Flesh seeks its own gratification by nature. If it is hungry, it seeks out food. If it is thirsty, it seeks out water. If it is cold, it seeks shelter. If there is a sexual arousal, it does whatever is necessary to satisfy that lust.
Flesh is flesh.
Man is not an animal, even though we are of flesh. Only man was created in God's image, according to His likeness. Out of the ground the LORD God formed every beast of the field and every bird of the air, and brought them to Adam to see what he would call them. And whatever Adam called each living creature, that was its name. So Adam gave names to all cattle, to the birds of the air, and to every beast of the field.