Lab-grown fat could give cultured meat real flavor and texture

Researchers have successfully bulk-produced fat tissue in the lab that has a similar texture and make-up to naturally occurring fats from animals.

The results, described in a study published today in eLife, could be applied to the production of cultured meat grown entirely from cells, giving it a more realistic texture and flavour.

Cultivated meat has been making waves in the news lately, with reports from startup companies around the world developing cell-grown chicken, beef, pork and fish -- mostly in early stages of development, not ready for large-scale production and with a couple of exceptions, not yet approved for commercial sale. Most of those products in development are in the form of an unstructured mixture of cells -- like chicken nuggets rather than a slice of chicken breast. What is lacking is the texture of real meat, created by muscle fibres, connective tissue and fat -- and it's the fat that gives meat flavour.

In fact, consumer testing with natural beef of different fat content showed that the highest scores were registered for beef containing 36% fat.

However, producing cultured fat tissue in sufficient quantities has been a major challenge because, as the fat grows into a mass, the cells in the middle become starved of oxygen and nutrients. In nature, blood vessels and capillaries deliver oxygen and nutrients throughout the tissue. Researchers still have no way to replicate that vascular network at a large scale in lab grown tissue, so they can only grow muscle or fat to a few millimetres in size.

To get around this limitation, the researchers grew fat cells from mice and pigs first in a flat, two-dimensional layer, then harvested those cells and aggregated them into a three-dimensional mass with a binder such as alginate and mTG, which are both already used in some foods.

"Our goal was to develop a relatively simple method of producing bulk fat. Since fat tissue is predominantly cells with few other structural components, we thought that aggregating the cells after growth would be sufficient to reproduce the taste, nutrition and texture profile of natural animal fat," says first author John Yuen Jr, a graduate student at the Tufts University Center for Cellular Architecture (TUCCA), Massachusetts, US. "This can work when creating the tissue solely for food, since there's no requirement to keep the cells alive once we gather the fat in bulk."

The aggregated fat cells immediately had the appearance of fat tissue, but to see if they truly reproduced the features of native fat from animals, the team carried out a series of further experiments.

First, they explored the texture, by compressing the fat tissue and seeing how much pressure it could withstand compared to natural animal fat. They found that cell-grown fat bound with sodium alginate was able to withstand a similar amount of pressure to fat from livestock and poultry, but the cell-grown fat that was bound with mTG behaved more like rendered fat -- similar to lard or tallow. This suggests it could be possible to fine-tune the texture of cultured fat, so it best resembles the real-life texture of fat within meat, using different types and amounts of binders.

Cooking releases hundreds of compounds that add flavour to the meat, and most of those compounds originate from fat, including lipids and their component fatty acids. The team therefore examined the composition of molecules from the cell-grown fat and found that the mix of fatty acids from cultured mouse fat differed from native mouse fat. However, the cultured pig fat had a much closer fatty acid profile to the native tissue. The team's preliminary research suggests it might be possible to supplement growing fat cells with the required lipids to ensure that they more closely match the composition of natural meat.

Read more at Science Daily

A new giant dinosaur gives insight into why many prehistoric meat-eaters had such tiny arms

A team co-led by University of Minnesota Twin Cities researcher Peter Makovicky and Argentinean colleagues Juan Canale and Sebastian Apesteguía has discovered a new huge, meat-eating dinosaur, dubbed Meraxes gigas. The new dinosaur provides clues about the evolution and biology of dinosaurs such as the Carcharodontosaurus and Tyrannosaurus rex—specifically, why these animals had such big skulls and tiny arms.

The study is published in Current Biology, a peer-reviewed scientific biology journal.

The researchers initially discovered Meraxes in Patagonia in 2012 and have spent the last several years extracting, preparing, and analyzing the specimen. The dinosaur is part of the Carcharodontosauridae family, a group of giant carnivorous theropods that also includes Giganotosaurus, one of the largest known meat-eating dinosaurs and one of the reptilian stars of the recently released “Jurassic World: Dominion” movie.

Though not the largest among carcharodontosaurids, Meraxes was still an imposing animal measuring around 36 feet from snout to tail tip and weighing approximately 9,000 pounds. The researchers recovered the Meraxes from rocks that are around 90-95 million years old, alongside other dinosaurs including several long-necked sauropod specimens.

