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kottke.org posts about genetics

Ken Burns Presents The Gene: An Intimate History

From Ken Burns and Dr. Siddhartha Mukherjee, The Gene: An Intimate History, a series about the history of genetics based on Mukherjee’s book of the same name. Here’s a trailer:

The series tells the story of the rapid evolution of genetic science from Gregor Mendel’s groundbreaking experiment in the 19th century to CRISPR, and the hope that newfound powers to alter DNA with pinpoint precision will transform the treatment of some of the world’s most complex and challenging diseases. The series also tackles the daunting ethical challenges that these technologies pose for humankind.

This looks great, especially if this clip about Nancy Wexler’s crusade to find a cure for Huntington’s disease is representative of the whole:

In 1968, Nancy Wexler’s mother was diagnosed with a rare genetic disease - Huntington’s. Facing a 50-50 chance of contracting Huntington’s herself, Wexler β€” a non-scientist β€” began an odyssey to find the gene that causes the disease. For three decades, Wexler searched for treatments but chose not to get tested. As time passed, she noticed changes in the way she moved. Finally, in early 2020, Wexler decided to face her fears.

Part 1 of the series is now streaming on PBS with part 2 set to premiere next week.


Meet Next-Gen CRISPR, “a True Search-and-Replace Function for DNA”

MIT Technology Review’s Antonio Regalado reports on an improved gene editing technique that can rewrite DNA without actually cutting the DNA (which can damage and introduce errors into the genome). It’s called “prime editing”.

Today, in the latest β€” and possibly most important β€” of recent improvements to CRISPR technology, Liu is introducing “prime editing,” a molecular gadget he says can rewrite any type of genetic error without actually severing the DNA strand, as CRISPR does.

The new technology uses an engineered protein that, according to a report by Liu and 10 others today in the journal Nature, can transform any single DNA letter into any other, as well as add or delete longer stretches. In fact, Liu claims it’s capable of repairing nearly any of the 75,000 known mutations that cause inherited disease in humans.

From the abstract of the report:

Prime editing substantially expands the scope and capabilities of genome editing, and in principle could correct about 89% of known pathogenic human genetic variants.

See more coverage of this story at Nature, Scientific American, and Wired.


Fighting Climate Change with CO2-Eating “Ideal Plants”

At the Salk Institute for Biological Studies, Dr. Joanne Chory is working on a project to create plants capable of storing more carbon for a longer period of time than normal plants in order to help mitigate the effects of climate change.

Suberin β€” also known as cork β€” is a naturally occurring carbon-rich substance found in plant roots. It absorbs carbon yet resists decomposition (which releases carbon back into the atmosphere), enriches soil and helps plants resist stress.

By understanding and improving just a few genetic pathways in plants, Salk’s plant biologists believe they can help plants grow bigger, more robust root systems that absorb larger amounts of carbon, burying it in the ground in the form of suberin.

The Salk team will use cutting-edge genetic and genomic techniques to develop these Salk Ideal Plants.

Salk Ideal Plants

According to this piece in the Guardian on the project, one of the techniques they’re using is CRISPR, basically a genetic copy/paste system. Once the team demonstrates they can grow these larger root systems in model plants, they’ll genetically transfer that capability to the world’s largest food crops like rice, wheat, and corn.

As a bonus, the team believes that Ideal Plants will have other positive effects:

In addition to mitigating climate change, the enhanced root systems will help protect plants from stresses caused by climate changes and the additional carbon in the soil will make the soil richer, promoting better crop yields and more food for a growing global population.

This project is firmly on the wizard end of the wizards vs prophets spectrum.


The Fertility Doctor’s Secret

For The Atlantic, Sarah Zhang tells the story of dozens of people who found out through DNA testing that a fertility doctor named Donald Cline had used his own sperm in artificial insemination procedures on their mothers. The piece begins with the story of a woman whose parents had been treated by Cline more than 30 years ago.

