Amazon River no younger than 9 million years, new study shows

Amazon river mouth.

Researchers from the University of Amsterdam (UvA) and the University of Brasilia (Brazil) have determined the age of the formation of the Amazon River at 9.4 to 9 million years ago (Ma) with data that convincingly refutes substantial younger estimates. Their results are published as early view in the journal Global and Planetary Change.

The study comprised geochemical and palynological analyses of sediments from a hydrocarbon exploration borehole, situated offshore of Brazil, that reached more than 4.5 kilometers below sea level.

The results show a distinct change in sediment composition and plant residual matter during the late Miocene (9.4 to 9 Ma). This represents a switch in river source area from the tropical lowlands to the high Andes, which is diagnostic of the onset of the transcontinental Amazon River. The new data contradict younger estimates (c. 2.6 Ma) that have been proposed in recent literature and postdates estimates from an earlier study of this borehole by about 1 to 1.5 million years.

Sediments record evolutionary history

'We were able to narrow down the age of onset of the Amazon River because we sampled the transition interval in a classical section of the Amazon submarine fan, where the sediments transported by this river are deposited and as a result accurately record its evolutionary history. We applied high resolution analytical techniques not previously performed in the region', says professor Farid Chemale, senior author from the University of Brasilia (now at Universidade do Vale do Rio dos Sinos, São Leopoldo).

The study also gives novel insights into overall changes in plant composition in the Amazon drainage basin. Particularly, the rise in grass remains suggests that mountain uplift and Quaternary climatic changes strongly affected the landscape and probably opened up new habitats for grass colonization.

Dramatic changes

'The changes detected in the sediment record lead to the tantalizing question of whether the Amazon region might have changed dramatically during Plio-Pleistocene global cooling', says Dr Carina Hoorn, lead author and researcher at the UvA's Institute for Biodiversity and Ecosystem Dynamics. 'Our new data confirm an old age for the Amazon River and also point at an expansion of grasslands during the Pleistocene that was not known before. Further research on land and at sea may give further answers but will require investment in both continental and marine drilling.'

Largest drainage basin of all rivers

The Amazon River contributes a fifth of the total fresh water supply to the global oceans and has the largest drainage basin of all rivers around the world. The onset of the river is a defining moment in the reorganization of the paleogeography of South America, forming both a bridge and a divider for biota in the Amazon landscape.

The history of the Amazon River and its drainage basin are hard to unravel, as the continental record is scarce and fragmented. The marine record is more complete, yet is equally difficult to access. Sediment aprons in the proximity of major rivers often hold continuous records of terrestrial material accumulated by the river over time. These records provide a unique insight into the historic climate, geography and biome evolution of the land.

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Last remnant of North American ice sheet on track to vanish

CU Boulder Professor Gifford Miller, shown here, is part of a team that has found the Barnes Ice Cap on Baffin Island, the last remnant of the Laurentide Ice Sheet, will vanish in several hundred years because of rising temperatures caused by human activity.

The last piece of the ice sheet that once blanketed much of North America is doomed to disappear in the next several centuries, says a new study by researchers at Simon Fraser University in British Columbia and the University of Colorado Boulder.

The Barnes Ice Cap, a Delaware-sized feature on Baffin Island in the Canadian Arctic, is melting at a rapid pace, driven by increased greenhouse gases in the atmosphere that have elevated Arctic temperatures. The ice cap, while still 500 meters thick, is slated to melt in about 300 years under business-as-usual greenhouse gas emissions.

The results provide compelling evidence that the current level of warming is almost unheard of in the past 2.5 million years, according to the authors. Only three times at most in that time period has the Barnes Ice Cap been so small, a study of isotopes created by cosmic rays that were trapped in rocks around the Barnes Ice Cap indicated.

"This is the disappearance of a feature from the last glacial age, which would have probably survived without anthropogenic greenhouse gas emissions," said Adrien Gilbert, a glaciologist at Simon Fraser University in British Columbia in Canada and lead author of the new study published online today in Geophysical Research Letters, a journal of the American Geophysical Union.

