Chapter 17, Problem 1TQ

Summary Introduction

A taxonomic tribal group those belonging to the subfamily Homininae are known as Hominins. This group consists of the genus Homo though it does not include the genus Gorilla. An example of earliest hominins is Sahelanthropus tchadensis. An example of early hominins is Ardipithecus ramidus. It is an ape.

Answer to Problem 1TQ

Originally it was described that a single evolutionary line exists between Ardipithecus ramidus and modern humans through a series of evolutionary stages and not a single line.  Later, Ardipithecus ramidus was discovered to be closely related to chimpanzees.

Therefore, option (a) is correct. 

Explanation of Solution

Justify the reasons for the correct statement:

The brains (400 cubic centimeters) and the teeth of all hominins, including Ardipithecus ramidus were small as compared to humans. These features of human resembled with those features of Chimpanzees. The volume of the human brain is 1,400 cubic centimeters. The earliest known hominin dates 6 to 7 million years ago, others dates 4.4 million years ago, and several others dates 3 to 4.2 million years. Anatomically modern human appears to be evolved over 200, 000 years ago. All these suggests that the ape does not evolve into human.

Option (a) is given as, “A single evolutionary line led from Ardipithecus ramidus to modern humans”.

Hence, the option (a) is correct.

Justify the reasons for the incorrect statements:

Option (b) is given as, “Some hominid traits evolved more rapidly than others”. 

The earliest known hominins, belonging to the Hominid family dated 6 to 7 million years ago, others dates 4.4 million years ago, and several others dates 3 to 4.2 million years. This data suggests that the hominid traits evolved more rapidly as compared to others. This statement is true. Hence, it is a wrong answer.

Option (c) is given as, “Brain size increased greatly from early hominids to Homo sapiens”.

The brains of early hominids measured 400 cubic centimeters that increased greatly to 1,400 cubic centimeters in humans. This statement is true. Hence, it is a wrong answer.

Option (d) is given as, “Tool making technology has improved greatly over the past 300, 000 years”. 

Hominids were the first to use stone tools and the tool making technology has improved over several years or the past 300, 000 years resulting in iron tools. This statement is true. Hence, it is a wrong answer.

Hence, options (b), (c), and (d) are incorrect.

Conclusion

Human beings are not just closely related to apes. They are a part of separate branch termed hominins. Hence, the given statement ‘a single evolutionary line led from Ardipithecus ramidus to modern humans’ is not true.