A heat map showing not just where living genetic relatives of the Catoctin Furnace are in the United States but also the ancestral contributions from Africa and Europe.

Roslyn Curry

Ethics and the Study of Historic DNA of African Americans Buried at the Catoctin Furnace

This past week we&#8217;re continuing to read about the response to the coronavirus, and the efforts to develop a vaccine. But that intense focus hasn&#8217;t been to the exclusion of other interesting articles in our reading list this week. So here is what we&#8217;re reading.
<h2>Wash Your Hands</h2>
<img loading="lazy" decoding="async" class="alignright size-medium wp-image-28040" src="https://blog-api.23andme.com/wp-content/uploads/2020/02/CDC-Image-of-Coronavirus-300x168.png" alt="" width="300" height="168" srcset="https://blogcms.23andme.com/wp-content/uploads/2020/02/CDC-Image-of-Coronavirus-300x168.png 300w, https://blogcms.23andme.com/wp-content/uploads/2020/02/CDC-Image-of-Coronavirus.png 512w" sizes="auto, (max-width: 300px) 100vw, 300px" />More on the <a href="https://www.nytimes.com/interactive/2020/world/asia/china-coronavirus-contain.html?action=click&amp;pgtype=Article&amp;state=default&amp;module=styln-coronavirus&amp;variant=show&amp;region=TOP_BANNER&amp;context=storyline_menu">coronavirus</a> — estimates are that China has now imposed travel restrictions on more than <a href="https://www.nytimes.com/2020/02/18/world/asia/china-coronavirus.html?action=click&amp;module=Top%20Stories&amp;pgtype=Homepage">10 percent of its population</a>! The outbreak has sharpened our focus on the public health response, as well as the need for rapid research required to create an effective vaccine. In the meantime, we are all becoming a little more diligent about things like washing your hands. On that note, here&#8217;s an illustration of the most often missed areas when washing your hands.
<h2>Glass Houses</h2>
<img loading="lazy" decoding="async" class="alignright size-medium wp-image-28039" src="https://blog-api.23andme.com/wp-content/uploads/2020/02/Real-Life-Book-Image-191x300.jpg" alt="" width="191" height="300" srcset="https://blogcms.23andme.com/wp-content/uploads/2020/02/Real-Life-Book-Image-191x300.jpg 191w, https://blogcms.23andme.com/wp-content/uploads/2020/02/Real-Life-Book-Image.jpg 318w" sizes="auto, (max-width: 191px) 100vw, 191px" />We often believe that working in the sciences is somehow more progressive than working in other fields. Still, Brandon Taylor&#8217;s book Real Life offers <a href="https://www.buzzfeednews.com/article/brandontaylor/i-dont-miss-being-a-scientist-except-when-i-do">a different point of view</a>. As a gay black man, he often felt isolated, silenced and marginalized. &#8220;Science was the constant humiliation of wondering if I had justified my presence,&#8221; Tayor writes in this Buzzfeed piece. He wondered if he had &#8220;made it harder for the next black person to get admitted.&#8221; Ultimately it&#8217;s what drove him from the field.
<h2>The Food We Eat</h2>
We eat <a href="https://www.theguardian.com/food/2020/feb/13/how-ultra-processed-food-took-over-your-shopping-basket-brazil-carlos-monteiro">a lot of junk</a>, and that may explain why we&#8217;re getting so fat. We&#8217;re not just consuming processed food loaded with sugar, salt, and fat, but what are called &#8220;ultra-processed foods.&#8221; These are &#8220;foods&#8221; are what the Guardian calls &#8220;concoctions of concoctions&#8221; that resemble food. According to this Guardian story, now more than half the calories consumed in the United States and the UK are made up of these ultra-processed foods. Makes us think that <a href="https://michaelpollan.com/books/">Michael Pollan&#8217;s</a> diet advice, &#8220;Eat food, not too much, mostly plants.&#8221; And when he says &#8220;food&#8221; he means real food, not processed stuff.
