Our family tree may be a lot messier than we thought - Axios
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Our family tree may be a lot messier than we thought

Different perspectives of a molar found at the Siberian cave Denisova. Credit: Slon et al. Sci. Adv. 2017

The story of human evolution goes something like this: humans evolved in Africa 300,000 years ago and about 70,000 years ago, a small group moved to other continents, giving us today's populations.

But two new studies suggest our family tree may be much more tangled than we previously thought. Scientists in Europe report evidence that modern humans and Neanderthals interbred much earlier than we thought, and that Neanderthals and their sister group of Denisovans may have had ample time to mingle.

The studies:

  • We knew humans had Neanderthal DNA from our entrance into Europe, but we didn't know that Neanderthals already in Europe had a human genetic legacy, too. Their DNA shows complex ancestry — their nuclear DNA (inherited from both parents) connects them with Denisovans, a group that lived thousand of miles away in the Siberian cave Denisova, whereas their mitochondrial DNA (passed on only from mothers) links them to humans. New DNA evidence from a 120,000-year-old Neanderthal fossil suggests Neanderthals inherited their mitochondrial DNA from an ancestor who lived 270,000 years ago. A revised picture: Neanderthals and Denisovans had a common ancestor half a million years ago that gave rise to Denisovans in Asia and to Neanderthals in Europe. More 270,000 years ago, African humans closely related to us migrated into Europe and bred with Neanderthals, that carried their DNA.

"But somewhere in prehistory, at least one female human from Africa must have carried the child of a male Neanderthal," Carl Zimmer writes in the NYT.

  • In a separate study, Svante Paabo and his team report the discovery of a "baby tooth" in Denisova. Unlike Neanderthals, the history of the Denisovans is largely unknown due to a sparse fossil record. (Until now, scientists have only found bone fragments of three Denisovan individuals.) The newly discovered molar is from a fourth Denisovan, a young female, and is believed to be at least 100,000 years old — 20,000 years older than the other Denisovan fossils. That means they may have had more time to mingle with Neanderthals than previously thought.

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Cows can produce antibodies that neutralize HIV

Carrie Antlfinger / AP

Cows can produce a type of antibodies that have been shown in laboratories to stop 96% of HIV strains from infecting human cells, according to a new study in Nature.

Why it matters: Scientists have been trying to elicit these so-called "broadly neutralizing antibodies" (bNAbs) by immunization for decades in hopes of creating a vaccine that can provide protection from HIV. The bNAbs made by the cows, which don't contract HIV, can be studied to understand how they might potentially be elicited in humans via a vaccine. "The study … doesn't tell us how to make a vaccine for HIV in people, but it does tell us how the virus evades the human immune response," John Mascola, director of vaccine research at NIAID, told STAT News.

Still TBD: We've "shown in a test tube that the antibodies can neutralize the virus," but not in a real human model, Anthony Fauci, the director of NIAID at the NIH, told Axios. He added it would be "pretty easy" for scientists to "modify [the bNAbs] so that they'd be compatible to administer them to humans" for short-term prevention or treatment. It is unclear whether effective antibodies can be produced at a scale and rate that works for widespread distribution.

Can't humans develop these antibodies on their own? It's true that 10-20% of humans living with HIV naturally develop bNAbs — but not until years after getting infected, rendering most of them irrelevant since the virus would likely have already evolved, Fauci said.

  • The bovine advantage: Cows' immune systems seem to have powerful bNAbs to protect their multiple stomach chambers. Plus, the researchers noted that cows developed these antibodies in a short period of time (4 weeks v. 3-5 years in humans).

How they did it: The researchers infected four cows with a protein that mimics the outside of the HIV virus and the cows' immune systems rapidly created antibodies in response. They were then able to isolate the antibodies and, in the laboratory, they blocked multiple strains of HIV from infecting cells.

