Ancient poop shows people in present-day Austria drank beer and ate blue cheese up to 2,700 years ago

Original article: eurekalert.org

13-Oct-2021Peer-Reviewed Publication

Cell Press

Human feces don’t usually stick around for long—and certainly not for thousands of years. But exceptions to this general rule are found in a few places in the world, including prehistoric salt mines of the Austrian UNESCO World Heritage area Hallstatt-Dachstein/Salzkammergut. Now, researchers who’ve studied ancient fecal samples (or paleofeces) from these mines have uncovered some surprising evidence: the presence of two fungal species used in the production of blue cheese and beer. The findings appear in the journal Current Biology on October 13.

“Genome-wide analysis indicates that both fungi were involved in food fermentation and provide the first molecular evidence for blue cheese and beer consumption during Iron Age Europe,” says Frank Maixner (@FrankMaixner) of the Eurac Research Institute for Mummy Studies in Bolzano, Italy.

“These results shed substantial new light on the life of the prehistoric salt miners in Hallstatt and allow an understanding of ancient culinary practices in general on a whole new level,” adds Kerstin Kowarik (@KowarikKerstin) of the Museum of Natural History Vienna. “It is becoming increasingly clear that not only were prehistoric culinary practices sophisticated, but also that complex processed foodstuffs as well as the technique of fermentation have held a prominent role in our early food history.”

Earlier studies already had shown the potential for studies of prehistoric paleofeces from salt mines to offer important insights into early human diet and health. In the new study, Maixner, Kowarik, and their colleagues added in-depth microscopic, metagenomic, and proteomic analyses—to explore the microbes, DNA, and proteins that were present in those poop samples.

These comprehensive studies allowed them to reconstruct the diet of the people who once lived there. They also could get information about the ancient microbes that inhabited their guts. Gut microbes are collectively known as the gut microbiome and are now recognized to have an important role in human health.

Their dietary survey identified bran and glumes of different cereals as one of the most prevalent plant fragments. They report that this highly fibrous, carbohydrate-rich diet was supplemented with proteins from broad beans and occasionally with fruits, nuts, or animal food products.

In keeping with their plant-heavy diet, the ancient miners up to the Baroque period also had gut microbiome structures more like those of modern non-Westernized individuals, whose diets are also mainly composed of unprocessed food, fresh fruits and vegetables. The findings suggest a more recent shift in the Western gut microbiome as eating habits and lifestyles changed.

When the researchers extended their microbial survey to include fungi, that’s when they got their biggest surprise: an abundance in one of their Iron Age samples of Penicillium roqueforti and Saccharomyces cerevisiae DNA.

“The Hallstatt miners seem to have intentionally applied food fermentation technologies with microorganisms which are still nowadays used in the food industry,” Maixner says.

The findings offer the first evidence that people were already producing blue cheese in Iron Age Europe nearly 2,700 years ago, he adds. In ongoing and future studies of the paleofeces from Hallstatt, they hope to learn more about the early production of fermented foods and the interplay between nutrition and the gut microbiome composition in different time periods.

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This work was supported by Programma Ricerca Budget prestazioni Eurac 2017 of the Province of Bolzano, Italy, and the South Tyrolean grant legge 14, the European Regional Development Fund, the European Research Council grant, the US National Institutes of Health, and the US National Science Foundation.

Current Biology, Maixner et al.: “Paleofeces analyses indicate blue cheese and beer consumption by Iron Age Hallstatt salt miners and a non-Westernized gut microbiome structure in Europe until the Baroque period”

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Research ‘final nail in the coffin’ of Paranthropus as hard object feeders

Original article: eurekalert.org

Long-held eating habits beliefs debunked

UNIVERSITY OF OTAGO

23-Jul-2021

Long-held eating habits beliefs debunked

New research from the University of Otago debunks a long-held belief about our ancestors’ eating habits.

For more than 60 years, researchers have believed Paranthropus, a close fossil relative of ours which lived about one to three million years ago, evolved massive back teeth to consume hard food items such as seeds and nuts, while our own direct ancestors, the genus Homo, is thought to have evolved smaller teeth due to eating softer food such as cooked food and meats. 

However, after travelling to several large institutes and museums in South Africa, Japan and the United Kingdom and studying tooth fractures in more than 20,000 teeth of fossil and living primate species, Dr Ian Towle, an Otago biological anthropologist, working with Dr Carolina Loch, of the Faculty of Dentistry, says this “neat picture is far more complex than once thought”.