While the melting of the Barnes Ice Cap will likely have negligible effects on sea level rise, its end could herald the eventual dissolution of the larger ice sheets like Greenland and Antarctica, said CU-Boulder Professor Gifford Miller, a study co-author.

"I think the disappearance of the Barnes Ice Cap would be just a scientific curiosity if it were not so unusual," said Miller, the associate director of CU Boulder's Institute of Arctic and Alpine Research who has conducted research on Baffin Island annually for the past five decades. "One implication derived from our results is that significant parts of the southern Greenland Ice Sheet also may be at risk of melting as the Arctic continues to warm."

Elevated sea rise created by a melting Greenland would automatically cause the Antarctic Ice Sheet, whose dimensions are controlled by sea level, to also shrink in size, Miller said.

The Barnes Ice Cap is part of the Laurentide Ice Sheet that has covered millions of square miles of North America episodically since the start of Quaternary Period roughly 2.5 million years ago. The ice sheet grew and shrank over time as Earth went through various climate cycles, and the ice was a mile thick at present-day Chicago about 20,000 years ago. It started receding substantially around 14,000 years ago when Earth slipped out of its last ice age.

The ice cap stabilized about 2,000 years ago until the effects of the recent warming caught up with it. Miller was conducting research on Baffin Island in 2009 when he realized the ice cap had shrunk noticeably as compared to images from a few decades earlier. He recruited Gilbert and Gwenn Flowers from Simon Fraser to develop a model of how the ice cap might behave in the future.

In the new study, the researchers used their model to estimate when the ice cap would disappear under different greenhouse gas emissions scenarios. They project that under all future emission scenarios the ice cap will be gone within 200 to 500 years. For a moderate emissions scenario that assumes Earth's greenhouse gas emissions will peak around the year 2040, they project the ice cap to be gone in 300 years.

"The geological data is pretty clear that the Barnes Ice Cap almost never disappears in the interglacial times," Miller said. "The fact that it's disappearing now says we're really outside of what we've experienced in 2.5 million-year interval. We are entering a new climate state."

The Barnes Ice Cap is like a canary in a coal mine, said Miller, who also is a professor in CU Boulder's Department of Geological Sciences. Even if humans stopped emitting greenhouse gases today, the ice cap would still disappear in the next few centuries.

In 2010, the project received a boost from Waleed Abdalati, current director of the Cooperative Institute for Research in Environmental Sciences (a joint venture of CUBoulder and NOAA), who was NASA's chief scientist at the time. Abdalati supported the flight of a NASA plane monitoring ice loss in the Arctic to revisit the Barnes Ice Cap.

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A 48-hour sexual 'afterglow' helps to bond partners over time

Happy couple.

Sex plays a central role in reproduction, and it can be pleasurable, but new findings suggest that it may serve an additional purpose: bonding partners together. A study of newlywed couples, published in Psychological Science, a journal of the Association for Psychological Science, indicates that partners experience a sexual 'afterglow' that lasts for up to two days, and this afterglow is linked with relationship quality over the long term.

"Our research shows that sexual satisfaction remains elevated 48 hours after sex," says psychological scientist Andrea Meltzer (Florida State University), lead author on the study. "And people with a stronger sexual afterglow -- that is, people who report a higher level of sexual satisfaction 48 hours after sex -- report higher levels of relationship satisfaction several months later."

Researchers had theorized that sex plays a crucial role in pair bonding, but most adults report having sex with their partners every few days, not every day. Meltzer and colleagues hypothesized that sex might provide a short-term boost to sexual satisfaction, sustaining the pair bond in between sexual experiences and enhancing partners' relationship satisfaction over the long term.

To test their hypothesis, the researchers examined data from two independent, longitudinal studies, one with 96 newlywed couples and another with 118 newlywed couples. All of the couples had completed at least three consecutive days of a 14-day daily diary as part of a larger study.

Every night, before going to bed, the newlyweds were asked to report independently whether they had sex with their partner that day. Regardless of the answer, they were also asked to rate how satisfied they were with their sex life that day and how satisfied they were with their partner, their relationship, and their marriage that day (on a 7-point scale, where 1 = not at all, 7 = extremely).