<h2>Heavy</h2>
<img loading="lazy" decoding="async" class="alignright size-medium wp-image-28041" src="https://blog-api.23andme.com/wp-content/uploads/2020/02/Tommy-Tomlinsons-Book-197x300.png" alt="" width="197" height="300" srcset="https://blogcms.23andme.com/wp-content/uploads/2020/02/Tommy-Tomlinsons-Book-197x300.png 197w, https://blogcms.23andme.com/wp-content/uploads/2020/02/Tommy-Tomlinsons-Book-768x1169.png 768w, https://blogcms.23andme.com/wp-content/uploads/2020/02/Tommy-Tomlinsons-Book-673x1024.png 673w, https://blogcms.23andme.com/wp-content/uploads/2020/02/Tommy-Tomlinsons-Book-578x880.png 578w, https://blogcms.23andme.com/wp-content/uploads/2020/02/Tommy-Tomlinsons-Book-775x1180.png 775w, https://blogcms.23andme.com/wp-content/uploads/2020/02/Tommy-Tomlinsons-Book.png 800w" sizes="auto, (max-width: 197px) 100vw, 197px" />It would all be so simple if we ate less and made better food choices, but it&#8217;s not so simple. There&#8217;s much more involved in what drives people to eat the way they do. We wish more people had read Tommy Tomlinson&#8217;s 2019 book, &#8220;<a href="https://www.simonandschuster.com/books/The-Elephant-in-the-Room/Tommy-Tomlinson/9781501111617">The Elephant in the Room, One Fat Man&#8217;s Quest to Get Smaller in a Growing America</a>.&#8221; A great writer and one-time finalist for a Pulitzer Prize, Tomlinson brings his story and a lot of humanity to the struggles of people trying to lose weight and improve their health. Helping people to make those changes requires a more profound understanding, or we&#8217;ll never deal with the looming obesity crisis. &#8220;What I want you to understand, more than anything else, is that telling a fat person to &#8216;eat less and exercise&#8217; is like telling a boxer, &#8220;Don&#8217;t get hit,&#8221; Tomlinson writes. Understanding the emotional and psychological hurdles people often need to clear before taking the actions they already know they need to take to be healthy is essential. Tomlinson&#8217;s writing brings that home, just as he vividly describes his weight&#8217;s toll on his body. Read his book, now in paperback, or at least read the piece he wrote last year for the <a href="https://www.theatlantic.com/health/archive/2019/01/weight-loss-essay-tomlinson/579832/">Atlantic</a>.
<h2></h2>
<h2>Ghost in the Machine</h2>
More good stuff on <a href="https://www.discovermagazine.com/planet-earth/genetic-traces-of-mysterious-human-lineage-detected-in-people-living-in">Ghost DNA</a> finding but no name for this ancient human cousin until we get the bones. Scientists found <a href="https://www.nytimes.com/2020/02/12/science/west-africa-ancient-humans.html">evidence of these ancient human cousins</a> in the DNA of modern living humans in West Africa. What we are learning is that it wasn&#8217;t just <a href="https://www.the-scientist.com/features/neanderthal-dna-in-modern-human-genomes-is-not-silent-66299">Neanderthals, </a>or <a href="https://www.sciencemag.org/news/2019/09/ancient-dna-puts-face-mysterious-denisovans-extinct-cousins-neanderthals">Denisovans</a>, or even <a href="https://www.nationalgeographic.com/science/2018/08/news-homo-floresiensis-hobbit-genetics-dna-pygmy-flores-island/">Hobbits</a>, that interbred with early modern humans. Our ancestors were also mixing with other as <a href="https://theconversation.com/early-humans-in-africa-may-have-interbred-with-a-mysterious-extinct-species-new-research-131699">yet unidentified ancient human cousins</a>.