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Elephant seals recognize signature calls

Mathevon et al. 2017

A new study found male northern elephant seals produce signature rhythmic calls to communicate with their rivals — and navigate their social network.

Why it matters: These are the only non-human mammals known to use rhythm, and the evolution of this type of communication in other species helps to better understand the origins of music among humans.

How they use it: Nicolas Mathevon, one of the study's authors from Université de Lyon/Saint-Etienne in France, said elephant seals "fight [for females] very violently, even to the point of killing one another." Recognizing competitors by the rhythm in their voice allows them to "choose the right strategy" when confronting a rival during mating.

Yes, but... seals most likely use "a multitude of factors to identify each other in a group," not just their calls, according to Caroline Casey, a PhD candidate at the University of California Stanford who participated in the study.

What comes next: Casey said the team is "in the process of tracking young elephant seals throughout their vocal development to see how these individual signatures emerge over time."

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How clouds could be engineered to cool the Earth

Simon A. Eugster / Wikipedia

Scientists are actively exploring – on a theoretical basis – what it might take to cool the Earth if governments, businesses and individual actions collectively fail to do so in the next 15+ years. But, in nearly every case, the potential downside of such scientific actions aren't yet known, and there is no regulatory mechanism yet in place to govern or monitor the efforts, several leading scientists argue in Science this week.

Two approaches:

1. The leading geoengineering theory, according to scientists, is essentially a large science experiment on a global scale that mirrors what clouds do naturally. It would diminish the sun's warming effects by continuously injecting sulfur particles into the stratosphere, thus filtering out some of the radiation entering our atmosphere.

  • Pros: Most scientists agree it would change the temperature on Earth.
  • Cons: It could have a dramatic (and unintended) effect on the Earth's major water cycles, like the monsoon, that provide fresh water necessary for billions of people to live.
  • Other unknowns: how effective it might be, or how much it might cost. (Initial estimate are on the order of $20 billion a year for a century or more, they wrote.)

2. A second approach is to artificially create thin cirrus clouds at low-altitude that trap less heat and would cool the Earth.

  • Risks: These artificial clouds would attract moisture, and could upset the Earth's water cycles as well. And if this grand science experiment was done poorly, it could actually heat the planet instead of cool it.

What's needed: Janos Pasztor, the former climate policy lead at the United Nations (who now leads a geoengineering institute affiliated with Carnegie) argues that all of this means government leaders need to move quickly to understand the profound implications of both the research and its potential impacts. There is also an immediate risk that just one country, a small group of countries or even a very wealthy individual could unilaterally deploy a planet-wide solar radiation management scheme before anyone truly understands the potential risks.

Go deeper: Read our Expert Voices conversation on the topic.
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Researchers developed bacteria that can create images

Felix Moser / AP

Researchers at MIT have engineered bacteria to sense red, green, and blue light — and then create a picture of what they've "seen," like the arrangement of fruit pictured above, by expressing pigments in those colors.

"At the most fundamental level, we've given E. Coli the ability to detect different kinds of light and then compose an image," says genetic engineer Felix Moser. "It's a demonstration that synthetic biology tools have come a long way in the last decade."

Synthetic biologists designed and custom built new genetic parts for bacterial cells that create: light-detecting proteins, a circuit to navigate and leverage the cell's mechanisms for turning genes on and off, a capacitor of sorts to regulate the energy burden being placed on the cell when it expresses these different proteins, and enzymes that actually produce the pigments.

Then, with the 1970s' finest slide projector technology, they projected an image onto a plate of bacteria and, the next morning, the bacteria had recreated the image they'd "seen."

Beyond bacteria with red-green-blue vision, precisely directed light could conceivably be used to control the production of chemicals or vaccines, essentially turning bacteria into optimized manufacturing facilities.

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Rush Holt wants you to know evidence isn't just for scientists

Lazaro Gamio / Axios

One of the first decisions Rush Holt made at the helm of American Association for the Advancement of Science earlier this year was to officially support the March for Science in Washington. It was delicate ground for the non-partisan organization but Holt maintained it was about defending the scientific process, not taking a political stand.

