Women influenced coevolution of dogs and humans

 Man's best friend might actually belong to a woman.

In a cross-cultural analysis, Washington State University researchers found several factors may have played a role in building the mutually beneficial relationship between humans and dogs, including temperature, hunting and surprisingly -- gender.

"We found that dogs' relationships with women might have had a greater impact on the dog-human bond than relationships with men," said Jaime Chambers, a WSU anthropology Ph.D. student and first author on the paper published in the Journal of Ethnobiology. "Humans were more likely to regard dogs as a type of person if the dogs had a special relationship with women. They were more likely to be included in family life, treated as subjects of affection and generally, people had greater regard for them."

While dogs are the oldest, most widespread domesticated animal, very few anthropologic studies have directly focused on the human relationship with canines. Yet when the WSU researchers searched the extensive collection of ethnographic documents in the Human Relations Area Files database, they found thousands of mentions of dogs.

Ultimately, they located data from more than 844 ethnographers writing on 144 traditional, subsistence-level societies from all over the globe. Looking at these cultures can provide insight into how the dog-human relationship developed, Chambers said.

"Our modern society is like a blip in the timeline of human history," she said. "The truth is that human-dog relationships have not looked like they do in Western industrialized societies for most of human history, and looking at traditional societies can offer a wider vision."

The researchers noted specific instances that showed dogs' utility, or usefulness, to humans, and humans' utility to dogs as well as the "personhood" of dogs -- when canines were treated like people, such as being given names, allowed to sleep in the same beds or mourned when they died.

A pattern emerged that showed when women were more involved with dogs, the humans' utility to dogs went up, as did the dogs' personhood.

Another prevalent trend involved the environment: the warmer the overall climate, the less useful dogs tended to be to humans.

"Relative to humans, dogs are really not particularly energy efficient," said Robert Quinlan, WSU anthropology professor and corresponding author on the paper. "Their body temperature is higher than humans, and just a bit of exercise can make them overheat on a hot day. We saw this trend that they had less utility to humans in warmer environments."

Quinlan noted there were some exceptions to this with a few dog-loving cultures in the tropics, but it was a fairly consistent trend.

Hunting also seemed to strengthen the dog-human connection. In cultures that hunted with dogs, they were more valued by their human partners: they were higher in the measures of dogs' utility to humans and in personhood. Those values declined, however, when food production increased whether it was growing crops or keeping livestock. This finding seemed to go against the commonly held perception of herding dogs working in concert with humans, but Quinlan noted that in many cultures, herding dogs often work alone whereas hunting requires a more intense cooperation.

This study adds evidence to the evolutionary theory that dogs and humans chose each other, rather than the older theory that humans intentionally sought out wolf pups to raise on their own. Either way, there have been clear benefits for the dogs, Chambers said.

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Street trees close to the home may reduce the risk of depression

 Depression, especially in urban areas, is on the rise, now more than ever. Mental health outcomes are influenced by, among other things, the type of environment where one lives. Former studies show that urban greenspace has a positive benefit on people experiencing mental ill health, but most of these studies used self-reported measures, which makes it difficult to compare the results and generalise conclusions on the effects of urban greenspace on mental health.

An interdisciplinary research team of UFZ, iDiv and Leipzig University tried to improve this issue by involving an objective indicator: prescriptions of antidepressants. To find out whether a specific type of 'everyday' green space -- street trees dotting the neighbourhood sidewalks -- could positively influence mental health, they focused on the questions, how the number and type of street trees and their proximity close to home correlated to the number of antidepressants prescribed.

The researchers analysed data from almost 10,000 Leipzig inhabitants, a mid-size city in Germany, who took part in the LIFE-Adult health study running at the University of Leipzig Medical Faculty. Combining that with data on the number and species type of street trees throughout the city of Leipzig, the researchers were able to identify the association between antidepressants prescriptions and the number of street trees at different distances from people's homes. Results were controlled for other factors known to be associated with depression, such as employment, gender, age, and body weight.

More trees immediately around the home (less than 100 meters) was associated with a reduced risk of being prescribed antidepressant medication. This association was especially strong for deprived groups. As these social groups are at the greatest risk for being prescribed antidepressants in Germany, street trees in cities can thereby serve as a nature-based solution for good mental health, the researchers write. At the same time, street trees may also help reduce the 'gap' in health inequality between economically different social groups. No association of tree types, however, and depression could be shown in this study.

