Modern Papuans' immune system likely evolved with a little help from the Denisovans, a mysterious human ancestor who interbred with ancient humans, according to a new study.

In rural Bangladesh, areas with high levels of arsenic contamination in drinking water, compared to areas with less contamination, have a higher prevalence of antibiotic-resistant Escherichia coli in both water and child stool samples, according to a new study.

Researchers have linked the artificial sweetener aspartame to anxiety-like behavior in mice. Along with producing anxiety in the mice who consumed aspartame, the effects extended up to two generations from the males exposed to the sweetener, according to the study.

Researchers found that certain drugs can change the fundamental makeup of cancer stem cells in mouse models of mucoepidermoid carcinoma -- a lethal form of salivary gland cancer that currently has no treatment options.

For decades, doctors have treated kids with attention-deficit/hyperactivity disorder (ADHD) with methylphenidate, a stimulant drug sold as Ritalin and Concerta, making it one of the most widely prescribed medications aimed at the central nervous system. One might expect that researchers would know how methylphenidate works in the brain by now, but little is known about the drug's mechanism of action. Now, a new study seeks to close this gap and understand how methylphenidate interacts with cognitive control networks and attentional behavior.