The Primary Mechanisms for Sex Determination Across the Animal Kingdom

Gender being ‘biologically determined’ means that whether gender is inherited or passed down by genetics. If a person is a man or woman, (which is usually called ‘The Sex’), that is biologically determined because they inherit the chromosomes to be born a man, or to be born as a woman. In the early 1970’s sex was described by “biology as: anatomy, hormones, and physiology” (West and Zimmerman 1987). Apart from gender being a biological factor, there are other things which are not biologically determined; “Gender was an achieved status, which was constructed through psychological, cultural and social means” (West and Zimmerman1987). Hence the answer

Biological sex is determined by chromosomes in your genes. At prenatal development, only a few weeks after conception, there is no notable difference between male and female structure until the Gonadal Ridges, the structure which develops either female or male sex organs, grows to determine the sex of the baby. All prenatal babies have genitalia that appears distinctly feminine until at three months, hormones- testosterone if the baby’s to be a boy, and oestrogen if the baby’s to be a girl- is released and the baby develops into the hormone determined gender. For these reasons it is believed that there is a direct link between chromosomes and sex, and therefore sex and

During the evolutionary adaptation time period, between 10-40 thousand years ago, our ancestors were hunter-gatherers. This created a division between men and women. The men would hunt for food and the women would be in charge of the domestic duties such as cleaning and cooking. Doing the domestic chores would have kept women more protected, as it is less strenuous and would have guarded the camp whilst the men were out hunting therefore increasing the chances of reproductive success. This division of labour would have made them less likely to sustain injuries and so the evolutionary approach would suggest that the groups who divided the labour were been more likely to

Judson contributes to onefs understanding of sex among different organisms in that she makes difficult concepts simple to comprehend. Although she uses scientific terminology, she limits it so that anyone can understand the technical information she shares. Judson also describes the types of environments in which each species and

In this chapter, Stephen Law starts out with talking about the selection of sex. Selection of sex is already possible through IVF (In vitro fertilization), and it can be very helpful

Throughout decades, sexual selection has been acknowledged in the explanation of evolutionary patterns. With research, we have had the opportunity to study species of animals like the Syngnathidae family. Animals that are included in this category include pipefish, seahorses, and sea dragons. This species is known for their sex role reversal, meaning that the male fertilizes and carries the eggs during incubation after the female has laid them. When we look more specifically at the pipefish, it is found that males are left with most of the parenting and care for the offspring. As the male carries its eggs, it supplies them with nutrients and oxygen through the placenta. During pipefish copulation, the female transfers her eggs through a small

The formation of gender identity is not completely understood as it is much more complex than just getting a sperm and egg cell to join; an XX or an XY genotype is only the first part in gender identity. There are many biological, psychological and sociological factors involved. The biological includes chromosomes, gonads, prenatal hormones, internal accessory organs, external genital appearance. The psychological includes assigned gender role and gender identity. The sociological could come from family, mass media and society (Kenyon, PhD, 2006). Sammons (2007) states that biological psychology

Viviparity (live birth) is a highly uncommon form of reproduction in the insect world, those that do have this type of reproduction fall into two main groups: those who have a high offspring rates and those who have low offspring rates. Viviparity, while uncommon, does serve a distinct purpose. In some cases the insect has very few ovarioles to begin with, in which case, it is essential for the offspring to be given the best chances at survival they can get. Having the embryo safely protected inside the insect while it develops gives the young insect a far better survival rate than those who are deposited in eggs outside the mother. In other cases, such as with Aphids, it allows for a ‘telescoping generations’ effect which greatly increases the numbers of

Usually women have two X chromosomes while men have one X chromosome and one Y chromosome. There are some cases where babies do not have any of these arrangements mentioned above (Through the Wormhole video). As people study these kind of cases, they have realized that there might be more than two sexes. For example, I learned that some women can be born with “Swyer syndrome”, which makes them anatomically and physiologically a female but they never achieve female sexual maturity (The Gene: An Intimate History). When their cells were examined, they discovered that they had XY chromosomes in their cells. Basically, they were chromosomally male but anatomically, physiologically, and psychologically female (The Gene: An Intimate History). Goodfellow discovered the SRY gene. This gene was the determinant of maleness but it was flicked off on women with Swyer

Gender selection works by sperm sorting. Sperm sorting is when specialist’s separate male from female sperm which is illegal in Australia. firstly, collecting the woman’s eggs and injecting each one individually with the partner’s sperm, which then you grow the embryo to approximately 130 cells. Then it makes it possible for experts to identify whether the chromosomes are which sex type via fluorescent dye.

Method/Approach: Describing the process between the egg and the sperm and shows how research gives gender attributions to the eggs and sperm.

Sexual selection can best be described by the definition given by Darwin himself. Sexual selection is “the advantage which certain individuals have over other individuals of the same species solely in respect of reproduction” (Hosken et al, 2011). Sexual selection occurs throughout the animal kingdom, where male frogs dominate through the depth of their croak, and certain peacocks reign superior based on the colour and intricate detail on their tails. They remain superior to their lesser counterparts as they bear more admirable characteristics, from which they are chosen by females of the same species.

Recently, scientists have developed a method to detect the gender of chicken embryo inside an egg. The technique need to take a blood sample from egg and then sending it to do chemical analysis. You can go through the details in the following article on the Scientific American website:

In most cases species tend to reproduce under polygynous conditions where one male mates with many females. An interesting example of a polygynous system in nature can be seen in the sea louse. A male releases chemicals that attracts females, and as the females approach the male’s nesting site, he “collects” them and lines them in a row until he senses they are ready to mate. More mates equate to more offspring, hence, this method for reproduction ensures that the male will pass his genes throughout a population.

When fertilization occurs within mammals, the sex is immediately determined. Each parent will contribute one or more chromosomes during the fertilization process, depending on the species. In the male heterogametic (XY) system, the absence of the Y chromosome results in a female offspring and the presence of the Y chromosome results in a male. The evolution of the sex determination system consists of the rise and development of sex chromosomes and concurrently the emergence and evolution of genes that guarantee the formation of equivalent traits and functions. This paper will examine three studies: the replication of Y chromosomes and how they have evolved overtime (Cortez et al. 2014), the structural variation found in Y chromosomes