Evolution Laboratory Report

Jonathan Paul Loomis

November 30, 1998

09.100.02 Great Experiments in Biology

TA: Heather Emmitte

Introduction

Overview

This laboratory exercise dealt with the theory of evolution as proposed by Charles Darwin some years ago. The basic concept is that all life evolved from some basic form and has branched off into the different species based on survival of the fittest, random selection, natural selection, and chance mutation. Animals that are examples of a recent split will demonstrate similar characteristics and are said to be divergently evolved. In some cases animals that branched apart at an earlier stage develop the need for particular characteristics and evolve similar characteristics even though they are at best distantly related. This is convergent evolution.

Purpose

The purpose of this laboratory exercise was to view a few examples of divergent and convergent evolution at the National Zoo in Washington, DC. The goal of the exercise was to repeat some of the same sort of observations that Darwin did when he first formulated his thesis and to eventually come to similar conclusions.

Hypothesis

I believed that although some animals may appear similar I would not find any reason to believe that evolution was at work. I believed that I would find examples of natural selection, but not evolution by way of mutation.

 

Procedure

The following is a list of the animals I observed for this lab:

Prevost Squirrel, Callosciuras prevosti

Slender Tailed Mercat, Suricata suricattaI

Lesser Tree Shrew, Tupaia minor

Nile Hippopotamus, Hippopotamus amphibus

Masai Giraffe, Giraffa camelopardalis

Cuban Crocodile, Crocodylus rhombifer

Gorilla, Gorilla gorilla

Orangutan, Pongo pygmaeus

 

 

Results

Divergent Small Mammal Pair

Prevost Squirrel, Callosciuras prevosti

  • Morphology: The Prevost Squirrel had a very small body that was similar to a North American chipmunk. It had a flexible backbone and was able to twist itself when climbing. It had a long tail that must have helped in jumping and climbing. It had large ears and eyes, but a short flat nose.
  • Environment: Forests of Southeast Asia.
  • Type of locomotion: Running and climbing. Was also able to jump some distance.
  • Food: Seeds, nuts, and fruits.
  • Skin, fur, etc.: Fur
  • Coloring: Black with a brown and white back and a bushy tail.
  • Behavior in general: The Provost Squirrels were in an environment with other small mammals which were much more active. The squirrels in question generally stood still as if on the lookout.
  • Predator: No.

Slender Tailed Mercat, Suricata suricattaI

  • Morphology: The Slender Tailed Mercat had a stout body about six to ten inches long. Its legs were short and it had a short tail. Its head was elongated like that of a house cat, but it had smaller ears. Did not have long claws for climbing.
  • Environment: Dry deserts and savannas of southern Africa.
  • Type of locomotion: Running.
  • Food: Roots and bulbs.
  • Skin, fur, etc.: Fur.
  • Coloring: Tan. Some had stripes on their backs of a brownish color.
  • Behavior in general: The Mercats move in groups of 25 or more and were running constantly. Their motion was all in the rapid movement of their legs without any movement in their backs in such a way that they looked like remote controlled cars.
  • Predator: No.
  • Type of reproduction: Has 2 to 5 young at a time.

Convergent Small Mammal Pair

Prevost Squirrel, Callosciuras prevosti

  • Morphology: The Prevost Squirrel had a very small body that was similar to a North American chipmunk. It had a flexible backbone and was able to twist itself when climbing. It had a long tail that must have helped in jumping and climbing. It had large ears and eyes, but a short flat nose.
  • Environment: Forests of Southeast Asia.
  • Type of locomotion: Running and climbing. Was also able to jump some distance.
  • Food: Seeds, nuts, and fruits.
  • Skin, fur, etc.: Fur
  • Coloring: Black with a brown and white back and a bushy tail.
  • Behavior in general: The Provost Squirrels were in an environment with other small mammals which were much more active. The squirrels in question generally stood still as if on the lookout.
  • Predator: No.

Lesser Tree Shrew, Tupaia minor

  • Morphology: The Lesser Tree Shrew had a small body very similar to that of a Chipmunk. It had powerful large hind legs for jumping and long claws for the same. It had large eyes and a pointed nose.
  • Environment: The forests of Borneo, Thailand, Malaysia, and Sumatra.
  • Type of locomotion: Running, jumping, and climbing.
  • Food: Fruits, seeds, and insects.
  • Skin, fur, etc.: Fur.
  • Coloring: Dark brown or black all over.
  • Behavior in general: The Lesser Tree Shrew is a solitary animal preferring to move along than in groups. It was observed to be constantly in motion running from one place to the next without a stop.
  • Predator: Only for insects.
  • Type of reproduction: One or two young at a time.

