seas off the Eastern coast particularly are warm, clear, tropical waters and thus totally nutrient deficient, moreso even than the soils, and because the soils are so impoverished the oceans can’t even be fertilised by runoff. The oceans are as much a desert as the land itself.
The continent gets very little rain due to being predominantly located under a high pressure system. On an annual basis the rain tends to be highly concentrated in the summer months with long, dry periods for 8 months or more. The rainfall is also extremely erratic from year to year, with frequent droughts punctuated with floods and relatively few ‘average’ years.
What all this has meant is that there is s chronic resource shortage for most of the continent. Not just water but protein and minerals are in very limited supply in most places. That in turn has produced an ecosystem that greatly favours slow-burn efficiency and an ability to conserve resources. Species that can manage to horde resources have been greatly favoured, as are species that are able to grab the scarce resources ain the brief periods when they are available. That’s seen in the plants, which are almost all sclerophyllous evergreens but it’s also seen in the animals, especially the predators.
Australia has a real dearth of mammalian predators. There have only ever been 5 species of cat size or larger, and currently only 2 survive. Compare that to the 30 odd species that currently live in the US alone, and the 50 or so that lived there before human interference. That’s because mammals require a lot of resources just to keep running and predators even moreso. Impoverished ecosystems just can’t support large numbers of mammalian predators. Instead Australia has an overrepresentation of reptilian and other ‘cold-blooded’ predators that can keep ticking over in the lean times on little or no food. A python or crocodile can ride out the worst droughts and periods of overhunting on one good meal a year. A dog or of the same size still needs to eat once a month. These cold blooded predators also have the ability to invest heavily in reproduction during the good season and can afford to take a gamble on the next season being able to support the offspring, something no mammal can afford to try.
And because the cold-blooded predators dominate those with venom also tend to dominate. That’s further amplified by the need to grab nutrients when they become available. A predator that only gets to hunt once a year really needs to eat at that time, it may never see another chance. A snake or spider or other predator with potent venom greatly increases its chances of making that successful kill.
Basically Australia has an over-representation of poisonous species because of a species desperately need to be able to ride out bad times and conserve resources. This has led to an overabundance of cold-blooded predators but also to an overabundance of predators that are able to sacrifice a small amount of energy in venom production to conserve or capture the small amount of energy available.
Because we don’t like visitors
Is it true that New Zealand doesn’t have any of these types of problems? Like no poisonous snakes or spiders worth mentioning?
-Tcat
There’s bears and there’s bears.
Black bears, which are the only kind of bears you’re likely to come across in most of the US, conform to your description of Australia’s toxic animals- they’re more afraid of you than you are of them. If you see one, you are supposed to make noise and look big to scare them off. They are almost always more interested in getting your food than tearing your head off. They might break into your car if you leave food there, or come into your campsite looking for food, or rummage through your garbage cans at night, but they don’t attack people, as a rule. Even mother black bears defending cubs aren’t likely to attack people- they might charge at you, but they rarely attack. Unless you do something really stupid (like feed a wild bear, or try to get someone to take your picture holding a black bear cub), you don’t have to worry about black bears attacking you.
Grizzly bears are different, but they’re much rarer. They’re only found in Alaska, Idaho, Wyoming, Washington, and Montana, generally nowhere near populated areas (except in Alaska). Even though they’re much rarer than black bears, they’re responsible for most bear attacks in the US. But you’re not going to see a wild grizzly bear unless you’re camping in the remote areas in the Rockies where they live, or if you’re in Alaska.
Polar bears are very dangerous, but you’d only run into them in northern Alaska, and probably not even then unless you went out on the sea ice.
In any US city that a tourist would be likely to visit (unless you’re on a camping trip or something like that), the only place you’re likely to see any kind of bear is at a zoo.
I’ve also wondered this: one explanation I came up with was that Australia was isolated from humans for the majority of the time we’ve been on this planet. On an archaeological timespan we’d either develop a natural resistance to the poison or kill off the poisonous creatures. You see the same thing in South America: much more poisonous things there than in the Old World if I’m not mistaken.