"Our finding suggests that street trees -- a small scale, publicly accessible form of urban greenspace -- can help close the gap in health inequalities between economically different social groups," says lead author of the study Dr Melissa Marselle. "This is good news because street trees are relatively easy to achieve and their number can be increased without much planning effort." As an environmental psychologist, she conducted the research at UFZ and iDiv and is now based at the De Montford University of Leicester, UK. Marselle hopes that the research "should prompt local councils to plant street trees to urban areas as a way to improve mental health and reduce social inequalities. Street trees should be planted equally in residential areas to ensure those who are socially disadvantaged have equal access to receive its health benefits."

"Importantly, most planning guidance for urban greenspace is often based on purposeful visits for recreation," adds Dr Diana Bowler (iDiv, FSU, UFZ), data analyst in the team. "Our study shows that everyday nature close to home -- the biodiversity you see out of the window or when walking or driving to work, school or shopping -- is important for mental health." This finding is especially now in times of the COVID-19 lock-downs, Bowler adds.

And it's not only human health which could benefit. "We propose that adding street trees in residential urban areas is a nature-based solution that may not only promote mental health, but can also contribute to climate change mitigation and biodiversity conservation," says senior author Prof Aletta Bonn, who leads the department of ecosystem services at UFZ, iDiv and Friedrich-Schiller-University Jena. "To create these synergy effects, you don't even need large-scale expensive parks: more trees along the streets will do the trick. And that's a relatively inexpensive measure."

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Dinosaur embryo find helps crack baby tyrannosaur mystery

 They are among the largest predators ever to walk the Earth, but experts have discovered that some baby tyrannosaurs were only the size of a Border Collie dog when they took their first steps.

The first-known fossils of tyrannosaur embryos have shed light on the early development of the colossal animals, which could grow to 40 feet in length and weigh eight tonnes.

A team of palaeontologists, led by a University of Edinburgh researcher, made the discovery by examining the fossilised remains of a tiny jaw bone and claw unearthed in Canada and the US.

Producing 3D scans of the delicate fragments revealed that they belonged to baby tyrannosaurs -- cousins of T. rex -- which, based on the size of the fossils, were around three feet long when they hatched.

The team's findings suggest that tyrannosaur eggs -- the remains of which have never been found -- were around 17 inches long. This could aid efforts to recognise such eggs in the future and gain greater insights into the nesting habits of tyrannosaurs, researchers say.

The analysis also revealed that the three-centimetre-long jaw bone possesses distinctive tyrannosaur features, including a pronounced chin, indicating that these physical traits were present before the animals hatched.

Little is known about the earliest developmental stages of tyrannosaurs -- which lived more than 70-million-years-ago -- despite being one of the most studied dinosaur families. Most tyrannosaur fossils previously studied have been of adult or older juvenile animals.

The study, published in the Canadian Journal of Earth Sciences, was supported by the Royal Society, Natural Sciences and Engineering Research Council of Canada, and National Science Foundation. It also involved researchers from the Universities of Alberta and Calgary, Canada, and Montana State and Chapman Universities, US.

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When galaxies collide

 It was previously thought that collisions between galaxies would necessarily add to the activity of the massive black holes at their centers. However, researchers have performed the most accurate simulations of a range of collision scenarios and have found that some collisions can reduce the activity of their central black holes. The reason is that certain head-on collisions may in fact clear the galactic nuclei of the matter which would otherwise fuel the black holes contained within.

When you think about gargantuan phenomena such as the collision of galaxies, it might be tempting to imagine it as some sort of cosmic cataclysm, with stars crashing and exploding, and destruction on an epic scale. But actually it is closer to a pair of clouds combining, usually a larger one absorbing a smaller one. It's unlikely any stars within them would collide themselves. But that said, when galaxies collide, the consequences can be enormous.

Galaxies collide in different ways. Sometimes a small galaxy will collide with the outer part of a larger one and either pass through or merge, in either case exchanging a lot of stars along the way. But galaxies can also collide head-on, where the smaller of the two will be torn apart by overpowering tidal forces of the larger one. It's in this scenario that something very interesting can happen within the galactic nucleus.