The partners also completed three measures of marriage quality at the beginning of the study and again at a follow-up session about 4 to 6 months later.

On average, participants reported having sex on 4 of the 14 days of the study, though answers varied considerably across participants.

Importantly, sex on a given day was linked with lingering sexual satisfaction over time. Having sex on a given day was linked with sexual satisfaction that same day, which was linked with sexual satisfaction the next day and even two days later. In other words, participants continued to report elevated sexual satisfaction 48 hours after a single act of sex. Importantly, this association did not differ according to participants' gender or age, and it held even after sexual frequency, personality traits, length of relationship and other factors were taken into account.

Overall, participants' marital satisfaction declined between the beginning of the study and the follow-up session 4 to 6 months later. But participants who reported relatively high levels of sexual afterglow seemed to fare better relative to their peers, reporting higher initial marital satisfaction and less steep declines in satisfaction across the first 4 to 6 months of marriage.

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For this New Zealand parrot, 'laughter' is contagious

This photographs shows a juvenile kea playing in the air.

When people are feeling playful, they giggle and laugh, making others around them want to laugh and play too. Now, researchers reporting in Current Biology on March 20 have found that the particularly playful kea parrot from New Zealand has a "play call" with a similarly powerful influence. When other kea hear that call, it puts them into a playful mood.

The findings make kea the first known non-mammal to have such an "emotionally contagious" vocalization, the researchers say. Earlier studies had made similar findings for chimpanzees and rats.

"We were able to use a playback of these calls to show that it animates kea that were not playing to do so," says Raoul Schwing of the Messerli Research Institute in Austria. "The fact that at least some of these birds started playing spontaneously when no other birds had been playing suggests that, similar to human laughter, it had an emotional effect on the birds that heard it, putting them in a playful state."

Schwing and his colleagues got interested in this particular call after carefully analyzing the kea's full vocal repertoire. It was clear to them that the play call was used in connection with the birds' play behavior. That made them curious to know how kea in the wild would respond to the recorded calls.

To find out, the researchers played recordings of play calls to groups of wild kea for a period of five minutes. The researchers also played other kea calls and the calls of a South Island robin as controls. When the birds heard the play calls, it led them to play more and play longer in comparison to the other sounds.

"Upon hearing the play call, many birds did not join in play that was already underway, but instead started playing with other non-playing birds, or in the case of solitary play, with an object or by performing aerial acrobatics," the researchers write. "These instances suggest that kea weren't 'invited' to play, but this specific call induced playfulness, supporting the hypothesis that play vocalizations can act as a positive emotional contagion."

While it might be a bit anthropomorphic, they continue, the kea play calls can be compared to a form of infectious laughter. The researchers say that they now plan to explore the effects of play and play calls on kea social groups more generally.

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Mystery of how sperm swim revealed in mathematical formula

The whip-like tail of the sperm has a particular rhythm that pulls the head backwards and sideways to create a jerky fluid flow.

Researchers have developed a mathematical formula based on the rhythmic movement of a sperm's head and tail, which significantly reduces the complexities of understanding and predicting how sperm make the difficult journey towards fertilizing an egg.

Researchers at the Universities of York, Birmingham, Oxford and Kyoto University, Japan, found that the sperm's tail creates a characteristic rhythm that pushes the sperm forward, but also pulls the head backwards and sideways in a coordinated fashion.

Successful fertility relies on how a sperm moves through fluid, but capturing details of this movement is a complicated issue.

The team aim to use these new findings to understand how larger groups of sperm behave and interact, a task that would be impossible using modern observational techniques. The work could provide new insights into treating male infertility.

Dr Hermes Gadêlha, from the University of York's Department of Mathematics, said: "In order to observe, at the microscale, how a sperm achieves forward propulsion through fluid, sophisticated microscopic high precision techniques are currently employed.

"Measurements of the beat of the sperm's tail are fed into a computer model, which then helps to understand the fluid flow patterns that result from this movement.