It was only when she got home and replaced her phone that she saw the barrage of messages from even more half siblings. They had found her on Facebook, she realized, after searching for the username linked to her Ancestry.com account. Her husband had given her a DNA test for Christmas because she was interested in genealogy. Her heritage turned out to be exactly what she had thought β€” Scottish, with English, Irish, and Scandinavian mixed in β€” and she never bothered to click on the link that would show whether anyone on the site shared her DNA.

Apparently she did have relatives on Ancestry.com β€” and not just distant cousins. The people now sending her messages said they were Cline’s secret biological children. They said their parents had also been treated by Cline. They said that decades ago, without ever telling his patients, Cline had used his own sperm to impregnate women who came to him for artificial insemination.

According to her DNA, Woock, too, was one of his children.

In the time since Woock’s half siblings got in touch with her, they have broken the news dozens more times. The children Cline fathered with his patients now number at least 48, confirmed by DNA tests from 23andMe or Ancestry.com. (Several have a twin or other siblings who likely share the same biological father but haven’t been tested.) They keep in touch through a Facebook group. New siblings pop up in waves, timed perversely after holidays like Christmas or Mother’s Day or Father’s Day, when DNA tests are given as well-intentioned gifts.

One of Cline’s patients said recently: “I feel like I was raped 15 times.”


AeroMexico Trolls Xenophobic Americans with “DNA Discounts” Commercial

This commercial from Mexican airline AeroMexico cleverly reminds some Americans of the melting pot nature of our nation, where even “white” folks living near the border share significant amounts of DNA with those in Mexico. According to this piece in Adweek, the ad features non-actors and their actual DNA test results.

For those wondering how legit the scenarios shown in the ad are, Agost CarreΓ±o says it’s all real and that each person featured in the video was a non-actor who did have a 23andMe DNA test done in advance of the reveal.

Update: A possible inspiration for the AeroMexico video is The DNA Journey commercial by travel search engine Momondo:

The folks in that commercial may seem a bit naive about how DNA and ancestry works, but I took the 23andMe DNA test many years ago and was also surprised to find a few significant possible geographic outliers (British/Irish, Dutch) that were not accounted for in the handed-down family genealogy. (via @rudhraigh)


Chinese Scientists Are Creating CRISPR Babies

In an article for MIT Technology Review, Antonio Regalado reports that researchers in Shenzhen, led by He Jiankui, are recruiting couples for a study to produce the first genetically edited human babies. They are hoping to use the CRISPR gene editing technique to “eliminate a gene called CCR5 in hopes of rendering the offspring resistant to HIV, smallpox, and cholera”.

The birth of the first genetically tailored humans would be a stunning medical achievement, for both He and China. But it will prove controversial, too. Where some see a new form of medicine that eliminates genetic disease, others see a slippery slope to enhancements, designer babies, and a new form of eugenics.

“In this ever more competitive global pursuit of applications for gene editing, we hope to be a stand-out,” He and his team wrote in an ethics statement they submitted last year. They predicted their innovation “will surpass” the invention of in vitro fertilization, whose developer was awarded a Nobel Prize in 2010.

A follow-up by the Associated Press indicates that He’s program is already underway and has resulted in a successful birth of twins earlier this month.

The researcher, He Jiankui of Shenzhen, said he altered embryos for seven couples during fertility treatments, with one pregnancy resulting thus far. He said his goal was not to cure or prevent an inherited disease, but to try to bestow a trait that few people naturally have - an ability to resist possible future infection with HIV, the AIDS virus.

He said the parents involved declined to be identified or interviewed, and he would not say where they live or where the work was done.

Update: He is now under investigation for legal and ethical misconduct.

On Sunday, the Shenzhen City Medical Ethics Expert Board said it would begin an investigation of He’s research and released a statement saying that HarMoniCare “according to our findings … never conducted the appropriate reporting according to requirements.” The former medical director of the private hospital, Jiang Su-Qi, told Southern Capital News he had no recollection of approving He’s research while he was on its ethics committee.

