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Darwin May Have Missed Something

aybala50's picture

CharlesDarwin in the Origin of Species explainsthe reasons for sexual behavior to be for the purpose of passing down one’sgenes and increase one’s chances of survival. This does not always seem to bethe case as research shows that there are many sexual behaviors that don’t fitin with Darwin’s theory. Some of these include human sexual behavior and manyof them include animal sexual behavior. If Darwin had known about these sexual behaviorsit is possible that he would have altered his theory to better fit the actualworld. The sexual behaviors that don’t fit Darwin’s theory suggest that Darwinmissed critical information about species on this planet hence his theory onsexual behavior is not completely true. Though Darwin may have been mislead bythe absence of information, his research created so much controversy andinterest that it lead to future research and helped expand science. The humanrace may have never been interested in the origin of species if it weren’t forDarwin’s work.

            WhenDarwin came up with his theory of sexual behavior, he did not consider allkinds of species that existed. He also could not have considered in his theorythose concepts that were not widely recognized at the time, such ashomosexuality. Homosexuality in humans was possibly known, but not openlydiscussed at the time. Also homosexual behavior in animals was not known at thetime. Hence the absence of these topics from Darwin’s work is understandable.

            Homosexualbehavior amongst humans and other species is common but unexplained by Darwin.Over 300 vertebrates practice homosexual behavior. Unlike other species, forexample, humans don’t seem to have an adaptive value for homosexual behavior.Speaking in terms of adaptation, does human homosexuality help in any way?Human homosexual couples have yet to reproduce in the way heterosexual couplesdo. There is no doubt that human homosexual couples can participate in sexualacts just as heterosexual couples, however according to Darwin, as the mainreason for sex is passing on genes, homosexual couples fail.

            Couldhuman homosexuality have evolved for other reasons, social reasons perhaps?Does homosexuality amongst humans increase the chances of survival? Taking intoaccount the history of homosexuality amongst humans, it can safely be concludedthat adapting socially to a normative society across history would not havewarranted homosexuality. Through out history, in general, homosexuality has hadnegative connotations, at least in nations that practice religions that forbidit. Social factors involve religion, depending on the society. If anything itcould be argued that homosexuality amongst humans did not “evolve” for thepurposes of adaptation because that would not make sense, at least in thesenations that forbid such acts.

            Justas homosexual sexual behavior in humans heterosexual sexual behavior in humanalso provides pleasure for the participants. Sex, at this time, is not purely areproductive method, if anything it is done for pleasure rather than creatingoffspring that will carry one’s genes to the next generation. Many heterosexualcouples want to avoid their sexual encounters resulting in offspring. Hencescience has worked hard to invent many different types of birth control. Bothfemale’s and male’s have control over their own reproduction. Women can takebirth control pills, amongst other things, and avoid getting pregnant even ifthe male is not being careful. Male can also use condoms or other surgicalprocedures that will still allow them to have sex but not get the partnerpregnant. If Darwin was correct in his theory of the importance of passing downgenes, then more human’s would reproduce rather than avoiding the passing on ofgenes.

            Inother areas of human social life it is also seen that sexual pleasure is moreimportant than reproduction. In the cases when people resort to using theservices of a prostitute, are they doing so for the reason of passing downtheir genes? If a man hires a prostitute, it is because they want the pleasureof having sex, not because they want to get the prostitute pregnant.Evolutionarily speaking, men look for healthy, younger women to carry theirchildren and though women who are prostitutes may be young, the job they aredoing means that they are having sex with many different males. A man who wantsa woman to have his child would not find this appealing as a candidate thatwould carry his child should be caring for her health, hence her child’s, ratherthan having sex with many men.

            Takinginto consideration the same scenario about human prostitution, if looked atfrom the prostitute’s perspective, Darwin’s theory of finding a mate to createoffspring, still does not seem to fit. Women who resort to prostitution aredoing so not because they want to find the perfect man to impregnate them inorder to have a child, but it’s because of a different reason such as survival.If a woman is selling her body for sex, it is not because she wants a child, butit’s because she is being paid for it. No matter what she is using this moneyfor the reason for this sexual behavior is money, not the want to reproduce.

            Masturbationis a sexual behavior that both male and female humans as well as some animalsparticipate in. Is there an evolutionary purpose for masturbation? The patternresearchers in this area see is that the animals that masturbate tend to have alarger neocortex (Anitei). It has been seen that some baboons masturbate ifthey are not the dominant male. If there is a dominant male that has sex withthe females, the younger males are left with masturbation to release theirsexual drive. Hence it doesn’t seem that masturbation serves a purpose beyondsexual release (Anitei).

            Sexualbehavior amongst species besides humans was widely studied by Darwin. Hestudied many different types of animals in order to observe their sexualbehavior and just as he did with humans, he decided that these animals have sexso that they can pass on their genes. If genes are not passed down specie candisappear. Hence it only seems logical that sexual behavior should be focusedon reproduction.

            Accordingto Darwin’s sexual behavior theory it would makes sense that in general malemembers of a specie will want to mate more than female members of a specie. Themale member of any specie would want to pass on it’s genes and because of thiswould want to mate with as many females as possible. On the contrary, becausefemales would be spending the time carrying the offspring until birth, as wellas caring for the offspring until it is old enough to care for itself, thefemale would want to find a more reliable suitor rather than finding manysuitors. If the female finds a male that is going to protect her and theoffspring it will increase her chances of passing down her genes and survival.However, if a female is of high status herself, then she is mating with a highstatus male. This means that she has no need to mate with a lower status male.In this case a female would want to mate less than the male. However if afemale is mating with a low status male, or she herself is low status, then itwould make sense that she would try to mate additionally with a higher statusmale to better her position as well as the status of her future offspring.