“By individually studying each tooth and recording the position and size of any tooth fractures, we show tooth chipping does not support regular hard food eating in Paranthropus robustus, therefore potentially putting an end to the argument that this group as a whole were hard food eaters,” he says.

Dr Towle says the findings challenge our understanding of dietary and behavioural changes during human evolution.

“The results are surprising, with human fossils so far studied – those in our own genus Homo – showing extremely high rates of tooth fractures, similar to living hard object eating primates, yet Paranthropus show extremely low levels of fracture, similar to primates that eat soft fruits or leaves.

“Although in recent years there has been a slow acceptance that another species of Paranthropus, Paranthropus boisei, found in East Africa, was unlikely to have regularly eaten hard foods, the notion that Paranthropus evolved their large dental apparatus to eat hard foods has persisted. Therefore, this research can be seen as the final nail in the coffin of Paranthropus as hard object feeders.”

The fact that humans show such contrasting chipping patterns is equally significant and will have “knock on” effects for further research, particularly research on dietary changes during human evolution, and why the human dentition has evolved the way it has, he says. 

“The regular tooth fractures in fossil humans may be caused by non-food items, such as grit or stone tools. However, regardless of the cause, these groups were subjected to substantial tooth wear and fractures. So, it raises questions to why our teeth reduced in size, especially compared to groups like Paranthropus.”

Dr Towle’s research will now focus on if our dentition evolved smaller due to other factors to allow other parts of the skull to expand, leading to evolution then favouring other tooth properties to protect it against wear and fracture, instead of increased tooth size. 

“This is something we are investigating now, to see if tooth enamel may have evolved different characteristics among the great apes. Our research as a whole may also have implications for our understanding of oral health, since fossil human samples typically show immaculate dental health.

“Since extreme tooth wear and fractures were the norm, our ancestors likely evolved dental characteristics to not just cope with but actually utilise this dental tissue loss. For example, without substantial tooth wear our dentitions can face all sorts of issues, including impacted wisdom teeth, tooth crowding and even increased susceptibility to cavities.”

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Paranthropus robustus tooth chipping patterns do not support regular hard food mastication, co-authored by Dr Towle and Dr Loch, was published in the Journal of Human Evolution.

Tooth chipping prevalence and pattern in extant primates, co-authored by Dr Towle and Dr Loch was published in the American Journal of Physical Anthropology.

Chipping and wear patterns in extant primate and fossil hominin molars: ‘Functional’ cusps are associated with extensive wear but low levels of fracture, co-authored by Dr Towle and Dr Loch was published in the Journal of Human Evolution.

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New research shows that Siberian Neanderthals ate both plants and animals

Original article phys.org

by  Asociacion RUVID

Domingo Carlos Salazar and associate. Credit: Asociacion RUVID

Neanderthals, extinct cousins of modern humans, occupied Western Eurasia before disappearing and although it was once thought that they traveled as far east as Uzbekistan, in recent years an international research team with the participation of the University of Valencia discovered that they reached two thousand kilometers further East, to the Altai Mountains of Siberia. An international research team led by Domingo Carlos Salazar, CIDEGENT researcher of excellence at the University of Valencia, published today in the Journal of Human Evolution the first attempt to document the diet of a Neanderthal through a unique combination of stable isotope analysis and identification of plant micro-remnants in an individual.

The analysis of Neanderthal bones and dental stones from Siberia sheds light on their dietary ecology, at the eastern limit of their expansion. It is a very dynamic region where Neanderthals also interacted with their enigmatic Asian cousins, the Denisovans. The work refers both to western Siberia, where there are studies that explain that modern humans responded with high mobility, and to the eastern part, where there is a lack of work that analyzes the behavior and subsistence of Neanderthals, who inhabited this Siberian forest steppe, which is drier and colder than the western one. Studying the diets of eastern Neanderthals allows us to understand their behaviors, mobility and potential adaptability.

A team of researchers from Spain, Germany, Canada, The Netherlands and Russia, led by physician and historian Domingo Carlos Salazar García from the University of Valencia, took bone samples and dental calculus from Neanderthal remains dated to 60 and 50 ka BP from the site of Chagyrskaya in the Altai Mountains in Southern Siberia, located just 100 km from the Denisova Cave. Analyzes of the stable carbon and nitrogen isotopes from one mandible (Chagyrskaya 6) revealed that this individual had a relatively high trophic level compared to the local food web, indicating that it consumed a large amount of animal protein from hunting large and medium-sized game. Using optical microscopy, the researchers identified a diverse assemblage of microscopic particles from plants preserved in the dental calculus from the same individuals as well as from others from the site. These plant microremains indicate that the inhabitants of Chagyrskaya also consumed a number of different plants.