Holt, who spent 16 years in Congress as a Democrat representing central New Jersey before becoming CEO of AAAS, chatted with Axios last week about how science is bumping up against politics today.

Here are the highlights:

Science is: a way of asking questions so that they can be answered empirically and verifiably. I think it's that simple.

That's something, by the way, that we're losing. The appreciation of it and the ability to do it has been eroding in our society. It's one of the things that has been really dominant in our advocacy recently — to try to restore what I call the reverence for evidence.

On the absence of a science advisor: I wish I could get the new administration to see that they would be well-served by having scientists scattered throughout their agencies. Next month's crisis, or the crisis the month after that — which will surely come — your ability to deal with them will be improved if you have scientists there to offer advice or comments in all of the agencies. Not just a science advisor in the White House sitting on the National Security Council, but also people in the Department of Transportation and the Department of Housing and Urban Development. It's people who get it about science.

There are dozens of positions in the administration that are designated to be explicitly for science experts. I think fewer than a dozen are filled now. That's a problem. You would think that the President and people around him would want to be prepared to deal with the crises that come up, because if you wait to collect information after the crisis is occurring, it's a little late.

This is a good time for science but…federal investment in research is the lowest it's been since Sputnik. The appreciation of evidence by the ordinary person is, I think, the lowest it's been in my lifetime. That's really troubling. If the work of a small number of people is more and more productive, but society at large has a poorer and poorer understanding of what science is and how it is relevant to them, then that doesn't bode well for the future of science.

It is this interesting contradiction and conundrum. We have this reasonably great opportunity with burgeoning research findings, but this is counterbalanced by policies that are more grounded in ideology than evidence and by a greater number of clueless people who are distrustful of science.

The politics problem: Should science avoid being politicized? Absolutely. Even with my simple definition, embedded in some of those simple words is the idea that science necessarily structures the questions and the gathering of evidence in the best way to exclude bias — of your instruments and experimental design, but also personal bias and wishful thinking — all of those things that can contaminate the evidence. You don't want to inject ideology or wishful thinking or party platforms into the collection and the analysis of evidence.

Scientists commit the logical fallacy that the converse is true. If the process of science — this precious, valuable, extraordinary thing — is challenged, then scientists should speak up. Scientists should go into the public square if they can shed light on an issue of importance or if the scientific process is challenged.

America the empirical: Our country was founded with a very scientific outlook. Some of the founders themselves were actual scientists — Thomas Jefferson and Benjamin Rush, but also Thomas Paine. People don't know he wrote a tract on swamp gas. John Adams studied astronomy at Harvard. They not only were scientists, but they had very much a scientific perspective. In the Federalist Papers arguing for the ratification of the Constitution, the word "experiment" appears far more often than the word "democracy."

Evidence is for everyone: It's important for civic education and social education, but it also means that people who are not professional scientists can still ask questions that can be answered empirically. I would like to get to the point where every citizen, every day, asks their political leaders and policymakers, "What's the evidence?"

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Scientists identify the different genes behind common childhood brain cancer

Researchers have used a detailed genetic analysis of the most common form of brain cancer in children (called medulloblastoma) to devise potentially new therapeutic strategies. If further tests confirm the findings, it could lead to novel treatments to mitigate the more severe side effects of cancer treatment.

Why it matters: Brain cancer in children is a profoundly difficult burden for both parents and doctors alike. The current medical treatments and therapies for this type of brain cancer in children have unpleasant side effects that can impair a child's quality of life following the treatments, the researchers wrote in Nature.

Compounding the problem is the fact that this type of cancer has several different genetic sub-types, which means that the current treatments are forced to take a "one-size-fits-all" approach with chemotherapy that leads to potentially toxic side effects. The new research should help scientists properly characterize each of these genetic sub-types, which in turn may allow for targeted chemotherapy treatment strategies that could minimize the toxic side effects.

What they found: The researchers looked at the genetic foundations and sequencing for 491 individual medulloblastoma cases; and at the expression of particular genes in another 1,256 cases. From there they were able to characterize all of the cancer sub-groups and the different genetic alterations associated with them. They even found several new sub-types that had not been previously identified, which they said shows this type of brain cancer in children should be considered a collection of diseases rather than just one cancer.

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The impending shortage of OB-GYNs

Alex Gilbert / AP

Obstetricians and gynecologists are getting burned out and retiring earlier, and fewer prospective medical students are choosing women's health as their speciality, according to an analysis by Doximity, a social networking site for doctors and other health care professionals. That could lead to a severe shortage of OB-GYNs, especially in parts of the country that have above-average birth rates.

Why it matters: OB-GYNs are crucial primary-care physicians for women. If their numbers continue to dwindle, women will be at a disadvantage to get vital health care services. The high rate of pregnancy-related deaths for mothers won't get any better, either.

Doximity looked at metropolitan areas that had the highest OB-GYN workloads (the average was 105 births annually per OB-GYN) as well as the average age of OB-GYNs in those areas. The site determined these cities are most at risk for an OB-GYN shortage based on high workloads and an older crop of doctors:

  1. Las Vegas
  2. Orlando, Florida
  3. Los Angeles
  4. Miami
  5. Riverside, California
  6. Detroit
  7. Memphis, Tennessee
  8. Salt Lake City
  9. St. Louis
  10. Buffalo, New York
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Unregulated stem cell therapies listed on government database

Victor / Flickr

Stem cell clinics are using ClinicalTrials.gov — the National Institute of Health's database of private and public clinical trials — to recruit patients to participate in potentially risky treatments, per a new study in Regenerative Medicine. People are paying big money to take part in these unregulated studies, even though people are typically not charged to join them.

One recent example: Three Florida women were blinded by a stem cell procedure meant to treat macular degeneration. They had each paid $5,000 for the trial.

Big picture: There are close to 600 stem cell clinics (many of them newcomers) advertising treatments unapproved by the FDA to patients in the U.S. "A lot of these studies are just marketing pitches designed to appeal to people with COPD, multiple sclerosis and Parkinson's disease," Leigh Turner, the study's author, told the Washington Post.

The NIH has put a disclaimer at the top of ClinicalTrials.gov: "Listing of a study on this site does not reflect endorsement by the National Institutes of Health."

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Humans may have arrived in Australia 65,000 years ago

Elspeth Hayes with Mark Djandjomerr and traditional owner May Nango extracting comparative samples Photo: David Vadiveloo / Gundjeihmi Aboriginal Corporation

Humans first arrived by sea to Australia around 65,000 years ago, according to a new archaeological study published in Nature Wednesday. The finding pushes the date of human arrival to the continent — a debated subject — back 5,000 to 20,000 years.

"This age increases the age of occupation of Australia by many thousands of years. This is extremely important as there has been an endless debate about the initial occupation of the continent, with some arguing it was late[r], only within the last 45,000 years, and others [arguing it was] earlier," said Michael Petraglia, an anthropologist from the Max Planck Institute for the Science of Human History. Petraglia, who was not part of this study, told Axios that the dating of the artifacts from the Madjedbebe site looks "rock solid."

Why this matters: This study indicates humans left Africa and had the ability and aspiration to traverse the ocean for weeks to an unseen land at a much earlier period than previously thought. It also means humans arrived in Australia when megafauna lived on the continent, which may influence the debate over what led to the extinction of the large animals like the 1000-pound kangaroos and Volkswagen-sized tortoises.

