Chapter 14 Lesson 4, "What Humanlike Fossils Show"

Materials:

• Vocabulary Review Sheet

Objective:

• Students will list characteristics that all primates share.
• Students will trace the evolution of hominids, based on fossil evidence.
• Students will describe how hominids changed over time.

Anticipatory Set:* Students will view several pictures of different animals and tell whether the organism is a primate or not. How do they know? What are the characteristics of a primate?, Picture 1, Picture2, Picture3, Picture4, Picture5, Picture6, Picture7, Picture8, Picture9, Picture10.

Here are some characteristics of primates:

* Forward-facing eyes for binocular vision (allowing depth perception)
* Increased reliance on vision: reduced noses, snouts (smaller, flattened), loss of vibrissae (whiskers), and relatively small, hairless ears
* Color vision
* Opposable thumbs for power grip (holding on) and precision grip (picking up small objects)
* Grasping fingers aid in power grip
* Flattened nails for fingertip protection, development of very sensitive tactile pads on digits
* Primitive limb structure, one upper limb bone, two lower limb bones, many mammalian orders have lost various bones, especially fusing of the two lower limb bones
* Generalist teeth for an opportunistic, omnivorous diet; loss of some primitive mammalian dentition, humans have lost two premolars
* Progressive expansion and elaboration of the brain, especially of the cerebral cortex
* Greater facial mobility and vocal repertoire
* Progressive and increasingly efficient development of gestational processes
* Prolongation of postnatal life periods
* Reduced litter size—usually just one (allowing mobility with clinging young and more individual attention to young)
* Most primates have one pair of mammae in the chest
* Complicated social organization

What distinguishes us, homo sapiens from the rest of the primates? High intelligence, use of sophisticated tools, ability to adapt to many different climates.

Teacher Input:* Any species that walked on two legs belonged to a group of organisms called hominids. (Hominid) We know what we know now about hominids because of the fossils we have found. (fossil) There is a lot of good fossils of many, a much better fossil record than most spieces. Probably because when someone finds something that looks human they notify the proper authorities. Since one of the first Hominids found (Lucy) was living 3.2 million years ago it is not hard to imagine small changes generation after generation for 3.2 million years to have become what we are today. By looking at these bones scientists have determined that "Lucy" walked upright although her brain was only about 1/3 the size of ours today. Footprints have also been found that suggest that hominids have been walking upright for millions of years.

Although Lucy was a hominid she was not as closely related to humans as fossils found in newer rock layers. Homo habilis which lived 1.6 to 2.4 million years ago was more closely related to humans. Tools have been found near their fossils which showed much larger brains.

In even newer rock layers paleontologists have found Homo erectus. Homo erectus has an even larger brain and because some of his fossils were found near burned bones it is thought that they learned how to use fire.

It is thought that Homo erectus evolved into Homo sapiens between 400,000 and 150,000 years ago. The first Homo sapiens were the Neanderthals. The Neanderthals lived 150,000 to 35,000 years ago. They used tools and lived in caves and the tools they used suggest they wore animal hides. The Neanderthal had a larger brain than today's humans. Neanderthals may or may not have evolved into Cro-Magnons who could make their own shelters drew on the walls of caves, and had a brain about the same size as ours. Cro-Magnons are our direct ancestors.

After 400,000 years ago it was thought that Homo sapiens were the last hominid species alive. Until recently. A new hominid species has been discovered. The Homo floresiensis, a new species of hominids was alive as little as 13,000 years ago. Here is some more information on them:

http://news.bbc.co.uk/1/hi/sci/tech/3948165.stm
http://www.nature.com/news/specials/flores/index.html
http://www.msnbc.msn.com/id/6346939/
http://www.godandscience.org/evolution/hobbit.html

Guided Practice:* Show the students the diagram for the timeline of different Hominid Species and discuss what it shows.

Independent Practice:* Students will complete the Vocabulary Review Sheet

Check for Understanding:* Students will take the quiz on Lesson 4, "What Humanlike Fossils Show"

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-11 Students will understand that similar features are passed on by genes through reproduction (Heredity).
• SCI A-12 Students will distinguish the patterns of similarity and differences in the living world in order to understand the diversity of life and understand the theories that describe the importance of diversity for species and ecosystems.
• SCI A-13 Students will understand the theory of natural selection as an explanation for evidence of changes in life forms over time (Evolution and Natural Selection).