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.

DALLAS, May 15, 2014 — Older migraine sufferers may be more likely to have silent brain injury, according to research published in the American Heart Association’s journal Stroke.

In a new study, people with a history of migraine headaches had double the odds of ischemic silent brain infarction compared to people who said they didn’t have migraines. Silent brain infarction is a brain injury likely caused by a blood clot interrupting blood flow to brain tissue. Sometimes called “silent strokes,” these injuries are symptomless and are a risk factor for future strokes.

Previous studies indicated migraine could be an important stroke risk factor for younger people.

Two decades ago, the inclusion of women in biomedical research was mandated by law but sex-specific research is still not the norm.

As a result, many women receive recommendations from their doctors for prevention strategies, diagnostic tests and medical treatments that may not have included women adequately. There is no evidence treatment has been worse due to that - and no one can force women to participate in studies - but diseases such as lung cancer, heart disease, Alzheimer’s and depression disproportionately affect women, which raises questions about the impact of research on women’s health.