23andMe Blog

23andMe Blog Team

Junk Food, Viruses, and Ghosts — What We’re Reading This Week

Overturning long-held beliefs about the past, new insights from ancient DNA have revealed exciting surprises about who we are as people and how we got here.
In just the last few years, the ability for scientists to extract and sequence DNA from bones that are tens of thousands of years old has changed our understanding of the human story. Perhaps there are few better to tell that tale than the population geneticist David Reich.<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2018/03/jackethighres-199x300.jpg" alt="" class="alignright size-medium wp-image-26087" width="199" height="300" srcset="https://blogcms.23andme.com/wp-content/uploads/2018/03/jackethighres-199x300.jpg 199w, https://blogcms.23andme.com/wp-content/uploads/2018/03/jackethighres-768x1160.jpg 768w, https://blogcms.23andme.com/wp-content/uploads/2018/03/jackethighres-678x1024.jpg 678w, https://blogcms.23andme.com/wp-content/uploads/2018/03/jackethighres-583x880.jpg 583w, https://blogcms.23andme.com/wp-content/uploads/2018/03/jackethighres-781x1180.jpg 781w, https://blogcms.23andme.com/wp-content/uploads/2018/03/jackethighres.jpg 1500w" sizes="auto, (max-width: 199px) 100vw, 199px" />
In his new book, Who We Are and How We Got Here, Ancient DNA and the New Science of the Human Past, Reich explains the significance this new technical innovation has had in the study of human history and prehistory. He has packed into this book, not just an explanation of the difficulty in initially finding and sequencing DNA from these samples, but also what it means and how it has changed what we know about out our history.
“Basically, it’s a gold rush right now;” Reich said in a February 2016 interview with <a href="http://edge.org/conversation/david_reich-the-genomic-ancient-dna-revolution">The Edge</a>. “It’s a new technology, and that technology is being applied to everything we can apply it to, and there are &#8230; many gold nuggets strewn on the ground that are being picked up very rapidly. That’s what’s happening now.”
In his book, Reich describes ancient DNA researchers like himself as barbarians overturning the old and long standing approaches to studying human history.
<div id="attachment_26088" style="width: 968px" class="wp-caption aligncenter"><img loading="lazy" decoding="async" aria-describedby="caption-attachment-26088" src="https://blog-api.23andme.com/wp-content/uploads/2018/03/Reic_9781101870327_jkt_ap1_r1-e1521242394539.jpg" alt="" class="wp-image-26088 size-full" width="958" height="1146" srcset="https://blogcms.23andme.com/wp-content/uploads/2018/03/Reic_9781101870327_jkt_ap1_r1-e1521242394539.jpg 958w, https://blogcms.23andme.com/wp-content/uploads/2018/03/Reic_9781101870327_jkt_ap1_r1-e1521242394539-251x300.jpg 251w, https://blogcms.23andme.com/wp-content/uploads/2018/03/Reic_9781101870327_jkt_ap1_r1-e1521242394539-768x919.jpg 768w, https://blogcms.23andme.com/wp-content/uploads/2018/03/Reic_9781101870327_jkt_ap1_r1-e1521242394539-856x1024.jpg 856w, https://blogcms.23andme.com/wp-content/uploads/2018/03/Reic_9781101870327_jkt_ap1_r1-e1521242394539-736x880.jpg 736w" sizes="auto, (max-width: 958px) 100vw, 958px" />David Reich &nbsp;&nbsp; Photo: Bizu Tesfaye (Howard Hughes Medical Institute)</div>
“Ancient DNA has allowed us to peer deep into time and force us to question our understanding of the past,” he writes.
A professor of Genetics at Harvard University and a Howard Hughes Medical Institute Investigator, Reich opened his own ancient DNA lab at Harvard in 2013, with the help of <a href="https://www.theguardian.com/science/2014/feb/15/svante-paabo-dna-neanderthal-genetics">Svante Paabo</a>, who was the first to use DNA extracted from ancient bones to sequence the Neanderthal genome. That has revealed the more than being just ancient cousins, early modern human and Neanderthal interbreed, and DNA fragments of those encounters live on today in all humans outside of Africa. Similar findings have been made around Denisovans, another ancient human cousin, and other “ghost populations” that have died out. And with each revelation comes a revision of human prehistory and mankind’s migration out of Africa and across the globe.
In his book, Reich also reveals in a chapter called “The Great Mixing” a refrain in of human history, that no matter how divergent the population, humans intermixed and that all populations today are mixed.
“The mixtures of highly divergent groups have happened time and time again,” he writes.
He uses examples <a href="https://www.nature.com/articles/nature08365">of populations in India</a>, that intermixed 2,000 to 4,000 years ago, as well as more recent mixing among <a href="http://www.cell.com/ajhg/pdfExtended/S0002-9297(14)00476-5">African Americans, Latinos and European Americans</a>. Some of that mixing also reflects the “deep history of inequality” among the different populations and sexes.
Toward the end of his book, Reich talks about his optimism that this work to highlight human connections, not their differences.
“[If] you actually take any serious look at this data, it just confounds every stereotype. It’s revealing that the differences among populations we see today are actually only a few thousand years old at most and that everybody is mixed,” he said in <a href="https://www.theatlantic.com/science/archive/2018/03/ancient-dna-history/554798/">a recent interview</a>.