Sarah Hrdy,a primatologist, however showed that female members of the langur monkeys matewith many males without the high consideration of status. According to Hrdy’sresearch, female members of this species try to mate with as many males aspossible to protect their offspring. The female members have outsmarted themale members. The dominant male langur monkey regularly kill babies that arenot their own. Because of this the female members try to procure moreprotection by mating with many males. After giving birth, all the males that aparticular female has mated with keep the offspring safe, as they believe thatthe offspring could be their own. With this example it is seen that femalesdon’t only mate for the purpose of finding a single stable male to stay withher and her offspring. Rather it is possible that a langur monkey does not caretoo much about the relationship, but rather chooses to protect her offspring(Baker et al. 304).

Evidencefor the evolution of sexual behavior is seen amongst female Japanese macaques.Unlike many other species females are more eager to mate rather than the malesamongst these animals. Female members of this species have adapted homosexualbehavior by the way of trying to coerce more males to mate with them. Eagerfemale members of this species will mount unwilling males and try to promptthem to mate with them. While this began as only male-female relations, thisbehavior was easily expanded to include female-female relations. Females thatwere eager to mate with a male member, but failed to do so, turned to otherfemales. Despite these evolutionary origins, this behavior among Japanesemacaques seems to have no adaptive value.

Sexualbehavior amongst a type of chimpanzee, the Bonobos, has many social reasons forit. Female bonobos mature sexually at approximately the age of ten and malebonobos mature sexually slightly sooner. Infants as young as four-months havebeen observed trying to participate in sexual contact with their mothers. Thisalone suggests that Bonobos sexual behavior is not only for reproductivepurposes, but also for social purposes. Less than one third of the sexualcontacts bonobos have are between a male bonobo and a female bonobo. Most ofthe sexual behavior seen in bonobos is being seen in same-sex couples. Some ofthese species’ homosexual behavior has an adaptive quality to it. Bonobos willhave sex with same-sex partners in order to calm tensions after they quarrel.Another reason Bonobos have sex with same-sex partners is to insure that thelarge amount of food that one Bonobo has is shared with the other Bonobos. Someof the other social reasons include: calming an infant, social bonding, and thecreation of a community.

            Phoenicopterusflamingos participate in homosexual behavior as well as the Bonobos. This ismore common amongst colonies with skewed sex ratios. However, other factorssuch as age structure and physiological synchrony may place increasedlimitations on the suitability of available opposite-sex mates. Often in thesespecies homosexual partnerships offer possibilities that are social, ratherthan for the purpose of passing on genes as Darwin would view as the purpose ofsexual behavior. This type of flamingo can gain experience in holding a nestagainst the same species of flamingo, just as regular male-female partnershipsdo. Also, these homosexual partnerships make possible to form alliances inaggressive encounters. As seen with this type of flamingo sexual behavior canbe determined for the purpose of social as well as biological survival (Sommeret al. 103).

            Darwin’stheory would be in support of species trying to spread their seed no matterwhat the consequence. Species try to reproduce so that they can leave somethingbehind that is a part of them. By reproducing they accomplish this, as theirgenes have a higher chance of surviving. In some species such as the waterbuck,however, individual males act as helpers to dominant males in order to gainsome rewards, hence their primary goal is not to pass on their genes, butrather to survive in a stable setting (Bio-Medicine). Male waterbuck aregenerally a quiet, inactive animal. They don’t move around a lot and they tendto settle in an area and stay there. He tries to retain females into his areafor the purpose of mating and this is where the ‘helper males’ come in. Thesubordinate males help the dominant male to protect the area. In turn they mayhave a chance to mate with a female waterbuck or inherit the area when thedominant waterbuck passes (Outofafrica).

            Asevident here Darwin either ignored or missed evidence that exists on thisplanet that contradicts his sexual behavior theory. The main purpose in life isto pass on your genes so that you are not forgotten in this world. We are allhere, both humans and animals, to pass on what we are in order to stay a partof this planet. We all want to survive and since we can’t live forever the nextbest thing is to leave something that is a part of us. Darwin argued that thiswas the reason for sexual behavior. More recent research shows that both humansand other species have sex for reasons well beyond reproduction. Darwin may nothave been wrong, but his theory has grown weaker in some aspects with thepassing of time. He has however proven very useful for the world of science, aswithout his research the research and observations stated above would not havebeen done. Not everyone may agree with Darwin’s work, but it is obvious thathis work has opened a portal for the sole purpose of finding where we all comefrom.

Anitei, Stefan.  Do Animals Masturbate?. 2007. <


Baker, Pamela and Eli Minkoff. Biology: Science and Ethics.





Sommer, Volker and Paul Vasey. Homosexual Behavior in Animals.


Waterbuck. Out ofAfrica. <



Paul Grobstein's picture

Sex, reproduction, and evolution

"We are all here, both humans and animals, to pass on what we are in order to stay a part of this planet. We all want to survive and since we can’t live forever the next best thing is to leave something that is a part of us. Darwin argued that this was the reason for sexual behavior. More recent research shows that both humans and other species have sex for reasons well beyond reproduction."

I'm not sure Darwin in fact had such an explicit story about sexual behavior, but regardless the issue is an important one.  What are the reasons for sex "beyond reproduction"?  Can one connect this with an evolutionary perspective and, if so, how?