HUMAN APPENDIX In humans, the appendix is a short piece of tissue off the large intestine. It is not used by humans for digestive functions. In other mammals, like rabbits and deer, the cecum is a large structure. It looks similar to the human appendix. Bacteria are often in this structure. This helps them to digest certain foods, mainly tough plants. It is believed that the appendix is a cecum. However, it went unused over time and got smaller. BATS & TROPICAL FLOWERS In this situation, many species of bats have developed longer snouts and tongues over time. This allows bats to extend into a flower to extract nectar for food. As the bat extends into the flower, the flower dusts pollen onto the bat s fur. The bat will then fly off to other flowers and deposit the pollen onto other flowers. This is how the flower will ultimately reproduce. SPINY ANTEATER & ANTEATER
In this situation, each animal is a mammal. The spiny anteater is a rare mammal that does not have live birth. Rather, it lays eggs to hatch. It eats ground insects and has a very long and sticky tongue to get these insects. The anteater lives in an entirely different part of the world and has live births. It also has a very long and sticky tongue. After analysis by scientists, it is determined that these tongues look similar initially. However, they are actually very different and evolved independently of each other. TASMANIAN WOLF & TIMBER WOLF In this situation, both animals look very similar to each other. They are short and walk on 4 legs. They eat meet and have good capacity to chew. They are also good runners. They have the same role as top predators wherever they live. However, the structures of their internal body are NOT similar. Tasmanian wolves are marsupials and only are pregnant for 2 weeks. Timber wolves are pregnant for many months. The internal reproductive systems are very different. Ultimately, scientists agree that these are NOT closely related to each other. DARWIN S FINCHES
In this situation, the many islands of the Galapagos have many different species of finches. A few finches are found on all islands. However, it is apparent that different islands have different finches. Different islands have different food sources and weather. This put pressures on birds over time to be successful on this island. As birds migrated to new islands, they evolved to succeed the conditions on that particular island. Over time, the differences between islands added up. Instead of one type of finch on all the islands, there are now 13 similar looking, but different species of finches throughout the Galapagos. BAT WING & PENGUIN FLIPPER In this situation, the bones of the bat s wing are long and extended to help create a wing to fly with. In a penguin, the bones are shorter and flatter to create a strong flipper to swim with. On the outside, the two structures look very different. However, if one looks at the internal anatomy, scientists find that the bones in the bat and the penguin are the same. The only difference is the exact size and shape of each bone. However, the bones are in the same order and set-up between the penguin and bat. HUMAN GILL SLITS
For this structure, all humans have gills at one point in their life. When the human embryo is growing inside the mother, there is a time when the embryo has gill openings. All vertebrates, including fish, reptiles, amphibians, birds, and mammals, will show gill slits during development. For humans, the gill slits eventually go away (although, not always). For some animals like fish, they stay. This is a good trait to show that we cam from a similar evolutionary line as something like fish. KANGAROOS & RABBITS For these animals, both eat grasses and plants. They are also similar sizes, for most species. They also have very large back feet, which allow them to hop better than run. Their behaviors and functions are very similar, even though they lie in very different places. However, they are a great many internal differences between the two species. Kangaroos have a short pregnancy (1-2 weeks), while rabbits will be pregnant for months. Their internal organ and bone structures are different enough that scientists agree they are not closely related. TAILS OF FISH AND WHALES
The back tails of a fish and whale provide the same function. They help push the animal through the water. They are large and powerful to help them with swimming. They have the same function. However, they are very different in structure. Fish tails are not made of bone and move from side to side. Whale tails are bony and move up and down. FEATHERS & REPTILE SCALES Scales on reptiles help to protect the animal, keep them warm, keep water in their body, and keep them dry. Feathers are ways for birds to do the same things. They also help the animal to fly and even catch food. When one looks at both structures, they are made of the same materials. When you look under the microscope, scales and feathers are structured the same and look very similar. Essentially, feathers look like reptile scales that have been exaggerated. BIRD BEAKS & TEETH
