One of the most distinctive characteristics of humans is probably one you don’t think of very often — the capacity to learn based merely on what someone tells you.

For instance, if we are told that our neighbors’ son has died his hair purple, we update our mental image of him to accommodate this newly acquired information.

What is unknown, however, is when we become capable of revising our mental representations of objects or situations based solely on what someone tells us.

It appears that chemical warfare has been around a lot longer than poison arrows, mustard gas or nerve weapons – about 100 million years, give or take a little.

A new study by researchers at Oregon State University has identified a soldier beetle, preserved almost perfectly in amber, which was in the process of using chemical repellants to fight off an attacker when an oozing flow of sap preserved the struggle for eternity.

The discovery is the earliest fossil record of a chemical defense response, scientists say, and indicates that this type of protective mechanism – now common in the insect world and among other animal species – has been around for more than 100 million years.

The decreased use of cocaine in the United States over the last 20 years mostly occurred among the highly educated, while cocaine use among non-high school graduates remained constant, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health.

The study authors suspect that the inverse relationship between cocaine use and education is related to access to health warnings and resources. They also concluded that the emerging disparity highlights the need for improved interventions that target persistent cocaine users who are lower educated.

“Much like smoking, people with a better understanding of the impact cocaine has on health are more likely to modify their behavior,” said Valerie S.

Volcanoes sometimes get a bad rap for belching CO2 but today it turns out they're also responsible for the air we breathe.

National Science Foundation-funded research published this week in the journal Nature indicates that billions of years ago, when the Earth was home largely to undersea volcanoes, a previously unknown agent was removing the gas.

The researchers suggest that mixture of gases and lavas produced by submarine volcanoes scrubbed oxygen from the atmosphere and bound it into oxygen-containing minerals.

In the debate about the climate effects of carbon dioxide emissions from transportation it is assumed that fuel is the key source of pollution from vehicle traffic.

“What you seldom think about is the huge amounts of brake linings and tires that are worn out in traffic and the fact that these products contain considerable amounts of metals,” says David Hjortenkrans, one of the scientists at The University of Kalmar in Sweden who performed a new study of the issue.

Despite the fact that authorities have regulated the metal content of auto parts and the fact that the auto industry has made improvements, brake linings and tires are still among the major sources of metals in urban environments.

The organs that produce sperm also may make it easier for mutations to pass to offspring, USC biologists say. The testes in humans may act as mutation multipliers that raise the odds of passing improved DNA to offspring – but that can also backfire by increasing the frequency of certain diseases.

The new theory is part of a study, appearing in PLOS Biology, that tries to explain the puzzlingly high frequency of Apert syndrome, a genetic cranial deformity found in approximately one out of every 70,000 newborns.

The study’s authors suggest that natural selection may favor “germline” cells – the precursors to sperm – carrying a mutation that causes Apert syndrome.