"Numerical simulations are used to identify the flow around the sperm, but as the structures of the fluid are so complex, the data is particularly challenging to understand and use. Around 55 million spermatozoa are found in a given sample, so it is understandably very difficult to model how they move simultaneously.

"We wanted to create a mathematical formula that would simplify how we address this problem and make it easier to predict how large numbers of sperm swim. This would help us understand why some sperm succeed and others fail."

By analysing the head and tail movements of the sperm, researchers have now shown that the sperm moves the fluid in a coordinated rhythmic way, which can be captured to form a relatively simple mathematical formula. This means complex and expensive computer simulations are no longer needed to understand how the fluid moves as the sperm swim.

The research demonstrated that the sperm has to make multiple contradictory movements, such as moving backwards, in order to propel it forward towards the egg.

The whip-like tail of the sperm has a particular rhythm that pulls the head backwards and sideways to create a jerky fluid flow, countering some of the intense friction that is created due to their diminutive sizes.

Dr Gadêlha said: "It is true when scientists say how miraculous it is that a sperm ever reaches an egg, but the human body has a very sophisticated system of making sure the right cells come together.

"You would assume that the jerky movements of the sperm would have a very random impact on the fluid flow around it, making it even more difficult for competing sperm cells to navigate through it, but in fact you see well defined patterns forming in the fluid around the sperm.

"This suggests that to achieve sperm stirs the fluid around in a very coordinated way locomotion, not too dissimilar to the way in which magnetic fields are formed around magnets. So although the fluid drag makes it very difficult for the sperm to make forward motion, it does coordinate with its rhythmic movements to ensure that only a few selected ones achieve forward propulsion."

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Hubble's glittering frisbee galaxy

This image from Hubble's Wide Field Camera 3 (WFC3) shows a section of NGC 1448, a spiral galaxy located about 50 million light-years from Earth in the little-known constellation of Horologium (The Pendulum Clock).

This image from Hubble's Wide Field Camera 3 (WFC3) shows a section of NGC 1448, a spiral galaxy located about 50 million light-years from Earth in the little-known constellation of Horologium (The Pendulum Clock). We tend to think of spiral galaxies as massive and roughly circular celestial bodies, so this glittering oval does not immediately appear to fit the visual bill. What's going on?

Imagine a spiral galaxy as a circular frisbee spinning gently in space. When we see it face on, our observations reveal a spectacular amount of detail and structure -- a great example from Hubble is the telescope's view of Messier 51, otherwise known as the Whirlpool Galaxy. However, the NGC 1448 frisbee is very nearly edge-on with respect to Earth, giving it an appearance that is more oval than circular. The spiral arms, which curve out from NGC 1448's dense core, can just about be seen.

Although spiral galaxies might appear static with their picturesque shapes frozen in space, this is very far from the truth. The stars in these dramatic spiral configurations are constantly moving as they orbit around the galaxy's core, with those on the inside making the orbit faster than those sitting further out."

This makes the formation and continued existence of a spiral galaxy's arms something of a cosmic puzzle, because the arms wrapped around the spinning core should become wound tighter and tighter as time goes on -- but this is not what we see. This is known as the winding problem.

From Science Daily

Warning of shortage of essential minerals for laptops, cell phones, wiring

University of Delaware researcher Saleem Ali at the Diavik Diamond Mine, Yellowknife, Northwest Territories, Canada.

An international team of researchers, led by the University of Delaware's Saleem Ali, says global resource governance and sharing of geoscience data is needed to address challenges facing future mineral supply.

Specifically of concern are a range of technology minerals, which are an essential ingredient in everything from laptops and cell phones to hybrid or electric cars to solar panels and copper wiring for homes. However, base metals like copper are also a matter of immense concern.

The research team, which included experts from academic, government and industrial institutions across five continents, the U.S., Europe, South Africa, Australia and South America, reported their findings today in a peer-reviewed paper in Nature.

