Did you know? Laughing gas may have ended the last glacial period

By Alexander McNamara
and Matt Hambly

Laughing gas, otherwise known as nitrous oxide, has been used as an anaesthetic since the 19th century. These days, it is most commonly found in small, steel cartridges sold to the catering industry for making whipped cream. However, nitrous oxide is also a potent greenhouse gas and ozone-depleting chemical. Although it is present in the atmosphere at much lower concentrations than carbon dioxide – just 330 parts per billion – it has 300 times the heat-trapping capability. Indeed, a pulse of nitrous oxide released from plants 14,500 years ago may have hastened the end of the last glaciation.

We don’t necessarily yawn because we are tired

We tend to think of yawning as a sign of being tired or bored. That probably explains the popular perception that it is a way to get more oxygen into the blood to increase alertness. However, psychologist Robert Provine at the University of Maryland tested this idea and found people were just as likely to yawn when breathing air high in oxygen. A closer look at when people yawn suggests another explanation. It turns out that most spontaneous yawning actually happens when we are limbering up for activity such as a workout, performance or exam, or simply when we wake up. That has led to the idea that yawning helps us gear up by increasing blood flow to the brain.

The placebo effect can depend on whether a pill is colourful

The placebo effect is the mysterious reduction in a patient’s medical symptoms via the power of suggestion or expectation, the cause of which remains unexplained. However, what we do know is that a number of different factors can affect the power of the placebo effect. It can be triggered by administering pills, injections or surgery, or even just an authority figure assuring a patient that a treatment will be effective. In fact, experiments have shown that the power of the placebo effect depends on surprising factors like the appearance of tablets. For example, colourful pills work better as a placebo than white ones.

Some people can taste music

Forget feeling the music, some of us can actually taste it. Around one in 20 of us have synaesthesia, a condition that creates a strange connection between our senses. For these people, words may take on certain colours and music may have a particular taste or texture.

Although we aren’t certain of the causes of this unusual condition, studies have given us some idea of what is happening. As infants, our brains’ cells have millions of connections that are pruned away as we get older. Some studies suggest that people with synaesthesia have genetic variations that prevent this pruning from happening normally in certain brain regions, giving them unusual connections between sensory areas.

Being stronger reduces your risk of death

Here’s the motivation you need for your next trip to the gym: having stronger muscles reduces the risk of dying of any cause, and is especially important in preventing type-2 diabetes, cardiovascular disease and cancer. Broadly speaking, exercise of any kind is good for you, but unlike aerobic fitness regimes, strength training also helps to build bone, which can decrease your risk of osteoporosis. It can even help to prevent cognitive decline and memory loss in old age. Maintaining and improving your strength throughout life has become such an important, yet forgotten, aspect of general fitness that the UK government recently placed it above aerobic exercise in its new guidelines.

We have 19 different smiles but only one is ‘genuine’

The 42 facial muscles it takes to break out into a grin are capable of producing 19 different types of smile, but, according to French anatomist Duchenne de Boulogne, only one is ‘genuine’. In 1862 Duchenne identified that the difference between a genuine smile and a fake one lay in the eyes — the orbicularis oculi — to be precise. All smiling involves contraction of the zygomatic major muscles, which lifts the corners of the mouth. But a Duchenne smile is characterised by the additional contraction of the orbicularis oculi, crumpling the skin around the eyes into crows’ feet. Largely overlooked at the time, the Duchenne smile’s reputation has grown. In the 1950s a study found that Duchenne smilers had a 70 per cent chance of living until age 80 compared with 50 per cent for non-smilers. However, more recent findings have suggested that smiles don’t necessarily indicate that we are happy, but instead signal collaboration or bonding.

Source: Humans - newscientist.com