The 10 most dangerous animals in the world

No 10: The bear
Forget gentle Ben - when a bear rears on its hind legs you know you're in trouble. Although bears have a fearsome reputation, you are statistically more likely to survive a bear attack than to perish, but that's small consolation to those who are faced with a bristling bear. With five attacks in Canada in 2005 alone, it seems that they're on the increase due to human destruction of, and encroachment on, bears' natural habitat

No 9: The shark
Sharks have a terrible reputation thanks to films such as Jaws and Deep Blue Sea, but it's one not entirely without cause. It seems that although great whites are often blamed for unprovoked attacks on humans, it is more likely to be down to those snappy bull sharks, who are very aggressive. Out of 360 species, only four are known killers: tiger, great white, oceanic whitetip and bull sharks. However, as we've seen with bears, although there are a high number of shark attacks, actual fatalities are fairly low.

No 8: Jellyfish
The sting-masters of the sea, Jellyfish are usually passive drifters who use their tentacles to dredge up small prey. However, anyone who becomes entangled with a jellyfish will experience degrees of pain from a nasty nip to excruciating pain, depending on the species. The box jellyfish is one of the most venomous marine creatures in the world; a sting can kill a man within minutes and most fatalities occur following a brush with a toxic jelly like this.

No 7: The hippopotamus
At first glance, these wallowing river-horses appear to be bulky, lazy beasts and not the fearsome predators you would expect to have a habit of mauling humans. However, with gaping mouths that can open four feet wide and swinging sledgehammer heads, as well as the fact that they can outrun us on land, these highly aggressive animals have plenty of scope for destruction and are considered one of the most dangerous of African animals. No 6: The elephant
Despite their friendly and approachable image thanks to zoo feeding times, these herbivores kill an alarming amount of people every year. Elephants are unpredictable creatures, and have been known to kill zookeepers who have been with them for as long as 15 years. It is recorded that even the tamest of elephants can attack without warning, though it is thought that most elephants do not realise the harm they do with almost no effort.

No 5: The crocodile
Crocodiles are dreaded prehistoric creatures capable of wreaking a terrible punishment on puny human flesh. North American, Estuarine and Nile crocodiles are the most dangerous and probably kill more people yearly than figures show due to the isolated areas where attacks are likely to take place and distance from help. One meal will keep a crocodile sated for a good while, so they like to wait in the water for the perfect time to strike.

No 4: Big cats
These big cats certainly mean business. With destruction of their natural habitat and a decline in prey species, particularly concerning the tiger and North American mountain lion or cougar, attacks on humans are increasing. The African lion is the biggest and most feared of big cats, but holidaymakers on safari are 100 per cent safe viewing from a vehicle, unless they decide to take a closer look and step down. Mountain lions are found in many national parks and are responsible for six attacks a year in the US and Canada.

No 3: The scorpion
Highly deadly and twice as ugly, the scorpion is a nasty critter that is probably responsible for more deaths per year than recorded, due to the isolated places they hang out and probable lack of access to antivenin. However, out of an estimated 1,500 species of scorpion worldwide, only around 25 are regarded dangerous. No 2: The venomous snake
Though there are more than 2,000 species of snake, 450 of which are venomous, only 250 are capable of killing a man. That's little consolation to the thousands who meet a nasty death due to snake bites each year - it's usually members of local populations who bear the brunt as they live and work where snakes inhabit and usually wear no protective gear.

No 1: The mosquito
Yes, the humble mosquito. What we Brits regard as an annoying pest is actually the most dangerous creature on the planet, thanks to its ability to spread disease with alarming efficiency. Best known for spreading deadly malaria, mossies also spread elephantiasis, yellow fever, dengue fever and West Nile virus, which was recently introduced to the US and is now prevalent in all states.

Mountain Climbing Bad for the Brain

If you’ve ever fantasized about scaling Mount Everest, think again. A new study of professional mountain climbers shows that high-altitude climbing causes a subtle loss of brain cells and motor function.
Italian researchers used magnetic resonance imaging to look at the brains of nine world-class mountain climbers who had at least 10 years of experience, including expeditions to Mount Everest and K2. The climbers ranged in age from 31 to 52, with an average age of just under 38, and were used to climbing to altitudes of at least 4,000 meters (two-and-a-half miles, or over 13,000 feet) several times a year.
The scientists, who published their findings in the October issue of the European Journal of Neurology, compared the climbers’ M.R.I. brain scans with 19 age- and sex-matched healthy control subjects. A number of neuropsychological tests were also carried out to assess the climbers’ cognitive abilities, including memory and motor functions.
On scans, the climbers showed a reduction in both white and gray matter in various parts of the brain. Overall, the researchers found that the cognitive abilities that were most likely to be affected were the climbers’ executive function and memory.
Six of the nine climbers had lower than average scores on the Digit Symbol test, which measures executive functions. Three out of nine scored lower than average on memory tests, while four scored below average on a visual-motor function test. The study authors noted that the results “are most likely to be due to progressive, subtle brain insults caused by repeated high-altitude exposure.”
Other studies have shown links between brain problems and repeated exposure to extreme conditions. The British Journal of Sports Medicine reported in 2004 that scuba diving may have long-term negative effects on the brain, particularly when performed in extreme conditions, such as cold water, more than 100 dives per year, and diving below 40 meters.
And last year, researchers at New York University noted that high-altitude illness is a growing concern in sports medicine given the increasing popularity of extreme sports like high-altitude mountaineering, skiing and snowboarding. The report noted that about 20 percent of tourists to Colorado report acute mountain sickness, and complications arising from sports activities at high altitudes, such as the potentially fatal conditions of pulmonary and cerebral edema, are on the rise.