7 Billion People by 2011

Earth's population will reach 7 billion people in 2011, a new report predicts. That's sooner than had been expected.

We hit 6.5 billion in February, 2006. The U.S. Census Bureau keeps a running projection of population, and at that time, the Bureau predicted we'd reach 7 billion on on Oct. 18, 2012 at 4:36 p.m. Eastern Daylight Time.

The new report, from Population Reference Bureau, forecasts that 97 percent of the population growth over the next four decades will occur in Asia, Africa, Latin America and the Caribbean.

In the year 1900, there were just 1.6 billion people. Back in the year 1000, there were only 310 million. Some 261 people are born every minute. As of this writing, the Census Bureau says there are 6,777,348,371 in the world.
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Submitted by LiveScience Staff
posted: 13 August 2009 08:46 am ET
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Fire Used to Make Better Tools 75,000 Years Ago

Early humans crossed a threshold around 75,000 years ago, when they started painting symbols, carving patterns and making jewelry. A new study found they also began to use fire to make tools around that time.

Until now, this complex, multi-step process for tool making was only known to occur as recently as 25,000 years ago in Europe. But the new findings show this breakthrough occurred much earlier, and in Africa, not Europe.

By heating up stones in a fire before chipping away at them to make blades, early humans could make tools sharper and produce them more efficiently.

Scientists think this advancement represents a link between the earlier use of fire for cooking and warmth, and the later production of ceramics and metals.

"Around 800,000 years ago we see some of the first evidence for hominid controlled use of fire," said study leader Kyle Brown, a graduate student in archaeology at the University of Cape Town in South Africa and at Arizona State University. "And then at about 10,000 years ago we see evidence for production of ceramics. And at about 5,000 years ago we see metal working."

"The heat treatment of tools is sort of a bridging technology," he said.

The development of this skill may represent a level of complex cognition that was just beginning in humans at this time.

Brown and colleagues discovered the remains of tools that had been made using fire at archaeological sites in South Africa. The tools were made out of a stone called silcrete. Some of the earliest examples could date back to 164,000 years ago, and the researchers found that by 72,000 years ago this technique was seemingly common for silcrete tools.

The heat-treated tools look almost like stone razor blades, and are small enough that they could have been set into a handle.

"It’s a big debate to figure out what people were doing with these things," Brown told LiveScience. "Some people argue that they are the first arrowheads. Other people argue that they were set in a handle and used as knives."

To make the tools, early humans would have had to bury the stone beneath a fire, then slowly heat it up, keep it at a high temperature for hours, and then let it cool. The process was complicated and could take one to two days of continuous heating.

The heat transforms the stone so that it's harder and more brittle, which allows it to be more easily chipped away into a sharper edge. It also gives the stone a special sheen, which helped the archaeologists identify the tools as resulting from fire treatment.

"The most noticeable thing about heat-treated stone is that it has a luster or a gloss to it that’s fairly distinctive," Brown said. "A stone that's heated will only show that gloss if it's been flaked after it's heated."

The researchers then confirmed that the tools had been warmed in a fire with a technique called archaeomagnetics, which measures the realignment of iron particles in stone that results from heating. Another chemical process called thermoluminescence provided further proof that the stones had been heated.


Fire pit and sand both used for heat treatment experiments. Silcrete is placed beneath a layer of sand and then a fire is built over the top. The temperature is gradually increased and then slowly decreased to avoid cracking the stone.

Caffeine Causes and Cures Headaches

Norwegian scientists' large, cross-sectional study of more than 50,000 people has found that caffeine seems to both cause and prevent hurting heads.

In a study published in the Journal of Headache Pain, scientists at the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway, concluded that people who consume high amounts of caffeine each day are more likely to suffer occasional headaches than those with low caffeine consumption.

However, they also found that low caffeine consumption was associated with a "greater likelihood of chronic headaches, defined as headaches for 14 or more days each month."

After noting that there was no obvious reason for the differences in the effect of caffeine on people, the researchers advised those who suffer from occasional headaches to try cutting back on caffeine. Those who suffer from chronic headaches may reduce the amount and frequency of headaches they receive by drinking caffeine.

Pollution Reduces Rain Vital to Crops

Air pollution in China has cut the amount of light rainfall by 23 percent over the past 50 years, a new study finds.
The cause: Particles in air pollution cause smaller drops of water to form, and smaller drops have a harder time making rain clouds.

The result: Bad air could hamper the country's ability to grow food.

It is the first such study to link pollution to altered climate that can directly affect agriculture.

"People have long wondered if there was a connection, but this is the first time we've observed it from long-term data," said study leader Yun Qian at the U.S. Department of Energy's Pacific Northwest National Laboratory. "Besides the health effects, acid rain and other problems that pollution creates, this work suggests that reducing air pollution might help ease the drought in north China."

The study is detailed in the Aug. 15 in the Journal of Geophysical Research-Atmospheres.

New Theory Questions Why We Sleep
By Charles Q. Choi, Special to LiveScience
posted: 25 August 2009 08:34 am ET

The purpose of sleep remains one of the greatest unsolved mysteries in science. Although we spend roughly one-third of life asleep, researchers still do not know why.

While sleep is often thought to have evolved to play an unknown but vital role inside the body, a new theory now suggests it actually developed as a method to better deal with the outside world.