“These two children are the guinea pigs. They will go through their whole maturing process having not understood the risks ahead of time,” said Liu Ying of Peking University’s Institute of Molecular Medicine.


Ancient Denisovan/Neanderthal human-hybrid discovered

Wow! Genetic analysis of a human bone fragment found in Siberia reveals that her parents belonged to two different groups of humans: her father was Denisovan and her mother Neanderthal.

A female who died around 90,000 years ago was half Neanderthal and half Denisovan, according to genome analysis of a bone discovered in a Siberian cave. This is the first time scientists have identified an ancient individual whose parents belonged to distinct human groups. The findings were published on 22 August in Nature1.

“To find a first-generation person of mixed ancestry from these groups is absolutely extraordinary,” says population geneticist Pontus Skoglund at the Francis Crick Institute in London. “It’s really great science coupled with a little bit of luck.”

Luck is right…what a needle in a haystack.


When you do a DNA test and find out your dad is not your father

Sarah Zhang writes about a support group on Facebook for people who have discovered surprising parentage through DNA testing.

Lisa, 44, admits she is still trying to go of that anger. She had always felt out of place in her family. Her hair β€” which she always straightened β€” was naturally fine and curly, her skin dark. “People would think I’m Hispanic, and would speak Spanish to me on the street,” she says. So when an DNA test in 2015 revealed her biological father was likely African American, it clicked into place. But her mom denied it. “She wouldn’t answer me. She would change the subject,” recalls Lisa. When she kept pressing, her mother broke down, saying it would destroy the family and that her dad β€” the man she grew up with β€” would kill her. She refused to say anything else about Lisa’s biological father.

I’ve written about this before (here and here) and reading these stories never gets any less heartbreaking. Back in 2010, I shared this:

I know someone who adopted a baby and they have never told her that she’s adopted and don’t plan to (she’s now in her 20s). When DNA testing becomes commonplace in another 5-15 years, I wonder how long that secret will last and what her reaction will be.

DNA testing confirms what we should have known all along: family is more than what biology says it is. Families already look quite differently than they did 40-50 years ago and they will continue to shift in the future, MAGA be damned.


There’s no scientific or genetic basis for race

Elizabeth Kolbert writing for National Geographic: There’s No Scientific Basis for Race β€” It’s a Made-Up Label.

“What the genetics shows is that mixture and displacement have happened again and again and that our pictures of past ‘racial structures’ are almost always wrong,” says David Reich, a Harvard University paleogeneticist whose new book on the subject is called Who We Are and How We Got Here. There are no fixed traits associated with specific geographic locations, Reich says, because as often as isolation has created differences among populations, migration and mixing have blurred or erased them.

She also observes that there’s more diversity in Africa than all the other continents combined (which is what happens when the rest of the world’s population is based on a relatively small population that left Africa 60,000 years ago).


Possible roadblock to CRISPR use in humans: we might be immune to it

Researchers from Stanford have published a study showing that immunity might hinder the use of the CRISPR gene editing technique in humans. The Cas9 bacterial protein commonly used in CRISPR is found in and around human bodies, so many of those bodies have already built up an immunity to it. That means if you send Cas9 into a body to do some gene editing, that body’s immune system might attack and destroy it before it can do its work. Sarah Zhang wrote about the study for The Atlantic.

Porteus and his colleagues focused on two versions of Cas9, the bacterial protein mostly commonly used in CRISPR gene editing. One comes from Staphylococcus aureus, which often harmlessly lives on skin but can sometimes causes staph infections, and another from Streptococcus pyogenes, which causes strep throat but can also become “flesh-eating bacteria” when it spreads to other parts of the body. So yeah, you want your immune system to be on guard against these bacteria.

