The widespread misuse of skin creams and lotions that contain steroids in India is harmful and out of control, argues an expert in The BMJ this week.

Corticosteroids, also known as steroids, are anti-inflammatory medicines used for a range of conditions. However, these can lead to substantial and permanent damage, especially on thin skin, such as on the face and groin.

Side effects include pigmentation and breakdown of the skin, small and widened blood vessels on the skin, as well as bacterial and fungal infections. Misuse can lead to resistance of infections that can make these difficult to diagnose and treat.

A new study from the University of Exeter has found that teaching is not essential for people to learn to make effective tools. The results counter established views about how human tools and technologies come to improve from generation to generation and point to an explanation for the extraordinary success of humans as a species. The study reveals that although teaching is useful, it is not essential for cultural progress because people can use reasoning and reverse engineering of existing items to work out how to make tools.

Anna's hummingbird from the US west coast has the spangly plumage of a ballroom dancer, could out-maneuver a fighter pilot and can out-hover a helicopter. New research to be published in the journal eLife shows that brute strength is surprisingly important to their abilities.

An intensive study of 20 Anna's hummingbirds, Calypte anna, led by the University of British Columbia, revealed that birds with the highest muscle capacity are able to accelerate faster and make more demanding, complex turns.

"We had expected wing morphology and body mass to have more of an influence on maneuverability so were surprised that muscle capacity is so important," says Doug Altshuler, lead author from the University of British Columbia.

UK researchers have unearthed ancient fossil forests, thought to be partly responsible for one of the most dramatic shifts in the Earth's climate in the past 400 million years.

The fossil forests, with tree stumps preserved in place, were found in Svalbard, a Norwegian archipelago situated in the Arctic Ocean. They were identified and described by Dr Chris Berry of Cardiff University's School of Earth and Ocean Science.

Prof John Marshall, of Southampton University, has accurately dated the forests to 380 million years.

In epilepsy, nerve cells or neurons lose their usual rhythm, and ion channels, which have a decisive influence on their excitability, are involved. A team of researchers under the direction of the University of Bonn has now discovered a new mechanism for influencing ion channels in epilepsy. They found that spermine inside neurons dampens the neurons excitability. In epilepsy, spermine levels decrease, causing hyperexcitability. The researchers hope that their findings can be exploited to develop new therapies for epilepsies. They are reporting their findings in "The Journal of Neuroscience".

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most commonly diagnosed childhood disorders and can continue through adolescence into adulthood. Diagnoses exploded in the 1990s and now it is found in about 5% of children, but such diagnosis is based on clinical judgment rather than objective diagnostic markers. Symptoms include difficulty focusing attention and remaining "on task", impulsive behavior and extreme hyperactivity but some diagnoses have been made even when those behaviors were mild, so chemical interventions should be cautiously - but they are not.