Meraxes is among the most complete carcharodontosaurid skeleton paleontologists have found yet in the southern hemisphere and includes nearly the entirety of the animal’s skull, hips, and both left and right arms and legs.

“The neat thing is that we found the body plan is surprisingly similar to tyrannosaurs like T. rex,” said Peter Makovicky, one of the principal authors of the study and a professor in the University of Minnesota N.H. Winchell School of Earth and Environmental Sciences. “But, they’re not particularly closely related to T. rex. They're from very different branches of the meat-eating dinosaur family tree. So, having this new discovery allowed us to probe the question of, ‘Why do these meat-eating dinosaurs get so big and have these dinky little arms?’”

“The discovery of this new carcharodontosaurid, the most complete up to now, gives us an outstanding opportunity to learn about their systematics, paleobiology, and true size like never before,” said Sebastian Apesteguía, a co-author of the study and a researcher at Maimónides University in Argentina.

With the statistical data that Meraxes provided, the researchers found that large, mega-predatory dinosaurs in all three families of therapods grew in similar ways. As they evolved, their skulls grew larger and their arms progressively shortened.

The possible uses of the tiny forelimbs in T. rex and other large carnivorous dinosaurs have been the topic of much speculation and debate.

“What we’re suggesting is that there’s a different take on this,” Makovicky said. “We shouldn’t worry so much about what the arms are being used for, because the arms are actually being reduced as a consequence of the skulls becoming massive. Whatever the arms may or may not have been used for, they’re taking on a secondary function since the skull is being optimized to handle larger prey.”

The researchers also found that carcharodontosaurids including species from Patagonia evolved very quickly, but then disappeared suddenly from the fossil record very soon after.

“Usually when animals are on the verge of extinction, it’s because they’re evolutionary rates are quite slow, meaning they aren’t adapting very quickly to their environment,” explained  Juan Canale, the study’s lead author and a researcher at the National University of Río Negro. “Here, we have evidence that Meraxes and its relatives were evolving quite fast and yet within a few million years of being around, they disappeared, and we don’t know why. It’s one of these finds where you answer some questions, but it generates more questions for the future.”

Read more at Science Daily

Bizarre meat-eating dinosaur joins 'Rogues' Gallery' of giant predators from classic fossil site in Egypt's Sahara Desert

An Egyptian-American team of researchers has announced the discovery of a new kind of large-bodied meat-eating dinosaur, or theropod, from a celebrated fossil site in Egypt's Sahara Desert. The fossil of a still-unnamed species provides the first known record of the abelisaurid group of theropods from a middle Cretaceous-aged (approximately 98 million years old) rock unit known as the Bahariya Formation, which is exposed in the Bahariya Oasis of the Western Desert of Egypt.

In the early 20th century, this locality famously yielded the original specimens of a host of remarkable dinosaurs -- including the colossal sail-backed fish-eater Spinosaurus -- which were then destroyed in World War II. Abelisaurid fossils had previously been found in Europe and in many of today's Southern Hemisphere continents, but never before from the Bahariya Formation. The team describes the Bahariya abelisaurid discovery in a paper published today in Royal Society Open Science.

The study was led by Ohio University graduate student Belal Salem, based on work he initiated while a member of the Mansoura University Vertebrate Paleontology Center (MUVP) in Mansoura, Egypt. The research team also included Ohio University Heritage College of Osteopathic Medicine professor of biomedical sciences Patrick O'Connor; Matt Lamanna, associate curator of vertebrate paleontology at Carnegie Museum of Natural History; Sanaa El-Sayed, a doctoral student at the University of Michigan and the MUVP's former vice director; Hesham Sallam, a professor at the American University in Cairo (AUC) and Mansoura University and the founding director of the MUVP; and additional colleagues from Benha University and the Egyptian Environmental Affairs Agency.

The fossil in question, a well-preserved vertebra from the base of the neck, was recovered by a 2016 MUVP expedition to the Bahariya Oasis. The vertebra belongs to an abelisaurid, a kind of bulldog-faced, small-toothed, tiny-armed theropod that is estimated to have been roughly six meters (20 feet) in body length. Abelisaurids -- most notably represented by the horned, demonic-looking Patagonian form Carnotaurus of Jurassic World and Prehistoric Planet fame -- were among the most diverse and geographically widespread large predatory dinosaurs in the southern landmasses during the Cretaceous Period, the final time period of the Age of Dinosaurs. Along with Spinosaurus and two other giant theropods (Carcharodontosaurus and Bahariasaurus), the new abelisaurid fossil adds yet another species to the cadre of large predatory dinosaurs that roamed what is now the Egyptian Sahara roughly 98 million years ago.