Ancient DNA offers new insight into the human story

It’s not quite waffles and paella, but it appears that Neanderthals<img loading="lazy" decoding="async" class="wp-image-421 size-full alignright" src="http://35.88.189.111/wp-content/uploads/2008/07/neanderthaler2.jpg" alt="" width="400" height="266" srcset="https://blogcms.23andme.com/wp-content/uploads/2008/07/neanderthaler2.jpg 400w, https://blogcms.23andme.com/wp-content/uploads/2008/07/neanderthaler2-300x200.jpg 300w" sizes="auto, (max-width: 400px) 100vw, 400px" /> were omnivores who adapted to eating whatever was available to them in the regions where they lived.
DNA samples extracted from ancient plaque on teeth found in a cave in Belgium and from those found at a site in Northern Spain indicate that Neanderthals had distinct regional cuisines.
In the area that is now Belgium, Neanderthals ate a lot of meat—woolly rhinos and wild sheep—while those in Spain were vegetarians, living off pine nuts, mushrooms, tree bark, and forest moss.
<div style="float: right; text-align: justified; width: 200px; background-color: #eee; padding: 15px; margin-left: 10px;">
<h2>Find Your Inner Neanderthal<img loading="lazy" decoding="async" class="aligncenter wp-image-24217 size-full" src="http://35.88.189.111/wp-content/uploads/2016/08/Neanderthal-Report-Home.png" alt="" width="2534" height="1396" srcset="https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home.png 2534w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-300x165.png 300w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-768x423.png 768w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-1024x564.png 1024w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-880x485.png 880w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-1180x650.png 1180w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-271x149.png 271w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-372x204.png 372w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-574x315.png 574w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Neanderthal-Report-Home-980x539.png 980w" sizes="auto, (max-width: 2534px) 100vw, 2534px" /></h2>
23andMe reports to customers the number of Neanderthal variants they carry, how that compares with other customers, and traits those variants are associated with, such as back hair and height.
</div>
<h2>Neanderthal Microbiome</h2>
Even more interesting than what was on the menu is the additional information scientists gleaned from the first microbiome sequence of an extinct species. Our microbiome is the collection of bacteria and microbes on and in our bodies that we depend on for survival. They can also tell us a lot about health, and researchers have, over the last decade, begun using DNA extracted from calcified plaque on teeth to help piece together the lives of our ancient ancestors. 
The most recent work is the first such successful effort focused on Neanderthals.
<h2>Medicinal Practices</h2>
In addition to learning about what our ancient cousins ate, the researchers also found signs of possible primitive medicinal practices. In one case, from an individual in Spain who appeared to have had a dental abscess and some sort of gastrointestinal parasite, the researchers found traces of the bark from a poplar tree, which has salicylic acid, a natural painkiller used in aspirin, as well as material that included Penicillium mold.
According to researchers, the data offer genetic evidence regarding not only diet but also Neanderthal behavior and the diseases they struggled with. 
The study also offered some exciting twists to speculation around the nature of Neanderthal and human interactions.
<h2>Neanderthal and Modern Human Interactions</h2>
Neanderthals went extinct about 40,000 years ago in Europe, but traces remain in the DNA of people with non-African ancestry. That intermixing likely offered humans an evolutionary advantage to survive as they migrated outside of Africa. But why modern humans thrived, and Neanderthals disappeared from the earth is still not fully understood.
The biggest spit-take of this most recent study had to do with … spit. One researcher said that genetic evidence of an oral microbe in the mouths of these Neanderthals — also found in the mouths of modern humans — suggested that this bacteria was transmitted between Neanderthals and humans, implying “that these interactions were much friendlier and much more intimate than anybody …  imagined.”
“If you’re swapping spit between species, there’s kissing going on, or at least food sharing,” co-author Laura Weyrich told the journal<a href="https://www.nature.com/news/neanderthal-tooth-plaque-hints-at-meals-and-kisses-1.21593"> Nature</a>.
While Neanderthals and humans may have kissed cousins, others were less willing to<a href="https://www.theatlantic.com/science/archive/2017/03/neanderthal-dental-plaque-shows-what-a-paleo-diet-really-looks-like/518949/"> draw those conclusions</a>. That doesn’t mean that the science wasn’t solid&#8211;just that it didn’t indicate how the oral microbe went from modern humans to Neanderthals. 
Much like the study of ancient human and Neanderthal DNA, the study of ancient microbiomes has added to what we know about human history. Historical changes such as the rise of agriculture and the industrialization age can be plotted in changes in the human microbiome. The information we glean from this research could also help us understand how changes in the microbiome influence human health.

The Neanderthal Cookbook

DNA extracted from bones at a burial site in a rocky valley on a remote island in the South Atlantic could hold important information for those with ancestral roots in Africa.<img loading="lazy" decoding="async" class="alignright size-medium wp-image-1974" src="https://blog-api.23andme.com/wp-content/uploads/2008/11/oldafricamap1508-300x221.png" alt="oldafricamap1508" width="300" height="221" srcset="https://blogcms.23andme.com/wp-content/uploads/2008/11/oldafricamap1508-300x221.png 300w, https://blogcms.23andme.com/wp-content/uploads/2008/11/oldafricamap1508.png 350w" sizes="auto, (max-width: 300px) 100vw, 300px" />
A fascinating article in <a href="https://www.nature.com/news/what-dna-reveals-about-st-helena-s-freed-slaves-1.21096?WT.mc_id=SFB_NNEWS_1508_RHBox">Nature</a>, describes work led by <a href="http://snm.ku.dk/english/staffsnm/staff/?pure=en/persons/368359">Hannes Schroeder</a> to make that connection. Schroeder, a researcher at the University of Copenhagen, and his team have extracted genetic material from skeletal remains of some of the thousands of slaves who were freed by the British Navy between 1840 and 1865.
Taken from slave ships on their way to the New World as many as 20,000 people, many of them children, were saved from enslavement in the Americas, but were then unceremoniously deposited on the island of St. Helena. Sick and emaciated from their brutal ordeal many of them died there. The island’s Rupert Valley is the final resting place of more than 8,000 people.

