In what way did an increased skull and brain size affect hominid evolution from early ancestors to modern humans?

The spontaneous enhancement in the size of the brain and of the skull, as well as the complexity of the neural network in the brains of hominids, has resulted in longer infant care and gestation period. In human beings, the development of the brain is only 25 percent complete by the time of birth, in comparison in the primates one can witness 45 percent of the development by the time of birth. In humans, the postnatal development of the brain requires more infant care period that plays an essential function in the development of the brain. This enhanced duration of the development of brain has led to enhanced size of the skull and evolution of modern-day man.

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.