"At the heart of most galaxies lies a massive black hole, or MBH," said Research Associate Yohei Miki from the University of Tokyo. "For as long as astronomers have explored galactic collisions, it has been assumed that a collision would always provide fuel for an MBH in the form of matter within the nucleus. And that this fuel would feed the MBH, significantly increasing its activity, which we would see as ultraviolet and X-ray light amongst other things. However, we now have good reason to believe that this sequence of events is not inevitable and that in fact the exact opposite might sometimes be true."

It seems logical that a galactic collision would only increase the activity of an MBH, but Miki and his team were curious to test this notion. They constructed highly detailed models of galactic collision scenarios and ran them on supercomputers. The team was pleased to see that in some circumstances, an incoming small galaxy might actually strip away the matter surrounding the MBH of the larger one. This would reduce instead of increase its activity.

"We computed the dynamic evolution of the gaseous matter which surrounds the MBH in a torus, or donut, shape," said Miki. "If the incoming galaxy accelerated this torus above a certain threshold determined by properties of the MBH, then the matter would be ejected and the MBH would be starved. These events can last in the region of a million years, though we are still unsure about how long the suppression of MBH activity may last."

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Puzzling six-exoplanet system with rhythmic movement challenges theories of how planets form

 Using a combination of telescopes, including the Very Large Telescope of the European Southern Observatory (ESO's VLT), astronomers have revealed a system consisting of six exoplanets, five of which are locked in a rare rhythm around their central star. The researchers believe the system could provide important clues about how planets, including those in the Solar System, form and evolve.

The first time the team observed TOI-178, a star some 200 light-years away in the constellation of Sculptor, they thought they had spotted two planets going around it in the same orbit. However, a closer look revealed something entirely different. "Through further observations we realised that there were not two planets orbiting the star at roughly the same distance from it, but rather multiple planets in a very special configuration," says Adrien Leleu from the Université de Genève and the University of Bern, Switzerland, who led a new study of the system published today in Astronomy & Astrophysics.

The new research has revealed that the system boasts six exoplanets and that all but the one closest to the star are locked in a rhythmic dance as they move in their orbits. In other words, they are in resonance. This means that there are patterns that repeat themselves as the planets go around the star, with some planets aligning every few orbits. A similar resonance is observed in the orbits of three of Jupiter's moons: Io, Europa and Ganymede. Io, the closest of the three to Jupiter, completes four full orbits around Jupiter for every orbit that Ganymede, the furthest away, makes, and two full orbits for every orbit Europa makes.

The five outer exoplanets of the TOI-178 system follow a much more complex chain of resonance, one of the longest yet discovered in a system of planets. While the three Jupiter moons are in a 4:2:1 resonance, the five outer planets in the TOI-178 system follow a 18:9:6:4:3 chain: while the second planet from the star (the first in the resonance chain) completes 18 orbits, the third planet from the star (second in the chain) completes 9 orbits, and so on. In fact, the scientists initially only found five planets in the system, but by following this resonant rhythm they calculated where in its orbit an additional planet would be when they next had a window to observe the system.

More than just an orbital curiosity, this dance of resonant planets provides clues about the system's past. "The orbits in this system are very well ordered, which tells us that this system has evolved quite gently since its birth," explains co-author Yann Alibert from the University of Bern. If the system had been significantly disturbed earlier in its life, for example by a giant impact, this fragile configuration of orbits would not have survived.

Disorder in the rhythmic system

But even if the arrangement of the orbits is neat and well-ordered, the densities of the planets "are much more disorderly," says Nathan Hara from the Université de Genève, Switzerland, who was also involved in the study. "It appears there is a planet as dense as the Earth right next to a very fluffy planet with half the density of Neptune, followed by a planet with the density of Neptune. It is not what we are used to." In our Solar System, for example, the planets are neatly arranged, with the rocky, denser planets closer to the central star and the fluffy, low-density gas planets farther out.

"This contrast between the rhythmic harmony of the orbital motion and the disorderly densities certainly challenges our understanding of the formation and evolution of planetary systems," says Leleu.

Combining techniques

To investigate the system's unusual architecture, the team used data from the European Space Agency's CHEOPS satellite, alongside the ground-based ESPRESSO instrument on ESO's VLT and the NGTS and SPECULOOS, both sited at ESO's Paranal Observatory in Chile. Since exoplanets are extremely tricky to spot directly with telescopes, astronomers must instead rely on other techniques to detect them. The main methods used are imaging transits -- observing the light emitted by the central star, which dims as an exoplanet passes in front of it when observed from the Earth -- and radial velocities -- observing the star's light spectrum for small signs of wobbles which happen as the exoplanets move in their orbits. The team used both methods to observe the system: CHEOPS, NGTS and SPECULOOS for transits and ESPRESSO for radial velocities.

