Friday, May 28, 2010

Thursday, May 20, 2010

Incredible Video: Hail Destroys Oklahoma City Day After Tornado Read more:

At one time, photographs told the story of freak storms and deadly weather. Now, it’s insant YouTube footage of what some Oklahoma City residents are calling “the most insane hail storm, or storm in general, I have ever seen!”

Sunday afternoon, as violent storms rolled across middle America – only a day after a tornado left a path of devastation in the same region – Oklahomans turned on the video cameras and filmed what is sure to be known as the great hailstorm of 2010.

Just check out this footage. The first video is posted by a family that can be heard screaming about the softball-sized hail, and the dents in the jeep that can be seen almost immediately (right around 4:00):

Read more:

I think this second video, though, better captures the extreme force and lethal velocity of the hail in question. Framing a family’s swimming pool, the speed and size of the ice is immediately apparent. But fast-forward to the sixty-second mark, as the storm reaches its apex, and the water is all but turned into a wave pool. It almost looks like a Jacuzzi, with the jets on full blast.

In the background, an utterly baffled homeowner sums it all up best: “That’s insane, I’ve never seen anything like this.”

Wednesday, May 19, 2010

Scientists stunned as grey whale sighted off Israel

JERUSALEM (AFP) - – The appearance of a grey whale off the coast of Israel has stunned scientists, in what was thought to be the first time the giant mammal has been seen outside the Pacific in several hundred years.

The whale, which was first sighted off Herzliya in central Israel on Saturday, is believed to have travelled thousands of miles from the north Pacific after losing its way in search of food.

"It's an unbelievable event which has been described as one of the most important whale sightings ever," said Dr Aviad Scheinin, chairman of the Israel Marine Mammal Research and Assistance Center which identified the creature.

A population of grey whales once inhabited the north Atlantic but became extinct in the 17th or 18th centuries and has not been seen there since.

The remaining colonies live in the western and eastern sectors of the north Pacific.

"What has amazed the entire marine mammal research community is there haven't been any grey whales in the Atlantic since the 18th century," he said. Scheinin said the creature, a mature whale measuring some 12 metres (39 feet) and weighing around 20 tonnes, probably reached the Atlantic through the Northwest Passage, an Arctic sea route that connects the Pacific and Atlantic oceans and is normally covered with ice.

"Here you have an animal that is supposed to live in the Pacific and because the ice in the Arctic is melting, it managed to get through this corridor near the Bering Strait," Scheinin told AFP.

The population which lives in the northeastern Pacific normally migrates southwards in around October, heading for warmer waters around the Gulf of California in a huge round trip of at least 5,000 miles (8,000 kilometres).

So when autumn came, this particular grey whale began travelling south, keeping the land mass on the left and heading for the Californian Gulf with the aim of "turning left" into the bay.

But instead, it reached Gibraltar and turned left into the Mediterranean and ended up off the shores of Israel, Scheinin said.

"The question now is: are we going to see the re-colonisation of the Atlantic?" he said. "This is very important ecologically because of the change of habitat. It emphasises the climate change that we are going through."

So far, the whale seems to be happy enough in the waters off the shores of Israel, he said.

"It is pretty thin, which indicates the trip was quite harsh, but we think it can survive here," he said. "Grey whales are very generalist in what they feed on."

Now experts are mulling the possibility of tracking the whale by satellite -- a costly operation that would need outside funding and expertise, Scheinin said.

"It's quite a big operation to do this. If it stays around here for the next month, it's worth having someone come in and do this professionally," he said.

"It will be interesting to see where it goes and to follow it."

Saturday, May 15, 2010

How spitting cobras shoot for the eyes

Bruce Young from the University of Massachusetts is antagonising a spitting cobra. He approaches, keeping outside of the snake’s strike radius, while moving his head from side to side. The cobra doesn’t like it and erects its hood in warning. Young persists, and the snake retaliates by launching twin streams of venom at him from forward-facing holes in its fangs. The aim is spot-on: right at Young’s eyes. Fortunately, he is wearing a Perspex visor that catches the spray; without it, the venom would start destroying his corneas, giving him minutes to seek medical aid before permanent blindness set in.

It may seem a bit daft to provoke a snake that can poison you from afar, but Young’s antics were all part of an attempt to show just how spitting cobras make their shots. Their venom is a potent defensive weapon, but it’s also completely useless if it lands on the skin or even in the mouth. To work, the cobra must aim for the eyes. Just think about how hard that is. The cobra must hit a moving target that’s up to 1.5 metres away, using a squirt gun attached to their mouth. The fang is fixed with no movable nozzle for fine-tuned aiming. And the venom spray lasts just 50 milliseconds – not long enough to correct the stream after watching its arc.

By taunting cobras from behind his visor, Young discovered their secret. The snake waits for a particularly jerky movement to trigger its attack and synchronise the movements of its heads in the same way. It shakes its head rapidly from side to side to achieve a wide spray of venom. And it even predicts the position of its target 200 milliseconds later and shoots its venom at where its eyes are going to be.

There are several species of Asian and African spitting cobras, and Young had individuals of three – the red, black-necked, and black-and-white spitting cobras. Getting the snakes was straightforward enough; getting them to spit is another matter. It’s very difficult to provoke a cobra to spit at a stationary object – you need a moving target for the best results. That sounds like the sort of job that graduate students normally do, but Young stepped up to it himself. As he wryly writes, “To maximize consistency, the last author served as a target for all trials.”

