双语阅读：如何获得积极向上的天性

导语:如何获得积极向上的天性呢?

在这个世界上，对于一些乐观的人来说，玻璃杯里的水似乎总是半满。对于另外一些悲观的人来说，玻璃杯里的水总是半空。乐观者是如何获得积极向上的天性的呢?这是个很有趣的问题。

For some people in this world， the glass always seems to be half-full. For others it is half-empty. But how someone comes to have a sunny disposition in the first place is an interesting question.

It has been known for a long time that optimists see the world selectively， mentally processing positive things while ignoring negative ones， and that this outlook helps determine their health and well-being. In recent years， it has also become clear that carriers of a particular version of a particular gene are at higher risk than others of depression and attempted suicide when they face traumatic events. The gene in question lies in a region of the genome that promotes the activity of a second gene， which encodes a protein called the serotonin transporter.

Serotonin is a messenger molecule that carries signals between nerve cells， and it is known to modulate many aspects of human behaviour， although the details are complex and controversial. The transporter protein recycles serotonin back into the cell that produced it， making it available for reuse， but also reducing the amount in the junctions between cells and thus， it is presumed， the strength of the signal.

It has looked increasingly likely， therefore， that genes—particularly those connected with serotonin—have a role to play in shaping a person’s outlook. So Elaine Fox and her colleagues at the University of Essex， in Britain， wondered whether genes play a part in the selective attention to positive or negative material， with consequent effects on outlook.