Here is a scientific Valentine's Day story! 😊
"While many animals take a pretty casual approach to sex, some species prefer to settle down with a single partner. Scientists who study the neurobiological basis of monogamy have taken a particular interest in California mice, which form lasting pair bonds with their mates, co-parent, and defend territory together. But what makes these rodents want to get hitched? According to new research, it may all come down to sex—and timing.
In a recent experiment, scientists tested how committed male and female mice were to one another after cohabitating for one, three, five, or seven days. Relationships can move pretty fast in the rodent world, because when a female mouse was in the most fertile, sexually receptive phase of her estrous cycle, the researchers saw evidence of partner preference after just 24 hours. Pairs that mated prior to being tested seemed particularly lovey-dovey: These animals visited their partner’s chambers more frequently and spent more time huddling, licking, and grooming than those that remained celibate.
Overall, while having sex on the first date may not be a requirement for the formation of lasting pair bonds, these findings suggest that being in the mood for love can play an important role—at least in rodents."
From the abstract:
"Pair bonds are a hallmark of many monogamous species, yet in the monogamous California mouse (Peromyscus californicus) pair-bond formation is poorly understood.
While pair bonds are often assumed to be present after a week of cohabitation, when they actually form in this species is debated.
To characterize pair bond latency in California mice, we conducted three-chamber partner preference tests for both males and females following 1, 3, 5, or 7 days of cohabitation. Since copulation may contribute to pair-bond formation, animals were paired when females were in estrus and were assessed continuously throughout the cohabitation period for copulatory behavior.
We found evidence of pair bonds after 24 h of cohabitation for both sexes with no significant changes in partner preference behaviors across cohabitation periods. Focal animals spent more time in the partner's chamber, were more affiliative toward the partner than the stranger and displayed more aggressive behavior toward the stranger.
Affiliative behaviors were consistent between the sexes, while males attacked the stranger more frequently and for longer durations than females.
Pairs that copulated prior to partner-preference testing spent more time in the partner's chamber and more time huddling, licking, and grooming their mate than those that did not copulate.
We conclude that although copulation may not be necessary for pair-bond formation, sexual receptivity at time of pairing is important for the development of these social relationships and that copulation may serve to enhance pair bonds in California mice."
ScienceAdviser
Fig. 2 Schematic of experimental timeline.
(A) Pair creation and cohabitation assignment. Females were lavaged, and, if confirmed to be in estrus, were paired with an unrelated male. The pair was placed in an observation cage and randomly assigned to cohabitate for a given period.
(B) Testing day immediately following cohabitation period.