His visor was fitted with accelerometers that recorded his own head movements, while his colleagues Guido Westhoff and Melissa Boetig filmed the snakes with a high-speed camera. Both films were synchronised with a laser pulse and together, the team recorded data from over 100 spits.

They found that a particular type of head wiggle provoked the snakes into spitting – not necessarily large or long-lasting, but always involving a jerky change of direction. This makes sense for the snake. At the moment when the target’s head changes direction, its movements are probably going to keep in the same direction for a short while. Also, to change direction, the head must briefly slow down before speeding up again, giving the snake more time to predict its future position.

On average, the cobra starts spitting 200 milliseconds after such movements, which is roughly the same as a human’s reaction time between sight and movement. But if it takes that long for the snake to contract its venom-shooting muscles, it’s at a 200 ms disadvantage. How can it possibly gun down a moving target and avoid spitting into empty space?

The answer is simple – even before the first droplets of venom emerge, the cobra is already taking aim. Around 65 ms before, it starts to waggle its head up and down, and from side to side, perfectly tracking the zig-zagging of its target’s face. When it actually starts to spit, it stops this synchronous bobbing and rapidly accelerates its head in the same direction as its target’s. The snake is compensating for its moving bull’s-eye, predicting where it’s going to be 200 ms in the future and ‘catching up’ to it well ahead of time.

Young thinks that the cobra’s calculations would be accurate enough to hit the eyes if it focused its venom jets on a specific point. As it is, the snake increases the odds of hitting its target even further by wiggling its head from side to side while releasing its poisonous payload. The result: a massive chance of a direct hit, and a reeling animal that will think twice about approaching a spitting cobra again.

Saturday, May 8, 2010

The Animal Odd Couple

Short lives, short size – why are pygmies small?

For decades, anthropologists have debated over why pygmies have evolved to be short. Amid theories about their jungle homes and lack of food, new research suggests that we have been looking at the problem from the wrong angle. The diminutive stature of pygmies is not a direct adaptation to their environment, but the side-effect of an evolutionary push to start having children earlier.

Andrea Migliano at the University of Cambridge suggests that pygmies have opted for a ‘live fast, die short’ strategy. Their short lives gives them very limited time as potential parents, and they have adapted by becoming sexually mature at a young age. That puts a brake on their pubescent growth spurts, leaving them with shorter adult heights.

Pygmies are technically defined as groups of people whose men are, on average, shorter than 155cm (or 5 feet and an inch for the Imperial-minded). Strictly speaking, the word is restricted to several ethnic groups of African hunter-gatherers, like the Aka, Efe and Mbuti. But the world is surprisingly replete with shorter-than-average groups who also bear the colloquial moniker of pygmies, including some from Brazil, Bolivia, South-East Asia and Papua New Guinea.

The earlier explanations for a short stature worked for some of these groups, but they could never account for all of them. Some scientists suggested that smaller people move more easily through dense jungles, but some pygmies live outside forests. Other theorised that they could maintain their body temperature more easily, but many live in cool and dry climes.

One of the more popular theories put forward by Jared Diamond suggested that small people are more resilient to starvation and malnourishment when food becomes scarce. But this can’t be the whole story for Africa groups like the Turkana and Massai manage to be some of the tallest people on Earth despite facing similarly unstable food supplies!

Migliano found more evidence against this theory by comparing the growth patterns of three groups of genuine pygmies – the Filipino Aeta and Agta, and the central African Biaka – with the shortest Americans, whose malnourished childhoods landed them in the bottom 0.01% of the population in terms of adult height.

Together with Lucio Vinicius and Marta Lahr, she found that the true pygmies grew slightly more slowly than the undernourished Americans, their growth spurts ended much earlier, at age 12 rather than 15. Typically, groups who lack free-flowing calories grow slowly over a long time – the pygmies’ pattern matched the first part but not the second. The pygmies’ growth curves disproved the malnutrition idea, but their lifespan pointed Migliano towards a better explanation.

Pygmies around the world are short in life expectancy as well as height, with the average adult dying at 16-24 years of age. Only 30-50% of children survive to the age of 15 and less than a third of women live to see menopause at 37. Taller African groups like the Ache or Turkana have lower adult mortality and twice the average lifespan, and compared to them, the pygmies’ pattern is closer to that of chimps.

Migliano argues that their early deaths are the driving force behind both their small size and their shorter growth spurts. It pays pygmies to divert resources away from growth and towards having children as early as possible, to compensate for their limited years. Indeed, Migliano found that they reach a peak of fertility earlier than taller groups.

In general, people who grow taller and larger tend to be more fertile and have larger and more capable offspring. That’s obviously advantageous but not if adult mortality is so low that you may not get a chance to have children at all. In this perilous situation, natural selection favours those who mature and reproduce early, to the cost of their growth.

Migliano’s theory has one important missing piece that needs to be filled in – why do many pygmies die early? It is here that the other earlier explanations for their short size may come in, including tropical diseases, thick jungle environments, hot climates and poor nutrition. None of these factors alone can account for pygmy evolution around the world, but Migliano speculates that one or more of them could lower the life expectancies of different populations.

If she’s right, it means that small body size could be an example of convergent evolution, where different groups of people in disparate parts of the globe independently evolved similar solutions to the shared problem of short and hazardous lives.