Behavioral Ecology and Sociobiology

, Volume 63, Issue 8, pp 1133–1140 | Cite as

The rarity of twins: a result of an evolutionary battle between mothers and daughters—or do they agree?

  • Gine Roll Skjærvø
  • Bård G. Stokke
  • Eivin Røskaft
Original Paper


The aim of this study was to test the hypothesis that parent–offspring conflict over parental investment might have led to the rarity of dizygotic twins in humans. We explored the theoretical prediction that twins maximize their inclusive fitness by the death of a co-twin, while mothers of twins maximize fitness by raising both twins to independence. We used life history data (1700–1900) from two parishes in Central Norway to compare differences in inclusive fitness (measured as number of children reared to the age of 16 years, using Hamilton's rule) between twins and mothers of twins. Our results show that twins maximize their inclusive fitness by the death of a co-twin, while mothers of twins raise more children by rearing both twins to adulthood. However, because twins growing up as singletons may produce higher or at least equal number of offspring than the sum of the two twins growing up together, mothers might gain more grandchildren by allowing twins to grow up as singletons. To conclude, both selfish twins and their mothers might benefit by the death of a co-twin, indicating that there is no parent–offspring conflict responsible for the rareness of twins in these human populations. Finally, we discuss the results in the light of “The Insurance Egg Hypothesis” and “The Natural Selection Hypothesis”.


Parent–offspring conflict Twins Lifetime reproductive success Evolutionary ecology Humans 