What they did: The research team first re-analyzed material in museums from excavations at the aboriginal rock shelter Madjedbebe in northern Australia in 1972 and 1989. They then completed their own expanded excavations in 2012 and 2015, allowing them to see the structure and intact details of the site. They collected charcoal from a fireplace and sand grains from the walls and analyzed them with single-grain optically stimulated luminescence (OSL) dating, which can be used to tell the last time the sand was exposed to sunlight. To confirm the findings, they did a blind test with some of their samples at an independent lab.

"The most significant finding in my opinion is that Aboriginal people arrived here 65,000 years ago, much earlier than previous thought, with a rich and sophisticated cultural repertoire, including complex stone tools and artistic behavior," study author Chris Clarkson, who is an archaeologist from the University of Queensland, told Axios.

Near the campfire, they found pigments that may have been used for painting walls and coloring their bodies. Peter Hiscock, an archaeologist from the University of Sydney who was not part of the study, told Axios: "Clarkson has found a remarkable scene...These artifacts include what are now the earliest known polished (ground) axes, a known marker of elaborate hafted tools - 20,000 years older than axes anywhere else in the world."

Debate on the demise of the megafauna: Clarkson told Axios the findings show humans coexisted with megafauna for a long time. He argues that this puts to rest the Blitzkreig theory (that humans quickly wiped out some species), and possibly disputes the belief that humans, not climate, were the main factor in their demise. "The extinction of the megafauna now seems to have been gradual and may not have directly involved humans at all," Clarkson said.

However, Petraglia said the "overlap between early human occupation and the extinction of megafauna suggests that humans may have played an important role in contributing to the demise of these great creatures...by [the] sophisticated hunting and gathering communities."

Further research needed: Curtis Marean, who wrote a view on this study, said this reiterates the need for archaeologists to not only discover new sites but retest old ones with new technology. "The latest work in Australia shows us the pay-off, and provides a reminder that this massive continent could reveal many other secrets during future fieldwork," Marean wrote.

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Elon Musk wants to go to space, but not yet

Elon Musk in 2016. Credit: Refugio Ruiz / AP

SpaceX chief executive Elon Musk set some expectations for the first launch of the Falcon Heavy rocket, and talked about opportunities in space for business and research at the ISS R&D conference today in Washington.

Asked whether he planned to go to space himself, he said he probably would — eventually. "I would like to at some point. Assuming things work out, maybe in 3 or 4 years."

  • Falcon Heavy rocket's first launch: "There is a real good chance that it doesn't make it to orbit. I want to manage expectations. I just hope it makes it far enough away from the launch pad that it does not cause pad damage. I would consider even that a win to be honest." Falcon Heavy simultaneously ignites 27 orbit class engines, which adds up to a lot of risk that can't be tested on the ground, he said.
  • Despite the challenges of developing the Falcon Heavy, Musk said they are focused on launching the Dragon 2 spacecraft to eventually carry crew to the International Space Station. He also said they are abandoning original plans to use propulsion to land the Dragon 2 because of safety concerns for the crew, suggesting the capsule won't be used to land on Mars as originally planned.
  • His team is working to reuse more of the rockets — faster. "We believe we can get to the point probably next year where the Falcon 9 booster can be re-flown within 24 hours. The key to that is all you do is inspections, no hardware is changed, not even the paint. That's our aspiration for next year.
  • About those tunnels... Musk says his project digging tunnels beneath L.A. is "a low stress activity because everyone expects it to fail" But it could inform efforts to mine Mars for ice and minerals.
  • How to excite people about space: "Having some permanent presence on another heavenly body — that's the continuance of the dream of Apollo."

Why it matters: SpaceX has delivered cargo and research experiments to the Space Station for NASA and a host of companies on the Falcon 9 rocket. The Falcon Heavy is the company's next version, which aims to have the largest cargo capacity of any rocket today. Beyond those services, Musk has essentially stepped in as a private sector generator of moonshots — last year he announced his plan to colonize Mars. (He said today he'd likely offer an update on that at the International Astronautical Congress in September).