Why does human development represent the unity of the biological and the social? How do you imagine that?

A person is a living being, which a person can become only while in society. The biological in a person determines his primary needs, and the social is secondary, which help a person to develop, to realize himself.

Primary and secondary human needs are related to each other, some are realized through others. For example, the need for procreation is associated with the need for love and understanding. You can create a family without love, for the sake of procreation, but the need to be happy is unlikely to be realized.