 

Divergent Large Mammal Pair

Nile Hippopotamus, Hippopotamus amphibus

  • Morphology: Very large animal with rolls of fat. The Nile Hippo has gigantic but stubby legs in a generally cylindrical shape. It has a large powerful jaw with nasty teeth that look like pieces of wood. It has almost no tail. Its eyes and nostrils are located on top of its head so that it can remain almost entirely underwater.
  • Environment: Rivers and grassy riverbanks of Africa.
  • Type of locomotion: Swimming or walking.
  • Food: Sugarcane and other semi-aquatic and tropical plants.
  • Skin, fur, etc.: Skin with a layer of fine fur.
  • Coloring: Variations of gray, pink, or brown.
  • Behavior in general: The Hippos were observed to be in the water the entire duration of my visit. They stayed entirely submerged for up to four minutes before coming up for air. When doing so they would put just their nostrils above the water that would open and close completely. They did not breathe or blow out air while submerged. They remained motionless most of the time.
  • Predator: No.
  • Shelter needs: Rivers or lakes.

Masai Giraffe, Giraffa camelopardalis

  • Morphology: The Masai Giraffe has a small body but tall skinny legs and a very long neck. It has short tail and hoofed feet. Its head is long, coming to a point at its mouth and nostrils. It has large ears on the top of its head and two knots just behind its ears. It also had a very long tongue for gathering in branches and leaves.
  • Environment: The open plains of Africa.
  • Type of locomotion: Running or walking.
  • Food: Plants.
  • Skin, fur, etc.: Short fur.
  • Coloring: A brown and yellow pattern of spots.
  • Behavior in general: The Giraffe was seen to stand the entire time, but occasionally moved about. It would move from one tree to another in order to eat. Occasionally it would swing its neck down toward the ground.
  • Predator: No.
  • Reproduction: One young at a time.

 

Convergent Large Animal Pair

Nile Hippopotamus, Hippopotamus amphibus

  • Morphology: Very large animal with rolls of fat. The Nile Hippo has gigantic but stubby legs in a generally cylindrical shape. It has a large powerful jaw with nasty teeth that look like pieces of wood. It has almost no tail. Its eyes and nostrils are located on top of its head so that it can remain almost entirely underwater.
  • Environment: Rivers and grassy riverbanks of Africa.
  • Type of locomotion: Swimming or walking.
  • Food: Sugarcane and other semi-aquatic and tropical plants.
  • Skin, fur, etc.: Skin with a layer of fine fur.
  • Coloring: Variations of gray, pink, or brown.
  • Behavior in general: The Hippos were observed to be in the water the entire duration of my visit. They stayed entirely submerged for up to four minutes before coming up for air. When doing so they would put just their nostrils above the water that would open and close completely. They did not breathe or blow out air while submerged. They remained motionless most of the time.
  • Predator: No.
  • Shelter needs: Rivers or lakes.

Cuban Crocodile, Crocodylus rhombifer

  • Morphology: Long flat body with a long tail. Short but strong and flexible legs. Its head was generally flat with eyes and small ears on top. Its nostrils were on the top of its head at the end of its snout. Its mouth extended almost the entire length of its head and its teeth lay outside its lips when resting. It also had large claws.
  • Environment: Rivers and riverbanks of Cuba.
  • Type of locomotion: Swimming and walking.
  • Food: Fish, eggs, rats, and other small mammals or birds.
  • Skin, fur, etc.: Scaly skin that was thicker on its back than its stomach.
  • Coloring: Greenish black. Its stomach was a whiter yellow color.
  • Behavior in general: The Cuban Crocodiles I observed lay still the entire time. Some were in the water while others lay on the bank. One sat with its mouth open. Not one moved at all.
  • Predator: Yes.
  • Shelter needs: River areas.
  • Type of reproduction: Multiple eggs.
  • Nests: Built on shore.

 

Primates similar to Humans

Gorilla, Gorilla gorilla

  • Morphology: Very large bodies with heavy torsos. Hunched over when walking and sat with their legs in an almost crossed position in front of them.
  • Environment: Jungles of Africa.
  • Type of locomotion: Walking on all fours and climbing.
  • Food: Plants.
  • Skin, fur, etc.: Fur.
  • Coloring: Black. The males have a silver covering on their backs.
  • Behavior in general: They mostly sat around. The zookeeper indicated that they have a strong sense of language and mathematics, roughly that of a one to three year old human. The elderly Gorilla who was sick lay in a fetal position with its hands under its head. The young male seemed curious as to who we were.
  • Predator: No.
  • Shelter needs: Trees.
  • Type of reproduction: Are sexually mature at age eight.

