Population size fails to explain evolution of complex culture

There is a growing consensus among archaeologists and anthropologists that the size of a population determines its ability to develop as well as to maintain complex culture. This view is however severely compromised by a paper published this week in the Proceedings of the National Academy of Sciences (PNAS) by a research team including technology philosopher Krist Vaesen of the Eindhoven University of Technology.

Archeologists observe a fairly sudden appearance of behavioural modernity, such as complex technologies, abstract and realistic art and musical instruments, some 40,000 years ago, in the Later Stone Age. For decades archeologists and antropologists are looking for an explanation for these and other 'cultural revolutions', and in this way finding the origin of human culture. Since ten years or so the predominant theory says the driving factor would be growing population numbers.

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Japan's Population Shrank by One Million People in the Last Five Years

Japan's latest census confirmed the hard reality long ago signaled by shuttered shops and abandoned villages across the country: the population is shrinking.

Japan's population stood at 127.1 million last fall, down 0.7 percent from 128.1 million in 2010, according to results of the 2015 census, released Friday. The 947,000 decline in the population in the last five years was the first since the once-every-five-years count started in 1920.

Unable to count on a growing market and labor force to power economic expansion, the government has drawn up urgent measures to counter the falling birth rate.

Prime Minister Shinzo Abe has made preventing a decline below 100 million a top priority. But population experts say it would be virtually impossible to prevent that even if the birth rate rose to Abe's target of 1.8 children per woman from the current birthrate of 1.4.

Without a substantial increase in the birthrate or loosening of staunch Japanese resistance to immigration, the population is forecast to fall to about 108 million by 2050 and to 87 million by 2060.

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Population Turnover in Europe circa 2500 BC With the Arrival of Farming?

DNA recovered from ancient skeletons reveals that the genetic makeup of modern Europe was established around 4,500 years ago in the mid-Neolithic, and not by the first farmers who arrived in the area around 7,500 years ago or by earlier hunter-gatherer groups. (Read about Europe's oldest known town.)

"The genetics show that something around that point caused the genetic signatures of previous populations to disappear," said Alan Cooper, director of the Australian Centre for Ancient DNA at the University of Adelaide, where the research was performed.

"However, we don't know what happened or why, and [the mid-Neolithic] has not been previously identified as [a time] of major change," he said.

Furthermore, the origins of the mid-Neolithic populations that did form the basis of modern Europe are also unknown.

"This population moves in around 4,000 to 5,000 years ago, but where it came from remains a mystery, as we can't see anything like it in the areas surrounding Europe," Cooper said.

The surprising findings are part of a new study, published in this week's issue of the journal Nature Communications, that provides the first detailed genetic history of modern Europe.

New Study on Population Collapse Mechanics

Many factors — including climate change, overfishing or loss of food supply — can push a wild animal population to the brink of collapse. Ecologists have long sought ways to measure the risk of such a collapse, which could help wildlife and fishery managers take steps to protect endangered populations.

Last year, MIT physicists demonstrated that they could measure a population's risk of collapse by monitoring how fast it recovers from small disturbances, such as a food shortage or overcrowding. However, this strategy would likely require many years of data collection — by which time it could be too late to save the population.

In a paper appearing in the April 10 online edition of Nature, the same research team describes a new way to predict the risk of collapse, based on variations in population density in neighboring regions. Such information is easier to obtain than data on population fluctuations over time, making it potentially more useful, according to the researchers.

"Spatial data are more accessible," says Lei Dai, an MIT graduate student in physics and lead author of the study. "You can get them by satellite images, or you could just go out and do a survey."

Led by Jeff Gore, an assistant professor of physics, Dai and Kirill Korolev, a Pappalardo Postdoctoral Fellow, grew yeast in test tubes and tracked the populations as they approached collapse. Yeast cells cooperate with other members of the population: Each of the organisms secretes an enzyme that breaks down sucrose in the environment into smaller sugars that it can use as a food source. All of the yeast benefit from this process, so a population is most successful when it maintains a certain density — neither too low nor too high.

In last year's study, the researchers found that in populations of yeast that are subjected to increasingly stressful conditions, populations become less and less resilient to new disturbances until they reach a tipping point at which any small disruption could wipe out a population.

This phenomenon can be spotted quickly in yeast, which produces about 10 new generations per day, but measuring these population fluctuations for species such as fish or deer would take much more time. In hopes of finding more useful signals, the researchers turned their attention to spatial information.

Those that study mass extinction ought to think on this one in a big way.

Have We Reached "Peak Farmland?" (DOOOOOOM)

The amount of land needed to grow crops worldwide is at a peak, and a geographical area more than twice the size of France will be able to return to its natural state by 2060 as a result of rising yields and slower population growth, a group of experts said on Monday.

Their report, conflicting with United Nations studies that say more cropland will be needed in coming decades to avert hunger and price spikes as the world population rises above 7 billion, said humanity had reached what it called "Peak Farmland".

More crops for use as biofuels and increased meat consumption in emerging economies such as China and India, demanding more cropland to feed livestock, would not offset a fall from the peak driven by improved yields, it calculated.

If the report is accurate, the land freed up from crop farming would be some 10 percent of what is currently in use - equivalent to 2.5 times the size of France, Europe's biggest country bar Russia, or more than all the arable land now utilized in China.

"We believe that humanity has reached Peak Farmland, and that a large net global restoration of land to nature is ready to begin," said Jesse Ausubel, director of the Program for the Human Environment at the Rockefeller University in New York.

"Happily, the cause is not exhaustion of arable land, as many had feared, but rather moderation of population and tastes and ingenuity of farmers," he wrote in a speech about the study he led in the journal Population and Development Review.

The doom tag is just for James.