0635529 Shannon McGonegal 599 words
The hypothesis that whales and dolphins evolved from land-dwelling ancestors can be supported by the theory of common descent, first proposed by Charles Darwin (Belk and Borden 2007). Homology proves this hypothesis through comparative anatomy. Although the forelimbs of bats, sea lions, lions, chimpanzees and humans are used in different ways, they have very similar bone structures (Belk and Borden 2007). The same similarities can be viewed in this picture of a beluga whale skeleton (Gingerich 2009).
  
(www.skullsunlimited.com)
Also its skull exhibits many similarities to other land animals.
-other land mammals ([link])-beluga whale skull (www.skullsunlimited.com)

Whales and Dolphins, both animals of the order of Cetacea, breathe through blow holes atop their bodies, and have to come up from the water for oxygen (Mead and Brownell 2005). If they had evolved from any other aquatic vertebrate, the likelihood is they would breathe similar to a fish. “Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gill filaments. The blood in the capillaries flows in the opposite direction to the water, causing counter current exchange” (www.wikipedia.org)
Additionally, biogeography can prove the theory of common descent with dolphins and whales. There are thirty-three different types of marine dolphins (Rice 1998). The figure below illustrates some of the anatomical differences between dolphin types.

bottled nosed dolphin white beaked dolphin black dolphin
found world wide found in north atlantic found in Chilean waters
(http:images.google.com)

This proves that dolphins have changed and evolved as they have migrated around the world (Belk and Borden 2007) developing new species to better themselves for their new environment. This supports the theory of common descent because they are an adaptive species so one can make a hypothesis that they would be able to adapt again.
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In 2000, the United States collected race in their statistics surveys. I do think that it’s important to collect race data from all citizens because we can use it to analyze evolution. Although we’ll want to be careful to stay away from the Social Darwinism mindset when looking at race, it does help biologists to see what’s changing among the human population. Scientists have found that people in Africa have darker skin than those in Europe because they have a warmer climate, and more sun exposure so their skin has adapted by producing more melanoma (Belk and Borden 2007). Perhaps if biologists record races of individuals and their environments we can make some more correlational hypotheses.
Recording variances in race shows us the development of new allele’s (Belk and Borden 2007) among the population. Regularly recording race allows us to historically account for when new alleles develop. This recording of information could be extremely valuable to future scientists and historians. The discovery that the former notion that cystic fibrosis was a “white” disease was made when we studied each geographic region and their alleles. The same discovery was made that sickle-cell anemia was not just a “black” disease (Belk and Borden 2007). However, studying the occurrence of these alleles in each race, and the statistics for how common they are could aid scientists in discovering how these alleles develop and why. Since each independent evolutionary lineage develops its own features that we can see on the outer surface, it’s likely that many developments within that subspecies are happening. It may be very helpful for government to record race, as well as the presence of malaria sickle-cell and cystic fibrosis in humans, since scientists may be able to make evolutionary discoveries and potentially create a cure.
References Cited
Belk C, Borden V. 2007. Biology: Science For Life. Second Edition. San Francisco: Pearson Benjamin Cummings. 417 pages.
Mead JG, Brownell RL. 2005. Mammal Species of the World. Third Edition . Johns Hopkins University Press. pp. 723–743
Rice DW. 1998. Marine mammals of the world: systematics and distribution. Society of Marine Mammalogy Special Publication Number 4: pp 231
Gingerich PD. February 4th 2009 . New Protocetid Whale from the the Middle Eocene of Pakistan: Birth on Land, Precocial Development, and Sexual Dimorphism. Science Daily. Available from: ([link])
Cited Picture References
[link]
[link]
http:images.google.com