  1. Anderson DJ (1990a) Evolution of obligate siblicide in boobies. 2. Food limitation and parent offspring conflict. Evolution 44:2069–2082CrossRefGoogle Scholar
  2. Anderson DJ (1990b) On the evolution of human brood size. Evolution 44:438–440CrossRefGoogle Scholar
  3. Ball HL, Hill CM (1996) Reevaluating “twin infanticide”. Curr Anthropol 37:856–863CrossRefGoogle Scholar
  4. Barash DP, Lipton JE (1997) Making sense of sex. Island, Washington DCGoogle Scholar
  5. Berg GF (1981) Smøla bygdebok, vol 1–4. Rune Forlag, Trondheim, NorwayGoogle Scholar
  6. Bongard T (2005) Life history strategies, mate choice, and parental investment among Norwegians over a 300-year period. PhD. Norwegian University of Science and Technology, Trondheim, NorwayGoogle Scholar
  7. Clutton-Brock TH (1991) The evolution of parental care. Princeton University Press, PrincetonGoogle Scholar
  8. Daly M, Wilson M (1980) A sociobiological analysis of human infanticide. Aldine, New YorkGoogle Scholar
  9. Fisher RA (1930) The genetical theory of natural selection. Clarendon Press, OxfordGoogle Scholar
  10. Forbes LS (1997) The evolutionary biology of spontaneous abortion in humans. Trends Ecol Evol 12:446–450CrossRefGoogle Scholar
  11. Forbes LS (2005) A natural history of families. Princeton University Press, PrincetonGoogle Scholar
  12. Frank LG, Glickman SE, Licht P (1991) Fatal sibling aggression, precocial development, and androgens in neonatal spotted hyenas. Science 252:702–704PubMedCrossRefGoogle Scholar
  13. Fraser D, Thompson BK (1991) Armed sibling rivalry among suckling piglets. Behav Ecol Sociobiol 29:9–15CrossRefGoogle Scholar
  14. Gabler S, Voland E (1994) Fitness of twinning. Human Biol 66:699–713PubMedGoogle Scholar
  15. Glinianaia SV, Skjaerven R, Magnus P (2000) Birthweight percentiles by gestational age in multiple births—a population-based study of Norwegian twins and triplets. Acta Obstet Gynecol Scand 79:450–458PubMedCrossRefGoogle Scholar
  16. Godfray HCJ, Partridge L, Harvey PH (1991) Clutch size. Annu Rev Ecol Evol Syst 22:409–429Google Scholar
  17. Golla W, Hofer H, East M (1998) Within-litter sibling aggression in spotted hyenas: effect on maternal nursing, sex and age. Anim Behav 58:715–726CrossRefGoogle Scholar
  18. Granzberg G (1973) Twin infanticide: a cross cultural test of a materialistic explanation. Ethos 1:405–412CrossRefGoogle Scholar
  19. Gregory KE, Echternkamp SE, Cundiff LV (1996) Effects of twinning on dystocia, calf survival, calf growth, carcass traits, and cow productivity. J Anim Sci 74:1223–1233PubMedGoogle Scholar
  20. Gurven M, Walker R (2006) Energetic demand of multiple dependents and the evolution of slow human growth. Proc Biol Sci 273:835–841PubMedCrossRefGoogle Scholar
  21. Gustafsson L, Sutherland WJ (1988) The costs of reproduction in the collared flycatcher Ficedula albicollis. Nature 335:813–815CrossRefGoogle Scholar
  22. Haig D (1993) Genetic conflicts in human pregnancy. Quart Rev Biol 68:495–532PubMedCrossRefGoogle Scholar
  23. Haig D (2000) The kinship theory of genomic imprinting. Annu Rev Ecol Evol Syst 31:9–32CrossRefGoogle Scholar
  24. Hamilton WD (1964) Genetical evolution of social behaviour I. J Theor Biol 7:1–52PubMedCrossRefGoogle Scholar
  25. Haukdal J (1971) Busetnad og Folkeliv i Soknedal. Gard og grend., vol 1–4. Midre Gauldal Forlag, Støren, NorwayGoogle Scholar
  26. Haukioja E, Lemmetyinen R, Pikkola M (1989) Why are twins so rare in Homo sapiens. Am Nat 133:572–577CrossRefGoogle Scholar
  27. Helle S, Lummaa V, Jokela J (2004) Selection for increased brood size in historical human populations. Evolution 58:430–436PubMedGoogle Scholar
  28. Hoekstra C, Zhao ZZ, Lambalk CB, Willemsen G, Martin NG, Boomsma DI, Montgomery GW (2008) Dizygotic twinning. Hum Reprod Updat 14:37–47CrossRefGoogle Scholar
  29. Koskela E (1998) Offspring growth, survival and reproductive success in the bank vole: a litter size manipulation experiment. Oecologia 115:379–384CrossRefGoogle Scholar
  30. Lack D (1947) The significance of clutch-size. Ibis 89:302–352CrossRefGoogle Scholar
  31. Landy HJ, Keith LG (1998) The vanishing twin: a review. Hum repr update 4:177–183CrossRefGoogle Scholar
  32. Lazarus J, Inglis IR (1986) Shared and unshared parental investment, parent offspring conflict and brood size. Anim Behav 34:1791–1804CrossRefGoogle Scholar