By combining the two techniques, astronomers were able to gather key information about the system and its planets, which orbit their central star much closer and much faster than the Earth orbits the Sun. The fastest (the innermost planet) completes an orbit in just a couple of days, while the slowest takes about ten times longer. The six planets have sizes ranging from about one to about three times the size of Earth, while their masses are 1.5 to 30 times the mass of Earth. Some of the planets are rocky, but larger than Earth -- these planets are known as Super-Earths. Others are gas planets, like the outer planets in our Solar System, but they are much smaller -- these are nicknamed Mini-Neptunes.

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Hair aging differs by race, ethnicity

 While aging is an unavoidable biological process with many influencing factors that results in visible changes to the hair, there is limited literature examining the characteristics of hair aging across the races. Now a new study describes the unique characteristics of hair aging among different ethnicities that the authors hope will aid in a culturally sensitive approach when making recommendations to prevent hair damage during one's life-time.

Among the findings: hair-graying onset varies with race, with the average age for Caucasians being mid-30s, that for Asians being late 30s, and that for Africans being mid-40s. Caucasians and Asians typically experience damage to the distal hair shaft, while African-Americans see damage occurring closer to the hair root. Postmenopausal changes include decreased anagen (active or growing) hairs in the frontal scalp, lower growth rates and smaller hair diameters.

Similar to skin, hair aging comprises both intrinsic aging, which includes the natural physiological changes that occur with time, and extrinsic aging, or changes associated with environmental exposures and physical stress caused by daily grooming.

"Despite a similar chemical composition, the structural properties of hair vary between different ethnicities and, consequently, the aging of hair differs as well. As the population ages and becomes more diverse, it is of greater necessity to understand the hair aging process in different types of hair," says corresponding author Neelam Vashi, MD, associate professor of dermatology at Boston University School of Medicine and director of the Boston University Cosmetic and Laser Center at Boston Medical Center.

The researchers performed a literature search among 69 publications to review what is known about changes in hair structure over time, focusing on the differences in hair aging according to ethnic background. Information regarding hair structure, aging characteristics and responses to extrinsic damage together with differences between races and ethnicities was collected.

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Immune system mounts a lasting defense after recovery from COVID-19, researchers find

 

Coronavirus illustration.

As the number of people who have fought off SARS-CoV-2 climbs ever higher, a critical question has grown in importance: How long will their immunity to the novel coronavirus last? A new Rockefeller study offers an encouraging answer, suggesting that those who recover from COVID-19 are protected against the virus for at least six months, and likely much longer.

The findings, published in Nature, provide the strongest evidence yet that the immune system "remembers" the virus and, remarkably, continues to improve the quality of antibodies even after the infection has waned. Antibodies produced months after the infection showed increased ability to block SARS-CoV-2, as well as its mutated versions such as the South African variant.

The researchers found that these improved antibodies are produced by immune cells that have kept evolving, apparently due to a continued exposure to the remnants of the virus hidden in the gut tissue.

Based on these findings, researchers suspect that when the recovered patient next encounters the virus, the response would be both faster and more effective, preventing re-infection.

"This is really exciting news. The type of immune response we see here could potentially provide protection for quite some time, by enabling the body to mount a rapid and effective response to the virus upon re-exposure," says Michel C. Nussenzweig, the Zanvil A. Cohn and Ralph M. Steinman Professor and head of the Laboratory of Molecular Immunology, whose team has been tracking and characterizing antibody response in Covid-19 patients since the early days of the pandemic in New York.

Long-lasting memory

Antibodies, which the body creates in response to infection, linger in the blood plasma for several weeks or months, but their levels significantly drop with time. The immune system has a more efficient way of dealing with pathogens: instead of producing antibodies all the time, it creates memory B cells that recognize the pathogen, and can quickly unleash a new round of antibodies when they encounter it a second time.

But how well this memory works depends on the pathogen. To understand the case with SARS-CoV-2, Nussenzweig and his colleagues studied the antibody responses of 87 individuals at two timepoints: one month after infection, and then again six months later. As expected, they found that although antibodies were still detectable by the six-month point, their numbers had markedly decreased. Lab experiments showed that the ability of the participants' plasma samples to neutralize the virus was reduced by five-fold.

