SEX DETERMINATION

In humans:

Human sex refers to the processes by which an individual becomes either a male or female during development.

Complex mechanisms are responsible for male sex determination and differentiation. The steps of formation of the testes are dependent on a series of Y-linked, X-linked and autosomal genes actions and interactions

The combination of sex chromosomes that determine the sex of an offspring; in humans the sex chromosomes of a normal female are XX and the sex chromosomes of a normal male are XY.

The ZW sex-determination system is found in reptiles (including birds) and some insects and other organisms.

The ZW sex-determination system is reversed compared to the XY system: females have two different kinds of chromosomes (ZW), and males have two of the same kind of chromosomes (ZZ).

  • In the chicken, this was found to be dependent on the expression of DMRT1.In birds, the genes FET1 and ASW are found on the W chromosome for females, similar to how the Y chromosome contains SRY. However, not all species depend upon the W for their sex.
  • For example, there are moths and butterflies that are ZW, but some have been found female with ZO, as well as female with ZZW.
  • Also, while mammals inactivate one of their extra X chromosomes when female, it appears that in the case of Lepidoptera, the males produce double the normal amount of enzymes, due to having two Z’s.
  • Because the use of ZW sex determination is varied, it is still unknown how exactly most species determine their sex.
  • Despite the similarities between ZW and XY, the sex chromosomes do not line up correctly and evolved separately.

Drosophila (Fruit fly) have both X and Y chromosomes as well as autosomes. Unlike humans, the Y chromosome does not confer maleness, rather it encodes genes necessary for making sperm. Sex is instead determined by the ratio of autosomes to X chromosomes. Further, each cell “decides” whether to be male or female independently of the rest of the organism resulting in the occasional occurrence of gynandromorphs.

X Chromosomes Autosomes Ratio of X:A Sex
XXXX AAAA 1 Normal Female
XXX AAA 1 Normal Female
XX AA 1 Normal Female
X AA 0.50 Normal Male
XXX AA 1.50 Metafemale
XXXX AAA 1.33 Metafemale
XX AAA 0.66 Intersex
X AAA 0.33 Metamale

 

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Anthropology: Society

SOCIETY

Society is made up of individuals and groups.

Individual : An individual in a society mainly have two characteristics

  1. Status : As an individual, what is the status he posses in the society,
  2. Role    : As a member of the society, what is the role is he playing?

Groups : A group is an assembly of more than two people or two individuals. There are different groups in the society.

Groups can be broadly classified into:

  • Community
  • Association

Community: A group of people who live together to achieve all the common interests, which are necessary for the human existence.

According to McIver, a community is an area of social living marked by some degree of social coherence.

There are two types of communities:

  1. Nomadic communities
  2. Settled communities

Nomadic communities are the ones in which the lifestyle of the people is primitive. Usually the size of the communities ranges in between 25 to 300 members. The economy of these people is subsistence and hence this makes a basis for them to live together.
Example : Band

Settled communities are the ones in which the lifestyle of people is developed. It always occupies a definite territorial area.
Example : A village community, a town community and city community.

Associations: An association is a group of people organized for a particular purpose or a limited number of purposes. These associations follow some prescribed rules and regulations in order to achieve their interests. Generally these groupings are goal- oriented.
Example: South Indian Priests associations, Economic associations like trade unions, social associations like gender associations, lineage associations and political associations like the UPA.

Institutions: The established set of rules, procedures or laws which will be followed by the associations are called the institutions. These institutions evolve with the growth of associations.