Cuáles son los caracteres sexuales primarios y secundarios de los hombres y de las mujeres?

Primary and secondary sexual features relate to specific physical attributes that distinguish between men and women in dimorphic species, that is to say the species in which men and women are distinct. There are primary sexual features (e.g. penises and vaginas) from birth. In puberty (such as low voices and beards in men and high voices in women, no facial hair in females), secondary sexual characteristics appear.

Explanation:

Primary sexual features are those present at birth. In mammals, sex is determined by hormonal events in the utero and regulated by the combination of X and Y chromosomes under normal circumstances. If the egg is fertilized by the X-color sperm, the gonads should become ovaries and the offspring should be feminine; if the sperm with the Y-chromosome is fertilized the eggs will turn into samples. (There are many exceptions to this, but anomalies are taken into account.)

Hormones secreted by hypothalamus facilitate the development of secondary sexual characteristics, classically male or female. Such secondary sexual characteristics are not used to replicate, but are apparent in many of the sexually dimorphic animals, which have two sex-determined forms. Secondary sex features include male breasts, male face hair and male makeup.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.