New Evidence to Human Evolution

New DNA evidence has been discovered in the genomes of modern hunter-gatherers of Africa. This evidence suggests that the development of the human species was driven by ethnic groups interbreeding rather than a superior original species

Members of the scientific community have long supported the “Y Chromosome Adam” theory. This theory explains that human genetic sequencing can be traced to one ancestor as the origin of the species. Genetically, Approximately 50,000 to 200,000 years ago, a doubling of the DAZ gene occurred in hominid males creating larger amounts of testosterone. The higher levels of testosterone led to the evolution of bigger and more developed brains

DNA evidence among modern hunter gathering tribes shows foreign-looking stretches of DNA not common amongst its original ancestors. The observations made of the Pygmies of Cameroon show that genetic differences in evolution like smell, taste, immunity, and a genetic variant that explains the short stature of the Pygmy people (4’11’’ avg. height). Similar foreign DNA could be found in other tribes separated by geography like the Hadza and Sandawe who have little to no intertribal contact.

Evidence suggests that “archaic” humans are the species involved like Neanderthals and other protohuman species more closely related to apes. They share ancient genetic material with “modern” species. The most notable fossil with similar genetic ties found of a protohuman is the skull of a “Homo Heidelbergensis”, a species existing 500,000 years ago and are ancestors to Neanderthals.

It is unclear whether this “ancient” DNA from primitive humans is helpful, harmful, or even relevant to humans today. The theory is still relatively incomplete but opens up the possibility that humans originated from different geographical positions. Also its important to note that Human evolution developed differently for species in different regions. Genetic similarities by no means guaranteed successful evolution as demonstrated by the point that ancient unsophisticated protohumans could exist alongside far more complex newly developing homo-sapiens.  

Conrad Oberbeck

žhttp://www.cio-today.com/story.xhtml?story_id=12300F5C52HX&page=1

žhttp://www.ncbi.nlm.nih.gov/pubmed/12449688

Infant DNA Testing for Rare Diseases

The NYTimes recently reported on a new method of analyzing the DNA of newborns that can zero in on mutations that cause disease in only a couple days instead of the typical couple weeks.

The test is a proof of concept and demonstrated in four infants that it is possible to scan a baby's DNA and pinpoint disease-causing mutations quickly. The main idea behind the testing is to take advantage of what is known about the symptoms to focus the search for genetic aberrations.  The researchers tested their methods by trying it with two babies whose disease was diagnosed only through an autopsy. Then they used the method on four babies who were having seizures and they found the mutated gene in three of the four.

This is a major step forward because instead of just searching the entire genome–specific suspected parts are targeted to expedite the process.

Moreover, this test avoids an ethical problem since it only focuses on the parts of the genes that cause disease in newborns. Unrelated genetic findings are such as Alzheimer's risk are unnecessary in these circumstances and would not be relevant. This is avoids a scene reminiscent of that from Gattaca (1997) where the baby is born and all of its potential genetic problems are listed.

About one in 20 babies in newborn intensive care units has genetic disease and many times it cannot be figured out. With this test, it will be much easier and much more efficient for diagnoses. Scientists identified faulty genes for about 3500 genetic diseases and about 500 have treatments.

One of the problems of this test is that many times there are not treatments for the diagnosis and that the test is helpful for the families to get closure. Only one of the six babies survived. Additionally, the cost of this test is currently $13,500 and is not covered by insurance but hopefully the price will decrease as the test becomes more mainstream.

Sources: http://www.redorbit.com/news/health/1112706540/genetic-blood-test-for-infant-disease-100412/
http://www.nytimes.com/2012/10/04/health/new-test-of-babies-dna-speeds-diagnosis.html?src=recg

Whole-Genome Sequencing of African Hunter-Gatherers Reveals Human Genetic Diversity

According to a recent article on EurekAlert.org, a new study by a University of Pennsylvania researcher has found that whole-genome sequencing of African hunter-gatherers give insights into how humans have adapted to distinct local environments over evolutionary history. Published in the scientific journal, Cell, on July 26, 2012, the study has significantly furthered knowledge about the scope of genetic diversity in humans.

