Name: Date: The Story of Human’s History



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Name: ______________________________ Date:__________

The Story of Human’s History
Directions: The goal of this investigation is to learn a bit about some of the ways modern man came to be, according to some of the scientific evidence that is presented around the room. You see, scientists don’t have video footage with the story of how life came about, or a textbook that fell from the sky describing how life has changed on earth over time. Instead, scientists have the very difficult task of using the clues around them that have been left by past organisms in order to deduce how humans, like all organisms, have evolved.

You must visit each lab table in the room, and figure out how the objects and information at the table reveal the story of humankind’s history. This packet will help to guide you through.


You can begin at any table around the room. Rotate clockwise.
Lab Table 1: Fossil Evidence (Materials: Human Skull, Afarensis Skull)

Fossils are the preserved remains of deceased organisms. They can be skeletons or impressions, and they are usually found in sedimentary rock (rock that forms in layers over millions of years. The fossil record shows the history of how species change over millions of years.



Layer 1

Layer 2

Layer 4


Layer 3

Sedimentary rock forms as bits of earth are compressed over thousands of years or more, forming rock. Layer after layer compacts on top of each other over millions of years, forming many layers of rock. As organisms die, they can become preserved in the layer of sedimentary rock being formed, which preserves and protects them for millions of years.


1. According to the picture above, which layer contains:
a. The oldest fossils? ______________________

b. The most recent fossils? __________________


2. How can the fossils found in each layer show scientists how life has

changed over time?

3. Examine the skulls on the lab table. One is the skull of a modern human being, like yourself, and the other is of an ancient primate fossil named Afarensis. CAREFULLY turn the skulls upside down, and examine the hole on the bottom. Note its position. This hole is called the foramen magnum, and this is where your spinal cord comes out of, connecting your brain to the rest of your body. The picture below shows the position of the foramen magnum of three different species of primates: modern day gorilla, Australopithecus africanus (2-3 million year old primate), and modern human.

A. Compare the position of the foramen magnum for each the four primate skulls. How do they compare?
Gorilla –
Africanus –
Human –

Afarensis –

B. What could the position of the Foramen Magnum tell you about how each species walked?

C. Based on the position and function of the foramen magnum, predict where the FM is located in the following organisms. Use the skull models to the right to show where they would be located.





  1. D
    Dog
    omesticated Dog -






  1. Boa Constrictor -


Boa





  1. Kangaroo -


Kangaroo

D. By studying the fossils, scientists have found that the FM has slowly moved closer to the base of the skull over millions of years, in many primate species, leading to modern human’s FM, which is further forward than all of the previous fossils. What do these clues tell you about the story of humans’ history, and how our ancestors walked, compared to how humans walk?




By examining the position of the foramen magnum through the fossil record, scientists can infer the angle at which the spinal column came out of skull. Scientists can infer that ancient primate ancestors walked more hunched over, and modern humans walk upright.

Gorilla




Lab Table 2: DNA / Molecular Evidence (Materials: None)

Every living organism on earth today speaks the same chemical language. That is, every organism contains DNA, from bacteria, plants, fungus, to humans. We all share the same type of chemical instructions.


Percentage of same DNA codes to humans

A. Examine the chart to the left. In your own words, summarize what the chart is showing.

B. How does this chart show how closely related, or distantly related, each of the organisms is to one another?

C. How can scientists use DNA to build evidence for the story of human’s evolution? Incorporate what you've explained in the two questions above. Explain.


DNA contains the instructions that give organisms their traits. DNA is passed from one generation to the next, and can slowly, and randomly get mutated, changing organisms features. The more similar two species DNA is, the more closely the two species are related. Scientists can determine how closely related two species are by how much DNA they share in common. In this case, it is evidence that chimpanzees are closely related to humans because of how much of their DNA is the same.



