I'm sure we all remember a time when we fell in love. For some it was a gradual realisation that the person you knew was actually amazing. For others, it was love at first sight – an instant lightning-bolt moment that you knew you'd met your perfect match. 

我相信我们都记得相爱的时光。有人日久生情，有人一见倾心——一刹那的火花，你就知道遇见了命定之人。 

What is it that makes someone instantly love someone? Physical attraction is an obvious answer but there are other reasons that can create affection for someone; compatibility, personality and a good sense of humour to name just a few. 

是什么让一个人立即爱上另一个人？身体吸引是一个显而易见的答案，但还有其他的因素可以同样的建立感情：举例如包容大度，个性和好的幽默感。

But according to one expert, there is a more scientific explanation. Dr Anna Machin, an Evolutionary Anthropologist at the University of Oxford says men look for signs of fertility and good health in a partner "and the major indicator of that in women is the waist-hip ratio… the absolute ideal." This is believed to be 0.7 which is "really your classic hourglass figure." And what do women look for in men? Well other experts have discovered they look for men who are taller, with broad shoulders and a relatively narrow waist – so a 'V' shaped torso. 

但是按照某位专家观点，还有更科学的解答。牛津大学人类进化学家AM博士表示，男性看重有利生产和健康身体择偶，所以主要指标是女性细腰肥臀，这样最理想不过。据信只有0.7腰臀比真正符合你理想的沙漏型身材。那么女性如何择偶呢？有些专家发现女性青睐高挑，宽肩和细腰的V型身材男士。 

If you're worried your figure isn't the perfect shape, there could be other factors that will cause someone to fall head over heels in love with you – people also use their sense of smell to sniff out their ideal mate. Apparently, we can detect whether people are genetically different to us by the way they smell. 

如果你担心你的身材不是完美的，还有其他的因素会导致某人爱上你-人们也会用嗅觉去嗅出他们理想的伴侣。显然，我们可以通过人们的嗅觉来检测他们是否在基因上与我们不同。 

Even if a potential partner's smell is a passion-killer, their facial expressions might make you infatuated with them. According to Professor David Perrett, at the School of Psychology and Neuroscience at St Andrews University, "we can change our faces by interacting with others and doing so in a pleasant manner, and that will aid our attractiveness and make others interested in us." 

即使潜在伴侣的气味是激情杀手，他们的面部表情也会让你迷恋上他们。圣安德鲁斯大学心理学和神经科学学院的大卫·佩雷特教授说：“我们可以通过与他人互动并以一种愉快的方式改变自己的容貌，这将有助于我们的吸引力，并使其他人对我们感兴趣。 

So it's good to know there are many reasons why we might be smitten with someone, but there is a problem; will the feeling be mutual and if it is, how long will it last? Nothing is guaranteed and, we know from Shakespeare, the course of true love never ran smoothly! 

所以，很高兴知道为什么我们会被某个人迷住，但也有一个问题：这种感觉是相互的吗？如果是的话，这种感觉会持续多久？没有什么是可以保证的，我们从莎士比亚那里知道，真爱的过程从来没有顺利进行过！