Editing Sexual selection (section)

=== In mammals ===
{{Main|Sexual selection in humans|Sexual selection in mammals}}

Darwin conjectured that [[Heritability|heritable]] traits such as beards, hairlessness, and [[steatopygia]] in different human populations are results of [[sexual selection in humans]].<ref>{{cite book |last=Darwin |first=Charles |author-link=Charles Darwin |title=The Descent of Man and Selection in Relation to Sex |year=1882 |location=London |publisher=John Murray |page=578<!--and much of the book--> |url=http://darwin-online.org.uk/content/frameset?itemID=F955&viewtype=text&pageseq=1}}</ref> Humans are sexually dimorphic; females select males using factors including voice pitch, facial shape, muscularity, and height.<ref>{{cite book |last=Buss |first=David |date=2019 |edition=Sixth |title=Evolutionary Psychology: The New Science of the Mind |chapter=Women's Long-Term Mating Strategies |url=https://books.google.com/books?id=Sn6JDwAAQBAJ |publisher=Routledge |isbn=9780429590061 }}</ref><ref name="Feinberg Jones 2006">{{cite journal |last1=Feinberg |first1=D. R. |last2=Jones |first2=B. C. |last3=Law Smith |first3=M. J. |last4=Moore |first4=F. R. |last5=DeBruine |first5=L. M. |last6=Cornwell |first6=R. E. |last7=Hillier |first7=S. G. |last8=Perrett |first8=D. I. |display-authors=3 |date=1 February 2006 |title=Menstrual cycle, trait estrogen level, and masculinity preferences in the human voice |journal=Hormones and Behavior |volume=49 |issue=2 |pages=215–222 |doi=10.1016/j.yhbeh.2005.07.004 |pmid=16055126 |s2cid=14884832}}</ref>

Among the many instances of sexual selection in mammals is extreme sexual dimorphism, with males as much as six times heavier than females, and male fighting for dominance among [[elephant seal]]s. Dominant males establish large [[Harem (zoology)|harem]]s of several dozen females; unsuccessful males may attempt to copulate with a harem male's females if the dominant male is inattentive. This forces the harem male to defend his territory continuously, not feeding for as much as three months.<ref>{{cite encyclopedia |title=Earless Seals |encyclopedia=Encyclopedia of Marine Mammals |edition=2nd |editor-last=Perrin |editor-first=William F. |editor2-last=Würsig |editor2-first=Bernd |editor3-last=Thewissen |editor3-first=J. G. M. |publisher=Academic Press |location=Burlington, Massachusetts |isbn=978-0-12-373553-9 |url=https://books.google.com/books?id=2rkHQpToi9sC&q=elephant+seal+greatest+sexual+dimorphism&pg=PA23 |page=346 |year=2008 }}</ref><ref name="McCann 1981">{{cite journal |last=McCann |first=T. S. |year=1981 |title=Aggression and sexual activity of male Southern elephant seals, ''Mirounga leonina'' |journal=Journal of Zoology |volume=195 |issue=3 |pages=295–310 |doi=10.1111/j.1469-7998.1981.tb03467.x }}</ref>

Also seen in mammals is sex-role reversal, as in the highly social [[meerkat]]s, where a large female is dominant within a pack, and female–female competition is observed. The dominant female produces most of the offspring; the subordinate females are nonbreeding, providing [[Altruism (biology)|altruistic]] care to the young.<ref>{{cite journal |last1=Clutton-Brock |first1=T. H. |last2=Hodge |first2=S. J. |last3=Spong |first3=G.  |year=2006 |title=Intrasexual competition and sexual selection in cooperative mammals |url=https://scholar.sun.ac.za/handle/10019.1/12319 |journal=Nature |volume=444 |issue=7122 |pages=1065–8 |doi=10.1038/nature05386 |pmid=17183322 |bibcode=2006Natur.444.1065C |s2cid=4397323 }}</ref><ref name=coop>{{cite journal |last1=Clutton-Brock |first1=T. H. |last2=Russell |first2=A. F. |last3=Sharpe |first3=L. L. |title=Behavioural tactics of breeders in cooperative meerkats |journal=Animal Behaviour |date=2004 |volume=68 |issue=5 |pages=1029–1040 |doi=10.1016/j.anbehav.2003.10.024 |s2cid=53175143}}</ref>{{Clear}}