Fenotipo frente a genotipo Cuando el cigoto madura y el organismo nace, crece y muere, sus caracteres genéticos interactúan con el entorno en que tienen lugar sus peculiares experiencias vitales. La interacción de los genes con el medio ambiente produce el *fenotipo*: la manifestación externa del organismo. Los organismos que tienen genotipos similares o incluso idénticos pueden mostrar fenotipos

Our mating minds—the glory of romance, the flush of passion, the triumph of love—are fortunate products of this evolutionary process.

Women, like female weaverbirds, prefer men with desirable “nests.” Consider one of the problems that women in evolutionary history had to face: selecting a man who would be willing to commit to a long-term relationship. A woman in our evolutionary past who chose to commit to mate with a man who was flighty, impulsive, philandering, or unable to sustain relationships found herself raising her child