It sounds like this was something geneticists were well aware of but wasn’t common knowledge among non-technical CRISPR enthusiasts. As Chang notes, scientists are already employing strategies to route around the potential immunity roadblock:

Modify Cas9 or use a different CRISPR protein altogether: It may be possible to redesign Cas9 to hide it from the immune system or to find other bacterial proteins that can do the job of Cas9 without provoking the immune response. Many different bacteria have CRISPR systems. “We already have lots of Cas enzymes and could get many more,” George Church, a geneticist at Harvard and a founding scientific advisor of Editas, wrote in an email.


New study: natural selection is getting rid of mutations that shorten human life

A massive genetic study led by Hakhamanesh Mostafavi, an evolutionary biologist at Columbia, suggests that evolution is weeding out certain genetic mutations in humans that shorten people’s lives.

Mostafavi and his colleagues tested more than 8 million common mutations, and found two that seemed to become less prevalent with age. A variant of the APOE gene, which is strongly linked to Alzheimer’s disease, was rarely found in women over 70. And a mutation in the CHRNA3 gene associated with heavy smoking in men petered out in the population starting in middle age. People without these mutations have a survival edge and are more likely to live longer, the researchers suggest.

This is not, by itself, evidence of evolution at work. In evolutionary terms, having a long life isn’t as important as having a reproductively fruitful one, with many children who survive into adulthood and birth their own offspring. So harmful mutations that exert their effects after reproductive age could be expected to be ‘neutral’ in the eyes of evolution, and not selected against.

But if that were the case, there would be plenty of such mutations still kicking around in the genome, the authors argue. That such a large study found only two strongly suggests that evolution is “weeding” them out, says Mostafavi, and that others have probably already been purged from the population by natural selection.


A biologist explains CRISPR to people at five different levels of knowledge

For the second part of an ongoing series, Wired asked biologist Neville Sanjana to explain CRISPR to five people with different levels of knowledge: a 7-year-old, a high school student, a college student, a grad student, and an expert on CRISPR. As I began to watch, I thought he’d gone off the rails right away with the little kid, but as soon as they connected on a personal issue (allergies), you can see the bridge of understanding being constructed.

The first installment in the series featured a neuroscientist explaining connectomes to five people.


Race, identity, and genetic stories

Finding out about your family history through a DNA test can be a thrilling or disturbing experience, particularly when it comes to race and identity. In the NY Times, researcher Anita Foeman writes about asking people how they identify and then DNA testing them. A man named Bernard identifies as black and predicted his test would show 50% European and 50% African ancestry (his father was black and his mother was white):

His comments before the test: My mother said, “I know you are me, but no cop is going to take the time to find out your mother is white.” She was very specific about raising me as a black man.

His DNA test showed he is “91% European, 5% Middle Eastern, 2% Hispanic; less than 1% African and Asian”:

Thoughts about his ancestry results: What are you trying to do to me? You have caused a lot of problems in my family. I know my nose is sharp and my skin is light, but my politics are as black as night. Today, I don’t identify as mixed. I reject my white privilege in a racist America. There is no way that I or my kids will identify as anything other than black.

In a follow-up newsletter, Times reader Carl Johnson writes:

I am a 55-year-old American male of African descent. I have a dark complexion and grew up in rural East Tennessee with my mother’s relatives. I wanted to have DNA testing done to confirm rumors of my Native American heritage. To my surprise, my results were 84 percent West African, 14 percent European, and 2 percent East Asian.

My bigger dilemma is: How do I embrace my European origins? It’s assumed that the European DNA was obtained by force during slavery. I think that is most likely. But what if my European ancestors were indentured servants who worked closely with African slaves and a real romance evolved, despite the cultural norms of that time, and now here I am?

If I am true to myself and the scientific evidence that provides richness to the DNA I’ve inherited, I now need to figure out a way to honor all of me and those who survived to make me possible. The journey and adventure continues.

