基因差異大 容易成夫妻

When it comes to choosing a mate, opposites really do attract, according to a Brazilian study that found people are subconsciously more likely to choose a partner whose genetic make-up is different to their own.

They found evidence that married couples are more likely to have genetic differences in a DNA region governing the immune system than were randomly matched pairs.

This was likely to be an evolutionary strategy to ensure healthy reproduction because genetic variability is an advantage for offspring, Maria da Graca Bicalho and her colleagues at the University of Parana in Brazil reported.

"Although it may be tempting to think that humans choose their partners because of their similarities, our research has shown clearly that it is differences that make for successful reproduction, and that the subconscious drive to have healthy children is important when choosing a mate," Bicalho said in a statement.

Scientists said it was not clear what signals attract the body to people who are genetically dissimilar to themselves, but suggested body odor or even face structure could play a role.

Bicalho said the team compared genetic data from 90 married couples with data from 152 randomly generated control couples.

They found the real couples had significantly more dissimilarities in MHC.

"Parents with dissimilar (genetic regions) could provide their offspring with a better chance to ward infections off because their immune system genes are more diverse," they wrote in a summary.

Previous studies have suggested animals may use body odor as a guide to identify possible mates as being genetically similar or dissimilar, she added, but other physical factors may also be involved.

"Other cues such as face symmetry might play a role as well, but they are still in the field of speculation," she said.

人們在選擇伴侶時，更容易被與自己基因差異大的人吸引。巴西一項最新研究表明，人們總是下意識地選擇基因構成和自己相異的人做伴侶。

研究結果表明，與隨機配對的搭檔相比，夫妻二人控制免疫系統的DNA區域中基因差異更大。

巴西巴拉那大學的瑪麗亞達·格拉薩·比卡盧和同事在研究報告中指出，這可能是人類確保生育健康的進化策略，因爲基因的差異性對後代有利。

比卡盧在聲明中稱：“雖然大家更願意相信人們會選擇相似的人做伴侶，但我們的研究明確顯示，存在差異的伴侶更能成功生育後代，而在選擇伴侶時，這種潛在的生育健康後代的意識很重要。”

科學家稱不清楚是何種身體訊息使人們吸引到基因相異的人，但表示體味甚至臉型都可能有關。

比卡盧稱，研究小組將90對夫妻的基因與152對隨機配對的“夫妻”的基因進行了對比。

研究人員發現，真夫妻的主要組織相容性複合體差異更顯著。

研究人員在一份總結中寫道：“基因相異的夫妻所生育的後代更不容易生病，因爲他們的免疫系統更加多樣化。”

比卡盧補充稱，此前研究已證實，動物用體味來識別潛在伴侶的基因與自己的異同，但其它身體特徵可能也起作用。

她說：“其它因素，比如臉型是否對稱都可能與之相關，但還沒有得到證實。”

Vocabulary:

ward off: 避開，擋住