These results can help us answer a long-standing enigma about the Altai Neanderthals: the region was tempting enough that Neanderthals colonized the area at least twice, but genetic data indicates they were barely hanging on, living only in small groups that were constantly at risk of extinction. The dietary data now indicates that this unusual habitation pattern was probably not due to a lack of adapting their diet to the local environment. Instead, other factors such as the climate or interaction with other hominins should be investigated in future studies.n

“Neanderthals were capable of having a diverse menu even in adverse climatic environments,” says Domingo C. Salazar García, “it was really surprising that these eastern Neanderthals had broadly similar subsistence patterns to those from Western Eurasia, showing the high adaptability of our cousins, and therefore suggesting that their dietary ecology was probably not a disadvantage when competing with anatomically modern humans.”

“These microremains provide some indication that even as Neanderthals expanded onto the vast and cold forest-steppe of Central Asia they retained patterns of plant use that could have been developed in Western Eurasia,” says Robert Power, researcher at the Max Planck Institute for Evolutionary Anthropology.

Dietary ecology

“A better grasp of Neanderthal dietary ecology is not only the key to better understand why they disappeared, but also to how they interacted with other populations who they coexisted with, like the Denisovans,” says Bence Viola, assistant professor at the Department of Anthropology at the University of Toronto.

“To really understand the diets of our ancestors and cousins, we need more studies like this one that make use of multiple different methods on the same individuals. We can finally understand both the plant and animal foods that they ate,” offers Amanda G. Henry, assistant professor at the Faculty of Archaeology of Leiden University.

“The steppe lowlands of the Altai Mountains were suitable for the habitation of the Neanderthals 60,000 years ago. Despite the sparse vegetation and its seasonal nature, the absence of tundra elements and relatively mild climate allowed eastern Neanderthals to keep the same food strategies as their western relatives,” says Natalia Rudaya, head of PaleoData Lab of the Institute of Archaeology and Ethnography Siberian Branch Russian Academy of Science.

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Ancient ‘Lucy’ Species Ate A Different Diet Than Previously Thought

this is a couple of days late…first published may3 2010
via Ancient ‘Lucy’ Species Ate A Different Diet Than Previously Thought

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Teeth reveal clues about people’s diet during the Irish Famine

An example of Killkenny dentitions (Queen’s University Belfast/PA)

Belfast Telegraph.com.uk

The mid-19th century famine wiped out around a million people after the potato crop failed in successive years.

Teeth analysed from the 1840s have shed new light on what people ate before and during the Irish Famine.

Scientific analysis of dental calculus – plaque build-up – of the Famine’s victims found evidence of corn, oats, potato, wheat and milk foodstuffs.

Researchers also discovered egg protein in the calculus of three people, which they said is more associated with diets of non-labouring or better off social classes at the time.

The mid-19th century famine wiped out around a million people after the potato crop failed in successive years.

It shows how the notoriously monotonous potato diet of the poor was opportunistically supplemented by other foodstuffs, such as eggs and wheat, when made available to them Dr Jonny Geber

Researchers analysed teeth from the human remains of 42 people, aged around 13 years and older, who died in the Kilkenny Union Workhouse and were buried in mass burial pits on its grounds.

The workhouse pits were discovered in 2005 and were found to contain the remains of nearly 1,000 people.

Potato and milk was virtually the only source of food for a vast proportion of the population in Ireland.

Many people were forced to seek refuge in the workhouses during the Famine, where they received meagre rations of food and shelter in return for work.

Researchers examined samples of calculus for microparticles and protein content linked to foodstuffs.

The microparticles showed a dominance of corn, as well as evidence of oats, potato and wheat.

The corn came from so-called Indian meal, which was imported in vast amounts to Ireland from the United States as relief food for the starving populace.

Analysis of the protein content identified milk, as well as the occasional presence of egg.

One of the lead researchers, Dr Jonny Geber of the University of Edinburgh’s School of History, Classics and Archaeology, said: “The results of this study is consistent with the historical accounts of the Irish labourer’s diet before and during the Famine.

“It also shows how the notoriously monotonous potato diet of the poor was opportunistically supplemented by other foodstuffs, such as eggs and wheat, when made available to them.

“The Great Irish Famine was one of the worst subsistence crises in history but it was foremost a social disaster induced by the lack of access to food and not the lack of food availability.”

The study is published in the Proceedings of the National Academy of Sciences of the United States of America.