I got DNA tested many years ago and I just went back to look at the results. My parents’ grandparents (or great grandparents, don’t really know) settled in Minnesota and Wisconsin in the mid-to-late 1800s as part of a wave of upper Midwestern immigration from Germany and Scandinavia.1 Unsurprisingly, my results came back as 100% European β€” mostly Northern European with some Eastern European2 β€” but with more British and Irish than I suspected (12%):

You most likely had a grandparent, great-grandparent, or second great-grandparent who was 100% British & Irish. This person was likely born between 1850 and 1910.

Huh.

  1. This resulted in some interesting family stories. During WWII, my great uncle Jens Jensen (Danish!) was fighting with the US Armed Forces over in Europe while his wife Hulda (German!) was sending food and clothing to family members in Germany. He was still wound up about it even 40 years later when I heard the story β€” “I was getting shot at by Nazis and she’s sending them goddamned care packages!” β€” but stories like that were always accompanied by a wink and a grin, so at least some of the sting had dissipated.↩

  2. In the 1800s, the territories of Prussia and Germany often included Poland. I don’t know exactly where my branch of the Kottke family lived in the “Old Country” but I’ve heard that it’s more likely to be in modern-day Poland than within the present German borders.↩


The facts, fears, and safety of GMO foods

Kurzgesagt takes a look at the debate over genetically modified foods. Decades of scientific research plainly says that GMO foods are safe to consume, but that’s not the only issue.

Over 90% of all cashed crops in the US are herbicide resistant, mostly to glyphosate. As a result, the use of glyphosate has increased greatly. That isn’t only bad, glyphosate is much less harmful to humans than many other herbicides. Still, this means farmers have a strong incentive to rely on this one method only, casting more balanced ways of managing weeds aside.

That’s one of the most fundamental problems with the GMO debate. Much of the criticism of this technology is actually criticism of modern agriculture and a business practice of the huge corporations that control our food supply. This criticism is not only valid, it’s also important. We need to change agriculture to a more sustainable model.

One thing is for certain…the debate online is polarized.


AIDS and the myth of Patient Zero

Some recent genetic testing of the blood of AIDS patients has determined that the strain of HIV responsible for the majority of the AIDS cases in the US spread from Zaire to Haiti around 1967, from Haiti to NYC around 1971, and from there to San Francisco around 1976 and that GaΓ©tan Dugas (aka Patient Zero) was not responsible for setting the epidemic in motion.

The strain of H.I.V. responsible for almost all AIDS cases in the United States, which was carried from Zaire to Haiti around 1967, spread from there to New York City around 1971, researchers concluded in the journal Nature. From New York, it spread to San Francisco around 1976.

The new analysis shows that Mr. Dugas’s blood, sampled in 1983, contained a viral strain already infecting men in New York before he began visiting gay bars in the city after being hired by Air Canada in 1974.

The researchers also reported that originally, Mr. Dugas was not even called Patient Zero β€” in an early epidemiological study of cases, he was designated Patient O, for “outside Southern California,” where the study began. The ambiguous circular symbol on a chart was later read as a zero, stoking the notion that blame for the epidemic could be placed on one man.


DNA evidence: humans are still evolving

Jerry Coyne, University of Chicago professor and author of Why Evolution is True, shares the results of a recent paper called Detection of human adaptation during the past 2000 years. In the study, DNA sequencing was used to find human genes that have changed so quickly in the past 2000 years that the authors conclude natural selection must be responsible.

Now, however, we can, by DNA sequencing, look at DNA directly, and with some fancy statistical footwork, get an idea of which genes have changed in frequency so fast that they must have been due to positive natural selection. That’s the subject of a new paper in Science by Yair Field et al. (reference and free download below). The authors conclude that several traits, including lactose tolerance, hair and eye color, and parts of the immune system, as well as height, have evolved within the last 2,000 years.

Other genes that might have changed during that period include those for infant head circumference, insulin levels, birth weight, and female hip size.