"During the mid-Cretaceous, the Bahariya Oasis would've been one of the most terrifying places on the planet," says Salem, a new student in the biological sciences graduate program at Ohio University. "How all these huge predators managed to coexist remains a mystery, though it's probably related to their having eaten different things, their having adapted to hunt different prey."

The new vertebra holds implications for the biodiversity of Cretaceous dinosaurs in Egypt and the entire northern region of Africa. It is the oldest known fossil of Abelisauridae from northeastern Africa, and shows that, during the mid-Cretaceous, these carnivorous dinosaurs ranged across much of the northern part of the continent, east to west from present day Egypt to Morocco, to as far south as Niger and potentially beyond. Spinosaurus and Carcharodontosaurus are also known from Niger and Morocco, and a close relative of Bahariasaurus has been found in the latter nation as well, suggesting that this fauna of large to gigantic theropods coexisted throughout much of northern Africa at this time.

How can the discovery of a single neck vertebra lead researchers to conclude that the fossil belongs to a member of Abelisauridae, a kind of carnivorous dinosaur that has never been found in the Bahariya Formation before? The answer is remarkably simple: it is virtually identical to the same bone in other, better-known abelisaurids such as Carnotaurus from Argentina and Majungasaurus from Madagascar. As coauthor and Salem's graduate advisor Patrick O'Connor, who in 2007 published an exhaustive study of the vertebral anatomy of Majungasaurus,explains, "I've examined abelisaur skeletons from Patagonia to Madagascar. My first glimpse of this specimen from photos left no doubt about its identity. Abelisaurid neck bones are so distinctive."

The Site

The Bahariya Oasis is renowned within paleontological circles for having yielded the type specimens (the original, first-discovered, name-bearing fossils) of several extraordinary dinosaurs during the early 20th century, including, most famously, Spinosaurus. Unfortunately, all Bahariya dinosaur fossils collected prior to World War II were destroyed during an Allied bombing of Munich in 1944.

As a graduate student in the early 2000s, study coauthor Matt Lamanna helped make the first dinosaur discoveries from the oasis since the infamous 1944 air raid, including the gargantuan sauropod (long-necked plant-eating dinosaur) Paralititan. "The Bahariya Oasis has taken on near-legendary status among paleontologists for having produced the first-known fossils of some of the world's most amazing dinosaurs," says Lamanna, "but for more than three quarters of a century, those fossils have existed only as pictures in old books." Thankfully, discoveries made during recent expeditions led by researchers from AUC and MUVP -- such as the new abelisaurid vertebra -- are helping to restore the paleontological legacy of this classic site. These expeditions have recovered a wealth of additional fossils that the researchers plan to unveil in the near future.

As team member Sanaa El-Sayed, who co-led the 2016 expedition that collected the abelisaurid vertebra, explains, "This bone is just the first of many important new dinosaur fossils from the Bahariya Oasis."

The Bahariya Formation holds promise to shed further light on mid-Cretaceous African dinosaurs and the vanished ecosystems in which they once lived. Unlike more thoroughly explored rocks of the same age in Morocco that tend to yield isolated bones, the Bahariya Formation appears to preserve partial skeletons of dinosaurs and other land-living animals with a relatively high degree of frequency. The more bones that are preserved within the skeleton of a given fossil backboned species, the more paleontologists can generally learn about it. The propensity of the Bahariya Oasis for producing associated partial skeletons suggests that much remains to be learned from this historic locality.

Read more at Science Daily

Diet restricted size of hunter-gatherer societies

Short growing seasons limited the possible size of hunter-gatherer societies by forcing people to rely on meat, according to a recent study by a team of international reseachers including McGill University professor Eric Galbraith.

After looking at population size for the roughly 300 hunter-gatherer societies which existed until quite recently, the researchers found that many of these groups were much smaller than might have been expected from the local ecosystem productivity. In regions with short growing seasons, hunter-gatherer groups had smaller populations per square kilometre than groups who depended on abundant plant foods throughout the year.

