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For as long as humans have lived in complex communities, cities and civilizations, they have divided and classified their societies. Those divisions have been based on age, gender, appearance or &#8211; in many cases &#8211; occupation. In many traditional societies artisans would share the same social status; as would soldiers, priests and workers in any number of other occupations.
<h6>Social Stratification</h6>
In antiquity, the status of a family rarely changed. If you were a farmer, your sons would be farmers, and so on. While today social status barriers are crumbling in many societies, in others they remain largely unchanged.
India&#8217;s complex social stratification, known as the caste system, has been one of the traditional cornerstones of society. Though urban Indians are shedding the caste labels of their parents and grandparents, many rural Indians &#8211; who make up 72% of the entire population &#8211; hold steadfast to the system. In small villages and towns, the Brahmin caste &#8211; consisting of scholars and priests &#8211; is still revered as one of the highest social strata. And members of the Dalit caste &#8211; formerly known as &#8220;Untouchables&#8221; &#8211; are still viewed as unclean and remain separated from others.
The rigidity of the system still present in rural India has made many wonder exactly how long castes have existed. Historical records are unclear, as early Hindu scriptures like the Bhagavad Gita are somewhat ambiguous when it comes to the topic. Some historians even propose that the caste system as we know it today is largely a construct of the English Colonial Era, arguing that the development of such a system could have been deemed necessary to instill order.
<h6>Genetic Analysis</h6>
Genetic analysis has also proven inconclusive, as analysis of small segments of the human genome has yielded different results. But a new study by geneticist David Reich and colleagues, published in the September 24 issue of <a href="https://www.nature.com/nature/journal/v461/n7263/abs/nature08365.html" target="_blank" rel="noopener">Nature</a>, takes a new approach to understanding the genetic history of India.
The core difference between Reich&#8217;s genetic analysis and previous studies is in the sheer amount of genetic material analyzed. Reich&#8217;s team examined more than 550,000 points across all segments of the human genome. In doing so, they hoped to obtain a more complete picture of Indian genetic history.
The research team analyzed the DNA of 132 individuals from India and neighboring regions, dividing them into 25 distinct groups based on geography, caste and language. They calculated how genetically &#8216;closed&#8217; each of these groups were. In the caste system it is rare to marry someone from another class, making caste societies very closed, or &#8216;endogamous.&#8217; If this endogamy continues over many generations, it will leave a behind a genetic signature for scientists to discover.
Reich and his team found such a signature, indicating a long history of endogamy in several of the groups. In fact, the research team calculated that the DNA of six of the groups can be traced back to just a few individuals who lived anywhere from 30 to more than 100 generations ago. Assuming a generation time of 25 years, that establishes the existence of the caste system in the range of 750 to more than 2,500 years ago – long before the British colonial era.
In a second analysis, Reich and his team examined how ancient migrations could have influenced the formation of castes. First the researchers divided the Indian groups into language families: Indo-European and Dravidian. Dravidian tongues, like Tamil and Malayalam, are mainly spoken in southern India and are believed to be a remnant of languages spoken by some of the earliest inhabitants of the region. Indo-European languages, like Punjabi and Urdu, are more common in the north. They are believed to have arrived with a migration of farmers from southwestern Asia or the Near East about 9,000 years ago.
Reich and his colleagues then compared the genetics of each of the Dravidian and Indo-European groups to a sample of European DNA. The team reasoned that, if Indo-European groups were really descended from the farmers, they would show more genetic similarity to the Europeans than the Dravidians.
Not surprisingly, the authors&#8217; hypothesis held true. The Indo-European speakers, like the Kashmiri Pandit and Vaish, were more genetically similar to Europeans. And because the majority of the upper castes speak Indo-European languages, while the lower ones tend to be Dravidian speakers, there could be a relationship between the arrival of Indo-European people and the formation of caste structure. Further evidence that an ancient caste system has permeated through India for thousands of years.

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23andMe Blog Team

New Genetic Analysis Sheds Light on Origins of Indian Castes

I spent the better part of my undergraduate career lugging around massive biology textbooks.  
General biology, genetics, embryology: It didn&#8217;t matter, they all weighed a ton. I pored over endless chapters of text, highlighting the important sentences, always wishing for more photos, more diagrams, more graphs. A single well-made diagram or image was easier to understand than the preceding 10 paragraphs about the same topic.   I always wished that my textbooks were a little more visual and a little less wordy.   An added benefit, I thought, would be that I could shave a few pounds from my backpack.
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My college days are long over. But my wish may have finally come true, in the form of a new graphic guide to genetics entitled The Stuff of Life: A Graphic Guide to Genetics and DNA, by Mark Schultz.   Published in December, it takes a more visual approach to presenting the most current knowledge on a particular branch of the biological sciences close to my heart: genetics.

The Stuff of Life is centered around a group of aliens who are trying to understand the genetics of all life on earth.  These aliens are both rather ugly (the illustrator has drawn them to resemble sea cucumbers) and rather arrogant.  They can&#8217;t seem to understand why a lowly, hairy primate has come to dominate the planet and make such amazing advances in science and technology. In the style of a comic book, with various windows and balloons leading us from the origins of the earth 4.6 billion years ago to modern day applications of genetics and DNA, it falls flat in oddly juxtaposing complex information and somewhat juvenile humor.
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For anyone who hasn&#8217;t taken a college (or advanced high school level) biology class, the information presented will seem overwhelming at best, and confusing at worst.  For those who are well versed in the biological sciences, the information may be understandable but the humor will seem trite and silly.   After the first few chapters of the cucumberesque aliens repeatedly exclaiming that they can&#8217;t believe humans have managed to understand how genes are passed down from parents to children, that they can&#8217;t believe humans have been able to sequence DNA, understand the genetics of cancer, and create genetically modified organisms, I began to dread their appearances. I stopped reading the sections focused on them, instead skipping to the parts that contained actual information. Once I did I began to enjoy the book much more.
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The organization of the book is similar to a standard introductory genetics textbook.   It begins with a description of the structure of the cell, DNA, and how the genes housed within our DNA can determine thousands of physical traits.   Schultz then moves quickly forward, presenting important genetics concepts such as inheritance, dominant vs. recessive alleles, and why my cat has two different colors of fur.   Finally, he spends the last one-third of the book examining modern-day applications to the study of genetics.
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The strategy works well by allowing the reader to understand the practical value of understanding the basic genetics concepts that were brought up in earlier chapters.   Indeed, having more applications-centric lectures during college might have silenced the students who never understood why this field is so important.   Undoubtedly, this section was written with the more general reader in mind.   It is easily the best section of the entire book.
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Though the constant banter from the sea cucumber-like aliens should not interest anyone over the age of 10, this book would be of use to those currently taking an introductory course in biology, as it might help solidify more difficult concepts that might prove difficult to students.   For educators, this book could prove useful in providing fresh ideas on how to present some of the most important genetics concepts.
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The uneven feeling I got from reading The Stuff of Life is something that must constantly be a fear for anyone who is trying to make science fun and accessible to the general populace.   Presenting such important topics as genetics and DNA that are easy for anyone to understand, scientifically accurate, AND enjoyable, is no easy feat.   And, while The Stuff of Life may have stumbled in some aspects, it is most certainly a noble effort, and may lighten the load in biology majors&#8217; backpacks in the coming months.   I sincerely hope that Schultz continues with more volumes, though I could do without those sea cucumbers next time.

What Happens After I Spit? A Saliva Sample’s Saga

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As talks began Saturday at Cold Spring Harbor&#8217;s first &#8220;Personal Genomes&#8221; conference, the first half of which I blogged on <a href="https://blog.23andme.com/2008/10/11/fuhgetabouddit-notes-from-long-island-the-frontier-of-personal-genomics-this-weekend/">here</a>, several leading explorers of the strange new world of &#8220;structural variation&#8221; in the human genome, such as Evan Eichler and Mike Snyder, shared some of their latest findings.
You can observe the most common kind of structural variation by lining up two corresponding chromosomes; if you notice that one of them is missing a stretch of DNA letters that is present in the other, that&#8217;s a deletion (or an insertion from the other chromosome&#8217;s viewpoint). Geneticists call these types of variations insertion/deletions, or indels for short.
The main way these variations seem to happen is during the production of sperm and eggs, when an individual&#8217;s homologous chromosomes recombine with one another. Usually, chromosome pairs line up perfectly for recombination, but when they don&#8217;t, you end up with chromosomes that have a little more or a little less DNA than the originals.

Problems can arise when the stretch of DNA lost in the shuffle was part of an essential gene. Recent work has shown that one form of autism is caused by a deletion, and the same is true for forms of schizophrenia and cystic fibrosis.
Both basic research and clinically-motivated research were presented Saturday. Eichler, of the University of Washington, and Snyder, of Yale, are among those making detailed maps of structural variation in the human genome. The consensus is emerging that there is a *lot* of it. Snyder showed that, at least in the handful of individual genomes he&#8217;s looked at so far, any two individuals differ by more than one thousand indels of at least 3,000 DNA letters. Eichler made a similar observation with respect to his comparison between a sample individual&#8217;s sequence and the reference human genome and commented that this means there are at least 3 million DNA letters (3,000 times 1,000) in the sample individual&#8217;s sequence not present in the reference genome. That&#8217;s on top of the 3 million one-letter SNP variants between any two humans. So it looks like genetic variation is the rule and not the exception, and the very notion of a &#8220;reference&#8221; sequence may need to stretch a bit in order to stay consistent with the data.
Derek Chiang of the Broad gave a fascinating talk about progress in trying to understand how structural variation can cause medical problems. Chiang, of the Broad Institute of MIT/Harvard, has developed sophisticated software to find structural variants associated with cancerous tissue based on microarray data. His efforts have already yielded a new oncogene for lung cancer. Chiang also described a clever algorithm for finding structural variants from next-generation sequence data that appears to work quite well by comparison to methods based on microarray data. Like the work Elaine Mardis presented Friday, Chiang&#8217;s talk suggests a future in which cancerous tumors could easily be distinguished from normal tissue using genetic scans.
The task of understanding what these differences *do* is another, very difficult, question entirely. And being able in turn to develop a therapy tailored to that specific change is yet another challenge.
Sunday&#8217;s talks took us into the world of *next next* generation sequencing, as though the prospect of plain old next-generation sequencing weren&#8217;t already shaking up the field enough. Steve Turner gave a talk on <a href="http://www.pacificbiosciences.com">Pacific Biosciences</a>&#8216; sequencing technology that kept the audience rapt. The technology is ingenious and solves a number of problems that have bedeviled sequencing since its inception. I will punt on explaining the basics of the technology since it&#8217;s so well-explained on their <a href="http://www.pacificbiosciences.com/index.php?q=technology-introduction">website</a>.
Turner offered an update that doesn&#8217;t appear on the website yet; the technology depends critically on the use of an enzyme, called DNA polymerase, which is responsible for copying DNA. Their team has modified the DNA polymerase used in the machine from the version that exists naturally in humans using a technique called experimental evolution. They generated a collection of mutant polymerases that each differ from the original at random. Then they tried each variant in their machine, retained the ones that do best, and repeated the process. It&#8217;s fair to say that horticulture and animal husbandry are slower, less direct forms of experimental evolution. After several generations, they ended up with a polymerase that was better suited to the environment of their machine than natural human polymerase is.
The meeting ended Sunday as Maynard Olson of the University of Washington, an eminent geneticist and one of the architects of the Human Genome Project, closed the conference with a witty and thoughtful summary of the proceedings. Olson suggested that true personalized medicine could be a long time coming, and expressed skepticism that it would arrive at all. One generalization from the talks, he said, was that it appears increasingly that the genetic mutations that impact health are rare, and it may be the case that many diseases can be caused in a large number of ways. The difficulty of working out what each version means could make it hard to work out therapies for so many different possibilities. He predicted a near-term future of unpredictability, especially in guessing which sequencing technologies will come to be adopted the genetics community. He closed by reciting the lyrics to Bob Dylan&#8217;s &#8220;<a href="http://www.bobdylan.com/#/songs/times-they-are-changin">The Times They Are A-Changin&#8217;</a>,&#8221; which seemed fitting to me.
&lt;span=&#8221;caption&#8221;&gt;Photo: Henryk Kotowski

Science in the Suburbs, Part II: More from the Personal Genomes Meeting at Cold Spring Harbor

