Zinc is essential for optimal plant growth and development but when high levels of the metal are present in the soil, it can become toxic to the plant. Consequently, plants need to trigger mechanisms capable of coping with that stress. Researchers from the Instituto Gulbenkian de Ciência (IGC) have now discovered a novel genetic mechanism that protects plants from toxic zinc levels. The research team, led by Paula Duque, identified a gene that produces a protein capable of sequestering zinc inside the cells of the root. In the presence of high levels of zinc, this gene undergoes a special processing which ensures more production of the protecting protein.

While American adults lead the world in science literacy, and America leads the world in science output and Nobel prizes, American students are only middle of the pack when it comes to international standardized tests.

Is science creativity, teaching how to think, disconnected from scores on standardized tests? It would seem so, but every time standardized tests are given, entrenched constituencies in education say education is broken but they can fix it.

Where did the earliest Americans come from? 

Speculation has pointed to Eastern Asia, Western Asia, Japan, Beringia and even Europe. Differences in cranial form between today's Native Americans and the earliest known Paleoamericans have lent credence to all possibilities but the analysis of a nearly complete Paleoamerican skeleton with Native American DNA that dates close to the time that people first entered the New World may have some answers to part of the puzzle.

The ancient remains of a teenage girl, researchers call her Naia, found deep in the water of a Yucatán Peninsula cave have established a definitive link between the earliest and modern Native Americans, according to a new study in Science.

So, yes, they really were here before you. 

Ancient human remains in the Americas have been a puzzle for science because their skulls are narrower and have other measurably different features from those of modern Native Americans. Some researchers have hypothesized that these individuals came to the Americas from as far away as Australia, Southeast Asia or Europe.  

Deep in the water of a Yucatán Peninsula cave, one of the oldest human skeletons found in North America has been discovered. 

"Naia" is the the researchers' name for the teenage girl who went underground, presumably to seek water, and fell to her death in a large pit named Hoyo Negro - "black hole" in Spanish.

Since the commercialization of medical marijuana in the middle of 2009, the proportion of marijuana-positive drivers involved in fatal motor vehicle crashes in Colorado has increased dramatically, according to data from the National Highway Traffic Safety Administration's Fatality Analysis Reporting System covering 1994 to 2011.

The University of Colorado School of Medicine  researchers analyzed fatal motor vehicle crashes in Colorado and in the 34 states that did not have medical marijuana laws, comparing changes over time in the proportion of drivers who were marijuana-positive and alcohol-impaired.