Secondary ancientity
The secondary altriciality is the growth of the brain far beyond birth. It is a peculiarity of humans. While in most primates the brain is largely developed at birth, the brain volume of a newborn child is only about 25 percent of the brain volume of an adult human (chimpanzees: 40 percent).
Human brain growth
In the first year of life, the brain continues to grow at the same rate as it did before birth, so that a one-year-old child has already reached 50 percent (for chimpanzees 80 percent) of the brain volume of an adult. Especially in the first ten years of life, which the brain needs to grow and mature, human children are heavily dependent on the support of their parents and their social environment. This long period of time in which the brain is still developing and new neural networks are constantly being formed promotes the development of cognitive abilities. The intensive interaction of somatic and sensory-motor brain regions over this long period could even have been a prerequisite for language to arise. Until now, however, it has been controversial among paleoanthropologists when in the evolution of man the secondary ancientity developed.
Cause of the secondary ancientity
Since humans move biped , i.e. on two legs, the configuration of the pelvis has changed. Overall, it became narrower and the pool exit therefore narrower. At the same time, the brain's volume has increased in the course of evolution. The offspring had to be born earlier so that the head could still fit through the narrower pelvic opening. After birth, the head and brain could then grow to full size.
Web links
- PM Magazin: Why it takes people so long to grow up ( Memento from February 12, 2013 in the web archive archive.today )
- Merkur-Online: Man has not been a child for long