Scientists crack mystery of how MS gene spread

 

In this article by Philippa Roxby, the author discusses research into why certain diseases such as multiple sclerosis (MS) are more common in certain parts of Europe.

To determine why, researchers extracted genetic information from 5,000 ancient humans. The discovered that the gene increasing the risk of MS entered North-Western Europe around 5,000 years ago along with the arrival of a population of nomadic cattle herders. It was discovered that that MS is driven by genes that would have protected the herders against diseases carried by their cattle. In the modern age, due to vastly different lifestyles, these gene variants are now associated with a higher risk of diseases such as MS.

The attached articles were also quite interesting to me. In the second article, something that stood out to me was a quote from a scientist not associated with the study. She stated that studies such as this should be extended outside of Europe to understand how historical population differences contribute to the risk of autoimmune diseases. I emphatically agree with her; I generally find that I only hear about discoveries such as this taking place in Europe. I believe we as scientists need to broaden our horizons and extend our research worldwide. 

Article: Scientists crack mystery of how MS gene spread

Additional Information: Gene that protected humans 5,000 years ago may be linked to debilitating modern disease

DNA from Mysterious Asian Mummies Reveals their Surprising Ancestry

     

Naturally mummified bodies were found in the desert-like Tarim Basin located in western China. These preserved bodies were determined to be from about 4000 to 1800 years ago. The 4000 year old mummies that were excavated belonged to the Xiaohe population. These people's culture revolved around herding animals and growing plants. Their coffins were very different from the others as they had preserved cheese, wheat, and clothes that were actually made from western Eurasian wool. This hinted that the Xiaohe people had distant contacts or origins.

Archaeologists in China performed at a study where they analyzed DNA from 13 of the bodies found in the Tarim Basin as well as five human mummies from the Dzugarian Basin. From the analysis of the study, the Tarim population had traceable ancestry to hunters and gatherers who inhabited northern Eurasia more than 9000 years ago. The studies also suggest that the Xiaohe culture did not mate with any outsiders for a very long time. The analysis of the mummies from the Dzungarian Basin showed that their ancestry dates back to the Afanasievo culture. Milk proteins were found in the dental tartar of these mummies which indicates that they consumed dairy products in their lifetime. 

The First Denisovan Fossil From Outside Siberia Has Been Found in China

In 2016, Jean-Jacques Hublin, paleoanthropologist and director of the Department of Human Evolution at the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, was emailed by archaeologist Dongju Zhang about a highly unusual hominin mandible found in a cave on the Tibetan Plateau in Xiahe, China. The photos she attached stunned Hublin. This fossil was quite complete and clearly nonmodern. It wasn’t long after that they met in Leipzig and began planning their collaboration and recruiting a team of specialists for a study on this strange fossil.

On May 1st of this year, Hublin, Zhang, and their team published the results of their study in the journal Nature. Their analysis confirmed that it belonged to the mysterious branch of hominins known as Denisovans, which were first identified in 2010. Never before had a bone fragment from a Denisovan been found outside a single cave in the Altai Mountains of Siberia.

Moreover, this is the most complete fossil of one ever discovered, as all the previous ones, including the recently uncovered skull piece I reported on in an earlier article, have been small and fragmented. The Xiahe jaw will help scientists tremendously, as now they will have a reference specimen to compare currently unidentified fossils to. Until this point, the anatomy of Homo denisova has been almost entirely unknown and speculative. This finding will thankfully add another eye-opening piece to the puzzle.

Hublin and his team were able to identify the fossil as Denisovan thanks to the work of his PhD student, Frido Welker, who had figured out that ancient proteins can be preserved much longer than ancient DNA, and therefore they could be used to map hominin groups in the absence of the latter material. Genome sequencing of Denisovans and their famous “sister” hominin, Neandertals, allowed the researchers to suppose the structure of these proteins and subsequently flesh out the separate branches. In the case of the Xiahe jaw, there was no ancient DNA, but the teeth yielded some proteins. These were then analyzed and matched using the aforementioned technique. The results were clear, this Tibetan fossil was a Denisovan.