"There are treaties on climate change, biodiversity, migratory species and even waste management of organic chemicals, but there is no international mechanism to govern how mineral supply should be coordinated," said Ali, the paper's lead author and Blue and Gold Distinguished Professor of Energy and Environment at UD.

The researchers reviewed data and demand forecasts on the sustainability of global mineral supplies in coming decades. The study showed that mining exploration is not keeping up with future demand for minerals and recycling in and of itself would not be able to meet the demand either.

At the same time, transitioning to a low carbon society will require vast amounts of metals and minerals to manufacture clean technologies and the researchers say society is not equipped to meet the additional needs for these raw materials.

According to the research team, international coordination is needed on where to focus exploration investment efforts, what kind of minerals are likely to be found in different locations and hence, what kind of bilateral agreements are needed between various countries.

Supply and demand

Global population numbers are expected to reach 8.5 billion by 2030, the target date for the United Nations sustainable development goals, meaning even more consumers in the marketplace.

The largest percentage of investment in a mineral for exploration is in gold, which although highly profitable, is largely used for jewelry.

Major commodity metals like iron ore, copper and gold (and other precious metals) are sold on a global market the way that oil is sold. Rare earth metals and other technology minerals, however, are sold through individual dealers and prices can vary remarkably.

For goods like clothing, cosmetics or electronics, price can easily trigger changes in supply. This is not possible with mineral supply, however, because the time horizon for developing a rare earth mineral deposit from exploration and discovery to mining is 10-15 years.

For instance, the last major deposit for copper was discovered in Mongolia 15 years ago and only began producing in fall 2016, creating huge supply challenges.

Added to this, only 10 percent of early exploration efforts actually lead to a minable deposit. Most discoveries are either not economically viable to mine or companies run into land use or zoning problems due to geopolitical challenges.

"Countries where minerals are likely to be found may have poor governance, making it higher risk for supply. But production from these countries will be needed to meet global demand. We need to be thinking about this," Ali said.

Few alternatives, difficult to recycle

Then there is the common consumer misconception that we can just use something else. For many mineral uses, there are no alternatives. There are few commercially viable replacement minerals for many applications of copper wiring, for example.

The same may be true for technology metals that could become essential in green technologies -- like neodymium, terbium or iridium. These minerals are only needed in small quantities, but they are indispensable to making the technology work, meaning that while the scale seems small, the value is immense.

Environmental costs and materials recycling options need to be considered, too.

Metals and carbon fiber used in the manufacture of aircraft or automobiles are often thought to have less environmental impact because they are light, but Ali explained that the manufacturing of carbon fibers currently is highly petroleum based.

"Because they are lighter, people think they are somehow greener, but they aren't and they are difficult, if not impossible, to recycle," he said.

Ali and his colleagues hope that this paper is the first step toward an intergovernmental mechanism or other solution that can empower nations to plan for mineral scarcity as both the public and private sector are mineral dependent.

The research team contends that positive strides can be made quickly through expansion of developing organizations, such as the United Nation's International Resource Panel or the Canadian-led Intergovernmental Panel on Mining Metals and Sustainable Development.

Longer term solutions will require greater transparency among nations, and could include global sharing of geological data and the creation of mechanisms to protect mineral deposit 'finds' much like we protect intellectual property.

"It's about managing the flow of resources from the ground to product to consumer to recycling," Ali said.

The bottom line

The hard truth, though, is that if nothing changes shrinking supply naturally will lead to rising prices. It also could lead to serious global challenges if essential resources that people have been so dependent on collapse.

Take the infrastructure around renewable energy technologies, such as wind turbines. Right now, the technology is new, but what if resources dry up for new production or repair of existing technology? A bottleneck in terms of material production could create a bottleneck in terms of energy production too.

Even nuclear power, often considered a universal cure for global energy woes, is not immune to mineral scarcity. In fact, all nuclear reactors today require uranium -- a metal that must be mined -- in order to function.

Read more at Science Daily

For female mosquitoes, two sets of odor sensors are better than one

This scanning electron microscope image of the head of a female Anopheles mosquito shows the antennae, proboscis and palps that contain its olfactory system.

Biologists who study the malaria mosquito's 'nose' have found that it contains a secondary set of odor sensors that seem to be specially tuned to detect humans. The discovery could aid efforts to figure out how the insects target humans and develop a preference for them.

If you could peer into the mind of a female mosquito, you would find that her world is dominated by smell rather than sight or sound.

She follows whiffs of carbon dioxide exhaled by animals to locate potential prey. As she closes in on a target, she uses the animal's body odors to decide whether it is a desirable host. After getting the blood meal she needs to reproduce, she follows the scent of stagnant water to find a place to lay her eggs.

Her delicate antennae, proboscis and a pair of mouth appendages called palps are what make this possible. They are covered by tiny hollow sensory hairs called sensilla that are filled with an impressive array of odor sensors that can discriminate among thousands of different aromatic compounds.

For the last 15 years, a team of biologists at Vanderbilt University have been studying a family of 79 odorant receptors (ORs) in the malaria mosquito (Anopheles gambiae) in hopes of finding better repellents and lures that can be used to prevent the spread of malaria and other mosquito-borne diseases.

As the researchers meticulously determined the specific compounds that triggered these receptors, however, they were surprised to discover that the Anopheles ORs did not respond to many of the smelly human odors that they know mosquitoes can detect.

The scientists think they now have a handle on at least one of the reasons for this disparity. In a paper published earlier this year in the journal Scientific Reports they report that the malaria mosquito has a second complete system of odor sensors -- discovered five years ago in the fruit fly (Drosphila melanogaster) -- that are specially tuned to at least two human-derived chemical signals, which the insect's OR system cannot detect. So adult females use this second system of odor sensors to seek human prey.

"This appears to be a more primitive olfactory system and one which Anopheles uses to detect humans," said Cornelius Vanderbilt Professor of Biological Sciences Laurence Zwiebel, who directed the study. "It fills important gaps in the mosquito's chemosensory perception that are not provided by the OR system."

In a series of extensive and painstaking experiments carried out for his senior honors thesis, undergraduate Stephen L. Derryberry (now a student at the Vanderbilt School of Medicine), along with Research Assistant Professor Jason Pitts, succeeded in functionally characterizing three of these different sensors, called ionotropic receptors (IRs), in Anopheles. The researchers determined that unique combinations of IRs respond to two classes of compounds found in human sweat: carboxylic acids that impart a vinegary tang and ammonia derivatives called amines.

"Stephen's project was more difficult than simply searching for a needle in a haystack," Zwiebel said. "It was more like searching for a needle in a HUGE haystack, because we had no idea of what odorant molecules would trigger the IR system. Even worse, we didn't know what combinations of IR receptors might be involved." (In flies IRs only detect target molecules in conjunction with co-receptors on the same neuron.)

There is still a great deal about the IR system that the scientists don't understand. For example, they think the mosquitoes may also use this ancient family of proteins to detect infrared radiation and humidity levels.

One measure of the importance of an olfactory system is the number of connections it has to the brain. By this measure the OR system is the most important because it has more neurons that link it to the mosquito's brain, but the IR system runs a close second.

"The mosquito is an extremely sophisticated organism," said Pitts. "They use a combination of finely tuned olfactory systems to locate their prey. We have now found two of these systems, but, based on what we know about the mosquito's genome, we think there are others that we haven't identified yet."

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Indigenous South American group has healthiest arteries of all populations yet studied, providing clues to healthy lifestyle

Village in the Amazon rain forest

The Tsimane people -- a forager-horticulturalist population of the Bolivian Amazon -- have the lowest reported levels of vascular aging for any population, with coronary atherosclerosis (hardening of the arteries) being five times less common than in the US, according to a study published in The Lancet and being presented at the American College of Cardiology conference.

The researchers propose that the loss of subsistence diets and lifestyles in contemporary society could be classed as a new risk factor for heart disease. The main risk factors are age, smoking, high cholesterol, high blood pressure, physical inactivity, obesity and diabetes.

