In the lab, female rodents sometimes terminate their pregnancies after being exposed to new males. It’s called the Bruce effect, for researcher Hilda Bruce. Now a study in the journal Science finds that the Bruce effect occurs in the wild, and likely ups evolutionary fitness.
在實驗室條件下,有時雌性嚙齒類動物會在更換配偶后選擇中止妊娠。這種現象首先被希爾達•布魯斯所發現,因此被稱為布魯斯效應。如今,刊登在《科學》雜志上的一項研究顯示,布魯斯效應同樣存在于野生動物界,而且這更像是為了滿足進化適應性之所需。
To discover whether the Bruce effect is a naturally occurring adaptive strategy, researchers from the University of Michigan observed a wild population of gelada monkeys. They measured hormones in the animals’ feces to identify pregnant females and their conception dates.
為了調查布魯斯效應是否是一種自然發生的適應策略,密歇根大學的研究人員對野生狒狒進行了觀察。他們測量了狒狒糞便中的激素含量,以確定其是否懷孕以及其受孕日期。

Gelada monkeys live in small groups, with several females and a single male. When a rival displaces the male in a gelada family, he frequently kills his predecessor’s progeny. And the females know it. The researchers found that females impregnated by the old male terminate 80 percent of their pregnancies after the new male takes over.
一個狒狒家族往往很小,其中只有一個雄性狒狒和數個雌性狒狒。當競爭者取代了某一雄性狒狒在該家族中的地位時,它會頻繁地殺死前任的后代。雌性狒狒知道這一點。研究人員發現,在被新的雄性狒狒掌握之后,80%的雌性狒狒會墮掉其和前任丈夫所懷有的胎兒。
Those females were quicker to conceive again with the new male than were females who hadn’t been pregnant. Rather than producing offspring at risk of death, females subject to the Bruce effect invest in new progeny—with a better chance of survival.
這些雌性狒狒與新丈夫再次受孕的速度要比沒有懷孕過的的雌性狒狒的受孕速度更快。這些雌性狒狒產崽時不會遭受死亡威脅。相反,布魯斯效應顯示,它們可以將精力放在新的胎兒身上——這其實是一種更佳的生存之道。