This little known history would have been forgotten altogether if the graves were not found a few years ago during a construction project. The find, and the promise of sequencing the DNA of some of the bones there, offered Schroeder and his team a tantalizing opportunity – a chance to sequence individuals who’d been destined for slavery in the New World but never got there. Their DNA could reveal what written records have failed to track, the specific regions in Africa from where slaves came.
This is the part of Schroeder’s work that is most interesting for us here at 23andMe, where our own <a href="https://blog.23andme.com/articles/the-african-genetics-project">African Genetics Project</a> is also trying to make that connection, albeit in a different way.
While much has been done to document the history of the enslavement of the more than 12 million Africans who survived the brutal Middle Passage to wind up in bondage in the New World, this effort, and 23andMe’s, offers a chance to look beyond the limitations of the written record. We know that the Africans enslaved in the Americas were not a monolithic group but individuals from different cultures and with different languages who were forced together into slavery.
Schroeder and his team have already sequenced partial genomes of about 20 individuals, and found that they represent a diverse collection of African groups. As the article notes some of the samples indicate shared ancestry with West and Central African ethnic groups, such as the Bamoun and Kongo. But for the others, matches could not be found. This is likely because there are not diverse reference data sets to compare them too. Schroeder is hoping that two medically-related sequencing efforts in Africa will help change that.
In the meantime 23andMe’s African Ancestry Project has begun to recruit people in the United States, who emigrated, or whose parents emigrated, from several specific countries in Sub-Saharan Africa to improve its set of African reference data. This will not just improve the information we can report back to people of African descent, it could also help yield new insights into the TransAtlantic slave trade.
“23andMe researchers hope to identify direct connections between locations in Africa and the Americas, possibly adding important details to the historical record,” said Joanna Mountain, Ph.D., senior director of research at 23andMe.
Like 23andMe Schroeder and his team are looking to make direct connections from specific locations in Africa and the individuals who wound up in St. Helena. In turn this may also help people of African descent living in the Americas a bridge to their own ancestral past.
Fatimah Jackson, a biological anthropologist at Howard University in Washington DC who is sequencing ancient DNA from other slave burial sites, is quoted in the Nature article as saying that his kind of research has the potential of changing people’s perception of the past.
“It&#8217;s a very personal thing for us,” Jackson said. “It&#8217;s not just ancient DNA. It&#8217;s ancient DNA of potential ancestors.”

Tracing Back to Africa

<img loading="lazy" decoding="async" class="alignright size-full wp-image-23616" src="http://35.88.189.111/wp-content/uploads/2016/02/Screen-shot-2016-01-22-at-12.33.27-PM.jpg" alt="" width="232" height="288" />
The ability to extract and then sequence ancient DNA, not just from ancient human bones, but also from the bones of our ancient cousins the Neanderthals, is upending old notions of human migration and history.
<h2>Ancient DNA</h2>
The latest in a rapid succession of<a href="https://www.nature.com/news/evidence-mounts-for-interbreeding-bonanza-in-ancient-human-species-1.19394#Early"> new findings</a> suggests that intermixing between Neanderthals and early modern humans happened earlier than we once thought – about <a href="https://www.nature.com/articles/nature16544.epdf?referrer_access_token=CMEgDNGJuW7rNIX8-5DetdRgN0jAjWel9jnR3ZoTv0MInt_2jYvKBG--7sOqWdGTzUvToNHVvyhzE6mZLLgJJmR7yoinCDiE3vg9Q5AVA-nZquOQOOQnhcfdq9lCTp4TcwdkXstlNRZ7xfdZRcnYB6sIPffF_OSID_rECaKCbx-nDNFAoD9EQPv4N_1WWd-A8l0yEwuBeZ6eFt0-g5i0T9MPLVmGCIKRPC0jEsDeYZxD78jhZvPiTcPMjQJT5jr-&amp;tracking_referrer=www.nature.com">100,000 years ago</a> versus <a href="http://sriramsankararaman.com/publications/sankararaman.pgen.2012.pdf" target="_blank" rel="noopener noreferrer">50,000 years ago</a> – at a time that challenges long held theories about when humans migrated out of Africa and how far those migrations took them. And by looking at DNA sequences extracted from several different Neanderthal bones, researchers discovered that the gene flow didn’t just go from Neanderthals to humans.
This latest finding illustrates the impact DNA data, specifically data from ancient DNA, has had. <a href="https://www.theguardian.com/science/2014/feb/15/svante-paabo-dna-neanderthal-genetics">Svante Paabo</a> of the Max Planck Institute for Evolutionary Anthropology pioneered this innovation for extracting ancient DNA and accurately sequencing, and it radically transformed our understanding of human history.
<h2>New Information About the Past</h2>
Harvard population geneticist David Reich puts this new innovation into context in a long interview he did with<a href="http://edge.org/conversation/david_reich-the-genomic-ancient-dna-revolution"> The Edge</a>. Reich, who studies genetic variation among human populations, said that scientists have gained great new insights into history by comparing ancient DNA sequences to present-day humans’ genetic data.
“It’s a radically new type of information about the past; it’s a great gift to be able to have access to it,” Reich said in the interview. “It’s a great surprise. Who would have thought DNA survived that long?”
Probably the most profound insight from looking at ancient DNA and making comparisons with data from modern humans is that all human populations today are mixed.
<h2>Neanderthals and Modern Humans</h2>
This isn’t just about mixing between humans and Neanderthals, but mixing among early human populations and that data offers great insight into human history. He’s also looked at non-ancient human DNA to garner similar insights. So for example, Reich has looked at populations in India where they found that populations mixed there between 2000 to 4000 years ago. Before that there were unmixed populations.
“Amazingly, what you could see from the genetic data was an event in which you could see cultural change,” he said.
You can see something similar in more recent history by looking at the DNA of African Americans, which includes European ancestry, a clear mark of the slavery in the United States.
“What you’re seeing in the imprint of these populations genetically is the history of power inequality, which is usually males of power from one group having preferential access to local females, and that’s what you see in these groups,” Reich said.
Listen to Reich’s interview below.
The Edge Foundation, also has a video of his interview on its site<a href="http://edge.org/conversation/david_reich-the-genomic-ancient-dna-revolution"> here</a>.
<iframe loading="lazy" src="https://w.soundcloud.com/player/?url=https%3A//api.soundcloud.com/users/65424416&amp;auto_play=false&amp;hide_related=false&amp;show_comments=true&amp;show_user=true&amp;show_reposts=false&amp;visual=true" width="100%" height="450" frameborder="no" scrolling="no"></iframe>

