The term physiological prematurity refers to the fact that compared to most animals, humans are born in a premature biological state. Although sensory organs and skeletal and muscular systems are largely developed prenatally, human babies at the time of their birth

Birth

Birth is the act or process of bearing or bringing forth offspring. The offspring is brought forth from the mother. The time of human birth is defined as the time at which the fetus comes out of the mother's womb into the world...

 are completely helpless and dependent on intensive care. This is in contrast to the maturity at birth found in other higher mammals (e.g. elephants, horses).
According to the Swiss biologist Adolf Portmann

Adolf Portmann

Adolf Portmann was a zoologist.Born in Basel, Switzerland, he studied zoology at the University of Basel and worked later in Geneva, Munich, Paris and Berlin, but mainly in marine biology laboratories in France and Helgoland.In 1931 he became professor of zoology in Basel...

, it is a characteristic feature of humans that due to their early birth, many developmental processes do not happen in isolation, but embedded in a sociocultural environment. Due to their complete dependence, humans are particularly amenable for social interactions and their environmental condition, which, according to Portmann, is a precondition for cultural and intellectual learning.