I say that one cannot generalize everyone because our bodys all grow at a different rate, depending on genetics and enviroment. The answer is multifactorial. Based on what we know, it was approximately in the past. Secondly, the brain being fully mature and the ability to raise a child that survives and reproduces aren't completely linked.
The age your brain matures at everything — it isn't even fully developed until age 25
Aging brain - Wikipedia
At an age when Americans are first considered adults, their brains are still maturing, a new study suggests. Researchers at Dartmouth College scanned the brains of nineteen year-old students who had moved more than miles to attend school. A group of 17 older students, ranging in age from 25 to 35, served as a control group for comparison. The results showed that the freshmen students' brains underwent significant changes and were very different from that of the older adults. The changes were localized to the cingulate, caudate and insula regions of the brain. These areas are believed to be where emotions and thoughts are integrated. The researchers believe the changes represent an increased awareness of the students' inner feelings and an improved ability to organize and integrate incoming sensory information; this synthesis helps shape the kinds of emotional and behavioral responses they have to new experiences.
Aging is a major risk factor for most common neurodegenerative diseases, including mild cognitive impairment , dementias including Alzheimer's disease , cerebrovascular disease , Parkinson's disease and Lou Gehrig's disease. While much research has focused on diseases of aging, there are few informative studies on the molecular biology of the aging brain usually spelled ageing brain in British English in the absence of neurodegenerative disease or the neuropsychological profile of healthy older adults. However, research suggests that the aging process is associated with several structural, chemical, and functional changes in the brain as well as a host of neurocognitive changes.
Verified by Psychology Today. Eyes on the Brain. When we think about brain development and plasticity, most of us think about the birth and death of neurons or changes in the number or strength of synapses. Yet, no part of the brain works in isolation. Brain maturation and plasticity also depends upon the large nerve fiber tracts that connect different brain regions together.