Need for meat limited population size

"Basically, if people had to live through long dry or cold seasons when plant food was scarce, in order to survive they had to depend on hunting a very limited number of animals," explains Galbraith, a professor in McGill's Department of Earth and Planetary Sciences and at the ICTA-UAB (Institut de Ciència i Tecnologia Ambientals of the Autonomous University of Barcelona), and a senior author on the paper published recently in the journal Nature Ecology & Evolution.

"This led to a seasonal bottleneck in the amount of food available, which then set the overall limit on the population size, no matter how much food there was during the plentiful times."

The team developed a mathematical model that simulates daily human foraging activities (gathering and hunting) and the resultant carbon (energy) flows between vegetation, animals, and hunter-gatherers in a realistic global environment.

"We were struck by the fact that -- despite a long list of unknowns -- a very strong result emerged from the model equations," says Galbraith. "Wherever growing seasons were short, hunter gatherers required meat to make up a high percentage of their diets. And -- just as in the modern world -- it took much more land to produce the same amount of meat as plant-based food."

Read more at Science Daily

Lab analysis finds near-meat and meat not nutritionally equivalent

Plant-based meat substitutes taste and chew remarkably similar to real beef, and the 13 items listed on their nutrition labels -- vitamins, fats and protein -- make them seem essentially equivalent.

But a Duke University research team's deeper examination of the nutritional content of plant-based meat alternatives, using a sophisticated tool of the science known as 'metabolomics,' shows they're as different as plants and animals.

Meat-substitute manufacturers have gone to great lengths to make the plant-based product as meaty as possible, including adding leghemoglobin, an iron-carrying molecule from soy, and red beet, berries and carrot extracts to simulate bloodiness. The texture of near-meat is thickened by adding indigestible fibers like methyl cellulose. And to bring the plant-based meat alternatives up to the protein levels of meat, they use isolated plant proteins from soy, peas, and other plant sources. Some meat-substitutes also add vitamin B12 and zinc to further replicate meat's nutrition.

However, many other components of nutrition do not appear on the labels, and that's where the products differ widely from meat, according to the study, which appears this week in Scientific Reports.

The metabolites that the scientists measured are building blocks of the body's biochemistry, crucial to the conversion of energy, signaling between cells, building structures and tearing them down, and a host of other functions. There are expected to be more than 100,000 of these molecules in biology and about half of the metabolites circulating in human blood are estimated to be derived from our diets.

"To consumers reading nutritional labels, they may appear nutritionally interchangeable," said Stephan van Vliet, a postdoctoral researcher at the Duke Molecular Physiology Institute who led the research. "But if you peek behind the curtain using metabolomics and look at expanded nutritional profiles, we found that there are large differences between meat and a plant-based meat alternative."

The Duke Molecular Physiology Institute's metabolomics core lab compared 18 samples of a popular plant-based meat alternative to 18 grass-fed ground beef samples from a ranch in Idaho. The analysis of 36 carefully cooked patties found that 171 out of the 190 metabolites they measured varied between beef and the plant-based meat substitute.

The beef contained 22 metabolites that the plant substitute did not. The plant-based substitute contained 31 metabolites that meat did not. The greatest distinctions occurred in amino acids, dipeptides, vitamins, phenols, and types of saturated and unsaturated fatty acids found in these products.

Several metabolites known to be important to human health were found either exclusively or in greater quantities in beef, including creatine, spermine, anserine, cysteamine, glucosamine, squalene, and the omega-3 fatty acid DHA. "These nutrients have potentially important physiological, anti-inflammatory, and or immunomodulatory roles," the authors said in the paper.

"These nutrients are important for our brain and other organs including our muscles" van Vliet said. "But some people on vegan diets (no animal products), can live healthy lives -- that's very clear." Besides, the plant-based meat alternative contained several beneficial metabolites not found in beef such as phytosterols and phenols.

"It is important for consumers to understand that these products should not be viewed as nutritionally interchangeable, but that's not to say that one is better than the other," said van Vliet, a self-described omnivore who enjoys a plant-heavy diet but also eats meat. "Plant and animal foods can be complementary, because they provide different nutrients."

Read more at Science Daily

Organic meat less likely to be contaminated with multidrug-resistant bacteria

Meat that is certified organic by the U.S. Department of Agriculture is less likely to be contaminated with bacteria that can sicken people, including dangerous, multidrug-resistant organisms, compared to conventionally produced meat, according to a study from researchers at the Johns Hopkins Bloomberg School of Public Health.