Lab Table 3: Embryological Development (Materials Needed: Embryo Poster)
*DO NOT LIFT THE FLAPS ON THE POSTER, and DO NOT READ AHEAD FOR THIS LAB TABLE ACTIVITY*

An embryo is what we call an organism early on during development. We call humans embryos from when fertilization occurs up until eight weeks of development. Almost all multicellular organisms exist as an embryo for some period of time.



  1. Lift the first flap, on the top of the poster. What do you see? Compare/Contrast the specimens.




  1. You are looking at eight embryos. Each embryo will become a mature vertebrate. Vertebrates are organisms with backbones. The embryos will become a pig, turtle, rabbit, cow, salamander, human, chicken, and fish. Can you tell, at this stage, which embryo is which (they aren’t in the order I listed)? List your guesses on the lines below.

Top picture guesses:


1._______ 2. _______ 3. _______ 4. _______ 5. ________ 6. ________ 7. ________ 8. ________



  1. Lift flap 2. Flap 2 shows the same embryos, but now they are further in development. How are the embryos different from the first image? Is it easier to tell them apart? List your guesses again below.

Flap 2 guesses:


1._______ 2. _______ 3. _______ 4. _______ 5. ________ 6. ________ 7. ________ 8. ________


  1. Lift flap 3. Flap 3 shows the same embryos, but now they are even farther in their development. List your guesses again below.

Flap 3 guesses:


1._______ 2. _______ 3. _______ 4. _______ 5. ________ 6. ________ 7. ________ 8. ________


  1. Lift flap 4. Flap 4 shows the answers to your guesses. Were your guesses more accurate for the later stages of the embryos? ___________. Make a generalization about how vertebrate embryos start out, and what happens during development.




  1. There are folds labeled “Gill Arches” in the first image of the embryos. How many gill arches does each embryo begin development with? ________. In fish and salamanders, the gill arches become internal and external gills in the adults. In the land vertebrates, they become parts of the mouth, muscles in the head and neck, and parts of their throat. Why do they start out the same, but develop into very different structures? Explain.

  1. How can scientists use vertebrate embryo development to build evidence for the claim that vertebrates are somewhat closely related in the evolutionary history of life on earth? Incorporate your answers from the two questions above. Explain.




If you examine the early embryo stages of all these organisms, you can see that they are indistinguishable from one another. All of their basic body plans are the same, whether they are fish, or birds, or mammals. This suggest that they could have evolved from a common ancestor. IN this case, a common vertebrate ancestor.


Lab Table 4: Vestigial Structures (Materials: String ruler, Africanus skull)

Archeologists (study fossils) have found many skull fossils of primates/ humanoids that date back from thousands to even millions of years ago. They measure the length of the mandible (jaw bone) from where it hinges in the back to the chin, and then up to the other side, where it hinges. Located on your table is a replica of the skull of one of these ancient primates, Australopithecus africanus. Measure the length of its mandible using the materials provided




  1. Length of Australopithecus africanus mandible _________________ inches

Use the materials provided (string, ruler, your mandible) to calculate the average length of the mandible for each human in your lab group.





  1. Average length of your lab group’s mandible: _________________ inches.




  1. How do human mandibles compare to ancient primate mandibles?



  1. Your mandible, like the mandibles of ancient primates, helps you digest food by grind your teeth together to break up food. Count the number of bottom teeth you have {include wisdom teeth (even if you have had them removed, count them in)}. Average the number of bottom teeth for the humans at your lab table.

Average number of bottom teeth

(including wisdom teeth that were removed) _______________ teeth



  1. By counting up all the teeth (and missing teeth holes) in the ancient primates jaws’, archeologists found that, on average, ancient primates had 16 teeth on the bottom.

Compare the amount teeth per inch of mandible that you have by filling in the chart below. INCLUDE YOUR WISDOM TEETH, EVEN IF THEY WERE REMOVED.







