狨猴（Marmoset），又称指猴，是生活在在南美洲亚马逊河流域的森林中的一种世界上最小的猴子。这种猴长大后身高仅10—12厘米，重80—100克。新生猴只有蚕豆般大小，重13克。这种猴子喜欢捉虱子吃，且性格温和，因此饲养它们便成了当地印第安人的嗜好。

Marmosets are small primates. Think of a monkey with huge fuzzy ears. Primatologists have often wondered whether nonhuman males evaluated their potential mates, or whether their sex drive was more like an on/off switch.

We may think of animals as just responding to sexual invitations without thinking, but a study conducted in both the U.S. and Germany shows this isn’t necessarily so. Male marmosets having their brains scanned were given sniffs of genital-gland secretions from ovulating females.

That’s a scent that should trigger a mating response in the brain, and it did! But guess what else happened? Many other brain areas lit up as well, such as memory formation, information integration–in other words, areas associated with decision-making.

Researchers are still studying the effect, but apparently a lot more happens in a marmoset brain than a simple “have sex now” program. The specific areas of brain activity suggest that the males are evaluating potential mates before agreeing to a sexual union.

This makes special sense for marmosets, because they are monogamous and both partners raise the offspring. Under those circumstances you wouldn’t want to enter into a relationship without any thought.

绒猴是很小的灵长类。试想一下，猴子长者一对大大的毛绒绒的耳朵。动物学家时常有这样的疑惑：雄性动物选择“另一半”或者控制性欲是否更像是一个开关键。

我们也许会认为动物对于性邀请基本是不假思索的，但最近美国和德国有研究称事实并非如此。雄性绒猴用它们的大脑扫描，闻正在排卵的磁性动物生殖腺的分泌物。

有一种气味会引起大脑里的交配反应，这样它们才会进行交配。但你猜还会发生什么情况？很多其它的大脑叶都会被“激活”，像信息形成，信息整合，也就是说，所有和决策相关的区域。

研究人员还在观察其影响，但很显然，绒猴的脑部有很多活动而不是一个简单的“性行为”指定。特定区域的大脑活动暗示雄性绒猴
在性结合之前会评估潜在的交配对象。

这对于绒猴有特殊的意义，因为它们是单配制，并且共同抚养后代。在这种情况下，就不会不假思索地介入这段关系了。