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Researchers continue to show the power behind our sense of smell. Recent studies have found, among other things, that the smell of foods like pizza can cause uncontrollable anger in drivers on roads.

The review explains that smell is unique in its effects on the brain. According to Conrad King, the researcher who carried out the review, "more than any other senses, the sense of smell goes through the logical part of the brain and acts on the systems concerned with feelings. This is why the smell of baking bread can destroy the best intentions of a dieter."

Smell, which dictates the unbelievable complexity of food tastes, has always been the least understood of our senses. Our noses are able to detect up to 10,000 distinct smells. Our ability to smell and taste this extremely large range of smells is controlled by something like 1,000 genes (基因), which make up an amazing 3% of the human genome. Researchers Richard Axel and Linda Buck were together awarded a Nobel Prize in 2004 for their ground-breaking research on the nature of this extraordinary sense. These two scientists were the first to describe the family of 1,000 olfactory (嗅觉) genes and to explain how our olfactory system works.

According to one study in the research review, smelling fresh pizza or even the packaging of fast foods can be enough to make drivers feel impatient with other road users. They are then more likely to speed and experience uncontrollable anger on roads. The most reasonable explanation is that these can all make drivers feel hungry, and therefore desperate to satisfy their appetites.

In contrast, the smells of peppermint and cinnamon were shown to improve concentration levels as well as reduce drivers’ impatience. Similarly, the smells of lemon and coffee appeared to promote clear thinking and mental focus.

However, the way genes regulate smell differs from person to person. A study by researchers in Israel has identified at least 50 olfactory genes which are switched on in some people and not in others. They believe this may explain why some of us love some smells and tastes while others hate them. The Israel researchers say their study shows that nearly every human being shows a different pattern of active and inactive smell-detecting receptors.