The findings highlight the risk for consumers to contract foodborne illness -- contaminated animal products and produce sicken tens of millions of people in the U.S. each year -- and the prevalence of multidrug-resistant organisms that, when they lead to illness, can complicate treatment.

The researchers found that, compared to conventionally processed meats, organic-certified meats were 56 percent less likely to be contaminated with multidrug-resistant bacteria. The study was based on nationwide testing of meats from 2012 to 2017 as part of the U.S. National Antimicrobial Resistance Monitoring System (NARMS).

In order for meat to be certified organic by the USDA, animals can never have been administered antibiotics or hormones, and animal feed and forage such as grass and hay must be 100 percent organic. A longstanding concern about antibiotic use in livestock and livestock feed is the increased prevalence of antibiotic-resistant pathogens. To monitor this trend, in 1996 the federal government developed NARMS to track antibiotic resistance in bacteria isolated from retail meats, farmed animals, and patients with foodborne illness in the U.S.

For their study, the Bloomberg School research team analyzed U.S. Food and Drug Administration-NARMS data from randomly sampled chicken breast, ground beef, ground turkey, and pork for any contamination and for contamination by multidrug-resistant organisms. The analysis covers four types of bacteria: Salmonella, Campylobacter, Enterococcus, and Escherichia coli.

The study covered a total of 39,348 meat samples, of which 1,422 were found to be contaminated with at least one multidrug-resistant organism. The rate of contamination was 4 percent in the conventionally produced meat samples and just under 1 percent in those that were produced organically.

The study was published May 12 in Environmental Health Perspectives.

"The presence of pathogenic bacteria is worrisome in and of itself, considering the possible increased risk of contracting foodborne illness," says senior author Meghan Davis, DVM, PhD, associate professor in the Department of Environmental Health and Engineering at the Bloomberg School. "If infections turn out to be multidrug resistant, they can be more deadly and more costly to treat."

The analysis also suggested that the type of processing facility may influence the likelihood of meat contamination. Meat processors fall into three categories: exclusively organic, exclusively conventional, or those that handle both organic and conventional meats -- so-called "split" processors. The study found that among conventional meats, those processed at facilities that exclusively handled conventional meats were contaminated with bacteria one-third of the time, while those handled at facilities that processed both conventional and organic meats were contaminated one-quarter of the time. The prevalence of multidrug-resistant bacteria was roughly the same in these two meat processor categories.

"The required disinfection of equipment between processing batches of organic and conventional meats may explain our findings of reduced bacterial contamination on products from facilities that process both types of meats," says Davis.

Read more at Science Daily

Increased meat consumption associated with symptoms of childhood asthma

 Substances present in cooked meats are associated with increased wheezing in children, Mount Sinai researchers report. Their study, published in Thorax, highlights pro-inflammatory compounds called advanced glycation end-products (AGEs) as an example of early dietary risk factors that may have broad clinical and public health implications for the prevention of inflammatory airway disease.

Asthma prevalence among children in the United States has risen over the last few decades. Researchers found that dietary habits established earlier in life may be associated with wheezing and potentially the future development of asthma.

Researchers examined 4,388 children between 2 and 17 years old from the 2003-2006 National Health and Nutrition Examination Survey (NHANES), a program of the National Center for Health Statistics, which is part of the U.S. Centers for Disease Control and Prevention. It is designed to evaluate the health and nutritional status of adults and children in the United States through interviews and physical examinations.

The researchers used NHANES survey data to evaluate associations between dietary AGE and meat consumption frequencies, and respiratory symptoms. They found that higher AGE intake was significantly associated with increased odds of wheezing, importantly including wheezing that disrupted sleep and exercise, and that required prescription medication. Similarly, higher intake of non-seafood meats was associated with wheeze-disrupted sleep and wheezing that required prescription medication.

"We found that higher consumption of dietary AGEs, which are largely derived from intake of non-seafood meats, was associated with increased risk of wheezing in children, regardless of overall diet quality or an established diagnosis of asthma," said Jing Gennie Wang, MD, lead author of the study, and a former fellow in Pulmonary, Critical Care and Sleep Medicine at the Icahn School of Medicine at Mount Sinai.