Average # of teeth on bottom jaw

Average length of bottom jaw (inches)

Average number of teeth per inches of space of bottom jaw (teeth/inch)


Human (Average)











Ancient Primates












  1. What is your conclusion? Do modern humans, or ancient primates, have more room for teeth in their mouth? Explain.

  1. Many humans have the misfortune of wisdom teeth. Wisdom teeth are molars, found all the way in the back of your mouth that can cause a person pain and problems because there is not enough room in your mouth to comfortably fit wisdom teeth. Thanks to modern dentistry, these annoying “extra teeth” can be removed. What is a possible explanation for why we have these extra teeth? (hint: Could ancient primates fit these teeth into their mouths’?)




  1. How can archeologists use this information to support the claim that ancient primates could be humans’ ancestors (AKA humans descended from ancient primates)? Incorporate what you've answered in the previous two questions.


Many people have the same number of teeth in their mouths as ancient primates. However, our mandibles (lower jaws) don't comfortably fit all the teeth. We call the extras wisdom teeth, and a likely explanation for the presence of these teeth is that they are left over traits from our ancestors, that have not evovled out of many people.

Lab Table 5: Homology (Materials: mini human skeleton, cat skeleton)
1: Explain how each of the following organisms uses their limbs.


  1. Human’s arm - _______________________________________________________

__________________________________________________________________




  1. Cat’s front leg - ______________________________________________________

__________________________________________________________________




  1. Whale’s front fin -_____________________________________________________

__________________________________________________________________




  1. Bat’s wing - _________________________________________________________

__________________________________________________________________

2. Do these organisms use their front limbs (forelimbs) to do the same things? Explain.

3. Now, let’s examine the skeletal anatomy of these forelimbs by looking at the bones in each.

Using the human skeleton model, and the cat skeleton model, compare the bones of the

Forelimbs. How are the bones arranged similarly? Differently?

4. Can’t see the connection yet? Examine the picture below. It shows skeletal structure for the forelimbs of a human, cat, whale, and bat. There are obvious differences between the lengths and angles of these bones, but what can you say about the overall arrangement of the bones?




1


1


1




2

1


2


3


3


2

2



4

4


3

3


4



4



5

Although the forearms have very different jobs to do, the arrangements of bones underneath are very similar. This suggests common ancestry between them all because the common ancestor to all of these vertebrates probably had the same arrangement of bones. Over many, many generations, mutation and natural selection led to the evolution of differently shaped and functioning forelimbs in these organisms.

. If they have such different functions (gripping, flying, swimming, running), then why are the bones arranged so similarly? Explain how the similarities in bone structure of vertebrate forelimbs illustrates that modern vertebrates (like cats, dogs, bats, and even whales) could be the descendants of a common vertebrate ancestor! Incorporate your answers from the previous two questions.

Lab Table 6: Two thumbs up! (Materials: Tape)


  1. On the following line, write this sentence: “I have a thumb, and it is helping me to write this sentence”. At least you know you got one answer correct in this packet ; )

______________________________________________________________________


What you wrote is true. It is so true that we take it for granted. You see, humans possess a special adaptation called an “opposable thumb”. In other words, you have a finger that bends in the opposite direction as the rest of your fingers, allowing you to grip with strength and precision.


  1. Tuck your thumbs across your palm, and then tape it, like shown in the picture. After it is taped, attempt the following activities:

  1. Write the same sentence from above

___________________________________________________


___________________________________________________


  1. Compose a text message that says, “You know what really grinds my gears?... Lindsay Lohan.”



  1. Tie your shoe laces


  1. Describe the level of difficulty of each task, comparing your ability with and without a thumb.




  1. Scientists have found that primate fossils from millions of years ago have opposable thumbs. List some of the ways opposable thumbs could have helped them.




  1. All primates have opposable thumbs. No other animals do. How can this evidence help support the claim that primates are closely related on the tree of life?

All primates have opposable thumbs, and no other organisms do. This suggests that they are closely related.


All these organisms have same number of Gill Arches






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