Excerpt from Introduction To Evolution:

Almost everyone intuitively understands the pictorial representation of a family tree. If you go to a family reunion there may be a big chart around somewhere, showing the entire clan for many generations. The chart below is how a family clan diagram might look. Some family names last for several generations until they change through marriage – or die out for lack of progeny. This is a simple pictorial guide to evolution through a small number of human generations.

When such a chart is accompanied with photos going back 100 years (or when lots of cousins, grandparents or great-grandparents are present) we can also visualize more easily how we change over time. A few generations of human evolutionary change is but a blink of an eye compared to what has gone before. It might take 25,000-50,000 generations -- a half million to a million years or more – for really significant change to occur.