Sleep is often seen as bad for survival. Sleeping animals might be vulnerable to predators and cannot eat, mate, scout for prey, care for relatives or perform other behaviors key to getting by. As such "it's been thought that sleep must serve some as-yet unidentified physiological or neural function that can't be accomplished when animals are awake," said sleep researcher Jerome Siegel at the University of California at Los Angeles.

However, Siegel noted that a number of species could make do without sleep for long spans of time.

For instance, newborn dolphins and killer whales and their mothers show an almost total lack of what might be called sleep in other animals — that is, extended periods of immobility — for several weeks after birth, when these animals normally migrate. Similar findings are seen in birds during migrations, "where birds can fly for days on end without stopping," he explained.

"So you have to start thinking — if sleep has a vital universal function, how are they able to survive without it?" Siegel said.

Carnivores get their zzzz's

In a survey of the sleep times of a broad range of animals, Siegel found that carnivores sleep more than omnivores, which in turn sleep more than herbivores. To him, this suggested the role of sleep was linked to an animal's niche in its ecosystem.

One example Siegel cited was the big brown bat, which sleeps 20 hours a day, perhaps the record for mammals.

"One might suppose this animal sleeps so much because of some unknown function that sleep has for it," Siegel said. "But it seems more easily explained by the fact that it preys on moths and mosquitoes that only come out at dusk and are active for only a few hours before the temperature falls and they can't function. If it spent more time awake, it would spend more energy but not be as successful at hunting, and if it came out in the day it would be exposed to predatory birds that can see much better than it can."

Siegel proposes the main function of sleep is to increase an animal's efficiency and minimize its risk by controlling how a species behaves with regards to its surroundings.

"All species have times when they need to be active and ones where they don't, and so you can see species optimizing their periods of inactivity in response to their environment," Siegel said. "I'm saying that sleep helps animals adapt to the world around them."

Other theories abound

There are many other theories as to what the function of sleep is. These include:

A role in learning — either helping to form new connections between brain cells or pruning unnecessary ones.
Reversing damage from oxidative stresses incurred while awake.
Promoting longevity.
However, Siegel contends that sleep cannot be explained by the relative size of the brain, lifespan, body size, "and other such variables that have been intensively examined over the years with conflicting and confusing results."

For instance, "if one knows the size or brain size of different animals you cannot predict or explain their sleep time or depth. The baboon has the same total sleep time and total REM sleep time as the guinea pig," he said. "The long-living elephant has one of the shorted sleep times whereas the long-living bat has one of the longest sleep times."

Siegel emphasized, "My theory doesn't mean that significant things don't happen in sleep — it just means there is no vital universal function for sleep. A whole spectrum of things are accomplished better in sleep than awake in some animals, such as digesting food, but it doesn't mean the function of sleep is digestion."

Brainy ideas

Siegel contends that sleep has a lot in common with inactive states observed in a wide range of species. This includes plants and simple microbes, which in many cases do not have nervous systems — a challenge to the idea that sleep is for the brain, Siegel said.

"We see sleep as lying on a continuum that ranges from these dormant states like torpor and hibernation, on to periods of continuous activity without any sleep, such as during migration," he said.

Hibernation is one example of an activity that animals use to regulate behavior for survival. A small animal cannot always migrate to a warmer climate in winter, so it hibernates, effectively cutting its energy consumption and thus its need for food, remaining secure from predators by burrowing underground.

However, unlike hibernation and torpor, Siegel said, sleep is rapidly reversible — that is, animals can wake up quickly, a unique mammalian trait that allows for a relatively quick response to outside events.

"The often cited example is that of a parent arousing at a baby's whimper but sleeping through a thunderstorm," he said. "That dramatizes the ability of the sleeping human brain to continuously process sensory signals and trigger complete awakening to significant stimuli within a few hundred milliseconds."

In humans, the brain constitutes, on average, just 2 percent of total body weight but consumes 20 percent of the energy used during quiet waking, so these savings have considerable significance. Besides conserving energy, sleep invokes survival benefits for humans too — for example, "a reduced risk of injury, reduced resource consumption and, from an evolutionary standpoint, reduced risk of detection by predators," Siegel said.

Sleep skeptics

Many sleep researchers are skeptical of the idea.

"I don't agree with his idea that sleep developed to keep animals out of trouble, and I'm not alone," said neuroscientist Amita Sehgal at the University of Pennsylvania in Philadelphia. "I think the rest of us claim that a process that takes up a significant portion of your daily life and that has been associated with deleterious consequences when it is lost in animal models is not something that is just passively there to keep animals out of trouble. Rest alone would do that."

Still, others do support the idea.

"I think this idea of 'adaptive inactivity' is an extremely useful way of thinking about the broader picture of sleep without getting lost in individual theories," said sleep researcher David Dinges at the University of Pennsylvania School of Medicine. Dinges noted that regular cycles of light and darkness "put enormous environmental pressures on animals that all play into forced 'time-outs.'"

To help test his idea, a better understanding of sleep is needed, Siegel said. "New small digital recorders and transmitters should make it possible for the first time to do such studies under truly natural conditions," he explained.

Siegel detailed his idea online August 5 in the journal Nature Reviews Neuroscience.

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