Journal Article

Reproductive inequality in humans and other mammals

Authors

  • Ross CT
  • Hooper PL
  • Smith JE
  • Jaeggi AV
  • Smith EA
  • Gavrilets S
  • Zohora FT
  • Ziker J
  • Xygalatas D
  • Wroblewski EE
  • Wood B
  • Winterhalder B
  • Willführ KP
  • Willard AK
  • Walker K
  • von Rueden C
  • Voland E
  • Valeggia C
  • Vaitla B
  • Urlacher S
  • Towner M
  • Sum CY
  • Sugiyama LS
  • Strier KB
  • Starkweather K
  • Major-Smith D
  • Shenk M
  • Sear R
  • Seabright E
  • Schacht R
  • Scelza B
  • Scaggs S
  • Salerno J
  • Revilla-Minaya C
  • Redhead D
  • Pusey A
  • Purzycki BG
  • Power EA
  • Pisor A
  • Pettay J
  • Perry S
  • Page AE
  • Pacheco-Cobos L
  • Oths K
  • Oh SY
  • Nolin D
  • Nettle D
  • Moya C
  • Migliano AB
  • Mertens KJ
  • McNamara RA
  • McElreath R
  • Mattison S
  • Massengill E
  • Marlowe F
  • Madimenos F
  • Macfarlan S
  • Lummaa V
  • Lizarralde R
  • Liu R
  • Liebert MA
  • Lew-Levy S
  • Leslie P
  • Lanning J
  • Kramer K
  • Koster J
  • Kaplan HS
  • Jamsranjav B
  • Hurtado AM
  • Hill K
  • Hewlett B
  • Helle S
  • Headland T
  • Headland J
  • Gurven M
  • Grimalda G
  • Greaves R
  • Golden CD
  • Godoy I
  • Gibson M
  • Mouden CE
  • Dyble M
  • Draper P
  • Downey S
  • DeMarco AL
  • Davis HE
  • Crabtree S
  • Cortez C
  • Colleran H
  • Cohen E
  • Clark G
  • Clark J
  • Caudell MA
  • Carminito CE
  • Bunce J
  • Boyette A
  • Bowles S
  • Blumenfield T
  • Beheim B
  • Beckerman S
  • Atkinson Q
  • Apicella C
  • Alam N
  • Mulder MB.
Publication Date

To address claims of human exceptionalism, we determine where humans fit within the greater mammalian distribution of reproductive inequality. We show that humans exhibit lower reproductive skew (i.e., inequality in the number of surviving offspring) among males and smaller sex differences in reproductive skew than most other mammals, while nevertheless falling within the mammalian range. Additionally, female reproductive skew is higher in polygynous human populations than in polygynous nonhumans mammals on average. This patterning of skew can be attributed in part to the prevalence of monogamy in humans compared to the predominance of polygyny in nonhuman mammals, to the limited degree of polygyny in the human societies that practice it, and to the importance of unequally held rival resources to women’s fitness. The muted reproductive inequality observed in humans appears to be linked to several unusual characteristics of our species—including high levels of cooperation among males, high dependence on unequally held rival resources, complementarities between maternal and paternal investment, as well as social and legal institutions that enforce monogamous norms.

Key Words

  • Reproductive Skew
  • Inequality
  • Egalitarian Syndrome
  • Mating Systems
  • Monogamy