Evidence for Evolution Web
Quest
Yanique Bell
April 1, 2010
Period 9/10
Fossil Evidence
Fossils have been used by scientists since as early as the seventeenth century. Fossils are physical
evidence of historic organisms that can appear in rocks, amber or ice. Fossils are used as proof of what
organisms lived in the past to paleontologists, scientist who study existing life forms through the use of fossils.
There are five types of fossils: trace, casts, molds, petrified or permineralized, and amber-preserved or frozen
fossils. To explain, a trace fossil is any indirect evidence left in a sedimentary rock, such as a footprint, trail, or
a burrow. A cast is formed when rock minerals fill the empty space left by an already decayed animal and an
identical shell or cast is formed. A mold is fossil evidence that is formed when an organism is buried in
sedimentary rocks and traces are left in the rock once the organism has decayed. A petrified and permineralized
fossil is formed when minerals go through and replace the hard parts of an organism or fill up the empty spaces
of the organism. Finally, frozen fossils are fossils of an entire organism frozen in ice or tree sap that turned into
amber (Biggs 370-371, 1127). Many fossils formed millions of years ago and scientists are able to gather
information from them today.
Furthermore, paleontologists use these fossils in several ways as evidence of evolution. For example,
fossils can be used to compare existing species to extinct ones. To illustrate, in the 17 th century Nicholas Steno
found that “tongue stones” resembled shark teeth. It turned out that the “tongue stone” was a fossil of a tooth of
a shark that was extinct. Second, fossils can also be used to determine the behavior of past organisms and how
they interacted with their environment. To explain, a trace fossil was left on a cast fossil of an ammonite.
There were several bite marks thought to be from a mosasaur, a carnivorous marine lizard, on the ammonite. It
would have been possible for the mark to be from a mosasaur because they are predators and their teeth and jaw
size and shape are similar to the marks. There are other possibilities such as limpets that could have made these
marks. This fossil evidence can tell paleontologists what and how mosasaurs ate or how limpets interacted with
their environment. In addition, fossils can also be viewed on a cellular level. In explanation, the photo on the
left is of a cross-section through a sub-adult thigh bone of a duckbill dinosaur called
Maiasaura. From this fossil you can see that this organism had many blood vessels
which are represented by the white spots; this means that it grows quickly. The dark,
almost black, curvy line towards the center shows a period of time when the organism
experienced a seasonal pause in growth (Fossil evidence). Finally, fossils are also
used to show transitional forms. Transitional forms are evidence of changes. An
example of transitional forms is that in the skull of a Pakicetus, which is one of the
early ancestors of a whale. The nostrils of the Pakicetus was low and it was a land animal. Then as
paleontologists continue to discover other whales, over time their noses became closer to the top of the skull
(Transitional forms). Clearly, fossils are a great source of evidence.
Biggs, Alton, et al. Biology: The Dynamics of Life. New York, New York: McGraw Hill, 2004. Print.
Fossil evidence. N.p., 2004. Web. 27 Mar. 2010. http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_02
Transitional forms. N.p., n.d. Web. 27 Mar. 2010. <http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_03>.
Anatomical Evidence
Anatomically we are all made of the same basic elements and have similar structures and division
processes. In fact, all living things are made of the same six most frequent elements out of ninety-nine. Also,
although there are an immense amount of living things on Earth, they all consist of twenty amino acids. By
using anatomical evidence, it is safe to say that organisms that are very similar came from a common ancestry.
Anatomical Evidence can be used in many ways. First, invertebrates are organisms with an internal skeleton,
such as, dogs, casts, birds, whales, and seals. These organisms all have the same type of bone structure inside
there arms; they all have a humerus, radius and ulna. Due to the fact that these vertebrates have similar
structures scientists are able to conclude that all vertebrates evolved from a common ancestry(Biggs 400-402).
These similar structures are known as homologous structures, structures with a common ancestral origin.
Homologous structures are seminal in alignment, function or both. Next, if organisms have structural or
functional similarities, it is possible that the organisms are not closely related. This means that these are
analogous structures. Analogous structures are body parts that are similar in function but are not from a
common evolutionary origin. To illustrate, birds and butterflies both have wings. These wings are not similar
in structure but they are similar in function. Bird and insect wings are not related and evolved over time
separately from each other because they have two completely different groups of ancestors. Clearly, analogous
structures do not prove that the organisms’ ancestors are related. On the other hand, it does show some
evidence of evolution. From the wings of flies and butterflies paleontologists can tell that they most likely
evolved away from each other and their ancestors independently adapted to their similar environment and
lifestyles. To continue, vestigial structures are body parts in a currently living organism that is no longer used
for its original job. Vestigial structures shows evolution because the structure was used by the species’
ancestors. The species would have had to evolve and it was no longer in need
but is still passed on to every generation.
Scientist can study vestigial
structures in animals like the baleen whale who has a pelvic bone that is no
longer needed and try to figure out what their ancestors were and what they
used this body part for(). In addition, in 1798 a French anatomist, É´ienne
Geoffroy St. Hilaire, traveled to Egypt with Napoleon and he saw and described a Cassowary bird that no
longer used its wings to fly. Instead of using its wings to fly as its ancestors did it now uses its wings to balance
when running and to attract attention while mating (Miller). Another way that anatomical evidence is used is to
compare organisms, whether it be two at a time or a group. For example, scientists have compared the
forelimbs of mammals like humans, whales, dogs and bats and they have the same amount of bones, structure
but different function; this means they share those homologous structures and evolved from a common ancestor.
Hence, anatomic evidence is used in many ways to find evolutionary evidence or relationships ().
