ABSTRACT

Primates evolved long before the dinosaur extinction 66 million years ago, relying on their small size and body heat to hide them and keep them warm during their nocturnal activities. Early on, they evolved grasping hands and feet to help them move along fine branches, an adaptation that would prove of considerable significance in furthering human cognition.

They spread worldwide. One particularly intriguing question, covered in Chapter 4, is how they came to South and Central America. New World monkeys, as they are called, had no ancestors north or south. They simply appeared, but how? From North America? There's that ancestor problem. From Asia? Same problem, as that requires coming through North America. From Africa? That's actually the leading hypothesis.

The trip must have occurred about 45 million years ago, when the minimum distance between South America and Africa was 800 miles. Under favorable conditions a large raft of vegetation, a "floating island", could have crossed with an accidental cargo of monkeys in about 9 days. Mammals that size can survive 13 days without water, and the vegetation would have expanded the survival period.

The chapter covers all the major primate branchings down to our human ancestors. Lavishly illustrated with color photographs, it steps through the chronology with examples of both living and fossil primates, and ends with the divergence of our closest relatives from our ancestral line. Those were the ancestors of the common chimpanzees and bonobos, about 7.5 million years ago.