“”Every sex is a threesome for those who believe their god is everywhere.
|We're so glad you came|
|Reach around the subject|
Sex can refer to a number of things:
- The number 6 in Latin (and in Swedish!)
- Biological sex:
- In the reproductive context of anisogamous organisms, their gametes are defined as "male" when the gamete is relatively smaller (a.k.a. sperm), and a gamete is defined as "female" when when the gamete is relatively larger (a.k.a. eggs). An organism is then itself classified as male or female based on what kind(s) of gametes it produces. This is because a biological classification should work for as much life as possible, and not just humans/mammals.[Note 1] Hermaphroditic organisms can produce both eggs and sperm, and may be classified as being both sexes, or as just one sex depending on the reproductive role the organism takes on during mating. Note that this definition of sex does not necessitate "male" or "female" as mutually exclusive binary oppositions.
- Alternatively, isogamous organisms have gametes that are of similar size and shape, and thus a classification of “female” or “male” cannot be made based on size. In this case, biologists avoid the terms “male” and “female”, and instead assign one strain as “+” and the other as “-”. Most single-cell eukaryotes are isogamous. Among multicellular organisms, isogamy is found only in fungi and algae.
- The action of identifying the biological sex of an (usually newborn) organism (sexing chickens but not having sex with chickens).
- Sexual intercourse: Interpersonal activities involving the reproductive organs. Check out our separate article on this subject to learn more!
- Sexual reproduction: When two different critters of approximately the same species each contribute roughly half of their genetic information in the form of gametes, which are then combined to be the genetic information of their offspring, in an embryo or seed of some sort. Closely related species, such as horses and donkeys, are capable of interbreeding, although the offspring are generally sterile. Asexual reproduction is basically cloning. Sexual reproduction, although a simple biological concept, is swaddled in fear and loathing by many odd subsets of the human race.
“”We do not even in the least know the final cause of sexuality; why new beings should be produced by the union of the two sexual elements... The whole subject is as yet hidden in darkness.
|—Charles Darwin, 1862|
The evolution of sexual reproduction was a mystery to scientists ever since Darwin mentioned the mysteries and problems of it in 1862. However, since that time, advances in genetics have shone light on how, and perhaps why, the evolution of reproduction occurred. Firstly, although sexual reproduction is a lottery, a shuffled genetic deck maximizes the chances of offspring surviving long enough to reproduce themselves. If children in a litter were all genetically identical clones of their (single) parent, if a virus gets one, it gets them all. Viruses typically look for stretches of DNA with a specific sequence. If that sequence happens to cross a recombination boundary in a sexually-reproducing species, it will be harder for the virus to latch onto. Secondly, sexually reproducing organisms evolve faster, being able to create more variations based on sexual recombination of genes. This has been indicated with microorganisms, where those capable of sexual reproduction adapted more effectively and at a faster rate than asexual organisms. Thirdly, asexual reproduction is at a disadvantage, because any beneficial mutation can only be passed on through direct descendants. With sexual reproduction, the beneficial mutations have a greater ability to spread and the potential to combine with other, complementary mutations.
The very first sexual reproduction is considered to have occurred around 2 billion years ago, sparking an increase in biodiversity. It is thought that in the first form, sexual reproduction was "optional", a way of reproducing when the organism was experiencing harsh conditions. This is seen today in many species of yeast. Due to the advantages of sexual reproduction described above, sexual reproduction eventually took over asexual reproduction in many species, resulting in the mandatory — and extremely entertaining — activity that we know today.
|“||-Can someone tell me who first suggested the idea of reproduction without sex?
-Um, your wife?
—David Lightman (Matthew Broderick), in WarGames
The opposite of sexual reproduction is asexual reproduction, which is reproduction without recourse to sexual intercourse.
For many monocellular and even small multicellular organisms, it effectively amounts to self-cloning. The creature grows, copies its DNA into two, and splits into two organisms. Each has the same DNA (discounting copy errors, etc.) and is thus effectively the same organism.
Parthenogenesis is the production of offspring by the female of the species without fertilization of the ovum. Some insects and, rarely, reptiles or amphibians have been known to use this method of reproduction.
Sex vs gender
Usually, a person's biological sex is congruent with their gender. However, unlike biological sex, gender refers to an individual's self-conception and self-presentation. A person assigned male at birth may feel more comfortable being a woman, or someone assigned female may feel more comfortable as a man, and presenting themselves as such to society. Other individuals may not want to identify with any gender at all, or some may prefer adopting a non-binary gender. These sorts of identities and presentations, however, is often forcibly suppressed in some countries (socially and/or legally). Many transgender people also take physical steps to align their physical body/sex with their gender, such as Hormone Replacement Therapy (HRT), Top/Chest Surgeries, Genital Reconstructive Surgery (GRS), and many more. For example, a transgender woman would identify as female, socially present as female, and in most cases, take HRT in the forms of estradiol & testosterone blockers. It is worth noting that one's sex cannot be entirely changed (notably at a chromosomal level), but various and numerous sexually dimorphic phenotypic traits can be modified and contest the individual's previous overall phenotypic sex classification.
Increasingly, some educators in biological science have been pushing for the use of gender-inclusive language in the science curriculum as to maintain standards of scientific accuracy with what is denoted but by minimizing if not outright removing gendered connotations. This is done by referring to organs, genetic traits, and functional roles directly rather than using terms like male/female. This is demonstrated with stating things like "XY individuals are more likely to be color blind" over "males are more likely to be color blind"; or alternatively, "ovaries most commonly produce eggs" instead of "females most commonly produce eggs".  This is all in the hopes of maintaing scientific accuracy and promoting scientific literacy but by doing so in a way that is not invalidating or alienating to LGBT+ students. 
Etymology of the less polite form
The Internet being what it is, occasionally an email will circulate telling a fanciful tale about how the "f" word came into existence. Supposedly it was an acronym for Fornication Under Consent of King. This of course is false from beginning to end. Words deriving from acronyms is a very modern phenomenon, unknown before the 20th century, there is no record of such an "F.U.C.K." pass being issued by any government, and the word has a long history derived from our fellow Germanic languages. So the next time you see this email in your inbox, you may reply to the sender and suggest they fornicate off (with or without consent of king).
- Roughgarden, J. (2004). Evolution's rainbow: Diversity, gender, and sexuality in nature and people. Berkeley: University of California Press
- "On the two forms, or dimorphic condition, in the species of Primula, and on their remarkable sexual relations", Journal of the Proceedings of the Linnean Society of London (Botany) 6: 77-96.
- Zimmer, Carl (5 June 2009). "On the Origin of Sexual Reproduction". Science 324 (5932): 1254-1256.
- As an example, male seahorses carry their larva and give "birth" of a sort, with the female sex depositing eggs into the male. So, we cannot consider which sex carries their fertilized developing offspring when classifying male/female organisms.