Because all modern humans originated from the African continent, it contains the highest level of genetic diversity in the world. Study author Sarah Tishkoff noted that although African populations have been instrumental in today's understanding of human evolutionary history, very little is known about variation in African genomes. Until now, scientists have only analyzed six African genomes, sequencing regions several times to reach the highest possible accuracy.



To better grasp the foundations of human genetic diversity and natural selection in diverse environments, the team sequenced the entire genome of 15 African hunter-gatherers from 3 different population: forest-dwelling, short-statured Pygmies from Cameroon, and click-speaking Hadza and Sandawe individuals from Tanzania. Researchers were able to identify over 13 million variations in DNA sequences in those genomes; more than 3 million of which were absent from existing databases.

This study also revealed signs of natural selection in genetics: compared to other populations, the hunter-gatherer populations showed distinct DNA patterns in genes involved in immunity, metabolism, smell, and taste, leading researchers to the conclusion that human populations adapted to specific environments.

Source: http://www.eurekalert.org/pub_releases/2012-07/cp-wso071912.php

Debunking the Hunter-Gatherer Workout

The current levels of obesity and obesity-related health issues are epidemic in the United States and in other developed countries. While there are numerous debates occurring in the healthcare, politics, economics, and cultural areas of society about what the causes are for this obesity crisis, evolutionary genetics has a debate of its own going on regarding the causes of obesity. When we look at Darwin’s theory of evolution, it is clear that obesity must have some roots in the fact that our lives are radically different from how they were for our hunter-gatherer ancestors. However, the point of contention lies in what aspect of this difference is to blame for our epidemic—is it the fact that our activity has changed, or that our diet has changed?

According to Debunking the Hunter Gatherer Workout, a New York Times article written by scientist Pontzer, the key is the change in our diet. Pontzer cites his own study, published in the PLoS ONE journal, as evidence. He and his colleagues went to Tanzania to get data from a tribe of hunter-gatherers—one of the few left in existence. The Hadza people live simple lives and their daily activity consists of just that—women are on the move scavenging over hilly terrain for food (sometimes while holding children and water), and men are traveling 15-20 miles a day hunting game. There is no obesity, diabetes, or heart disease in the tribe.

Pontzer measured the Hadza’s physical activity level and how many kcal/day they burned, comparing the data with that of a typical American or European, and accounting for age, sex, body mass, and fat mass. His results were interesting: they showed essentially no correlation between physical activity level and BMI. An idea that the Hadza people might have more efficient bodies was ruled out through other data. Therefore, Pontzer and his team reached the conclusion that Hadza tribesman’s bodies must have adjusted over time to account for their intense physical activity, possibly by expending less energy in behind-the-scenes cellular processes that the majority of our energy expenditure consists of.

The implications of this study and article for obesity are that America must encourage a change in diet over activity. This is the most key aspect of our lives that has changed from the time we were hunter gatherers to our current status as modern human beings. It is certainly necessary to educate our country about this study and to encourage healthy eating habits in order to improve the well-being of our fellow citizens. 

Sources:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0040503

http://www.nytimes.com/2012/08/26/opinion/sunday/debunking-the-hunter-gatherer-workout.html

Gene Therapy for "Bubble Boy" Disease

"Stem Cell Researchers Use Gene Therapy to Restore Immune Systems in 'Bubble Boy' Disease"

(ScienceDaily)

(credit: iStockphoto)
According to a recent ScienceDaily article, UCLA stem cell researchers have just completed an 11-year study which showed that gene therapy can be used to treat ADA-deficient severe combined immunodeficiency (SCID) or "Bubble Boy" disease. This disease is usually diagnosed when a child is six months old and can be fatal within one or two years. Children with SCID are very vulnerable to infectious diseases. This study looked at a combined gene therapy and chemotherapy treatment regimen, which restored the immune function in three out of the six children who received the treatment. The size of the study was very small; only ten children were involved. The study tested two different viral vectors to deliver healthy ADA genes into the bone marrow cells of the patients. This would then allow the enzyme to be produced in the body and, as the article says, "make up for the cells that don't have the gene." The patients who received the additional chemotherapy treatment had more success than the patients who did not and who continued with the enzyme therapy in addition to the gene therapy.