Biggs, Alton, et al. Biology: The Dynamics of Life. New York, New York: McGraw Hill, 2004. Print.
Miller, Brandon. “The top 10 useless limbs (and other vestigial organs).” LiveScience. N.p., 2010. Web. 28 Mar. 2010. <http://www.livescience.com/animals/top10_vestigial_organs-1.html>.
“Comparative anatomy.” Science.jrank. N.p., 2010. Web. 28 Mar. 2010. <http://science.jrank.org/pages/348/AnatomyComparative.html>.
O’Neil, Dennis. “Evidence of Evolution.” Anthro.palomer. N.p., 2010. Web. 28
Mar. 2010. <http://anthro.palomar.edu/evolve/evolve_3.htm>.
Embryology Evidence
Embryology is a branch of biology that studies how
embryos form, develop, their structure and function (Embryology).
An embryo is the earliest stage of growth and development in pants
and animals. By comparing and contrasting embryos, scientists can
find evidence of evolution. For example, when looking at the embryos of a fish, bird, reptile, bird and mammal,
it is clear that they look very similar and almost identical. Each embryo has a tail and pharyngeal pouches.
These pouches develop into different parts of the body in different organisms. The pouch forms gills in fish,
but par, jaw, and throat body parts in the reptile, bird, and mammal. Overall, these similar embryos tell
scientists that these organisms evolved from a common ancestor (Biggs 402). Furthermore, embryos can be
compared but the way they develop can also show proof of evolution. To demonstrate, human embryos along
with rabbits, dogs and apes, undergo a stage of development where they have a tail. Also, at some point in
development, humans have a fish like heart, gill- slits and circulatory system. These similarities in development
show that mammals, birds and reptiles probably evolved from fish like ancestors (Embryological). Next,
scientists are also able to view the development of the embryos. Although, Ernest Haeckel (1834-1919), a
German biologist, created fake drawings of embryos to prove that he was right about certain embryo were
similar from the beginning, he was not completely wrong about the similarities of the embryos. Invertebrates,
fish, and other groups of organisms do not look completely identical at the beginning of development. On the
other hand, during some stages a group of organisms develop a familiar trait. For example, during one stage, all
vertebrates develop a two chambered heart with a single circulation. Then, as development continues, embryos
gain their special features and they no longer look identical. Therefore, by analyzing the development of
embryos scientists can see what structures the organisms’ ancestors had and their many adaptations during
evolution (Comparative). Clearly, embryological evidence is very useful.
Biggs, Alton, et al. Biology: The Dynamics of Life. New York, New York: McGraw Hill, 2004. Print
“Embryology.” Dictionary.com. N.p., 2010. Web. 28 Mar. 2010. <http://dictionary.reference.com/browse/embryology>.
“Embryological Evidences Of Evolution.” Transtutors. N.p., n.d. Web. 28 Mar. 2010. <http://www.transtutors.com/
homework-help/Biology/Evidences+of+Evolution/embryological-evidences-of-evolution.aspx>.
“Comparative embryology.” Tutorvista. N.p., 2008. Web. 28 Mar. 2010. <http://www.tutorvista.com/content/biology/
biology-ii/heredity-and-evolution/comparative-embryology.php>.
Biochemistry Evidence
Biochemistry evidence is great proof of evolution because almost all organisms have DNA, ATP, and
many enzymes within their biochemical molecules.
First, biochemistry evidence can be used to prove
relationships between organisms. To explain, the enzyme cytochrome c is located in many different organisms.
Biologists can use cytochrome c to see how diverse or similar species are by finding the amino acid sequences
in this enzyme and comparing them. If the sequence is very different then the species are very different and
probably evolved separately. Meanwhile, if there are fewer differences and many similarities then they are
closely related and most likely share a close ancestor (Biggs 402-403). So, the cytochrome of cows and
monkeys are more similar than those of moneys and fish. This means that cows and monkeys are more similar
(Evolution). Furthermore, protein homologies are great evidence of evolution. To illustrate, all organisms are
made of the same twenty amino acids. This suggests that all organisms were from a common ancestor. Plus,
the protein, hemoglobin, has many different amino acid sequences that have the same function.
The reason
why these proteins are so similar in many different organisms is due to the fact that they probably evolved from
a common ancestor (Cline).
Moreover, genetic homologies are also used as biochemistry evidence to prove that all organisms
descended from a common descendent. In explanation, all organisms have the same four bases that make up
DNA and genetic buildup. These bases can base pair with other bases from other organisms as well. Second,
all organisms use ATP as an energy storing molecule. This and many other biochemistry evidence proves that
all organisms have a common ancestor but non believers might believe that there is a divine plan by whatever
god they worship. This is a very controversial part of evolution and debates will continue to go on. To
conclude, biochemistry is one of the best sources of evidence because there is a lot of detailed evidence and it
always leads to organisms having a common ancestor (Cline).
Currently, scientists are continuing to use fossil, anatomy, embryology and biochemistry in their
searches and connections to evolution. These forms of evidence support the theory of evolution that is known
today. Therefore, the theory of evolution would be nothing without evidence.
Biggs, Alton, et al. Biology: The Dynamics of Life. New York, New York: McGraw
Hill, 2004. Print
Cline, Austin. “Genetic & Protein jomologies - How genetic & protein homologies prove evolution.” About.com. N.p.,
2010. Web. 28 Mar. 2010. <http://atheism.about.com/od/evolutionexplained/a/
GeneticProteinHomologies.htm>.
“Evolution.” Earlham. N.p., n.d. Web. 28 Mar. 2010. <http://bioweb.cs.earlham.edu/9-12/evolution/HTML/live.html>.