Orangutan, Pongo pygmaeus

  • Morphology: The Orangutans had a pair shaped torso with long stringy legs and arms. Their hands possessed a thumb, which enabled them to cling and climb efficiently. They had human-like faces but with much larger mouths and flatter noses and cheeks.
  • Environment: The forests of Borneo and Sumatra.
  • Type of locomotion: Walking on all fours and climbing.
  • Food: Leaves and fruit, mostly figs.
  • Skin, fur, etc.: Fur, which is long on the arms and legs.
  • Coloring: Reddish orange.
  • Behavior in general: Liked to sit and watch us. One of the Orangutans had a sheet, which it carried about like children do a baby blanket. At times it seemed as if she was playing peek-a-boo with us. Once when she dropped it she immediately climbed down to pick it up off the floor. She moved slowly and deliberately though. There didn't seem to be any rush. They also had distinct facial expressions. She appeared to smile or become worried.
  • Predator: No.
  • Shelter needs: Trees.

 

Discussion

This laboratory exercise was really very enjoyable. I gave me a good excuse to go visit the National Zoo, which is always a favorite. However, I can't keep going on about what a great day it was, I have to address the burning question: what did I find out about Darwin's theory of evolution. Well this is an interesting question, because I didn't actually find anything to support it. In fact I was overwhelmed with the evidence that pointed against this holier-than-thou theory.

Let me begin with that untouchable example of the black and white butterflies. I know that I didn't observe butterflies, but they serve well as a beginning of my discussion. I am speaking, of course, about the black and white variations of the same butterfly, which sleep on the trees of England. During the industrial revolution all the trees were covered with soot and predators easily spotted the white butterflies. If it hadn't been for the environmentalist movements in the later part of this century the white variation might just have disappeared all together. However, now that we've cleaned up our act a bit the trees once again have their lighter colored bark and it's the black variation that is in danger. This is always cited as an example of natural selection evolution. It is the same concept that goes to work with the giraffe. Long ago it was only those animals with longer necks that could reach the leaves of tall trees and survive long droughts. Over time all the short-necked mammals in the area died out and we are left with Giraffes.

This is all well and good, but it is not evolution. In each of these cases natural selection has eliminated a variation of the species. It has not created anything. Evolution argues that life goes from the less complicated to the more complicated. This is crazy. In every other aspect of science we argue that the universe is constantly moving toward greater and greater levels of entropy. Why would it be that animals are not? One can not argue that eliminating variations of animals creates new and more complicated types of animals or plants. The survival of the fittest concept that uses the Giraffe as an example necessitates a prehistoric animal with every variation possible, from which only those suited to the environment would survive. This might have been the case, although the fossil record shows no sign of such an animal.

Then there is that great theory of mutation. Mutation argues that an animal or plant, by some random mutation in its DNA, acquires a new characteristic. This could be just about anything. For example, it is said that some fish had mutations, which allowed them to move onto land. Because these fish could then find more food they survived to pass along their mutated genes and land dwelling animals appeared. But there is a problem here. If random chance were involved, how would it be that a fish would suddenly acquire the mutation that enables it to breathe air. If a fish suddenly had a mutation which enabled it to breath air, wouldn't it be equally likely now that a human acquired fully functioning gills which enable them to breath underwater. Somehow the idea strikes me as being a bit far fetched… a little bit like a bad Kevin Costner movie.

What about some other organs, like the eyes. Did some animals mutate eye socets by accent and then millennia later their offspring mutated the rest of the eye. It strikes me as rather hard to believe that a single mutation could produce such a complicated item as an eye. Even if the process of mutation could get close, say within one step or two of the completed work, why would an animal with only an eye socket have a better chance of survival than one without. Darwin's theory does place emphasis on the concept that the mutations give the animal some advantage.

Of course I observed animals with similar traits, the observations which lead Darwin and his contemporaries to develop the theory of evolution. However, the concept of having similar designs for similar functions does not necessarily mean that two animals are related. Naturally the convergent pairs, say the Cuban Crocodile and the Nile Hippopotamus, are not, but even in the case of the divergent pairs I find it hard to believe that they are related. What would be the advantage of having a Hippopotamus with a long neck, or a Giraffe with huge feet? Mutations couldn't have created the differences these animals posses.

This argument is not scientifically based. It is in fact contrary to an established scientific theory. However it is not one that science has been able to disprove yet, and I feel that our biology courses textbooks have done us a great disservice to present the Darwinist theory of evolution as if it were established fact, when it is not and is still under continued scrutiny.

Extra Credit Question

Give one interesting fact about Charles Darwin.

Darwin was not the only person to come up with the theory of evolution. In fact, another Englishman named Alfred Wallace produced an identical thesis at the same time as Darwin. Darwin was wise however and managed to present his essay first and thereby gain the public acclaim lauded to the creator of this new theory.

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