Vitamin C And Common Ancestry

From WikiCaptions

Jump to: navigation, search

Best0fScience5,600 views
Interactive transcript
 [
, 
]
You need Flash player 8+ and JavaScript enabled to view this video.

The following video demonstrates that the theory of evolution is useful for making sense out of biological observations.

According to an article published in an American journal of Clinical Nutrition in 1991, vitamin C is unique, as its essentiality as a nutrient is restricted to only a limited number of exceptional species among phylogenetically higher animals. In other words, nearly all higher animals can synthesize vitamin C.

Vitamin C is a chemical compound required for a range of essential metabolic reactions in both plants and animals. Most higher animals, like this dog, are able to internally synthesize their own vitamin C. Vitamin C is an essential dietary nutrient for some members of the animal kingdom, most notably humans. Because our bodies lack the ability to synthesize vitamin C we must obtain this essential nutrient from the food that we consume. Indeed, people who consume no vitamin C will become sick with a disease called scurvy after just a few weeks. Their small blood vessels will rupture, their bones will be weakened, and their joints will swell. Without vitamin C death will likely occur within a few months. In human history, scurvy has been most common among sailors who traveled long distances without access to a balanced diet including fruits and vegetables.

In 1747 a Scottish physician named James Lind discovered that sailors suffering from scurvy were cured by eating citrus fruit. Lind and his contemporaries did not know that it was vitamin C in the fruit that was responsible for the cure. What follows is a brief history of scientific discoveries concerning scurvy and vitamin C. In 1907 researchers working with guinea pigs were surprised to find that they too were susceptible to scurvy. In 1913 researchers found that they can experimentally induce scurvy in rhesus monkeys. Later research has shown that all of the higher primates including tarsiers, monkeys, gibbons, orangutans, gorillas, and chimpanzees are susceptible to scurvy. In 1933 researchers reported the discovery of the chemical structure of vitamin C and identified IT as the nutrient that prevents the development of scurvy. The following year, in 1934, researchers succeeded in artificially synthesizing vitamin C allowing for mass production of vitamin C supplements that could prevent the development of scurvy. In 1957 researchers discovered that susceptibility to scurvy is due to the inability to produce the enzyme L-gulonolactone oxidase, or GULO. GULO is the last of a series of four enzymes that function to convert glucose into vitamin C. Thus, susceptibility to scurvy was determined to be an internal error of metabolism. In a sense, it means that all animals susceptible to scurvy suffer from a genetic disorder that prevents their bodies from making the vitamin C.

At this point researchers were able to use evolutionary theory to make some testable predictions. If the ancestors of humans, the other higher primates, and guinea pigs originally had the ability to synthesize vitamin C then each of these species should still carry the evidence of this lost ability in their genetic material. In addition, researchers predicted that humans and the other higher primates would likely have the same cause for this lost ability, since the scientific evidence suggested that they have all descended from a relatively recent common ancestor. In other words, they predicted that it wasn't a mere coincidence; decent from a common ancestor was the explanation for why humans and other primates are all unable to synthesize vitamin C. Finally, researchers predicted that guinea pigs, a species that was known to be only distantly related to primates, would most likely show evidence of a different cause for this lost ability.

Eventually, researchers confirmed each of these predictions by finding GULO-related DNA sequences in genomes of humans, other higher primates, and guinea pigs. Just as predicted, the sequences exist as broken genes meaning that they are present but non-functional. Here you can see a portion of the human, chimpanzee, orangutan, macaque, and guinea pig sequences compared to the functional GULO sequence found in a cow. This evidence suggests that a frame shift mutation is what originally rendered the GULO gene non-functional in the ancestor of higher primates by creating a premature stop codon. Just as expected, this particular mutation is not found in the same location of the guinea pig sequence. Instead, the evidence suggests that a point mutation in a different part of the guinea part sequence may have been what broke the GULO gene in the ancestor of the modern guinea pigs, again, by creating a premature stop codon. These completely separate mutations both had the same result: they deactivated the GULO enzyme and rendered the bearers of the mutation and all of their descendants unable to produce their own vitamin C. For the animals that originally inherited these mutations their natural diet probably provided all of the vitamin C they needed. This explains how such a seemingly harmful mutation could become so prevalent that it is now found in all members of these populations. A closer analysis of the DNA sequences confirms another prediction of evolutionary theory. In comparison to humans, the chimpanzee's sequence was the most similar, followed by the orangutan's sequence, followed by the macaque's sequence, followed by the guinea pig and cow sequences. Furthermore, ever since the original mutations broke the genes the altered genetic material has accumulated mutations at exactly the rate that is predicted by the evolutionary theory.

So, there you have it. A close examination of the evidence leads to a powerful explanation of a large set of biological observations. These observations only make sense using the real science of evolution.

I'm Jeremy Mohn. Thanks for watching my video. This video lesson has been brought to you by "Stand up for real science", a website devoted to defending the teaching of mainstream science in public school science classrooms. Visit us at www.anevolvingcreation.net/standup/

Author's description [hide]
"Evolution is REAL Science #2" by
• http://www.youtube.com/standup4REALscience
• http://www.anevolvingcreation.net/standup/

Does the evidence support Evolution?

Theories are crucial to science because they provide a coherent framework for making sense out of scientific observations.

An example of such a theory is the Theory of Evolution. Without the theoretical framework of evolution, biologists would be limited to observing living things and noting the similarities and differences between them.

---
• http://www.youtube.com/Best0fScience
• http://www.youtube.com/FFreeThinker
---

Basic biochemistry combined with cutting-edge molecular research leads us to a powerful explanation of a large set of biological observations. These observations only make sense using the REAL science of evolution.

Read more about this topic:
• http://www.talkorigins.org/faqs/comdesc/section2.html#mol_vestiges

---

Jeremy Mohn is a Biology teacher doing everything he possibly can to stand up to the influential creationist organizations currently trying to sway public opinion in their favor. He feels that it is extremely important to stand up for REAL science in public school science classrooms.
.
You need JavaScript enabled for viewing comments
Retrieved from "http://en.wikicaptions.org/wiki/Youtube:SF2N2lbb3dk"
Personal tools