This would also explain why we have so few natural predators: it’s not that we’re so new, or clean, or imposing looking running on two feet, but that we killed the animals that naturally ate us. (There are exceptions, of course: the alligator and hippo come to mind.)
From the FAQs at the Auckland Museum:
Which makes no sense at all since Australia was colonised around 60, 000 years ago, compared with 40, 000 years ago for Europe and 10, 000 years ago for North and South America.
Australia was isolated from humans for less time than most continents.
No, we wouldn’t. What you suggest is pretty much impossible biologically. It would require poisonous creatures to be a significant cause of death as well as being unavoidable through behavioural changes.
Humans evolved in Africa and then moved into Asia. Both Africa and Asia are full of poisonous snakes and no human has evolved a resistance yet. Nor have any poisonous snake species been killed off on either of those continents to the best of my knowledge.
You’re mistaken. Once we take into account air temperatures and land areas there are no more poisonous things in South America than in Asia or Africa.
That’s probably true to a very limited extent, but I fail to see how you make the distinction between being imposing and having the ability to kill off predators.
Those are exceptions?
Nobody in the history of the world has ever been eaten by a hippo. Hippos are herbivores. And the number of healthy adults who have been preyed on by alligators probably numbers less than 20. Alligators do occasionally kill people who wander into their territory, especially during breeding season, but in the vast majority of cases there is no sign that they attempted to eat the person afterwards. Defensive attacks do not a predator make.
Depends on what you mean by “city” and “likely to visit”, but around here, there’s a few bears (mostly black) sighted per year in town. And tourists do come here for hiking, skiing, and as a stopover to Yellowstone. Then again, someone visiting Yellowstone is probably hoping to see bears, from a safe distance at least.
Clearly the bear patrols aren’t working. Perhaps you would you like to buy my rock, it also keeps tigers away.
Uh, is it just me or are virulent and common two words that I would not like to be associated with flesh eating bacteria? :eek:
Seems to me that neither of those apply to Bozeman.
Alright, so I chose the wrong word. It wouldn’t be the first time. By that token, however, there aren’t that many poisonous predators that go after humans in Australia. But no matter the source of death, a dead human is a dead human even if it’s killer doesn’t eat them.
DUDE. The very first Google hit for ‘africa deaths hippos’ goes to this site called the Straight Dope, specifically: http://www.straightdope.com/mailbag/mhippo.html
Unless you’re taking a very strict view of the word “eaten”, you need to read that page. I had heard about this many years ago from my Kenya-missionary-kid roommate. Hippos were what people were really scared of, because you would accidently surprise them when you were out of your element, and they weren’t more scared of you than you were of them.
All perfectly true. But goes no way at all to explaining why there are so many lethal animals in Australia.
If what you suggested was correct and number of lethal animals corralates with length of human occupation then we would expect Africa to have the fewest dangerous animals, followed by Asia, Australia, Europe, North America, South America and Antarctica in that order. In reality only Antarctica is where your theory predicts it should be.
If we define a lethal animals as ones that live on land or coastal waters and and can readily kill an adult human then I suspect the species count would run Africa, Asia, Australia, North America, South America and Europe. But that’s just an educated guess.
DUDE I read that page. Taking a very moderate, lenient, standard and uncontroversial view of the word “eaten” (ie To include habitually or by preference in one’s diet, To take into the body by the mouth for digestion or absorption.) there is no suggetsion anywhere on that page that any hippo has ever eaten a person.
Dude, if you believe that page does say that hippos eat people then please quote where it says so, or even implies it.
What bizzarre defintion of ‘eaten’ are you using that includes biting without any intent or possibility of digetsion or utilisation as food? Please post said definition here, dude. It ought to be a hoot since it will necessitate concluding that every ant that bites a human eats that person.
By your “reasoning” ants eat millions of people every day :rolleyes: