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The genes of the oldest known residents of the Caribbean link them with the earliest populations that settled in Central and South America.

Part of the problem is that scientists have yet to find ancient DNA in the Caribbean that is more than 3,000 years old

The other problem is that ancient DNA is still scarce on the Caribbean coast of the mainland.

About 2,500 years ago, the archaeological record shows, there was a drastic shift in the cultural life of the Caribbean. People started living in bigger settlements, intensively farming crops like maize and sweet potatoes. Their pottery became more sophisticated and elaborate. For archaeologists, the change indicates the end of what they call the Archaic Age and the start of a Ceramic Age.

The skeletons from the Ceramic Age largely shared a new genetic signature. Their DNA links them to small tribes still living today in Colombia and Venezuela.

We don’t know a lot about these languages, although some words have managed to survive. Hurricane, for example, comes from hurakán, the Taino name for the god of storms.

These words bear a striking resemblance to words from a family of languages in South America called Arawak. The DNA of the Ceramic Age Caribbeans most closely resembles that of living Arawak speakers.

The people bearing Ceramic Age ancestry came to dominate the Caribbean, with almost no interbreeding between the two groups.

the new DNA findings had surprised him in many ways, giving him a host of new questions to investigate.

Over the course of the Ceramic Age, for example, strikingly new pottery styles emerged every few centuries. Researchers have long guessed that those shifts reflect the arrival of new groups of people in the islands. The ancient DNA doesn’t support that idea, though. There’s a genetic continuity through those drastic cultural changes. It appears that the same group of people in the Caribbean went through a series of major social changes that archaeologists have yet to explain.

Dr. Reich and his fellow geneticists also discovered family ties that spanned the Caribbean during the Ceramic Age. They found 19 pairs of people on different islands who shared identical segments of DNA — a sign that they were fairly close relatives. In one case, they found long-distance cousins from the Bahamas and Puerto Rico, separated by over 800 miles.

“The original idea was that people start in one place, they establish a colony someplace else, and then they just cut all ties to where they came from,” Dr. Keegan said. “But the genetic evidence is suggesting that these ties were maintained over a long period of time.”

Rather than being made up of isolated communities, in other words, the Caribbean was a busy, long-distance network that people regularly traveled by dugout canoe. “The water is like a highway,”

The genetic variations also allowed Dr. Reich and his colleague to estimate the size of the Caribbean society before European contact. Christopher Columbus’s brother Bartholomew sent letters back to Spain putting the figure in the millions

The DNA suggests that was an exaggeration: the genetic variations imply that the total population was as low as the tens of thousands.

now, with a population of about 44 million people, the Caribbean may contain more Taino DNA than it did in 1491.

Dr. Aviles and his colleagues have uploaded the ancient Caribbean genomes to a genealogical database called GEDMatch. With the help of genealogists, people can compare their own DNA to the ancient genomes. They can see the matching stretches of genetic material that reveal their relatedness.

In the new study, researchers, including chemist Shankar Balasubramanian, of the University of Cambridge and Cambridge Research Institute, crafted antibody proteins specifically for this type of DNA. The proteins were marked with a fluorescent chemical, so when they hooked up to areas in the human genome packed with G-quadruplexes, they lit up.

Next, they incubated the antibodies with human cells in the lab, finding these structures tended to occur in genes of cells that were rapidly dividing, a telltale feature of cancer cells. They also found a spike in quadruplexes during the s-phase of the cell cycle, or the phase when DNA replicates just before the cell divides.

the researchers think the four-stranded DNA could be a target for personalized medicine in the future

"What makes me personally very happy about this work is that it again demonstrates that mechanisms first described in ciliated protozoa hold also true for other organisms up to human, demonstrating the strength of this model organism," wrote Lipps wrote.

Large-scale surveys of the genome have led a number of researchers to expect that the human genome will turn out to be even more full of activity than previously thought.

“It was pretty much a case of hubris to imagine that we could dispense with any part of the genome — as if we knew enough to say it wasn’t functional.”

If every piece of the genome were essential, then many of those mutations would lead to significant birth defects, with the defects only multiplying over the course of generations; in less than a century, the species would become extinct.

“Much of what has been called ‘junk DNA’ in the human genome is actually a massive control panel with millions of switches regulating the activity of our genes.”

It’s no coincidence, researchers like Gregory argue, that bona fide creationists have used recent changes in the thinking about junk DNA to try to turn back the clock to the days before Darwin. (The recent studies on noncoding DNA “clearly demonstrate we are ‘fearfully and wonderfully made’ by our Creator God,” declared the Institute for Creation Research.)

Over millions of years, the human genome has spontaneously gotten bigger, swelling with useless copies of genes and new transposable elements.

Wolves are hard to tame, even as puppies, and many researchers find it much more plausible that dogs, in effect, invented themselves.

gradually evolved to become tamer and tamer, producing lots of offspring because of the relatively easy pickings

researchers question whether dogs experience feelings like love and loyalty, or whether their winning ways are just a matter of instincts that evolved because being a hanger-on is an easier way to make a living than running down elk.

dogs and wolves interbreed easily and some scientists are not convinced that the two are even different species

generally agree that there is good evidence that dogs were domesticated around 15,000 years ago

“Maybe dog domestication on some level kicks off this whole change in the way that humans are involved and responding to and interacting with their environment,

most dog breeds were invented in the 19th century during a period of dog obsession that he called “the giant whirlwind blender of the European crazy Victorian dog-breeding frenzy.

“There’s hardly a person working in canine genetics that’s not working on that project

Almost every group has a different origination hypothesis

jaws and occasionally nearly complete skulls from old and recent dogs, wolves and canids that could fall into either category.

will be able to determine whether the domestication process occurred closer to 15,000 or 30,000 years ago,

major achievement in the world of canine science, and a landmark in the analysis of ancient DNA to show evolution, migrations and descent,

based on DNA evidence and the shape of ancient skulls, that dog domestication occurred well over 30,000 years ago.

he became fed up with the lack of ancient DNA evidence in papers about the origin of dogs.

identified a skull about 32,000 years old from a Belgian cave in Goyet as an early dog.

arguing that the evidence just wasn’t there to call the Goyet skull a dog,

claims are controversial and is willing, like the rest of the world of canine science, to risk damage to the fossils themselves to get more information on not just the mitochondrial DNA but also the nuclear DNA.

geneticists try to establish is how different the DNA of one animal is from another. Adding ancient DNA gives many more points of reference over a long time span.

will be able to identify changes in the skulls or jaws of those wolves that show shifts to more doglike shapes, helping to narrow the origins of domestication

the project will publish a flagship paper from all of the participants describing their general findings

a group in China was forming with the goal of sequencing 10,000 dog genomes

growing increasingly confident that they will find what they want, and come close to settling the thorny question of when and where the tearing power of a wolf jaw first gave way to the persuasive force of a nudge from a dog’s cold nose.

The scale of this phenomenon is contributing to the emergence of mental health professionals who specialize in DNA-related discoveries, and strengthening a growing movement advocating everyone’s right to know his or her genetic identity.

In the tug between a person’s right to know her genetic origins and her parents’ right to privacy, which should prevail? Mothers may not want to share how their children came into the world.

Maybe a child was donor-conceived during an era when experts encouraged parents not to disclose this truth to their children. Or perhaps the circumstances involved coercion or violence

The reality of our genes may collide with the narratives we hold dear. We construct stories about who we are and what we value; about our parents’ characters and our spouses’ loyalties. The results of consumer genetic testing can serve as Rorschach tests for our beliefs about family, morality and the past.

Just as the loss of a species decreases the richness of an ecosystem, the addition of new animals could achieve the opposite effect.

National Geographic Society hosted a larger conference to debate the scientific and ethical questions raised by the prospect of “de-extinction.

“De-extinction went from concept to potential reality right before our eyes,

less scientific, if more persuasive, argument was advanced by the ethicist Hank Greely and the law professor Jacob Sherkow, both of Stanford. De-extinction should be pursued, they argued in a paper published in Science, because it would be really

“This may be the biggest attraction and possibly the biggest benefit of de-extinction. It would surely be very cool to see a living woolly mammoth.”

They will replace chunks of band-tailed-pigeon DNA with synthesized chunks of passenger-pigeon DNA, until the cell’s genome matches their working passenger-pigeon genome.

Scientists predict that changes made by human beings to the composition of the atmosphere could kill off a quarter of the planet’s mammal species, a fifth of its reptiles and a sixth of its birds by 2050

This cloning method, called somatic cell nuclear transfer, can be used only on species for which we have cellular material.

There is a shortcut. The genome of a closely related species will have a high proportion of identical DNA, so it can serve as a blueprint, or “scaffold.”

By comparing the fragments of passenger-pigeon DNA with the genomes of similar species, researchers can assemble an approximation of an actual passenger-pigeon genome.

As with any translation, there may be errors of grammar, clumsy phrases and perhaps a few missing passages, but the book will be legible. It should, at least, tell a good story.

the genome will have to be inscribed into a living cell.

“We’ve framed it in terms of conservation,”

MAGE (Multiplex Automated Genome Engineering). MAGE is nicknamed the “evolution machine” because it can introduce the equivalent of millions of years of genetic mutations within minutes

Developmental and behavioral biologists would take over, just in time to answer some difficult questions. Chicks imitate their parents’ behavior. How do you raise a passenger pigeon without parents of its own species? And how do you train band-tailed pigeons to nurture the strange spawn that emerge from their eggs; chicks that, to them, might seem monstrous: an avian Rosemary’s Baby?

For endangered species with tiny populations, scientists would introduce genetic diversity to offset inbreeding.

They will try to alter the birds’ diets, migration habits and environment. The behavior of each subsequent generation will more closely resemble that of their genetic cousins.

For species threatened by contagion, an effort would be made to fortify their DNA with genes that make them disease-resistant

The scientific term for this type of genetic intervention is “facilitated adaptation.”

This optimistic, soft-focus fantasy of de-extinction, while thrilling to Ben Novak, is disturbing to many conservation biologists, who consider it a threat to their entire discipline and even to the environmental movement.

The first question posed by conservationists addresses the logic of bringing back an animal whose native habitat has disappeared. Why go through all the trouble just to have the animal go extinct all over again?

There is also anxiety about disease

“If you recreate a species genetically and release it, and that genotype is based on a bird from a 100-year-old environment, you probably will increase risk.”

“There’s always this fear that somehow, if we do it, we’re going to accidentally make something horrible, because only nature can really do it right. But nature is totally random. Nature makes monsters. Nature makes threats. Many of the things that are most threatening to us are a product of nature. Revive & Restore is not going to tip the balance in any way.”

De-extinction also poses a rhetorical threat to conservation biologists. The specter of extinction has been the conservation movement’s most powerful argument. What if extinction begins to be seen as a temporary inconvenience?

De-extinction suggests that we can technofix our way out of environmental issues generally, and that’s very, very bad.

How will we decide which species to resurrect?

Philip Seddon recently published a 10-point checklist to determine the suitability of any species for revival, taking into account causes of its extinction, possible threats it might face upon resurrection and man’s ability to destroy the species “in the event of unacceptable ecological or socioeconomic impacts.”

But the most visceral argument against de-extinction is animal cruelty.

“Is it fair to do this to these animals?” Shapiro asked. “Is ‘because we feel guilty’ a good-enough reason?” Stewart Brand made a utilitarian counterargument: “We’re going to go through some suffering, because you try a lot of times, and you get ones that don’t take. On the other hand, if you can bring bucardos back, then how many would get to live that would not have gotten to live?”

In “How to Permit Your Mammoth,” published in The Stanford Environmental Law Journal, Norman F. Carlin asks whether revived species should be protected by the Endangered Species Act or regulated as a genetically modified organism.

He concludes that revived species, “as products of human ingenuity,” should be eligible for patenting.

The term “de-extinction” is misleading. Passenger pigeons will not rise from the grave

Our understanding of the passenger pigeon’s behavior derives entirely from historical accounts.

There is no authoritative definition of “species.” The most widely accepted definition describes a group of organisms that can procreate with one another and produce fertile offspring, but there are many exceptions.

Theseus’ ship, therefore, “became a standing example among the philosophers . . . one side holding that the ship remained the same, and the other contending that it was not the same.”

What is coming will go well beyond the resurrection of extinct species. For millenniums, we have customized our environment, our vegetables and our animals, through breeding, fertilization and pollination. Synthetic biology offers far more sophisticated tools. The creation of novel organisms, like new animals, plants and bacteria, will transform human medicine, agriculture, energy production and much else.

that domestication probably began around 20,000 years ago.

much more diverse genetically than modern dogs.

All European dogs appear to have descended from one group of ancient European dogs, and the great modern diversity of dog shapes and sizes indicates an emphasis by breeders on certain very powerful genes.

Modern wolves, however, do show the incorporation of some dog DNA.

The extraordinarily rich amount of information gathered from the 27 genomes provided many new perspectives on dog domestication and their association with humans.

even while they were sometimes breeding with wolves, no new wolf DNA entered their genomes.

Pigs can be a little wild but “if you’re a dog and you’ve got a little bit of wolf in you, that’s not a good thing and those things get knocked on the head very quickly or run away or disappear but they don’t get integrated into the dog population.”

But then there was the sudden loss of diversity in dogs starting around 4,000 years ago.

The exact where and when of dog domestication remain unclear, and will never be pinned down to the kind of moment in time that dog owners like to imagine, but, in terms of a period of time and geographic area, Dr. Larson said, “We’re getting closer.”

Globally, the numbers can be even worse, and the stakes often higher. “Say a person comes into the hospital in Sierra Leone with a fever and flulike symptoms,” DeRisi says. “After a few days, or a week, they die. What caused that illness? Most of the time, we never find out. Because if the cause isn’t something that we can culture and test for” — like hepatitis, or strep throat — “it basically just stays a mystery.”

It would be better, DeRisi says, to watch for rare cases of mystery illnesses in people, which often exist well before a pathogen gains traction and is able to spread.

Based on a retrospective analysis of blood samples, scientists now know that H.I.V. emerged nearly a dozen times over a century, starting in the 1920s, before it went global.

Zika was a relatively harmless illness before a single mutation, in 2013, gave the virus the ability to enter and damage brain cells.

The beauty of this approach” — running blood samples from people hospitalized all over the world through his system, known as IDseq — “is that it works even for things that we’ve never seen before, or things that we might think we’ve seen but which are actually something new.”

In this scenario, an undiscovered or completely new virus won’t trigger a match but will instead be flagged. (Even in those cases, the mystery pathogen will usually belong to a known virus family: coronaviruses, for instance, or filoviruses that cause hemorrhagic fevers like Ebola and Marburg.)

And because different types of bacteria require specific conditions in order to grow, you also need some idea of what you’re looking for in order to find it.

The same is true of genomic sequencing, which relies on “primers” designed to match different combinations of nucleotides (the building blocks of DNA and RNA).

Even looking at a slide under a microscope requires staining, which makes organisms easier to see — but the stains used to identify bacteria and parasites, for instance, aren’t the same.

The practice that DeRisi helped pioneer to skirt this problem is known as metagenomic sequencing

Unlike ordinary genomic sequencing, which tries to spell out the purified DNA of a single, known organism, metagenomic sequencing can be applied to a messy sample of just about anything — blood, mud, seawater, snot — which will often contain dozens or hundreds of different organisms, all unknown, and each with its own DNA. In order to read all the fragmented genetic material, metagenomic sequencing uses sophisticated software to stitch the pieces together by matching overlapping segments.

The assembled genomes are then compared against a vast database of all known genomic sequences — maintained by the government-run National Center for Biotechnology Information — making it possible for researchers to identify everything in the mix

Traditionally, the way that scientists have identified organisms in a sample is to culture them: Isolate a particular bacterium (or virus or parasite or fungus); grow it in a petri dish; and then examine the result under a microscope, or use genomic sequencing, to understand just what it is. But because less than 2 percent of bacteria — and even fewer viruses — can be grown in a lab, the process often reveals only a tiny fraction of what’s actually there. It’s a bit like planting 100 different kinds of seeds that you found in an old jar. One or two of those will germinate and produce a plant, but there’s no way to know what the rest might have grown into.

Such studies have revealed just how vast the microbial world is, and how little we know about it

“The selling point for researchers is: ‘Look, this technology lets you investigate what’s happening in your clinic, whether it’s kids with meningitis or something else,’” DeRisi said. “We’re not telling you what to do with it. But it’s also true that if we have enough people using this, spread out all around the world, then it does become a global network for detecting emerging pandemics

One study found more than 1,000 different kinds of viruses in a tiny amount of human stool; another found a million in a couple of pounds of marine sediment. And most were organisms that nobody had seen before.

After the Biohub opened in 2016, one of DeRisi’s goals was to turn metagenomics from a rarefied technology used by a handful of elite universities into something that researchers around the world could benefit from

metagenomics requires enormous amounts of computing power, putting it out of reach of all but the most well-funded research labs. The tool DeRisi created, IDseq, made it possible for researchers anywhere in the world to process samples through the use of a small, off-the-shelf sequencer, much like the one DeRisi had shown me in his lab, and then upload the results to the cloud for analysis.

he’s the first to make the process so accessible, even in countries where lab supplies and training are scarce. DeRisi and his team tested the chemicals used to prepare DNA for sequencing and determined that using as little as half the recommended amount often worked fine. They also 3-D print some of the labs’ tools and replacement parts, and offer ongoing training and tech support

The metagenomic analysis itself — normally the most expensive part of the process — is provided free.

But DeRisi’s main innovation has been in streamlining and simplifying the extraordinarily complex computational side of metagenomics

IDseq is also fast, capable of doing analyses in hours that would take other systems weeks.

“What IDseq really did was to marry wet-lab work — accumulating samples, processing them, running them through a sequencer — with the bioinformatic analysis,”

“Without that, what happens in a lot of places is that the researcher will be like, ‘OK, I collected the samples!’ But because they can’t analyze them, the samples end up in the freezer. The information just gets stuck there.”

Meningitis itself isn’t a disease, just a description meaning that the tissues around the brain and spinal cord have become inflamed. In the United States, bacterial infections can cause meningitis, as can enteroviruses, mumps and herpes simplex. But a high proportion of cases have, as doctors say, no known etiology: No one knows why the patient’s brain and spinal tissues are swelling.

When Saha and her team ran the mystery meningitis samples through IDseq, though, the result was surprising. Rather than revealing a bacterial cause, as expected, a third of the samples showed signs of the chikungunya virus — specifically, a neuroinvasive strain that was thought to be extremely rare. “At first we thought, It cannot be true!” Saha recalls. “But the moment Joe and I realized it was chikungunya, I went back and looked at the other 200 samples that we had collected around the same time. And we found the virus in some of those samples as well.”

Until recently, chikungunya was a comparatively rare disease, present mostly in parts of Central and East Africa. “Then it just exploded through the Caribbean and Africa and across Southeast Asia into India and Bangladesh,” DeRisi told me. In 2011, there were zero cases of chikungunya reported in Latin America. By 2014, there were a million.

Chikungunya is a mosquito-borne virus, but when DeRisi and Saha looked at the results from IDseq, they also saw something else: a primate tetraparvovirus. Primate tetraparvoviruses are almost unknown in humans, and have been found only in certain regions. Even now, DeRisi is careful to note, it’s not clear what effect the virus has on people. “Maybe it’s dangerous, maybe it isn’t,” DeRisi says. “But I’ll tell you what: It’s now on my radar.

it reveals a landscape of potentially dangerous viruses that we would otherwise never find out about. “What we’ve been missing is that there’s an entire universe of pathogens out there that are causing disease in humans,” Imam notes, “ones that we often don’t even know exist.”

“The plan was, Let’s let researchers around the world propose studies, and we’ll choose 10 of them to start,” DeRisi recalls. “We thought we’d get, like, a couple dozen proposals, and instead we got 350.”

Metagenomic sequencing is especially good at what scientists call “environmental sampling”: identifying, say, every type of bacteria present in the gut microbiome, or in a teaspoon of seawater.

“When you draw blood from someone who has a fever in Ghana, you really don’t know very much about what would normally be in their blood without fever — let alone about other kinds of contaminants in the environment. So how do you interpret the relevance of all the things you’re seeing?”

Such criticisms have led some to say that metagenomics simply isn’t suited to the infrastructure of developing countries. Along with the problem of contamination, many labs struggle to get the chemical reagents needed for sequencing, either because of the cost or because of shipping and customs holdups

we’re less likely to be caught off-guard. “With Ebola, there’s always an issue: Where’s the virus hiding before it breaks out?” DeRisi explains. “But also, once we start sampling people who are hospitalized more widely — meaning not just people in Northern California or Boston, but in Uganda, and Sierra Leone, and Indonesia — the chance of disastrous surprises will go down. We’ll start seeing what’s hidden.”

"Cancers develop by a lineage, too," Alex Schier told the BBC. "Our technique can be used to follow these lineages during cancer formation - to tell us the relationships of cells within a tumour, and between the original tumour and secondary tumours formed by metastasis."

the subject is taught bafflingly minimally and late in the curriculum even today; evolution by natural selection is crucial to every aspect of the living world. In the words of the Russian scientist Theodosius Dobzhansky: “Nothing in biology makes sense except in the light of evolution.”

his true legacy is The Selfish Gene and its profound effect on multiple generations of scientists and lay readers. In a sense, The Selfish Gene and Dawkins himself are bridges, both intellectually and chronologically, between the titans of mid-century biology – Ronald Fisher, Trivers, Hamilton, Maynard Smith and Williams – and our era of the genome, in which the interrogation of DNA dominates the study of evolution.

Genes aren’t what they used to be either. In 1976 they were simply stretches of DNA that encoded proteins. We now know about genes made of DNA’s cousin, RNA; we’ve discovered genes that hop from genome to genome

Since 1976, our understanding of why life is the way it is has blossomed and changed. Once the gene became the dominant idea in biology in the 1990s there followed a technological goldrush – the Human Genome Project – to find them all.

None of the complications of modern genomes erodes the central premise of the selfish gene.

Much of the enmity stems from people misunderstanding that selfishness is being used as a metaphor. The irony of these attacks is that the selfish gene metaphor actually explains altruism. We help others who are not directly related to us because we share similar versions of genes with them.

In the scientific community, the chief objection maintains that natural selection can operate at the level of a group of animals, not solely on genes or even individuals

To my mind, and that of the majority of evolutionary biologists, the gene-centric view of evolution always emerges intact.

the premise remains exciting that a gene’s only desire is to reproduce itself, and that the complexity of genomes makes that reproduction more efficient.

“Your results are not the least bit surprising,” he told me. “Anything short of sequencing is going to be short on accuracy — and even then, there’s almost no comprehensive data sets to compare to.”

“Even if they are accurately looking at 5 percent of the attributable risk, they’ve ignored the vast majority of the other risk factors — the dark matter for genetics — because we as a scientific community haven’t yet identified those risk factors,”

There are only 23 diseases that start in adulthood, can be treated, and for which highly predictive tests exist. All are rare, with hereditary breast cancer the most common. “A small percentage of people who get tested will get useful information,” Dr. Klitzman said. “But for most people, the results are not clinically useful, and they may be misleading or confusing.”

To be sure, my tests did provide some beneficial information. They all agreed that I lack markers associated with an increased risk of breast cancer and Alzheimer’s. That said, they were testing for only a small fraction of the genetic risks for these diseases, not for rare genetic variants that confer much of the risk. I could still develop those diseases, of course, but I don’t have reason to pursue aggressive screenings as I age.

He added: “If you want to spend money wisely to protect your health and you have a few hundred dollars, buy a scale, stand on it, and act accordingly.”

The technique holds the power to repair or enhance any human gene. “It raises the most fundamental of issues about how we are going to view our humanity in the future and whether we are going to take the dramatic step of modifying our own germline and in a sense take control of our genetic destiny, which raises enormous peril for humanity,”

The paper’s authors, however, are concerned about countries that have less regulation in science. They urge that “scientists should avoid even attempting, in lax jurisdictions, germline genome modification for clinical application in humans” until the full implications “are discussed among scientific and governmental organizations.”

Though such a moratorium would not be legally enforceable and might seem unlikely to exert global influence, there is a precedent. In 1975, scientists worldwide were asked to refrain from using a method for manipulating genes, the recombinant DNA technique, until rules had been established.

Though highly efficient, the technique occasionally cuts the genome at unintended sites. The issue of how much mistargeting could be tolerated in a clinical setting is one that Dr. Doudna’s group wants to see thoroughly explored before any human genome is edited.

“We worry about people making changes without the knowledge of what those changes mean in terms of the overall genome,” Dr. Baltimore said. “I personally think we are just not smart enough — and won’t be for a very long time — to feel comfortable about the consequences of changing heredity, even in a single individual.”

Many ethicists have accepted the idea of gene therapy, changes that die with the patient, but draw a clear line at altering the germline, since these will extend to future generations. The British Parliament in February approved the transfer of mitochondria, small DNA-containing organelles, to human eggs whose own mitochondria are defective. But that technique is less far-reaching because no genes are edited.

There are two broad schools of thought on modifying the human germline, said R. Alta Charo, a bioethicist at the University of Wisconsin and a member of the Doudna group. One is pragmatic and seeks to balance benefit and risk. The other “sets up inherent limits on how much humankind should alter nature,” she said. Some Christian doctrines oppose the idea of playing God, whereas in Judaism and Islam there is the notion “that humankind is supposed to improve the world.” She described herself as more of a pragmatist, saying, “I would try to regulate such things rather than shut a new technology down at its beginning.

The Doudna group calls for public discussion, but is also working to develop some more formal process, such as an international meeting convened by the National Academy of Sciences, to establish guidelines for human use of the genome-editing technique.“We need some principled agreement that we want to enhance humans in this way or we don’t,” Dr. Jaenisch said. “You have to have this discussion because people are gearing up to do this.”

"Dogs are our oldest and closest animal partner. Using DNA from ancient dogs is showing us just how far back our shared history goes and will ultimately help us understand when and where this deep relationship began."

If there were multiple domestication events around the world, these other lineages did not contribute much DNA to later dogs.