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Just two weeks before the scheduled start of the Beijing Olympics, a German film crew <a href="http://www.dw-world.de/dw/article/0,2144,3505381,00.html" target="_blank" rel="noopener noreferrer">caught</a> a Chinese doctor on film offering to give athletes stem cell treatments to enhance their performance.
The reporter has since <a href="http://www.msnbc.msn.com/id/25886378/" target="_blank" rel="noopener noreferrer">refused</a> to identify the doctor on the tape and China has vehemently <a href="http://www.chinadaily.com.cn/olympics/2008-07/24/content_6874846.htm" target="_blank" rel="noopener noreferrer">denied</a> the documentary’s claims about the availability of so-called “gene doping” in this year’s Olympics host country. Still, the specter of a new kind of cheating hovers over the Games.
For years it’s been known that some athletes have resorted to using performance-enhancing drugs to live up to the Olympic motto of “faster, higher, stronger.” But the possibility of a new, undetectable kind of cheating made possible by advances in gene therapy has the World Anti-Doping Agency (WADA) worried.
Take for example the case of Italian cyclist Riccardo Ricci, who was recently thrown out of the Tour de France after tests showed he’d injected the hormone erythropoietin (also known as EPO) to get more oxygen into his bloodstream. In a world where gene doping is a reality, Ricci could have gotten away with enhancing his oxygen capacity by inserting the EPO-producing gene into his genome, gifting him with what would have appeared to doping tests to be a natural advantage.
WADA is <a href="http://www.wada-ama.org/en/dynamic.ch2?pageCategory.id=347" target="_blank" rel="noopener noreferrer">taking steps</a> to counter potential gene doping cheaters at the <a href="http://www.popsci.com/scitech/gallery/2008-07/juicing-30" target="_blank" rel="noopener noreferrer">2012 Olympics</a> by funding researchers around the world to develop tests that could determine if athletes are using gene therapy techniques to improve their performance.

For example, researchers in Canada are working on a test that checks changes in gene activity to find out if athletes have tinkered with their genome, inserting the EPO-producing gene to increase their bodies’ oxygen production. They hope to be able to have a sample test ready by next year.
French and American researchers are also working on a test to determine if athletes have doped their DNA. Their test is expected to compare the number of copies of a specific gene in an athlete suspected of gene doping against the number of copies of the same gene in the average person. A preliminary survey on the practicality of their idea is due this year.
Even as they work on countering gene doping, scientists and sports officials alike are finding that genetics may already have an impact on current drug doping tests.
In the July issue of the Journal of Clinical Endocrinology &amp; Metabolism, Swedish researchers identified a variation of the UGT2B17 gene found in two-thirds of Asians and 10 percent of Caucasians that caused a <a href="https://www.ncbi.nlm.nih.gov/pubmed/18334593?ordinalpos=1&#038;itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum" target="_blank" rel="noopener noreferrer">negative result</a> on the standard testosterone doping test, even if the men tested were actually taking the steroid.<a id="_anchor_1" class="msocomanchor" onmouseover="msoCommentShow('_anchor_1','_com_1')" onmouseout="msoCommentHide('_com_1')" name="_msoanchor_1" href="#_msocom_1"></a>
This latest finding suggests that even if athletes don’t resort to gene doping, they may have genes that allow them to dope with drugs and not get caught.
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The Olympic Games and Genes

<img loading="lazy" decoding="async" width="290" height="400" class="right size-full wp-image-281" style="float: right;" title="jessejamessmall" src="https://blog-api.23andme.com/wp-content/uploads/2008/06/jessejamessmall.jpg" alt="" srcset="https://blogcms.23andme.com/wp-content/uploads/2008/06/jessejamessmall.jpg 290w, https://blogcms.23andme.com/wp-content/uploads/2008/06/jessejamessmall-218x300.jpg 218w" sizes="auto, (max-width: 290px) 100vw, 290px" />Jesse James

Editor&#8217;s note: This post has been corrected from the original, which gave the incorrect location of Jesse James&#8217; grave. 