Blast from the Past

Consider the cow, and this humble herbivore’s contribution to the human story.<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2015/06/dairy-cow-300x200.jpg" alt="dairy cow" class="alignright size-medium wp-image-22620" width="300" height="200" srcset="https://blogcms.23andme.com/wp-content/uploads/2015/06/dairy-cow-300x200.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2015/06/dairy-cow-768x511.jpg 768w, https://blogcms.23andme.com/wp-content/uploads/2015/06/dairy-cow.jpg 849w" sizes="auto, (max-width: 300px) 100vw, 300px" />


We’re not just talking burgers and ice cream, archeological evidence suggests that cows were likely first domesticated from aurochs (extinct wild oxen) as long as 11,000 years ago when farmers used their milk to <a href="https://www.npr.org/sections/thesalt/2012/12/27/168144785/an-evolutionary-whodunit-how-did-humans-develop-lactose-tolerance" target="_blank" rel="noopener noreferrer">make cheese</a> and yogurt.
Nutrient-rich with plenty of vitamin D for the sun-starved in Northern Europe, milk was a kind of superfood of the Bronze Age.
But <a href="https://www.nature.com/news/dna-data-explosion-lights-up-the-bronze-age-1.17723" target="_blank" rel="noopener noreferrer">new research</a> suggests that it took a long time before Europeans could actually benefit from this potent potable.
Looking at DNA samples from the remains for more than 100 individuals who lived in Eurasia from 3,000 to 5,000 years ago, researchers in Norway found that it took a surprisingly long time before Europeans could tolerate milk.
The study looked at much more than whether those early Europeans could tolerate dairy, and focused more broadly on a wide variety of physical and physiological traits including hair thickness, height and skin color.
But the DNA samples indicate that those early Europeans were mostly lactose intolerant, suggesting that even though they had domesticated cows at the time they were unable to digest raw milk as adults. The exception appears to be among the Yamnaya, a group of people who migrated into Northern Europe from an area near the Altai Mountains in what is now central Russia. Researchers speculate that natural selection favored this trait, giving those with it a rich source of nutrition that could sustained them during times of famine when harvests failed. 
 
<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2015/06/milk-287x300.jpg" alt="Glass of milk isolated on white. Vector illustration" class="alignright size-medium wp-image-22621" width="287" height="300" srcset="https://blogcms.23andme.com/wp-content/uploads/2015/06/milk-287x300.jpg 287w, https://blogcms.23andme.com/wp-content/uploads/2015/06/milk-768x802.jpg 768w, https://blogcms.23andme.com/wp-content/uploads/2015/06/milk-980x1024.jpg 980w, https://blogcms.23andme.com/wp-content/uploads/2015/06/milk-843x880.jpg 843w, https://blogcms.23andme.com/wp-content/uploads/2015/06/milk-1130x1180.jpg 1130w" sizes="auto, (max-width: 287px) 100vw, 287px" />

<h5>
Intolerant, even today 
</h5>

Most people are actually lactose intolerant as adults. Only about <a href="https://www.sciencedirect.com/science/article/pii/S0958694611002536" target="_blank" rel="noopener noreferrer">35 percent of people worldwide</a> can digest lactose beyond the age of about seven or eight.
The numbers tell a deeper story when demographically divided. While the majority of people of European ancestry <a href="https://www.nature.com/news/archaeology-the-milk-revolution-1.13471" target="_blank" rel="noopener noreferrer">can tolerate milk</a> into adulthood, only a small minority of people of Asian ancestry can. Among 23andMe customers who consented to research only about 16 percent of those of European ancestry reported that they were <a href="https://www.23andme.com/topics/wellness/lactose-intolerance/">lactose intolerant</a> compared to about 85 percent of people of Asian ancestry.

