The human brain is a biological engineering marvel created from the tip of a 3 millimeter neural tube. It expands at a rate of roughly 250,000 nerve cells per minute on average during pregnancy to reach more than 100 billion neurons that make up a newborn baby's typical complement. But it's not just the rate of growth that makes the production of human brains so astounding. Even though the brain dependably performs a large number of functions and the specificity with which these are allocated to one or another sort of cell or small place in the entire assembly, the feat of creating a human brain occurs in hundreds of millions of people each year. The brain's estimated 100 trillion interconnections form the physical foundation for its speed and intelligence.
