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Life history

The different life stages of the macaque, from prenatal development through to adulthood and senescence.

In this section

Prenatal development: 5.5 months

  • Gestation – Gestation lasts approximately 5.5 months in macaques (rhesus: 146 – 180 days; cynomolgus: 153 – 179 days) [1].
  • Maternal health – Maternal health has a profound influence on infant development. Stress and poor health in pregnant females may lead to permanent developmental and behavioural abnormalities in their offspring [2].

Infancy: 0-12 months

  • Birth – Typically a single infant is born, usually at night [2]. Infant weight at birth is 0.4 – 0.55 kg (rhesus) 0.33 – 0.35 kg (cynomolgus) [3,4].
  • 1 hour – Infant begins to suckle.
  • 2 weeks – Mother begins introducing solid foods into the diet [1,5].
  • 4 weeks – Infant weight is ~0.65 kg (rhesus).
  • 6 weeks – Infant is able to move independently and starts to explore away from the mother.
  • 1 to 3.5 months – Milk composition is 4.6% fat, 1.8% protein and 7.6% sugar [6]. Breast milk contains a higher energy density for male infants than for female infants [7].
  • 4 months – Nutritional weaning begins gradually [8].
  • 5 months – Infant weight is ~1 kg [9].
  • An infant rhesus suckling on its mother.
    Infant suckling (Image: Alexander Georgiev)
  • A mother rhesus carries her infant dorsally
    A mother rhesus carries her infant dorsally (Image: Alexander Georgiev)
  • An adolescent rhesus macaque walking from a pebble beach towards female that is keeping eye contact
    Female eye contact on infant (Image: Alexander Georgiev)
  • an infant rhesus plays with a leaf that its mother is holding
    an infant rhesus plays with a leaf that its mother is holding (Image: Alexander Georgiev)
In this video, an adult male rhesus macaque protects a young infant.
In this video, a young infant cries as it approaches its mother in an effort to make contact (Credit: Jade Brooks and David Massey)

Yearlings and juveniles: 12-36 months

  • 12 months – Yearlings weigh ~1.3 kg [3,9].
  • 12-14 months – Nutritional weaning is complete [7] In captivity, nutritional weaning can occur as early as 8 months of age in cynomolgus macaques.
  • Artificial weaning (permanent separation of infants from their mothers) should not occur before 10-14 months of age [11]. Infants separated early from the mother show development abnormalities, including impaired cognition, altered physiology, disrupted endocrine response to stress, behavioural abnormalities and inability to function in a social group [12-16]. These effects can be life-long and impact negatively on the suitability of such animals as research models.
  • 18 months – Juveniles usually remain close to their mother until the birth of a sibling ~1 – <2 years [3,6]. Juveniles develop social skills, through sex-specific patterns of play. Their diet now resembles that of adults. Both cynomolgus and rhesus macaques are omnivorous frugivores, with dietary composition varying greatly with location and season.
  • A mother rhesus macque sitting on a tree log in contact with her newest infant and and weanling
    Female with infant and yearling
In this video, the infant on the left tries to suckle from its mother, but is rejected. (Credit: MRC Centre for Macaques)
In this video, a yearling carries its infant sibling, which cries and is then taken by their mother. (Credit: MRC Centre for Macaques)
In this video, juvenile rhesus macaques are seen playing on the floor (Credit: Jade Brooks and David Massey).

Adolescence and sexual maturity: 3-8 years

  • 3 years – Rhesus macaque females reach sexual maturity [18,19]. Maturity may be reached sooner in captivity [20].
  • 4 years – Rhesus macaque males and cynomolgus macaque females reach sexual maturity [17].
  • 7 years – Cynomolgus macaque males reach sexual maturity; can be earlier in some captive colonies [18,19].
  • Sexual maturity – Increases in sex hormones influence secondary sexual characteristics and behaviour [18,19].
    • Female oestrous cycle is 26-29 days in rhesus macaques [21] and 26-38 days in cynomolgus macaques [20,22]. Accompanied by reddening of the sexual skin on the rump and face. Peak fertility (ovulation) occurs 11-14 days after onset of menstruation in both species regardless of cycle length [23].
    • Males may become more aggressive and begin exploring away from the natal group.
    • Females may reproduce from 3-4 years of age. In the wild males are unlikely to sire young until they reach full adult size [24].