"Our study shows that the Tsimane indigenous South Americans have the lowest prevalence of coronary atherosclerosis of any population yet studied," said senior anthropology author, Professor Hillard Kaplan, University of New Mexico, USA. "Their lifestyle suggests that a diet low in saturated fats and high in non-processed fibre-rich carbohydrates, along with wild game and fish, not smoking and being active throughout the day could help prevent hardening in the arteries of the heart. The loss of subsistence diets and lifestyles could be classed as a new risk factor for vascular aging and we believe that components of this way of life could benefit contemporary sedentary populations."

Although the Tsimane lifestyle is very different from that of contemporary society, certain elements of it are transferable and could help to reduce risk of heart disease.

While industrial populations are sedentary for more than half of their waking hours (54%), the Tsimane spend only 10% of their daytime being inactive. They live a subsistence lifestyle that involves hunting, gathering, fishing and farming, where men spend an average of 6-7 hours of their day being physically active and women spend 4-6 hours.

Their diet is largely carbohydrate-based (72%) and includes non-processed carbohydrates which are high in fibre such as rice, plantain, manioc, corn, nuts and fruits. Protein constitutes 14% of their diet and comes from animal meat. The diet is very low in fat with fat compromising only 14% of the diet -- equivalent to an estimated 38 grams of fat each day, including 11g saturated fat and no trans fats. In addition, smoking was rare in the population.

In the observational study, the researchers visited 85 Tsimane villages between 2014 and 2015. They measured the participants' risk of heart disease by taking CT scans of the hearts of 705 adults (aged 40-94 years old) to measure the extent of hardening of the coronary arteries, as well as measuring weight, age, heart rate, blood pressure, cholesterol, blood glucose and inflammation.

Based on their CT scan, almost nine in 10 of the Tsimane people (596 of 705 people, 85%) had no risk of heart disease, 89 (13%) had low risk and only 20 people (3%) had moderate or high risk. These findings also continued into old age, where almost two-thirds (65%, 31 of 48) of those aged over 75 years old had almost no risk and 8% (4 of 48) had moderate or high risk. These results are the lowest reported levels of vascular aging of any population recorded to date.

By comparison, a US study of 6814 people (aged 45 to 84) found that only 14% of Americans had a CT scan that suggested no risk of heart disease and half (50%) had a moderate or high risk -- a five-fold higher prevalence than in the Tsimane population.

In the Tsimane population, heart rate, blood pressure, cholesterol, and blood glucose were also low, potentially as a result of their lifestyle. The researchers also note that the low risk of coronary atherosclerosis was identified despite there being elevated levels of inflammation in half of the Tsimane population (51%, 360 of 705 people).

"Conventional thinking is that inflammation increases the risk of heart disease," said Professor Randall Thompson, cardiologist at Saint Luke's Mid America Heart Institute, USA. "However, the inflammation common to the Tsimane was not associated with increased risk of heart disease, and may instead be the result of high rates of infections."

Because the study is observational it cannot confirm how the Tsimane population is protected from vascular aging, or which part of their lifestyle (diet, physical activity or smoking) is most protective. The researchers suggest it is more likely to be a result of their lifestyle than genetics, because of a gradual increase in cholesterol levels coinciding with a rapidly changing lifestyle.

"Over the last five years, new roads and the introduction of motorised canoes have dramatically increased access to the nearby market town to buy sugar and cooking oil," said Dr Ben Trumble, Arizona State University, USA. "This is ushering in major economic and nutritional changes for the Tsimane people."

The researchers did not study whether coronary artery hardening in the Tsimane population impacted on their health, but note that deaths from heart attacks are very uncommon in the population so it is likely that their low levels of atherosclerosis and heart disease are associated. The researchers are investigating this in further research.

Read more at Science Daily

Unproven stem cell 'therapy' blinds three patients at Florida clinic

Jeffrey Goldberg and his colleagues examined the cases of three women who were blinded after undergoing an unproven stem cell treatment for macular degeneration.