Should we use CRISPR to engineer mosquitoes incapable of transmitting malaria?

Thousands of people die every day from malaria, a disease that is transmitted to humans solely through mosquitoes. With CRISPR, scientists can easily genetically engineer mosquitoes incapable of transmitting malaria and using a technique called gene drive, they can force that genetic change into the native mosquito population. So, should we do it?


Scientists discover giraffes are actually four separate species

Giraffe Species

Suddenly, there are four species of giraffe now. Previously there was only one. Scientists have analyzed the genetic code of hundreds of giraffes in Africa and found much variation in their DNA, enough to split one species into four.

Some of the differences were as large or larger than the differences between brown bears and polar bears.

Despite their similar appearances, members of the different species don’t appear to mate with each other. It’s amazing that scientists didn’t know this until now.


The coming CRISPR revolution

Perfect eyesight. Curing cancer. Designer babies. Super-soldiers. Because of CRISPR, genetic engineering might make tinkering with life as easy as playing with Lego.

Imagine you were alive back in the 1980’s, and were told that computers would soon take over everything β€” from shopping, to dating, and the stock market, that billions of people would be connected via a kind of web, that you would own a handheld device orders of magnitudes more powerful than supercomputers.

It would seem absurd, but then all of it happened. Science fiction became our reality and we don’t even think about it. We’re at a similar point today with genetic engineering. So let’s talk about it.

Relatedly, I’m finishing up Neal Stephenson’s Seveneves right now and while it starts out as space science fiction, much of the book is concerned with the sort of genetic engineering issues discussed in the video.


The Gene: An Intimate History

Siddhartha Mukherjee, who wrote The Emperor of All Maladies, a biography of cancer and one of my favorite recent reads, is out with a new book called The Gene: An Intimate History.

Siddhartha Mukherjee has a written a biography of the gene as deft, brilliant, and illuminating as his extraordinarily successful biography of cancer. Weaving science, social history, and personal narrative to tell us the story of one of the most important conceptual breakthroughs of modern times, Mukherjee animates the quest to understand human heredity and its surprising influence on our lives, personalities, identities, fates, and choices.

The book comes recommended by Tyler Cowen, who IIRC also recommended Emperor of All Maladies to me.

This book filled in a number of gaps in my knowledge, plus it is engaging to read. Overall it confirmed my impression of major advances in the science, but not matched by many medical products for general use.

This is on the must-read list this summer. Somehow. When I get a second.


CRISPR, a cheap and accurate copy/paste for DNA

Michael Specter has a truly fascinating piece in the New Yorker about CRISPR, a relatively new genetic tool for editing genes that geneticists are very excited about.

With CRISPR, scientists can change, delete, and replace genes in any animal, including us. Working mostly with mice, researchers have already deployed the tool to correct the genetic errors responsible for sickle-cell anemia, muscular dystrophy, and the fundamental defect associated with cystic fibrosis. One group has replaced a mutation that causes cataracts; another has destroyed receptors that H.I.V. uses to infiltrate our immune system.

The story has everything: the cheap copy/paste of DNA, easily editable mice, pig Hitler, “destroyer of worlds” overtones, and an incredible tale of science that could actually revolutionize (or ruin, depending on who you talk to) the world. I was shocked at how easy it is to do genetic research nowadays.

Ordering the genetic parts required to tailor DNA isn’t as easy as buying a pair of shoes from Zappos, but it seems to be headed in that direction. Yan turned on the computer at his lab station and navigated to an order form for a company called Integrated DNA Technologies, which synthesizes biological parts. “It takes orders online, so if I want a particular sequence I can have it here in a day or two,” he said. That is not unusual. Researchers can now order online almost any biological component, including DNA, RNA, and the chemicals necessary to use them. One can buy the parts required to assemble a working version of the polio virus (it’s been done) or genes that, when put together properly, can make feces smell like wintergreen. In Cambridge, I.D.T. often makes same-day deliveries. Another organization, Addgene, was established, more than a decade ago, as a nonprofit repository that houses tens of thousands of ready-made sequences, including nearly every guide used to edit genes with CRISPR. When researchers at the Broad, and at many other institutions, create a new guide, they typically donate a copy to Addgene.

