Humanity’s brush with extinction

Human beings may have had a brush with extinction 70,000 years ago, an extensive genetic study suggests.

The human population at that time was reduced to small isolated groups in Africa, apparently because of drought, according to an analysis published Thursday in the American Journal of Human Genetics.

The report noted that a separate study estimated that the number of early humans may have fallen as low as 2,000 before numbers began to expand again.

A black hole’s ejection recorded

Using powerful radio telescopes, scientists have captured a supermassive black hole just as it was belching out a jet of supercharged particles, offering a first look at how these cosmic jets are formed, the scientific team reported Thursday in the journal Nature.

Supermassive black holes are believed to form the core of many galaxies, and astronomers have long suspected they eject jets of particles at nearly the speed of light.

A kind of supermassive black hole known as a blazar was suspected of spewing out a pair of forceful streams of plasma 950 million light years from Earth.

Using the National Radio Astronomy Observatory’s Very Long Baseline Array, the team imaged this charged material winding in corkscrew fashion out of the supermassive black hole, behaving just as astronomers had predicted.

Volcano made 1601 a cold year

The 1600 eruption of the volcano Huaynaputina in Peru caused global disruptions in food production, researchers from UC Davis reported in the journal Eos, Transactions of the American Geophysical Union.

According to tree ring studies, 1601 was a very cold year, presumably because of large amounts of light-blocking sulfur released by the volcano.

In Russia, 1601-03 brought the worst famine in the country’s history. In France, the 1601 wine harvest was late, and wine production collapsed in Germany and colonial Peru. China’s peach trees bloomed late, and Lake Suwa in Japan had one of its earliest freezing dates in 500 years.

Greenhouse gases on the increase

Major greenhouse gases are accumulating faster than in the past despite efforts to curtail their increase.

Carbon dioxide concentration in the air increased by 2.4 parts per million last year, the National Oceanic and Atmospheric Administration reported Wednesday, and methane concentrations also rose rapidly.

Global concentration of carbon dioxide is now nearly 385 parts per million. Carbon dioxide levels hovered around 280 ppm until 1850. Methane in the atmosphere rose by 27 million tons last year after nearly a decade with little or no increase, according to a NOAA researcher.

Downtrends in children’s health

Rising obesity rates and a large percentage of low-birth-weight children are dragging down the overall health of American children in their first decade of life, according to a report tracking the health and well-being of young children in the United States.

Though U.S. children overall have seen improvements in their well-being in recent years, American children ages 6 to 11 are four times more likely to be obese than children of those ages in the 1960s, the report found. The study, led by researchers at Duke University in North Carolina and the Foundation for Child Development, a private advocacy group, also found that the percentage of babies born with low weight rose 12.3% from 1994 to 2005, an increase they said was probably tied to delayed childbearing among working mothers and an increased use of fertility drugs.

Low birth weight has been linked in large studies to a higher risk of developmental and learning problems and to lower academic achievement.

What are little boys made of?

Surprising new research suggests that what a woman eats before pregnancy influences the gender of her baby.

Having a hearty appetite, eating potassium-rich foods such as bananas and not skipping breakfast all seemed to raise the odds of having a boy, British researchers reported Wednesday in the journal Proceedings of the Royal Society B.

The British research is described as the first to show a link between a woman’s diet and whether she has a boy or girl.

It just might be that it takes more nutrients to build boys than girls, researchers from the University of Exeter said.

From Times Staff and Wire Reports