Three people with macular degeneration were blinded after undergoing an unproven stem cell treatment that was touted as a clinical trial in 2015 at a clinic in Florida. Within a week following the treatment, the patients experienced a variety of complications, including vision loss, detached retinas and hemorrhage. They are now blind.

A paper documenting the cases will be published March 16 in The New England Journal of Medicine.

The article is a "call to awareness for patients, physicians and regulatory agencies of the risks of this kind of minimally regulated, patient-funded research," said Jeffrey Goldberg, MD, PhD, professor and chair of ophthalmology at the Stanford University School of Medicine and co-author of the paper.

The three patients -- all women, ranging in age from 72 to 88 -- suffered from macular degeneration, a common, progressive disease of the retina that leads to loss of vision. Before the surgery, the vision in their eyes ranged from 20/30 to 20/200. Now, the patients are likely to remain blind, said co-author Thomas Albini, MD, an associate professor of clinical ophthalmology at the University of Miami, where two of the patients were subsequently treated for complications from the stem cell treatments. "Although I can't say it's impossible, it's extremely unlikely they would regain vision."

Appealing to patients 'desperate for care'

Two of the patients learned of the so-called clinical trial on ClinicalTrials.gov, a registry and results database run by the U.S. National Library of Medicine, where it was called "Study to assess the safety and effects of cells injected intravitreal in dry macular degeneration." Some of the patients believed they were participating in a trial, although the consent form and other written materials given to the patients did not mention a trial, Albini said.

"There's a lot of hope for stem cells, and these types of clinics appeal to patients desperate for care who hope that stem cells are going to be the answer, but in this case these women participated in a clinical enterprise that was off-the-charts dangerous," Albini said.

Each patient paid $5,000 for the procedure. Any clinical trial that has a fee should raise a red flag, the authors said.

"I'm not aware of any legitimate research, at least in ophthalmology, that is patient-funded," Albini said.

At the clinic, which is not named in the paper, the patients had fat cells removed from their abdomens and a standard blood draw. The fat tissue was processed with enzymes, with the goal of obtaining stem cells. Platelet-dense plasma was isolated from the blood. The cells were then mixed with the platelet-dense plasma and injected into their eyes. Patients reported that the entire process took less than an hour, Albini said. The patients had both eyes treated at once -- another red flag, Albini and Goldberg said, because most doctors would opt for a conservative approach to observe how one eye responds to an experimental treatment before attempting the other eye.

Shoddy stem cell preparation may have led to some of the patients' complications, which could have been caused by injection of a contaminant or the cell wash solution into the eye, Albini said. When injected into the eye, the stem cells also could have changed into myofibroblasts, a type of cell associated with scarring.

No evidence of vision restoration

But even if executed correctly, there is no evidence suggesting that the procedure could help restore vision, Goldberg and Albini said. In fact, there is sparse evidence that adipose-derived stem cells, the type of cells that the clinic claimed to use, are capable of differentiating, or maturing, into retinal pigment epithelium or photoreceptor cells, which play a critical role in macular degeneration and are the cells some researchers are targeting to develop therapies.

"There is a lot of very well-founded evidence for the positive potential of stem therapy for many human diseases, but there's no excuse for not designing a trial properly and basing it on preclinical research," Goldberg said.

The "trial" lacked nearly all of the components of a properly designed clinical trial, including a hypothesis based on laboratory experiments, assignment of a control group and treatment group, collection of data, masking of clinical and patient groups, and plans for follow-up, Goldberg and Albini said. "There was a whole list of egregious things," Albini said.

Listings on ClinicalTrials.gov are not fully scrutinized for scientific soundness, Goldberg said. Although still visible on the website, the listing now states: "This study has been withdrawn prior to enrollment." The clinic is also no longer performing these eye injections, although it is still seeing patients, Albini said.

The procedures were arguably not subject to Food and Drug Administration approval because the cells were not transferred between patients and were considered "minimally processed," according to Title 21, Part 1271.10, of the Code of Federal Regulations. The FDA released more specific guidelines in October 2015, after these procedures were performed, establishing the requirement for FDA oversight and approval for these types of procedures.

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