Chapter 16, Problem 24A

Summary Introduction

To correct: The given sentence by replacing the underlined blank.

Introduction: Evolution is the change in traits of a species over generations, which is mainly dependent on the natural selection.

Explanation of Solution

Cro-Magnons are the first evidence of complex human culture which appeared in Europe, before the disappearance of Neanderthals. They developed artificial, sophisticated tools and weapons which included spears and bows and arrows. Cro-Magnons represent the initiation of historic hunter-gatherer societies.

The fossil record of Homo ergaster is believed to be 1.8-1.2 million years ago. They had an average brain capacity of $1000c{m}^3$ . It is known that, these had the thinner skull bones and had human like nose. They are the first African Homo species to migrate to Asia and Europe, in large numbers.

The transition from Homo ergaster to Homo sapiens happened gradually. There are various transitional fossils which show a mosaic pattern of Homo ergaster and Homo sapiens .

Conclusion

Homo ergaster were adapted to cold climates. They eventually were replaced by modern humans.