Before gene therapy became a possibility, the only treatment for ADA-deficient SCID is a very expensive and life-long regime of twice-weekly enzyme injections or, rarely, bone marrow transplants from matched siblings. So far, gene therapy treatment has been given to 40 children in the world.

Dr. Donald Kohn, a professor of pediatrics, microbiology, immunology, and molecular genetics in Life Sciences, who contributed to this study, says "We were very happy that in the human trials we were able to see a benefit in the patients after we modified the protocol. Doctors treating ADA-deficient SCID have had too few options for too long, and we hope this will provide them with an efficient and effective treatment for this devastating disease."

This study indicates that gene therapy is getting closer to saving the lives children suffering from ADA-deficient SCID.

Article: http://www.sciencedaily.com/releases/2012/09/120911111626.htm
Journal Article: http://bloodjournal.hematologylibrary.org/content/early/2012/09/10/blood-2012-02-400937

"Healing Broken Batteries"

"Regulator to consult public plans for new fertility treatments" (Ian Sample, The Guardian)

In the United Kingdom, 1 in every two hundred people are affected by diseases caused by glitches in the genetic material in the mitochondria.  These diseases most often affect the brain, heart and muscle function.  

Mitochondria, often thought of as the batteries for they provide energy, are composed of 37 genes.  The genes contribute to 0.2% of the genetic makeup.  Mitochondria are only passed down from mothers. 

The Welcome Trust Centre for Human Genetics at the University of Oxford would like to reduce, and ultimately end, the number of diseases caused by glitches in the genetic material in the mitochondria.  

To do so, the Centre has been developing two processes of genetic modification; maternal spindle transfer and pronuclear transfer.  Of the two processes, maternal spindle transfer is the more developed of the two.


During maternal spindle transfer, the nucleus of the mother's egg is removed and inserted into a healthy female donor's egg.  Thus, the egg has the mother's chromosome (held inside the nucleus) and the donor's healthy mitochondria.  This new egg is then fertilized by the father's sperm, and the resulting offspring contains the DNA of both parents and the mitochondria of the healthy female donor.  

Pronuclear transfer is essentially the same process, but is performed on an early-stage embryo as opposed to an egg.  

This form of genetic modification is not yet legal or public.  It is rather controversial, for it is yet another step using genetic modification.  Jeremy Hunt, the Health Secretary, is to be informed of public opinion and of the process by the Human Fertilization and Embryology Authority.  A parliamentary debate will be held to consult Jeremy Hunt and HFEA to determine the legality.  

There is great controversy surrounding the work of the Welcome Trust Centre.  How far will genetic modification go?  Will we eventually be creating "ideal" offspring by using different parts of cells?  Should the donor be anonymous?  These questions are all of great concern in determining whether this form of genetic modification will be approved.  

Interacting Mutations Promote Diversity

Genetic diversity is maintained through the balance of mutation, genetic drift, and selection. This evolutionary biology study from Mac Planck Institute explores the competition between mutations within a population and how it promotes diversity. To do so, the study analyzes the fitness value of a gene and uses evolutionary game theory principles to come to the conclusion that the fitness of a mutation depends on its frequency. Fitness is a measure of success for a given gene, i.e. the number of offspring produced in the next generation that survive and reproduce. Basic evolutionary theory states that a single allele must compete with other alleles in a given gene pool and either become established or die out. The emergence of a mutation within a gene pool, in particular, creates diversity because it increases the number of phenotype possibilities for offspring (see above figure, a). This same reasoning can also be applied to competition between different mutations. Therefore, evolutionary competition between mutations has produced "stable polymorphisms." This study is significant in that it helps us develop a greater understanding of population genetics and the inheritance of genes.

News Article: http://phys.org/news/2012-06-interacting-mutations-diversity.html

Primary Research Article: http://www.nature.com/ncomms/journal/v3/n6/full/ncomms1930.html

Other Sources: http://www.uic.edu/classes/bms/bms655/lesson13.html