<h5>
So what gives? 
</h5>

There are a number of <a href="https://www.npr.org/sections/thesalt/2012/12/27/168144785/an-evolutionary-whodunit-how-did-humans-develop-lactose-tolerance" target="_blank" rel="noopener noreferrer">theories</a> about why there are differences among people of different ancestry, and a recent study of ancient Northern European DNA suggests the ability to digest dairy is a relatively new phenomena.
Drinking milk is a problem for most adults. It contains high amounts of a sugar named lactose. As children, we all produce lactase, an enzyme that allows us to break up lactose in our mother&#8217;s milk. As we grow older lactase levels go down, making it harder for adults to breakdown the lactose sugars and causing gastrointestinal &#8220;discomfort.&#8221;
In populations with domesticated cattle, however, there may have been an evolutionary incentive to being able to drink milk as adults and several populations – including populations in Northern Europe – developed genetic variants that enabled adults to continue to breakdown lactose into adulthood. This genetic variant offered a likely evolutionary advantage because milk is nutrient rich, plentiful, and cleaner than many sources of water. In times of famine it offered an alternative source of food for those who could tolerate it.


In the book 10,000 Year Explosion: How Civilization Accelerated Human Evolution, anthropologists Gregory Cochran and Henry Harpending called humans with this variant “<a href="https://westhunt.wordpress.com/2012/10/23/mampires/" target="_blank" rel="noopener noreferrer">mampires</a>,” because it allowed people to feed on the milk of other animals. It’s a clever term, but maybe with a little darker connotations than necessary. As the anthropologist <a href="http://johnhawks.net/weblog/reviews/accel/question-on-selection-and-lactase-2014.html" target="_blank" rel="noopener noreferrer">John Hawkes noted</a> in his blog, milk from domesticated animals is a much more efficient use of farm animals than raising them for meat. In places in Europe, Arabia and in parts of Africa where cold or arid climates made consistent yields from farming grain difficult, milk was a good alternative source of nutrition.

23andMoo

<img loading="lazy" decoding="async" class="alignright size-full wp-image-6209" title="6Denisova_cave" src="https://blog-api.23andme.com/wp-content/uploads/2010/03/6Denisova_cave.jpg" alt="" width="346" height="517" />Denisova cave from the outside. / Bence Viola. 
DNA isolated from a tiny bone fragment from the finger of a being that walked the earth between 30,000 and 50,000 years ago has possibly added a new branch to the human family tree.
<h6>denisovan</h6>
The piece of bone was found in the Denisova Cave in the Altai Mountains, Russia.   Thanks to the preserving effects of the area&#8217;s relatively chilly temperatures, researchers from the Max Planck Institute for Evolutionary Anthropology were able to recover mitochondrial DNA (mtDNA) suitable for sequencing.
Their results, published online today in the journal <a href="https://dx.doi.org/10.1038/nature08976" target="_blank" rel="noopener">Nature</a>, show that compared to present-day humans, mtDNA from the so-called &#8220;Denisova <a href="http://archaeology.about.com/od/hterms/g/hominin.htm" target="_blank" rel="noopener">hominin</a>&#8221; contains twice as many differences as do mtDNAs from Neanderthals.
<h6>Another Human Cousin</h6>
From this the researchers conclude that the Denisova hominin was a member of a previously unknown species of human ancestor.   Further analysis allowed them to estimate that the most recent common maternal ancestor shared by all three species lived about one million years ago.
&#8220;Their discovery is remarkable not just for the insight it gives into the human past.   For the first time a hominin has been described, not from the morphology of its fossilized bones, but from the sequence of its DNA,&#8221; wrote Terence A. Brow, in a News &amp; Views article that accompanied the Nature study.
There is evidence that both Neanderthals and anatomically modern humans were in the area of the Denisova cave at around the same time as the individual whose mtDNA was sequenced in the current study. This suggests that each wave of hominins that moved out of Africa and into Eurasia did not replace the last.   Instead, multiple lineages coexisted for long periods of time.
More work will be needed to definitively determine the relationship of the Denisova hominin to Neanderthals and modern humans.   Ongoing research is attempting to isolate nuclear DNA for further comparisons and to look for evidence of interbreeding.
<h6>Update 3/29/10</h6>
There&#8217;s quite a bit of discussion about whether or not the Denisova hominin really is a distinct species. A good place to learn more about the debate is Carl Zimmer&#8217;s blog The Loom.   <a href="http://theatavism.blogspot.com/2010/03/does-forty-thousand-year-old-finger.html" target="_blank" rel="noopener">The Atavism</a> also has a post about this topic.
<ul>
<li>Read more about this story at ScienceNews.</li>
<li>More from the Blog on ancient DNA:
<ul>
<li><a href="../2010/02/10/researchers-use-snp-analysis-to-paint-picture-of-an-ancient-human/" target="_blank" rel="bookmark noopener">Researchers Use SNP Analysis to Paint Picture of an Ancient Human</a></li>
<li><a href="../2009/02/12/researchers-announce-draft-version-of-complete-neanderthal-genome/" target="_blank" rel="bookmark noopener">Researchers Announce Draft Version of Complete Neanderthal Genome</a></li>
<li><a href="../2009/07/22/novel-techniques-suggest-neanderthal-populations-dwindled-in-the-face-of-expanding-humans/" target="_blank" rel="bookmark noopener">Novel Techniques Suggest Neanderthal Populations Dwindled in the Face of Expanding Humans</a></li>
</ul>
</li>
</ul>

