Final answer:
The relationship between brain size and the life cycle involves periods of growth and development followed by pruning for a more efficient brain. While brain size does not significantly increase during adolescence, the brain becomes more complex and functional. Throughout human evolution, an increase in brain size was driven by various factors and allowed for the development of culture and technology.
Step-by-step explanation:
The relationship between brain size and the life cycle is complex and multifaceted. During early childhood, the brain undergoes a period of rapid growth and development known as blooming, where neural pathways are formed. This is followed by a period of pruning, where unnecessary neural connections are eliminated, resulting in a more efficient brain. However, after early childhood, the brain does not significantly increase in size.
While brain size does not change much during adolescence, the brain becomes more complex, with an increase in folds in the cerebral cortex. This process, called synaptic pruning, eliminates unused pathways and increases myelination, leading to a more efficient and functional brain. These changes in the brain during adolescence bring about major cognitive changes.
The increase in brain size throughout human evolution occurred between 800,000 and 100,000 years ago, along with the appearance of early Homo sapiens. This increase in brain size was likely driven by factors such as climate change and the need to adapt to an unpredictable environment. A larger, more complex brain allowed our ancestors to develop culture, technology, and behavioral adaptations that helped them thrive.