  33. Lessells CM (1986) Brood Size in Canada geese: a manipulation experiment. J Anim Ecol 55:669–689CrossRefGoogle Scholar
  34. Low BS, Clarke AL (1992) Resources and the life course: patterns through the demographic transition. Ethol Sociobiol 13:463–494CrossRefGoogle Scholar
  35. Lummaa V (2001) Reproductive investment in pre-industrial humans: the consequences of offspring number, gender and survival. Proc Biol Sci 268:1977–1983PubMedCrossRefGoogle Scholar
  36. Lummaa V, Haukioja E, Lemmetyinen R, Pikkola M (1998) Natural selection on human twinning. Nature 394:533–534PubMedCrossRefGoogle Scholar
  37. Lummaa V, Jokela J, Haukioja E (2001) Gender difference in benefits of twinning in pre-industrial humans: boys did not pay. J Anim Ecol 70:739–746CrossRefGoogle Scholar
  38. Lummaa V, Pettay J, Russel A (2007) Male twins reduce fitness of female co-twins in humans. PNAS 104:10916–10920CrossRefGoogle Scholar
  39. Mock DW, Forbes LS (1992) Parent offspring conflict: A case of arrested development. Trends Ecol Evol 7:409–413CrossRefGoogle Scholar
  40. Mock DW, Parker GA (1997) The evolution of sibling rivalry. Oxford University Press, Oxford, EnglandGoogle Scholar
  41. Moilanen I (1987) Dominance and submissiveness between twins. 1. Perinatal and developmental aspects. Acta Genet Med Gemellol 36:249–255PubMedGoogle Scholar
  42. O’Connor RJ (1978) Brood reduction in birds: selection for fratricide, infanticide and suicide? Anim Behav 26:79–96CrossRefGoogle Scholar
  43. O’Gara BW (1969) Unique aspects of reproduction in female pronghorn (Antilocapra americana Ord). Am J Anat 125:217–232PubMedCrossRefGoogle Scholar
  44. Orlebeke JF, Vanbaal GCM, Boomsma DI, Neeleman D (1993) Birth-weight in opposite sex twins as compared to same-sex dizygotic twins. Eur J Obstet Gynecol Reprod Biol 50:95–98PubMedCrossRefGoogle Scholar
  45. Parker GA, Macnair MR (1979) Models of parent–offspring conflict: 4 suppression–evolutionary retaliation by the parent. Anim Behav 27:1210–1235CrossRefGoogle Scholar
  46. Parker GA, Royle NJ, Hartley IR (2002) Intrafamilial conflict and parental investment: a synthesis. Philos Trans R Soc Lond B Biol Sci 357:295–307PubMedCrossRefGoogle Scholar
  47. Røskaft E, Espmark Y, Järvi T (1983) Reproductive effort and breeding success in relation to age by the rook Corvus frugilegus. Ornis Scand 14:169–174CrossRefGoogle Scholar
  48. Røskaft E, Wara A, Viken A (1992) Reproductive success in relation to resource- access and parental age in a small Norwegian farming parish during the period 1700–1900. Ethol Sociobiol 13:443–461CrossRefGoogle Scholar
  49. Royle NJ, Hartley IR, Parker GA (2004) Parental investment and family dynamics: interactions between theory and empirical tests. Popul Ecol 46:231–241CrossRefGoogle Scholar
  50. Sear R, Shanley D, McGregor IA, Mace R (2001) The fitness of twin mothers: evidence from rural Gambia. J Evol Biol 14:433–443CrossRefGoogle Scholar
  51. Stearns SC (1992) The evolution of life histories. Oxford University Press, Oxford, EnglandGoogle Scholar
  52. Stein Z, Stein W, Susser M (1986) Attrition of trisomies as a maternal screening device - an explanation of the association of trisomy-21 with maternal age Lancet 1:944–947Google Scholar
  53. Taylor GM, Owen P, Mires GJ (1998) Foetal growth velocities in twin pregnancies. Twin Res 1:9–14PubMedCrossRefGoogle Scholar
  54. Trivers RL (1972) Parental investment and sexual selection. Aldine, ChicagoGoogle Scholar
  55. Trivers RL (1974) Parent–offspring conflict. Am Zool 14:249–264Google Scholar
  56. Vander Werf E (1992) Lack clutch size hypothesis: an examination of the evidence using metaanalysis. Ecology 73:1699–1705CrossRefGoogle Scholar
  57. Williams GC (1966) Natural selection costs of reproduction and a refinement of Lacks principle. Am Nat 100:687–689CrossRefGoogle Scholar
  58. Wyshak G, White C (1969) Fertility of twins and parents of twins. Hum Biol 41:66–82PubMedGoogle Scholar
  59. Ydenberg RC, Bertram DF (1989) Lack clutch size hypothesis and brood enlargement studies on colonial seabirds. Colonial Waterbirds 12:134–137CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Gine Roll Skjærvø
    • 1
  • Bård G. Stokke
    • 1
  • Eivin Røskaft
    • 1
  1. 1.Department of BiologyNorwegian University of Science and TechnologyTrondheimNorway

Personalised recommendations