In birds, beaks are notched and used in a way to catch food, tear it up, chew it, or manipulate it. In mammals, teeth are used in the same way. Even though the functions are the same between beaks and teeth, the actual make-up of each structure is very different. Teeth are made of enamel and dentine. Beaks do not have this material and are made of bone. ELEPHANT TRUNK Some believe that elephants evolved their trunks because the trunks were helpful in getting food. Some believed that elephants needed longer trunks to get food. So, elephants would tie their trunks to a tree stump and pull backwards on it. This would stretch the trunk out. If the elephant had babies, the offspring would have stretched trunks as well. After a while, it was determined that this theory was incorrect. LEMURS
On the island of Madagascar, all of the world s lemur species can be found. Lemurs are a type of primate. All the lemur species have the same body structures and forms. It is believed that one type of lemur developed on the island many millions of years ago. This lemur spread throughout the island. The island has many different habitats, which require different adaptations to succeed in. Over time, lemurs living in different habitats started showing differences that would help them in their environment. Over time, the differences added up and there are now over 20 different lemur species (each usually found only in one type of habitat). CAT CLAWS One could pose the theory as why cats have sharp claws. Some might say that early cats had dull nails, such as what humans have. However, cats ground the nails down on rocks and the ground. Once a cat ground the nail down, it was sharp and could be used to grip the ground in running. It could also be used to catch prey. Once a cat had sharp claws created from nails, their babies would also have sharp claws. This theory is NOT correct in regards to the development of cat claws. GARTER SNAKE & RED-BELLIED NEWT
Newts are eaten by snakes. Red-bellied newts started to evolve a poison to make predators sick if they tried to eat them. Most snakes would avoid the newts. However, some snakes then evolved immunity to the poison. So, they continued eating newts. In response, the newts evolved to make more poison. Eventually, snakes developed more immunity. Now, current newts make enough poison to kill hundreds of men. However, the snakes are still evolving immunity to the toxin. JAWBONES OF REPTILES & EAR BONES OF MAMMALS In some groups of advanced reptiles, there were many jawbones in the lower jaw of the animal. Over time, many of the bones were not used in the jaw and were lost. Many advanced reptiles soon had 1 really large lower jaw bone with 2 tiny ones at the end of it. In mammals, the ear has 3 ear bones. 2 of the 3 bones look just like the tiny bones found in the reptile jaws. Scientists believe that the lower jaw bones of reptiles became useful to mammal hearing and eventually became incorporated in the ear. This seems to indicate that mammals and reptiles are related. INSECT EYES & HUMAN EYES
Both insects and humans have eyes, which are used for the same function of seeing things. However, if you look closely at the internal structure, it is clear that these eyes are structured very differently. Insects have compound eyes, which are eyes with many lens. Human eyes are simple and only have 1 lens. Scientists tend to think that these eyes are not related to each other. EYES OF THE CAVEFISH Cavefish are types of fish that lives in very dark caves. In certain areas, there is little to no light in the environment. Therefore, eyes are not useful to the fish, since eyes require light to be used. Over time, the eyes of the cavefish have sunk underneath the skin. They are still there. However, they are not used and are very small. CICHLID FISHES IN LAKE MALAWI
In this situation, a general fish found its way to this freshwater lake in Africa. The lake is very large. There are many different environments within the lake for fish to succeed in. Over time, certain fish became adapted to certain environments. Therefore, they started to behave and look differently, since each environment selected for particular traits. Now, there are over 500 species of cichlids only found in Lake Malawi. All are believed to have evolved from one or a few basic type of fish many millions of years ago. CHEETAHS & PRONGHORNS At one point on Earth, cheetahs lived in North America. They ate an antelope-like animal called a pronghorn. Pronghorn needed to be quick to outrun the cheetah. Therefore, fast pronghorn survived and this trait moved to the next generation. In response, the cheetah needed to be faster. So, future cheetah populations were faster. Faster cheetahs meant pronghorns got faster. This back and forth battle continued to result in cheetahs being the fastest land mammal and pronghorns being the fastest land mammal in North America currently. OSTRICH WINGS
Ostrichs are birds that do not fly. They have changed over time to be very large and good at running. Their feet are equipped to run over long distances. Since the bird is too large to fly, the wings are not needed for this purpose. Over time, the ostrich wings have been smaller and reduced. The wings represent that they are birds and are related to other birds (since the wings are internally the same as flying birds). However, they are small and not used anymore.