DNA Analysis Unveils Fate of Ancient Canaanites

The New York Times published an article about Dr. Tyler Smith and a team of geneticists and archaeologists that recently found DNA evidence that contradicts a story in the Hebrew Bible.  In the story, God requests the annihilation of all living things including the Ancient Canaanite population.  Dr. Smith and the teams excavated five Canaanite bodies and recovered DNA from the bones; the bodies are known to be between 3,650 to 5,750 years old.  Teams compared the DNA with the genomes of 99 people living in modern day Lebanon and found that modern Lebanese people shared about 93% of their ancestry with the excavated bodies.  Unlike other civilizations from this time period, not much information is known about the Canaanite population.  The discovery of modern day Canaanite ancestry could possibly answer some questions about the population.  These finding are interesting because it shows that the population only changed slightly over a long period of time.    The results also bring up many questions for the Hebrew religion.

Modern Human Ancestors Interbred with Extinct Hominins

A study recently published in the journal Science found that the ancestors of modern humans interbred with Neanderthals and Denisovans over the course of prehistory.  The interbreeding may have given us an evolutionary advantage, particularly with increased immunity to pathogens.  A review of the article was published by the New York Times last week and authored by Carl Zimmer.  Zimmer included a quote in the review by Charles Lalueza-Fox, a research scientist at the Institute of Evolutionary Biology in Barcelona Spain, who was not involved in the study who said, “This is yet another genetic nail in the coffin of our oversimplistic models of human evolution." 

The data from this new study expands on a series of findings that has been collected over the past several years.  This body of information concludes that the ancestors of modern humans interbred with extinct hominins.  This shows that the ancestors of modern humans once shared the planet with a surprising number of near relatives; specifically the Denisovans and the Neanderthals.  The interbreeding between these ancient human groups has left its mark in our DNA, which still carry from these encounters.  The first studies that discovered the ancient interbreeding were published in 2010 when scientists found that certain modern humans, mostly of European decent, had DNA that matched the genetic material extracted from Neanderthal fossils.

 Later studies  hypothesized that the ancestors of modern humans encountered Neanderthals over 50,000 years ago after leaving the African continent.  However, Neanderthals were not the only extinct humans our ancestors found.  A finger bone of a modern human was found to contain Denisovan DNA in a Siberian cave.  Later research concluded the modern humans, Denisovans, and Neanderthals share a common ancestor who lived around 600,000 years ago. A geneticist from the University of Washington, Joshua M. Akey, and his colleagues also found in their study that all the non-Africans had Neaderthal DNA and those of African descent had very little or none.  This is yet another study that supports the Out of Africa model. I like learning about human evolution and I think it is awesome that we can use genetic analysis to learn more about our ancestry.  The archeological field is benefitting from the genetics field and it helps the scientific community put together a more accurate picture of how we evolved. 

Royal Bones Found in Parking Lot

Two years ago an old skeleton was found under a parking lot in Leicester England. The archaeologists who found the skeleton claimed they found the bones of Richard III, a 15th century monarch. This claim was based on the fact that the skeleton was male, the right age, had battle injuries, and scoliosis. The scientists couldn't be entirely sure it was him so of course DNA evidence was needed.

Image from http://www.thetimes.co.uk/tto/multimedia/archive/00380/RichardIII_380709a.jpg

Today, December 2nd, it was announced that the DNA analysis of the skeleton was completed. It was reported in Nature Communications. The DNA analysis proved that they bones did belong to the former king. The scientists were able to trace the genetic evidence through more than 20 generations of the dead King's family tree to his living descendants. This means that the oldest DNA identification case of known individual was completed.  Turi King, the lead geneticist who lead the analysis stated that they were even 99.999% sure that the remains belong to Richard III.
What the team did was scrape together a DNA profile from a very old skeleton. Since the DNA was so old and damaged, scientists had to look through millions of ribbons of splintered DNA strings. Also to make sure the analysis wasn't contaminated, scientists did the sequencing in multiple clean rooms at multiple locations. Then the profile was compared to Richard III's living relatives. That was still difficult though because an ancestor from 20 generations back would only contribute .000001 of an individual's DNA. What does go almost unchanged through generations is mitochondrial DNA and the DNA on the Y chromosome. Mitochondrial DNA only comes from the mother allowing scientists to look at an all female line through the family tree. It was discovered that the descendants had the exact same mitochondrial DNA except for 1 single mutation. Richard did not have a pure male-line descendants making the tracking of the Y chromosome difficult. The team had more than enough information though.
I thought this was extremely interesting and relevant to class because we were looking at case studies similar to this with mummies and learning about how difficult it is to extract DNA from the dead and how there is a great risk of contamination. It is amazing what can be done with information on someone's DNA.

Article: http://www.popularmechanics.com/science/health/genetics/scientists-confirm-remains-king-richard-iii-17487010