In contrast, the patients' memory B cells, specifically those that produce antibodies against SARS-CoV-2, did not decline in number, and even slightly increased in some cases. "The overall numbers of memory B cells that produced antibodies attacking the Achilles' heel of the virus, known as the receptor-binding domain, stayed the same," says Christian Gaebler, a physician and immunologist in Nussenzweig's lab. "That's good news because those are the ones that you need if you encounter the virus again."

Viral stowaways

A closer look at the memory B cells revealed something surprising: these cells had gone through numerous rounds of mutation even after the infection resolved, and as a result the antibodies they produced were much more effective than the originals. Subsequent lab experiments showed this new set of antibodies were better able to latch on tightly to the virus and could recognize even mutated versions of it.

"We were surprised to see the memory B cells had kept evolving during this time," Nussenzweig says. "That often happens in chronic infections, like HIV or herpes, where the virus lingers in the body. But we weren't expecting to see it with SARS-CoV-2, which is thought to leave the body after infection has resolved."

SARS-CoV-2 replicates in certain cells in the lungs, upper throat, and small intestine, and residual viral particles hiding within these tissues could be driving the evolution of memory cells. To look into this hypothesis, the researchers have teamed up with Saurabh Mehandru, a former Rockefeller scientist and currently a physician at Mount Sinai Hospital, who has been examining biopsies of intestinal tissue from people who had recovered from COVID-19 on average three months earlier.

In seven of the 14 individuals studied, tests showed the presence of SARS-CoV-2's genetic material and its proteins in the cells that line the intestines. The researchers don't know whether these viral left-overs are still infectious or are simply the remains of dead viruses.

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Saturn's tilt caused by its moons, researchers say

 

Saturn illustration.

Two scientists from CNRS and Sorbonne University working at the Institute of Celestial Mechanics and Ephemeris Calculation (Paris Observatory -- PSL/CNRS) have just shown that the influence of Saturn's satellites can explain the tilt of the rotation axis of the gas giant. Their work, published on 18 January 2021 in the journal Nature Astronomy, also predicts that the tilt will increase even further over the next few billion years.

Rather like David versus Goliath, it appears that Saturn's tilt may in fact be caused by its moons. This is the conclusion of recent work carried out by scientists from the CNRS, Sorbonne University and the University of Pisa, which shows that the current tilt of Saturn's rotation axis is caused by the migration of its satellites, and especially by that of its largest moon, Titan.

Recent observations have shown that Titan and the other moons are gradually moving away from Saturn much faster than astronomers had previously estimated. By incorporating this increased migration rate into their calculations, the researchers concluded that this process affects the inclination of Saturn's rotation axis: as its satellites move further away, the planet tilts more and more.

The decisive event that tilted Saturn is thought to have occurred relatively recently. For over three billion years after its formation, Saturn's rotation axis remained only slightly tilted. It was only roughly a billion years ago that the gradual motion of its satellites triggered a resonance phenomenon that continues today: Saturn's axis interacted with the path of the planet Neptune and gradually tilted until it reached the inclination of 27° observed today.

These findings call into question previous scenarios. Astronomers were already in agreement about the existence of this resonance. However, they believed that it had occurred very early on, over four billion years ago, due to a change in Neptune's orbit. Since that time, Saturn's axis was thought to have been stable. In fact, Saturn's axis is still tilting, and what we see today is merely a transitional stage in this shift. Over the next few billion years, the inclination of Saturn's axis could more than double.

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Butterfly wing clap explains mystery of flight

 

Silver-washed fritillary butterfly on flower.

The fluttery flight of butterflies has so far been somewhat of a mystery to researchers, given their unusually large and broad wings relative to their body size. Now researchers at Lund University in Sweden have studied the aerodynamics of butterflies in a wind tunnel. The results suggest that butterflies use a highly effective clap technique, therefore making use of their unique wings. This helps them rapidly take off when escaping predators.

The study explains the benefits of both the wing shape and the flexibility of their wings.

The Lund researchers studied the wingbeats of freely flying butterflies during take-off in a wind tunnel. During the upward stroke, the wings cup, creating an air-filled pocket between them. When the wings then collide, the air is forced out, resulting in a backward jet that propels the butterflies forward. The downward wingbeat has another function: the butterflies stay in the air and do not fall to the ground.