One of the most engaging features of 23andMe’s Personal Genome Service is a customer’s ability to trace his or her genetic ancestry using the mitochondrial DNA and the Y-chromosome.
Once customers learn their own ancestry, the Genome Sharing feature allows them to see how they compare with friends and family.
However, the ancestry section of 23andMe also allows customers to see how they compare to well-known individuals. In the maternal and paternal ancestry features, customers can view the haplogroup assignments of such figures as Thomas Jefferson, Genghis Khan and Bono.
<h6>Am I Related to Someone Famous? Sort of.</h6>
But how can anyone know the ancestry of someone like Thomas Jefferson, who has been dead for a few hundred years, or Genghis Khan, who has been dead for close to a thousand?
It turns out there are several ways to find out these well-known figures’ ancestry. The most obvious: Celebrities can sign up for 23andMe’s Personal Genome Service, just like the rest of us! For example, Jimmy Buffett and Warren Buffett have been interested for years in finding out whether their shared surname was an indication of common genetic ancestry. Unfortunately, their genetic profiles show the two are not closely related.
<h6>
 Founding Fathers&#8217; Haplogroups</h6>

But what about people like Thomas Jefferson?
He is no 23andMe customer, but this does not mean that scientists cannot trace his ancestry by other means. Tracing the maternal or paternal ancestry of any deceased individual is usually done by one of two ways: either getting DNA from the physical remains of the individual, or getting DNA from direct descendants of a relevant lineage.
He is no 23andMe customer, but this does not mean that scientists cannot trace his ancestry by other means. Tracing the maternal or paternal ancestry of any deceased individual is usually done by one of two ways: either getting DNA from the physical remains of the individual, or getting DNA from direct descendants of a relevant lineage.
In the cases of Thomas Jefferson and Benjamin Franklin, scientists used DNA from direct descendants of their ancestors. For example, in 1998 scientists inferred Jefferson’s paternal ancestry by analyzing the Y-chromosome of direct descendants of Jefferson’s paternal uncle (Jefferson had no confirmed sons).
<h6>Marie Antoinette and other Royal Haplogroups</h6>
Likewise, in the case of historical royalty such as Tsar Nicholas II of Russia or Marie Antoinette of France, extensive and detailed royal pedigrees make finding direct descendants a breeze.
Likewise, in the case of historical royalty such as Tsar Nicholas II of Russia or Marie Antoinette of France, extensive and detailed royal pedigrees make finding direct descendants a breeze.
In the case of the infamous outlaw Jesse James, a more direct approach was used. It had been widely believed that after James died in 1882, his body was buried at Mt. Olivet Cemetery in Kearney, Missouri. In order to test this hypothesis, scientists exhumed the body, extracting a few teeth. They compared DNA from the teeth to that of the great-grandson and great great-grandson of James’ sister. Scientists found an exact match between the extracted teeth and James’ sister&#8217;s descendants, thus confirming that the body in Mt. Olivet Cemetery was most likely that of Jesse James and establishing his ancestry to boot.

<h6>
How about Genghis Khan?</h6>
He is listed in our famous people sidebar as being a member of Y-chromosome Haplogroup C. But we do not have any information on his direct descendants alive today, nor do we have any preserved remains of his body. However, scientists have examined the Y-chromosomes of many present-day inhabitants of Mongolia (the ancestral home of Genghis Khan).
In doing so, they have found that about 8% of Mongolian males share the exact same DNA pattern in a highly variable part of their Y-chromosomes. Further analysis has revealed that this particular Y-chromosome type, which falls into haplogroup C, originated about 1,000 years ago and that its dispersal across Central Asia corresponds to the boundaries of the Mongol Empire. Historians have long noted Khan’s prolific nature; he is rumored to have fathered more than 40 sons, with some of his descendants also fathering many sons of their own. So it&#8217;s a good bet that we&#8217;re seeing Genghis Khan&#8217;s legacy in the 8% of Mongolian males alive today who have identical Y-chromosome signatures.
There are a number of ways we can determine the haplogroups of well-known figures — both past and present — and displaying information about these individuals adds to the fun of understanding and comparing the genetic ancestry of ourselves, our friends and family, and the rich and famous (or infamous).
Explore the origins of your ancestry at <a href="https://www.23andme.com/dna-ancestry/">23andMe.com</a>.

DNA — Page 2

New Genetic Analysis Sheds Light on Origins of Indian Castes

Recommended Reading: The Stuff of Life

What Happens After I Spit? A Saliva Sample’s Saga

Science in the Suburbs, Part II: More from the Personal Genomes Meeting at Cold Spring Harbor

The Olympic Games and Genes

Haplogroups of the Rich and Famous

Stay in the know.