Read more at Science Daily

Red hot meat: The wrong recipe for heart disease

 From MasterChef to MKR, the world's best chefs have taught us how to barbeque, grill and panfry a steak to perfection. But while the experts may be seeking that extra flavour, new research from the University of South Australia suggests high-heat caramelization could be bad for our health.

Conducted in partnership with the Gyeongsang National University the study found that consuming red and processed meat increased a protein compound that may increase the risk of heart disease, stroke, and complications in diabetes.

UniSA researcher Dr Permal Deo says the research provides important dietary insights for people at risk of such degenerative diseases.

"When red meat is seared at high temperatures, such as grilling, roasting or frying, it creates compounds called advanced glycation end products -- or AGEs ¬- which when consumed, can accumulate in your body and interfere with normal cell functions," Dr Deo says.

"Consumption of high-AGE foods can increase our total daily AGE intake by 25 per cent, with higher levels contributing to vascular and myocardial stiffening, inflammation and oxidative stress -- all signs of degenerative disease."

Published in Nutrients, the study tested the impacts of two diets -- one high in red meat and processed grains and the other high in whole grains dairy, nuts and legumes, and white meat using steaming, boiling, stewing and poaching cooking methods.

It found that the diet high in red meat significantly increased AGE levels in blood suggesting it may contribute to disease progression

Largely preventable, cardiovascular disease (CVD) is the number one cause of death globally. In Australia, it represents one in five of all deaths.

Co-researcher UniSA's Professor Peter Clifton says while there are still questions about how dietary AGEs are linked to chronic disease, this research shows that eating red meat will alter AGE levels.

"The message is pretty clear: if we want to reduce heart disease risk, we need to cut back on how much red meat we eat or be more considered about how we cook it.

"Frying, grilling and searing may be the preferred cooking methods of top chefs, but this might not be the best choice for people looking to cut their risk of disease.

"If you want to reduce your risk of excess AGEs, then slow cooked meals could be a better option for long-term health."

From Science Daily

No need to cut down red and processed meat, controversial findings suggest

Meats and vegetables on a grill.

Most people can continue to eat red and processed meat as they do now. A major study led by researchers at McMaster and Dalhousie universities has found cutting back has little impact on health.

A panel of international scientists systematically reviewed the evidence and have recommended that most adults should continue to eat their current levels of red and processed meat.

The researchers performed four systematic reviews focused on randomized controlled trials and observational studies looking at the impact of red meat and processed meat consumption on cardiometabolic and cancer outcomes.

In one review of 12 trials with 54,000 people, the researchers did not find statistically significant or an important association between meat consumption and the risk of heart disease, diabetes or cancer.

In three systematic reviews of cohort studies following millions of people, a very small reduction in risk among those who had three fewer servings of red or processed meat a week, but the association was uncertain.

The authors also did a fifth systematic review looking at people's attitudes and health-related values around eating red and processed meats. They found people eat meat because they see it as healthy, they like the taste and they are reluctant to change their diet.

The five systematic reviews, a recommendation and an editorial on the topic were published in the Annals of Internal Medicine today.

McMaster professor Gordon Guyatt, chair of the guideline committee, said the research group with a panel of 14 members from seven countries used a rigorous systematic review methodology, and GRADE methods which rate the certainty of evidence for each outcome, to move from evidence to dietary recommendations to develop their guidelines.

"There is a worldwide interest in nutrition and the issue of red meat in particular. People need to be able to make decisions about their own diet based on the best information available," he said.

Bradley Johnston, corresponding author on the reviews and guideline, said the research team realizes its work is contrary to many current nutritional guidelines.

"This is not just another study on red and processed meat, but a series of high quality systematic reviews resulting in recommendations we think are far more transparent, robust and reliable," said Johnston, who is a part-time associate professor at McMaster and an associate professor of community health and epidemiology at Dalhousie.

He added: "We focused exclusively on health outcomes, and did not consider animal welfare or environmental concerns when making our recommendations.

"We are however sympathetic to animal welfare and environmental concerns with a number of the guideline panel members having eliminated or reduced their personal red and processed meat intake for these reasons."

The accompanying editorial by authors at the Indiana University School of Medicine said: "This is sure to be controversial, but is based on the most comprehensive review of the evidence to date. Because that review is inclusive, those who seek to dispute it will be hard pressed to find appropriate evidence with which to build an argument."

Read more at Science Daily