The wings colliding was described by researchers almost 50 years ago, but it is only in this study that the theory has been tested on real butterflies in free flight. Until now, the common perception has been that butterfly wings are aerodynamically inefficient, however, the researchers suggest that the opposite is actually true.

"That the wings are cupped when butterflies clap them together, makes the wing stroke much more effective. It is an elegant mechanism that is far more advanced than we imagined, and it is fascinating. The butterflies benefit from the technique when they have to take off quickly to escape from predators," says biology researcher Per Henningsson, who studied the butterflies' aerodynamics together with colleague Christoffer Johansson.

"The shape and flexibility of butterfly wings could inspire improved performance and flight technology in small drones," he continues.

In addition to studying the butterflies in a wind tunnel, the researchers designed mechanical wings that mimic real ones. The shape and flexibility of the mechanical wings as they are cupped and folded confirm the efficiency.

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Much of Earth's nitrogen was locally sourced

 

Protoplanetary disk illustration

Where did Earth's nitrogen come from? Rice University scientists show one primordial source of the indispensable building block for life was close to home.

The isotopic signatures of nitrogen in iron meteorites reveal that Earth likely gathered its nitrogen not only from the region beyond Jupiter's orbit but also from the dust in the inner protoplanetary disk.

Nitrogen is a volatile element that, like carbon, hydrogen and oxygen, makes life on Earth possible. Knowing its source offers clues to not only how rocky planets formed in the inner part of our solar system but also the dynamics of far-flung protoplanetary disks.

The study by Rice graduate student and lead author Damanveer Grewal, Rice faculty member Rajdeep Dasgupta and geochemist Bernard Marty at the University of Lorraine, France, appears in Nature Astronomy.

Their work helps settle a prolonged debate over the origin of life-essential volatile elements in Earth and other rocky bodies in the solar system.

"Researchers have always thought that the inner part of the solar system, within Jupiter's orbit, was too hot for nitrogen and other volatile elements to condense as solids, meaning that volatile elements in the inner disk were in the gas phase," Grewal said.

Because the seeds of present-day rocky planets, also known as protoplanets, grew in the inner disk by accreting locally sourced dust, he said it appeared they did not contain nitrogen or other volatiles, necessitating their delivery from the outer solar system. An earlier study by the team suggested much of this volatile-rich material came to Earth via the collision that formed the moon.

But new evidence clearly shows only some of the planet's nitrogen came from beyond Jupiter.

In recent years, scientists have analyzed nonvolatile elements in meteorites, including iron meteorites that occasionally fall to Earth, to show dust in the inner and outer solar system had completely different isotopic compositions.

"This idea of separate reservoirs had only been developed for nonvolatile elements," Grewal said. "We wanted to see if this is true for volatile elements as well. If so, it can be used to determine which reservoir the volatiles in present-day rocky planets came from."

Iron meteorites are remnants of the cores of protoplanets that formed at the same time as the seeds of present-day rocky planets, becoming the wild card the authors used to test their hypothesis.

The researchers found a distinct nitrogen isotopic signature in the dust that bathed the inner protoplanets within about 300,000 years of the formation of the solar system. All iron meteorites from the inner disk contained a lower concentration of the nitrogen-15 isotope, while those from the outer disk were rich in nitrogen-15.

This suggests that within the first few million years, the protoplanetary disk divided into two reservoirs, the outer rich in the nitrogen-15 isotope and the inner rich in nitrogen-14.

"Our work completely changes the current narrative," Grewal said. "We show that the volatile elements were present in the inner disk dust, probably in the form of refractory organics, from the very beginning. This means that contrary to current understanding, the seeds of the present-day rocky planets -- including Earth -- were not volatile-free."

Dasgupta said the finding is significant to those who study the potential habitability of exoplanets, a topic of great interest to him as principal investigator of CLEVER Planets, a NASA-funded collaborative project exploring how life-essential elements might come together on distant exoplanets.

"At least for our own planet, we now know the entire nitrogen budget does not come only from outer solar system materials," said Dasgupta, Rice's Maurice Ewing Professor of Earth, Environmental and Planetary Sciences.

"Even if other protoplanetary disks don't have the kind of giant planet migration resulting in the infiltration of volatile-rich materials from the outer zones, their inner rocky planets closer to the star could still acquire volatiles from their neighboring zones," he said.

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