科学研究发现，我们总是容易信任与我们相像的人。与此同时，与我们相像的人对于我们而言，却更不会引起我们的性欲。

Would you buy a used car from this man? The answer depends on whether he looks like you, researchers believe.

We are more likely to trust people who look like us, psychologists told the British Science Festival yesterday - even though we find them less attractive.

Researchers tested how willing players of a game were to entrust¹ money to strangers whose faces they could see on a computer screen. They found that players were more trusting when those faces had been digitally manipulated to resemble their own.

"Normally they trusted people about 50 per cent of the time. But when the faces were changed to look like them, they trusted 73 per cent of the time," said Lisa DeBruine of the University of Aberdeen, who conducted the research.

She said she believed that the response had an evolutionary² basis, as we subconsciously³ assume those who look like us must be relatives. But because we are programmed to avoid finding close relatives sexually attractive, this means those we trust are not necessarily the ones we find attractive. Dr DeBruine's team found that even when looking at members of the opposite sex, subjects found those who looked like them trustworthy - but they did not want to sleep with them.

"When the players were judging the faces for physical attractiveness they thought similar faces less attractive," she said. "So we believe resemblance is trustworthy - but not lustworthy."These two conflicting evolutionary drives highlight a tension in choosing reproductive partners, Dr DeBruine said. For although we avoid pairing up with siblings⁴, we must not choose partners too genetically⁶ distant.

Dr DeBruine said this was a real problem for other animals, some of whom risked accidentally mating with the wrong species. Even in humans, she said, there is evidence that we breed better with people who have some genetic⁵ similarity.

"A study in Iceland showed that partners who are third or fourth cousins have more surviving grandchildren than people who are either more closely related or less closely related," she said. "People choose partners that are kind of intermediate."Anthony Little, a research fellow at the University of Stirling, said this may help to explain why we are prone⁷ to pick partners who look a bit like our parents."People select partners similar to their opposite sex parent," he said. "The best predictor of someone's partner's hair and eye colour is the hair and eye colour of their opposite sex parent."你会从一个人手里买下他的二手车吗？研究显示，它取决于这个人是否长得像你。

心理学家在英国科学节（British Science Festival）上说，对于跟我们长得像的人，我们总是更容易信赖，即使他们的魅力值并不高。

研究者做了一个游戏，测试参与者是否愿意将金钱委托给一个陌生人。这些人的脸都会在电脑的大屏幕上出现。研究者发现，当那些脸被电脑处理成与参与者的脸相似时，他们的信任度就会更高。

"一般来说，50%的情况下他们会相信他人。但当这些脸被处理过，看起来像他们时，信任度就会提高到73%."发起研究的阿伯丁大学（ the University of Aberdeen）的丽莎·德布琳（Lisa DeBruine）说。

她认为这种种反应是有进化论基础的，在潜意识里，我们总认为那些与我们相似的人一定与我们有血缘关系。同时，由于我们已经形成了避免在近亲身上发现性吸引力 的定律，因此，我们所信赖的人未必就是我们觉得有魅力的人。德布琳博士的团队发现，即使是面对异性成员，参与者也认为与他们相似的人更可信，--但他们并不想和对方上床。

"当参与者通过脸来判定身体的吸引力时，他们便会认为相似的面孔的吸引力不高。因此我们认为相像更可靠，--但却不吸引人。"德布琳博士说。

她认为，这两种相冲突的进化进一步加剧了选择配偶时的压力。虽然我们尽力避免近亲结婚，但我们也不会选择与我们基因相差太远的人。

而这在其它的动物里也是一个无法回避的问题，有一些动物有时会冒险与另一个物种发生交配。即使在人类社会中，也有证据表明基因相似的人在哺育后代上做得更好。

"冰岛的一个研究表明，如果是第三或第四代的表亲结为夫妇，他们孙辈的存活率比近亲结婚或者是基因相差很远的夫妇的都要高。因此人们倾向于折中的做法。"斯特林大学（University of Stirling）的研究成员安东尼 里特（Anthony Little）认为这也许有助于解释为什么我们总是倾向于选择与我们父母相似的人为配偶。"在择偶时，人们会选择与他们性别相对的父母相似的人。想要知道一个人配偶的头发或者眼睛的顔色，看看与他们性别相对的父母吧。"