And CRISPR in particular has quickened the pace. A scientist studying lung cancer mutations said of her research:

“In the past, this would have taken the field a decade, and would have required a consortium,” Platt said. “With CRISPR, it took me four months to do it by myself.”

Also recommended: Radiolab’s podcast on CRISPR from back in June.


Copy and paste, but for DNA

No hunger. No pollution. No disease. Wired’s Amy Maxmen welcomes you to the age of copy and paste DNA editing and the end of life as we know it.

Genome editing started with just a few big labs putting in lots of effort, trying something 1,000 times for one or two successes. Now it’s something that someone with a BS and a couple thousand dollars’ worth of equipment can do. What was impractical is now almost everyday. That’s a big deal.

[I recently listened to Radiolab’s show on Crispr. Recommended. -jkottke]


Self-destructing mosquitos

A company called Oxitec has genetically modified mosquito eggs so that the mosquitos born from them pass along a gene to their offspring that prohibits the mosquitos from reaching sexual maturity and mating. They release the mosquitos into the wild, they mate with the local population of mosquitos, and those born from those matings will die before mating themselves. Voila! Pest control.

Oxitec has conducted trials with its modified mosquito in dengue-ridden regions of Panama, Brazil, Malaysia, and the Cayman Islands. The results show population suppression rates above 90 percent-far greater than the typical 30 percent achieved with insecticides.

The company is currently planning a trial in Florida using this technique to curb an influx of mosquito-borne illness.


Genetic algorithm walkers

Genetic Walker

This simulator evolves increasingly effective walking creatures through genetic algorithms. After each round, the winners are sent through to the next round and copied by the rest of the competitors, with mutations introduced. At first, the pace of improvement is swift β€” two orders of magnitude within 100 generations β€” but slows pretty dramatically after that. (via @nickrichter)


The human family grows

A new analysis of the genomes of two extinct human species (Neanderthals and Denisovans) shows more clearly that they interbred with our species of human, contributing 2-4% of our modern genomes in some cases.

“What it begins to suggest is that we’re looking at a Lord of the Rings-type world β€” that there were many hominid populations,” says Mark Thomas, an evolutionary geneticist at University College London who was at the meeting but was not involved in the work.

But, more interestingly, the analysis also detected the Denisovans also bred with an as-yet-unknown species of humans.

The Denisovan genome indicates that the population got around: Reich said at the meeting that as well as interbreeding with the ancestors of Oceanians, they also bred with Neanderthals and the ancestors of modern humans in China and other parts of East Asia. Most surprisingly, Reich said, the genomes indicate that Denisovans interbred with yet another extinct population of archaic humans that lived in Asia more than 30,000 years ago β€” one that is neither human nor Neanderthal.

Is this the first time a new human species has been discovered through DNA evidence alone?


The potential landmines of genetic testing services

As part of a course he was teaching, a biologist sent away for a genetic testing kit from 23andMe for himself and his parents. When he went looking for other relatives on the service (which is now an automatic opt-out feature), he discovered he had a half-brother his dad had not told his family about.

At first, I was thinking this is the coolest genetics story, my own personal genetics story. I wasn’t particularly upset about it initially, until the rest of the family found out. Their reaction was different. Years of repressed memories and emotions uncorked and resulted in tumultuous times that have torn my nuclear family apart. My parents divorced. No one is talking to my dad. We’re not anywhere close to being healed yet and I don’t know how long it will take to put the pieces back together.

After this discovery was made, I went back to 23andMe and talked to them. I said, “I’m not sure all your customers realize that when they participate in your family finder program, what they’re participating in what are essentially really advanced paternity tests.” People find out that their parents aren’t who they think they are. They have nearly a million people in the database. If there happens to be anyone in there you’re related to, they’ll find your match. This is a solid science.

