1. What is the point of human beauty?

Why it matters Beauty is hard to define, but we know it when we see it. Although today this superficiality often seems pointless and even destructive, it may have served a useful purpose for our distant ancestors.

What we know Some traits that humans find beautiful may correlate with health and reproductive viability, but preferences for certain traits could simply have evolved as by-products of the way in which the brain processes information.

Next steps Models that incorporate dozens of variables for describing facial features are better ways to test evolutionary and non-evolutionary hypotheses, and may offer insight into how we weight different cues in human faces.

2. How can we overcome our obsession with physical beauty?

Why it matters Many researchers think that attractiveness is too closely bound up with personal worth in society. This can lead to prejudice, as well as psychological conditions such as eating disorders and depression.

What we know When we find others attractive, we tend to assume that they are also good people. Being attractive can lead to benefits at work, in the courtroom and in politics. Media images and 'fat talk' can fuel negative body images.

Next steps Interventions that treat body-image disorders are having some success, but they need to be adapted for men and all ethnic groups. Work on other types of prejudice could open up ways to override our subconscious beauty bias.

3. What is so special about youthful skin?

Why it matters Some people retain young-looking skin as they age, whereas others resort to creams and procedures. Little is known about the mechanisms of skin ageing, including whether younger-looking skin — however it is achieved — is any healthier.

What we know Studies have revealed many gene variants and molecular pathways associated with skin ageing. Combining those findings with data on proven treatments, such as topical creams and broadband light therapy, could tease out the biochemical details of skin ageing.

Next steps Cosmetics companies hope to use these findings to develop products that will delay or reverse skin ageing, but further steps are needed before any personalized, evidence-based treatment comes to market.

4. Why do we take pleasure in aesthetic things?

Why it matters Humans have been coveting art for millennia. Today, the global fine-art market is worth more than US$50 billion annually. Scientists are finally getting a grip on the biology behind our passion for objects — beautiful or otherwise.

What we know No one brain region is involved in art appreciation. Instead, complex and widely distributed neural activity characterizes the aesthetic experience. Much of this activity is in the brain's reward circuitry, which also responds to drugs, sex and attractive faces.

Next steps Researchers still do not agree on the definition of an aesthetic experience, much less on how the brain regions work together to create it. Answers will require coordination between many scientific fields, as well as art theory and philosophy.