October 13, 2021

Menopause in Toothed Whales

The only other group of animals that experiences menopause to the extent that humans do is the toothed whale. Short-finned pilot whale and ecotype resident killer whale females can live to the age of ninety; however, they lose their ability to reproduce at approximately the mid-point of their lives in much the same way that humans do. For killer whale females, 95% of their own lifetime fecundity has been accomplished by the time they are
First-time moms may be more likely to allonurse newborns that don’t belong to them because they lack the experience and knowledge of multiparous or older moms. This situation is described by the misdirected care hypothesis, and it’s seen in both monotocous and polytocous species. In polytocous species living in groups, the costs of making an allonursing mistake are not exceedingly high. When there are many newborns to contend with at any given time, there is
Gelada baboon mothers have been observed to carry their deceased infants for extremely varied amounts of time – less than an hour to over forty-eight days. Photo via Adobe Stock The mother who carried her infant for the longest period continued to do so long after most of the flesh had rotted away from its skull. As with chimpanzee mothers, geladas continue the grooming process with their infants, and other group members show marked interest
Some newborns can take milk from moms other than their own. In these cases, it’s important to discern whether the mom has a hand in mistakenly identifying an allosuckling pup for her own pup, or whether it’s a case of milk-stealing – a behaviour of the pup that is outside of the awareness of the allonursing mom. Many mammalian newborns are much more capable than human newborns. They know whether they are being adequately fed
Multiple cases of primate mothers carrying and providing care to deceased infants have been observed. From chimpanzees and geladas to spider, squirrel, Japanese, and snub-nosed monkeys, mothers of diverse species have been known to carry and care for deceased young. Photo via Adobe Stock There have been several hypotheses proposed as to the existence of postmortem maternal care. Postparturient Condition Hypothesis The postparturient condition hypothesis states that the circulating hormones in mom’s postbirth body influence
Adult male killer whales are the world’s biggest mama’s boys. Literally. Matriarchs strongly protect their adult sons, keep them free from agonistic interactions with other groups or individuals, and make sure that they get enough food. Photo via Adobe Stock Although they also provide help to their adult daughters as well, the vast majority of killer whale effort goes to their sons. Maternal food-sharing with their daughters declines when the daughters reach sexual maturity and
Primates are the most well-observed group of animals when it comes to the topic of a mother’s reaction to offspring death. Cases of continued postmortem maternal care have been observed across several species of monkeys and apes, and many show similar patterns. Essentially, when an infant is newly deceased, mothers go through a phase of continued care, as though the infant is perfectly fine. Over time, the lack of response of the body, in addition

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