There is no longer any doubt: We are entering a mass extinction that threatens humanity's existence, according to a rather ridiculous claim by doomsday prophet Professor Paul Ehrlich, the same author of the Population Bomb who has been saying this same thing since the 1960s.

 Ehrlich and fellow hysterics Anthony D. Barnosky of the University of California at Berkeley, Andrés García of Universidad Autónoma de México, Robert M. Pringle of Princeton University and Todd M. Palmer of the University of Florida, say there are threatened species, too many humans, and issues with habitat. 

New, ultra-high-field magnetic resonance images (MRI) of the brain provide the most detailed images to date to show that while the brain shrinks with age, brain cell density remains constant.

The images of cognitively normal young and old adults provide the first evidence that in normal aging, cell density is preserved throughout the brain, not just in specific regions, as previous studies on human brain tissue have shown. The findings also suggest that the maintenance of brain cell density may protect against cognitive impairment as the brain gradually shrinks in normal aging.

Doctors often misdiagnose zinc deficiency, and seem to be unaware of the impact of excess zinc on the body, according to a small audit of clinical practice.

Zinc is an essential trace element that is required in daily quantities of 5.5 to 9.5 mg for men, and 4 to 7 mg for women. But zinc supplements are usually only available in formulations of 45 or 50 mg. The US recommended tolerable limit is 40 mg/day.

Working women are "leaning in" and supporting more females in leadership roles, but a new study finds that having a female manager doesn't necessarily equate to higher salaries for female employees.

Instead, women can sometimes take an earnings hit relative to their male colleagues when they go to work for a female manager.

Melanoma patients with high levels of a protein that controls the expression of pro-growth genes are less likely to survive, according to a study led by researchers at Icahn School of Medicine at Mount Sinai and published online in the journal Molecular Cell.

The research team found that the protein, called H2A.Z.2, promotes the abnormal growth seen in melanoma cells as they develop into difficult-to-treat tumors. H2A.Z.2 is part of the chromosome structure that packages genes, and has the ability to switch them on off. Having high levels of this protein aberrantly activates growth-promoting genes in melanoma cells.

Often referred to as the "body clock", circadian rhythm controls what time of day people are most alert, hungry, tired or physically primed due to a complex biological process that is not unique to humans. Circadian rhythms, which oscillate over a roughly 24-hour cycle in adaptation to the Earth's rotation, have been observed in most of the planet's plants, animals, fungi and cyanobacteria, and are responsible for regulating many aspects of organisms' physiological, behavioral and metabolic functions.