I know a family in which one of the children is adopted and they haven’t told her. Which is crazy…she’s gonna find out eventually (through something like 23andMe or because of some medical emergency or test) and go totally berzerk.


Alien DNA

For the first time, scientists have created a living cell with DNA containing more than just the familiar A, T, C, and G units.

Hailed as a breakthrough by other scientists, the work is a step towards the synthesis of cells able to churn out drugs and other useful molecules. It also raises the possibility that cells could one day be engineered without any of the four DNA bases used by all organisms on Earth.

“What we have now is a living cell that literally stores increased genetic information,” says Floyd Romesberg, a chemical biologist at the Scripps Research Institute in La Jolla, California, who led the 15-year effort.

So instead of just using the GATTACA alphabet, scientists may eventually gain the use of an alphabet containing dozens or even hundreds or thousands of different letters. Potentially powerful stuff.


Test tube time machine

Richard Lenski and his team of researchers utilize a clever technique to observe and study evolution of bacteria in realtime. Periodically freezing a sample of the bacteria every few generations allows them to go back in time to study particular traits and to pinpoint when differences occur.

After 30,000 generations, researchers noticed something strange. One population had evolved the ability to use a different carbon-based molecule in the solution, called citrate, as a power source.

Researchers wondered whether it was the result of a rare, single mutation, or a more complex change involving a series of mutations over generations. To find out, one of Lenski’s postdocs, Zachary Blount, took some of the frozen cells and grew them in a culture lacking glucose, with citrate as the only potential food source.

After testing 10 trillion ancestral cells from early generations, he got no growth. But when he tested cells from the 20,000th generation on, he began to get results, eventually finding 19 mutants that could use citrate as a power source. The results showed that the citrate-eating mutation was most likely not the result of a single mutation, but one enabled by multiple changes over 20,000 generations.


Supreme Court: human genes not patentable

In a unanimous decision, the US Supreme Court ruled today that human genes cannot be patented.

The case involved Myriad Genetics Inc., which holds patents related to two genes, known as BRCA1 and BRCA2, that can indicate whether a woman has a heightened risk of developing breast cancer or ovarian cancer.

Justice Clarence Thomas, writing for the court, said the genes Myriad isolated are products of nature, which aren’t eligible for patents.

The high court’s ruling was a win for a coalition of cancer patients, medical groups and geneticists who filed a lawsuit in 2009 challenging Myriad’s patents. Thanks to those patents, the Salt Lake City company has been the exclusive U.S. commercial provider of genetic tests for breast cancer and ovarian cancer.

The challengers argued the patents have allowed Myriad to dictate the type and terms of genetic screening available for the diseases, while also dissuading research by other laboratories.

Fuck yes. A defect in her BRCA1 gene is what caused Angelina Jolie to recently have a preventive double mastectomy. (via @tylercowen)


Charlemagne for everyone!

We are all mostly related to each other. But weirder still, you’re just about as related to the stranger next to you as to your greatΓ—12 grandparents.

Now, there’s another important implication of genomic ancestry studies: Most of the people you are descended from are no more genetically related to you than strangers are. Or to put it another way, your genealogical family tree, which includes all the history of your family going back thousands of years, is much larger than your genetic family tree-the people whom genome sequencing would pinpoint as related to you. 99.9 percent of your genome is the same as that of every other human being (apart from the x and y chromosomes), and that .1 percent of variation in each person gets thinned out pretty quickly across the generations, as each child gets half of each of her parents’ genomes, passes on half to each of her children, and so on. Geneticist Luke Jostins did a nice mathematical analysis and estimated that you have only about a 12 percent chance of being genetically related to an ancestor 10 generations ago; by the time you get to a 14-generation ancestor, the probability is nearly zero.