Adulthood

  • ~8 years – Rhesus macaque males reach full body size.
  • Breeding – Rhesus macaques are seasonal breeders, with births in the wild coinciding with the end of the rainy season, or during the period of highest food abundance [25]. Breeding season varies in timing and length between locations and over time (e.g. in the mid-1980s, the rhesus macaque mating season on Cayo Santiago lasted from July to December [26,27]; today the mating season runs from January to June, with variation on a year-to-year basis). Breeding seasonality is less pronounced in cynomolgus macaques and varies across their range [28].
  • Mating – Macaques mate promiscuously [29,30]. The testes of male macaques increase up to twice their normal size during the breeding season [26,31].
  • Birth – Single young are born approximately every 1-2 years [3,19,29,31] from 3 – 20 years of age [18,29], higher-ranked females reproduce more often, from an earlier age, and have higher infant survival rates [34]. Birth usually occurs at night, preceded by behavioural signs, such as touching the vagina, squatting, body shakes, tail wagging and frequent position changing. Labour lasts 1 – 3 hours [35].
  • adult rhesus macaques in copulation, the male displays it’s teeth indicating affiliation
    adult rhesus macaques in copulation
  • A female rhesus carries her baby ventrally. The umbilical cord is still attached.
    A female rhesus carries her baby ventrally. The umbilical cord is still attached (Image: Alexander Georgiev)
  • an adult female rhesus forages with her cheek pouches full
    an adult female rhesus forages with her cheek pouches full
  • adult rhesus macaques in copulation, the male displays it’s teeth indicating affiliation
    Mount

Senescence

  • Old age – Geriatric illnesses are rarely seen in wild populations, but geriatric captive macaques exhibit illnesses such as arthritis, atherosclerosis, cataracts, gum disease, cancer, diabetes and obesity [36-38]. Low ranking macaques are at higher risk of chronic psychosocial stress, leading to more health problems in old age [6,39].
  • It is important that captive enclosures meet the physical needs of geriatric animals, with lower platforms and easy access to food and resting areas. Softer foods should be supplied to geriatric macaques with gum disease and weakened or missing teeth; failure to eat hard foods, or observation of the animal soaking dry foods in water, may indicate teeth or gum problems.
  • <15 years – Median lifespan in the wild; <5% reach 25 years [40].
  • >25 years – Median lifespan in captivity; maximum recorded is 40 years [6,41]. Females >25 years of age go through menopause [42].
At this cynomolgus macaque breeding facility, wooden stairs have been installed to enable geriatric animals to more easily climb up to the shelving platforms. For more information, see Waitt et al. 2010 (Credit: BFC)

References

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  2. Bauman MD et al. (2014). Activation of the maternal immune system during pregnancy alters behavioral development of rhesus monkey offspring. Biological Psychiatry 75(4): 332-41. https://doi.org/10.1016/j.biopsych.2013.06.025

  3. Fooden J (2000). Systematic review of the rhesus macaque, macaca mulatta (zimmermann, 1780) / jack fooden  1 ed. Field Museum of Natural History. https://doi.org/10.5962/bhl.title.7192

  4. Van Schaik CP and Van Noordwijk MA (1988). Scramble and contest in feeding competition among female long-tailed macaques (macaca fascicularis). Behaviour 105(1): 77-98.

  5. Nowak RM (1999). Walker's primates of the world  I and II ed., Vol. 6. John Hopkins University Press.

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  7. Maestripieri D and Hoffman CL (2012). Behavior and social dynamics of rhesus macaques on cayo santiago. In: Bones, genetics, and behavior of rhesus macaques: Macaca mulatta of cayo santiago and beyond ((pp. 247-62). Springer New York. https://doi.org/10.1007/978-1-4614-1046-1_12

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  9. Hinde K (2007). First-time macaque mothers bias milk composition in favor of sons. Current Biology 17(22): R958-R9. https://doi.org/10.1016/j.cub.2007.09.029

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  12. Prescott MJ et al. (2012). Laboratory macaques: When to wean? Applied Animal Behaviour Science 137(3-4): 194-207. https://doi.org/10.1016/j.applanim.2011.11.001

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