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Humans

Human Male and Female - Anatomical Features pointed out

See Human sexuality for information about sexual activities, sexual sensation, sexual gratification, and sexual intimacy between human beings

In humans, "sex" is often perceived as a dichotomous state or identity for most biological and social purposes - such that a person can only be female or male. But many factors, including one's biology, environment, psychology and social context, have a role in determining how a particular person, and those around them, view their sex. Although the table below shows common differences between males and females, many people do not correspond to "male" or "female" with regard to every criterion.

"Primary" sexual characteristics are typically present at birth and directly involved in reproduction. "Secondary" sexual characteristics typically develop later in life (usually during puberty) and are not directly involved in reproduction. Differences between the sexes are known as sexual dimorphism. At the biological level these differences are usually:

Level	Characteristics	Female	Male
Primary
	Sex chromosomes	XX	XY
	Gametes	Ova	Spermatozoon
	Sex organs	Ovaries	Testes
	Predominant Sex hormones	Estrogen and Progesterone	Testosterone
	Anatomy of internal genitalia	clitoral crura, vagina, uterus, fallopian tubes	corpora cavernosa, urethra, prostate, seminal vesicles
	Anatomy of external genitalia	glans clitoris, labia, vulva, clitoral hood, perineal urethra	penis, scrotum, foreskin fused perineum
Secondary
	Skeletal Structure	Relatively shorter, wider in hips	Relatively taller, wider in shoulders, bigger chest
	Face	None	Bigger nose, brow bone, squarer jaw, facial hair
	Body fat and muscles	Relatively more fat	Relatively more muscles[10]
	Fat Distribution	More in buttocks, hips and thighs	More in abdomen
	Body form development	"Hourglass" shape: 8	"Triangular" shape: ▼
	Other	Breasts and menstrual cycle[citation needed]	Adam's apple and body hair

The relationship between the various levels of biological sexual differentiation is fairly well understood. Many of the biological levels are said to cause, or at least shape, the next level. For example, in most people, the presence of a Y chromosome causes the gonads to become testes, which produce hormones that cause the internal and external genitalia to become male, which in turn lead parents to assign 'male' as the sex of their child (assigned sex), and raise the child as a boy (gender of rearing). However, the degree to which biological and environmental factors contribute to the psychosocial aspects of sexual differentiation, and even the interrelationships between the various psychosocial aspects of differentiation, is less well understood as illustrated by the ongoing nature versus nurture debate.

Source from : http://en.wikipedia.org/wiki