Sexual differentiation in humans Sexual differentiation in humans Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following gonadal determination. Sexual differentiation includes development of different genitalia and the internal genital tracts, breasts, body hair, and plays a role in gender identification. The development of sexual differences begins with the XY sex-determination system that is present in humans, and complex mechanisms are responsible for the development of the phenotypic differences between male and female humans from an undifferentiated zygote. Females have two X
Reciprocal altruism in humans that memes are the medium of the spread of altruism. The transmission of altruism has been carried out through memes. Memes are true evolutionary replicators like genetics and undergo evolutionary change. Reciprocal altruism in humans Reciprocal altruism in humans refers to an individual behavior that gives benefit conditionally upon receiving a returned benefit, which draws on the economic concept – ″gains in trade″. Human reciprocal altruism would include the following behaviors (but is not limited to): helping patients, the wounded, and the others when they are in crisis; sharing food, implement, knowledge. The concept of ″altruism″ was firstly coined by