In the late 1900s, researchers discovered that mitochondria were free-living bacteria at some point in the past. Somehow they were drawn inside another cell, providing new fuel for their host. In 2015, Thijs Ettema of Uppsala University in Sweden and his colleagues discovered fragments of DNA in sediments retrieved from the Arctic Ocean. The fragments contained genes from a species of archaea that seemed to be closely related to eukaryotes.Dr. Ettema and his colleagues named them Asgard archaea. (Asgard is the home of the Norse gods.) DNA from these mystery microbes turned up in a river in North Carolina, hot springs in New Zealand and other places around the world.

Masaru K. Nobu, a microbiologist at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, and his colleagues managed to grow these organisms in a lab. The effort took more than a decade.The microbes, which are adapted to life in the cold seafloor, have a slow-motion existence. Prometheoarchaeum can take as long as 25 days to divide. By contrast, E. coli divides once every 20 minutes.

In the lab, the researchers mimicked the conditions in the seafloor by putting the sediment in a chamber without any oxygen. They pumped in methane and extracted deadly waste gases that might kill the resident microbes.The mud contained many kinds of microbes. But by 2015, the researchers had isolated an intriguing new species of archaea. And when Dr. Ettema and colleagues announced the discovery of Asgard archaea DNA, the Japanese researchers were shocked. Their new, living microbe belonged to that group.The researchers then undertook more painstaking research to understand the new species and link it to the evolution of eukaryotes.The researchers named the microbe Prometheoarchaeum syntrophicum, in honor of Prometheus, the Greek god who gave humans fire — after fashioning them from clay.

This finding suggests that the proteins that eukaryotes used to build complex cells started out doing other things, and only later were assigned new jobs.Dr. Nobu and his colleagues are now trying to figure out what those original jobs were. It’s possible, he said, that Prometheoarchaeum creates its tentacles with genes later used by eukaryotes to build cellular skeletons.

Before the discovery of Prometheoarchaeum, some researchers suspected that the ancestors of eukaryotes lived as predators, swallowing up smaller microbes. They might have engulfed the first mitochondria this way.

Instead of hunting prey, Prometheoarchaeum seems to make its living by slurping up fragments of proteins floating by. Its partners feed on its waste. They, in turn, provide Prometheoarchaeum with vitamins and other essential compounds.

prevent patients from examining their own genetic information” and “made it impossible to obtain second opinions.”

he legal question for the justices is whether isolated genes are “products of nature” that may not be patented or “human-made inventions” eligible for patent protection.

“The isolated DNA molecules before us are not found in nature,” wrote Judge Alan D. Lourie, who was in the majority. “They are obtained in the laboratory and are man-made, the product of human ingenuity.”

Dr. Arthur Beaudet, a professor at the Baylor College of Medicine and the chairman of its department of molecular and human genetics, applaud the effort. He believes that the acts committed by men like Mr. Lanza and the gunmen in other rampages in recent years — at Columbine High School and in Aurora, Colo., in Norway, in Tucson and at Virginia Tech — are so far off the charts of normal behavior that there must be genetic changes driving them.

Everything known about mental illness, these skeptics say, argues that there are likely to be hundreds of genes involved in extreme violent behavior, not to mention a variety of environmental influences, and that all of these factors can interact in complex and unpredictable ways.

The National Institutes of Health was embroiled in controversy about 20 years ago simply for proposing to study the biological underpinnings of violence. Critics accused researchers of racism and singling out minorities, especially black men.

Studies of people at the far end of a bell curve can be especially informative, because the genetic roots of their conditions can be stark and easy to spot, noted J. H. Pate Skene, a Duke University neurobiologist. “I think doing research on outliers, people at an end of a spectrum on something of concern like violent behavior, is certainly a good idea,” he said, but he advised tempering expectations.

“If we know someone has a 2 percent chance or a 10 percent chance or a 20 percent chance of violent behavior, what would you do with that person?” Dr. Skene said. “They have not been convicted of anything — have not done anything wrong.”

Ultimately, understanding the genetics of violence might enable researchers to find ways to intervene before a person commits a horrific crime. But that goal would be difficult to achieve, and the pursuit of it risks jeopardizing personal liberties.