Ancient DNA of An Extinct Human Ancestor

<img loading="lazy" decoding="async" class="alignright size-full wp-image-5968" title="inuk" src="https://blog-api.23andme.com/wp-content/uploads/2010/02/inuk.jpg" alt="" width="350" height="367" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/02/inuk.jpg 350w, https://blogcms.23andme.com/wp-content/uploads/2010/02/inuk-286x300.jpg 286w" sizes="auto, (max-width: 350px) 100vw, 350px" />Artist&#8217;s impression of Inuk based on genetic analysis 
Nuka Godfredsen/Nature
Editor&#8217;s note: This post has been edited from the original to reflect changes in 23andMe&#8217;s product.
Tufts of hair rescued from the permafrost in Greenland and then tucked away in a basement in Denmark for more than 20 years have given scientists their first glimpse into the genetics of an ancient human.
Eske Willerslev and Morten Rasmussen of the Centre for GeoGenetics at the Natural History Museum of Denmark and the University of Copenhagen, along with an international team of collaborators, have sequenced 80% of the genome of a man from the <a href="http://www.natmus.dk/sw18632.asp" target="_blank" rel="noopener">Saqqaq Culture</a> who walked the earth about 4,000 years ago.   By comparing this ancient DNA sequence to what is known about the genetics of modern humans, the researchers were able to piece together a picture of what the man they call Inuk (&#8220;human&#8221; or &#8220;man&#8221; in Greenlandic) likely looked like, where his people came from, and how he&#8217;s related to modern populations.   The results were published online today in the journal <a href="https://dx.doi.org/10.1038/nature08835" target="_blank" rel="noopener">Nature</a>.
Inuk&#8217;s DNA revealed that he had type A+ blood.   He likely had brown eyes and thick, dark hair.   His skin was probably not the light color found in modern day Europeans.   Inuk&#8217;s earwax was dry and he had shovel-graded front teeth, both characteristics common in Asian and Native American populations.   Several of the genetic variants he carried suggest that he had a metabolism and body mass well-suited to cold climates. The researchers even found that Inuk&#8217;s genetics are indicative of an increased risk of baldness.
&#8220;Because we found quite a lot of hair from this guy, we presume he died quite young,&#8221; Willerslev said in a press briefing.
(Although as Harvard professor and <a href="http://improbable.com/2009/01/12/lfhcfs-members-genome-sequenced/" target="_blank" rel="noopener">Luxuriant Flowing Hair Club for Scientists</a> member Steven Pinker found when analysis of his DNA also suggested a propensity for baldness, DNA is not always destiny.)
Analysis of Inuk&#8217;s <a href="https://www.23andme.com/gen101/graphics/ancestry/" target="_blank" rel="noopener">Y chromosome</a> revealed that his paternal haplogroup is Q1a, which is commonly found among Siberian and Native American populations. <a href="https://dx.doi.org/10.1126/science.1159750" target="_blank" rel="noopener">Previous analysis</a> by the same research group had revealed that Inuk&#8217;s maternal haplogroup, determined by his mitochondrial DNA, is D2a1.   This same lineage is commonly found in modern-day Aleuts of the Commander Islands in the Bering Sea and the Siberian Sireniki Yuits (Asian Eskimos).
Since discovery of the remains of the Saqqaq Culture in the 1950s, there has been disagreement over how these people were related to others that crossed the Bering Strait into the New World.   By analyzing Inuk&#8217;s DNA and comparing it to modern populations, the researchers determined that the Saqqaq are most closely related to the <a href="https://en.wikipedia.org/wiki/Nganasan_people" target="_blank" rel="noopener">Nganasans</a>, <a href="https://en.wikipedia.org/wiki/Koryaks" target="_blank" rel="noopener">Koryaks</a> and <a href="https://en.wikipedia.org/wiki/Chukchi_people" target="_blank" rel="noopener">Chukchis</a> of Siberia.   The long-gone Saqqaqs most likely left Siberia for the New World about 5,500 years ago, independently from the ancestors of present-day Native Americans and Inuit.
Now that his team has shown that full genome sequence analysis of ancient samples is feasible, Willerslev expects that there will be an explosion of work in the field.   He says that sequencing of DNA from South American mummies could help illuminate the population history and genetic diversity of Native Americans from before the arrival of Europeans.   Willerslev also suggests that sequencing ancient human DNA could reveal when certain genetic diseases become prevalent in different populations.

Ancient DNA — Page 2