What animals, along with humans, experience menopause and menstruation?

Research suggests that female humans are not the only species that menopause and menstruation arises in. All iteroparous organisms menstruate, however only a handful overtly menstruate (blood flows from the uterus through the vagina) while others menstruate covertly (by reabsorbing the uterine lining into the body). Overt menstruating females are generally sexually active throughout their cycle, whilst covert menstruating females are only ‘in heat’ mid-cycle (Wallen & Zehr, 2004).

Figure 1. Chimpanzee (Pan troglodytes). C.Bromhall (2015)

Overt menstruation occurs in humans, most primates (including chimpanzees, orang-utans, gorillas and rhesus monkeys etc.), some species of fruit bats, and elephant shrews. Menstrual bleeding in non-human primates is minimal. However, orang-utans and opossums have an average cycle length of 28 days which is closest to that of humans, while chimpanzees have an average cycle length of 35 days (Lacreuse et al., 208). Covert menstruation occurs in all placental mammals (including cats, dogs, rats, horses, pigs and elephants etc.)

 

Figure 2. Placental Mammals and Marsupial Mammals. Anon. (2015).

Most other egg-laying mammals (including some reptiles, some amphibians, some fish and most birds, excluding macaques; Brenner et al. 2012) do not menstruate. It is interesting to note that humans actually reabsorb about two-thirds of the uterus lining in each cycle (covert menstruation). Therefore only one-third of the human uterus lining is overtly menstruated (Lacreuse et al., 208), while the other two-thirds is covertly menstruated. 

It is found that a vast majority of animals do actually menstruate, whether it is overtly or covertly mensuration, only a few species actually experience menopause. The species that do experience menopause (apart from humans) include the killer whales and (short-finned) pilot whales (Johnstone et al. 2010; Peccei, 2001; Flinn, 2013).

So why does menopause only occur in these three species?

References:

Anonymous. (2015). Convergent Evolution Marsupials and Placental Mammals. http://becuo.com/convergent-evolution-marsupials-and-placental-mammals; Retrieved 27/03/2015.

Bromhall, C. (2015). Chimpanzee (Pan troglodytes). http://www.arkive.org/chimpanzee/pan-troglodytes/image-G4540.html; Retrieved 27/03/2015.

Brenner, R.M., & Slayden, O.D. (2012). Molecular and functional aspects of menstruation in the macaque. 10.1007/s11154-012-9225-5.

Flinn, M.V. (2013). Are humans the only species that go through menopause? http://www.researchgate.net/post/Are_humans_the_only_species_that_go_through_menopause; Retrieved 27/03/2015.

Johnstone, R.A., & Cant, M.A. (2010). The evolution of menopause in cetaceans and humans: the role of demography, 277(1701):3765-3771. Doi: 10.1098/rspb.2010.0988.

Lacreuse, A., Chennareddi, L., Gould, K.G., Hawkes, K., Wijayawardana, S.R., Chen, J., Easley, K.A., Herndon, J.G. (2008). Menstrual Cycles Continue into Advance Old Age in the common Chimpanzee (Pan troglodytes). 79(3): 407- 412. Doi:10.1095/biolreprod.108.068494.

Peccei, J.S. (2001). Menopause: Adaptation or Epiphenomenon. Evolutionary Anthropology, 10:43-57.

Wallen, K. & Zehr, J.L. (2004). Hormones and History: The evolution and Development of Primate Female Sexuality. 41(1): 101-112. Doi:10.1080/00224490409552218.