Twenty thousand years ago, when humans were still nomadic hunters and gatherers, low concentrations of carbon dioxide in the atmosphere allowed the earth to fall into the grip of an ice age. But despite decades of research, the reasons why levels of the greenhouse gas were so low then have been difficult to piece together.

New research, published today in the leading journal Nature, shows that a big part of the answer lies at the bottom of the world. Sediment samples from the seafloor, more than 3 kilometers beneath the ocean surface near Antarctica, support a long-standing hypothesis that more carbon dioxide was dissolved in the deep Southern Ocean at times when levels in the atmosphere were low.

Boston, MA - A new study suggests that the current recommendation to treat severely malnourished children with routine antibiotics does not increase the likelihood of nutritional recovery in uncomplicated cases. Given this finding, the study's authors say that routinely using antibiotics may not be necessary or beneficial for severely malnourished children being treated at home when there is adequate local health infrastructure.

Reducing routine antibiotic use would be prudent given global concern over the problem of antibiotic resistance, say the researchers.

The study will appear in the February 4, 2016 issue of the New England Journal of Medicine (NEJM).

ROCHESTER, Minn. -- In a review article published in the Feb. 4 issue of the New England Journal of Medicine, a pair of Mayo Clinic Cancer Center researchers provide an in-depth look at the issues associated with the care of women in families with hereditary breast and ovarian cancer syndrome who have not yet developed cancer themselves. The article addresses optimal risk assessment for breast and ovarian cancers, the usefulness of risk-reducing surgery, side effects of these procedures, alternative strategies for cancer prevention and the best ways to help with the decision-making process.

PHILADELPHIA (February 3, 2016) - Cases of pertussis (whooping cough) have increased dramatically over the past five years, putting infants at risk of serious illness or death. Most infants are infected by a caregiver who has not received a Tdap (tetanus, diphtheria, and pertussis) booster, so caregiver immunization is particularly important. However, many caregivers go unvaccinated, and new strategies are needed to convince those living with infants to get the Tdap booster.

MAYWOOD, Il. - The widespread belief that radiation from X rays, CT scans and other medical imaging can cause cancer is based on an unproven, decades-old theoretical model, according to a study published in the American Journal of Clinical Oncology.

The model, known as linear no-threshold (LNT), is used to estimate cancer risks from low-dose radiation such as medical imaging. But risk estimates based on this model "are only theoretical and, as yet, have never been conclusively demonstrated by empirical evidence," corresponding author James Welsh, MD and colleagues write. Use of the LNT model drives unfounded fears and "excessive expenditures on putative but unneeded and wasteful safety measures."

Prolonged hammering and chiselling accelerated degenerative arthritis in the hands of Michelangelo Buonarroti, sculptor, painter and one of the greatest artists of all time. But the intense work probably helped him keep the use of his hands right up until he died.