The study is a collaboration between researchers from the Universities of Edinburgh, Harvard, Otago in New Zealand, York, Zurich, and the Max Planck Institute for the Science of Human History in Germany.

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Archaeologists discover that Roman dockers ate surprisingly well – until the barbarians arrived

British-led study finds that all inhabitants of the town of Portus had a similar diet rich in meat and North African wine

Inews.co.uk

By Cahal Milmo

Roman port of Portus

 

Ancient Rome may have not have had much to offer its subjects by way of equality but when it came to the diet of its dockers at least it seems they dined something like emperors.

A British-led archaeological study of remains found in Portus, the maritime port which served Rome, has found that its labouring inhabitants benefited from the flow of goods through the town by having a diet entirely similar to that of its wealthy ruling citizens – at least until the “barbarians” arrived.

Exotic goods

The study, based on an analysis of food and human remains at locations around the manmade port to the west of Rome, found that dockers or “saccarii” benefited from their work unloading the flow of exotic goods – including bears and crocodiles – to the heart of the ancient empire with a diet rich in animal protein, imported wheat, olive oil and wine from North Africa.

Comparison with remains found at locations where rich and middle class inhabitants lived during the second to the fifth centuries AD found the same sort of diet, suggesting that Portus was unusual in the Roman world in that rich and poor ate similarly well.

Dr Tamsin O’Connell, the archaeologist at Cambridge University who led the study, said: “It is interesting that although there are differences in social status between these burial populations, they both have access to similar food resources. This contradicts what we see elsewhere in the Roman world at this time. But, later on, something changes.”

Vandals

The researchers compared diet samples with those dated after 455AD, when Rome was attacked by the Vandals, the Germanic tribe who expanded south into modern Italy, and subsequent conflicts with invaders which signalled the fall of the Roman empire.

The results suggested that the aftereffects of the disruption by the Vandals coincided with a marked drop in the standard of the dockers’ diets with meat replaced by bean stew.

Dr O’Connell said: “We see a shift to something more akin to a ‘peasant diet’, made up of mainly plant proteins in something like potages and stews. They’re doing the same kind of manual labour and hard work , but were sustained by beans and lentils.”

Silt

The researchers suggest this thinner gruel may have arisen from political shifts in Rome following the arrival of the Vandals and the subsequent breakdown of the empire. They also appear to coincide with physical changes in Portus itself, including the silting up of part of the harbour as trade begins to diminish.

Dr O’Connell said: “In the case of Portus, we see that when Rome was rich, everybody – from the local elite to the dockworkers – was doing fine nutritionally. Then this political rupture happens and wheat and other foodstuffs have to come from elsewhere. When Rome is on the decline, the manual labourers at least are not doing as well as previously.”

 

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New research reveals what was on the menu for medieval peasants

University of Bristol

Phys.org

Scientists from the University of Bristol have uncovered, for the first time, definitive evidence that determines what types of food medieval peasants ate and how they managed their animals.

Using chemical analysis of pottery fragments and animal bones found at one of England’s earliest medieval villages, combined with detailed examination of a range of historical documents and accounts, the research has revealed the daily diet of peasants in the Middle Ages. The researchers were also able to look at butchery techniques, methods of food preparation and rubbish disposal at the settlement Dr. Julie Dunne and Professor Richard Evershed from the University of Bristol’s Organic Geochemistry Unit, based within the School of Chemistry, led the research, published today in the Journal of Archaeological Science.

Julie said: “All too often in history the detail, for example food and clothing, of the everyday life of ordinary people is unknown.

“Traditionally, we focus on the important historical figures as these are the people discussed in ancient documents.

“Much is known of the medieval dietary practices of the nobility and ecclesiastical institutions, but less about what foods the medieval peasantry consumed.”

The scarce historical documents that exist that tell us that medieval peasant ate meat, fish, dairy products, fruit and vegetables but there is little direct evidence for this.

The OGU team used the technique of organic residue analysis to chemically extract food residues from the remains of cooking pots used by peasants in the small medieval village of West Cotton in Northamptonshire.

Organic residue analysis is a scientific technique commonly used in archaeology. It is mainly used on ancient pottery, which is the most common artefact found on archaeological sites worldwide.

Researchers used chemical and isotopic techniques to identify lipids, the fats, oils and natural waxes of the natural world, from the ceramics.

These can survive over thousands of years and the compounds found are one of the best ways scientists and archaeologists can determine what our ancestors ate.

The findings demonstrated that stews (or pottages) of meat (beef and mutton) and vegetables such as cabbage and leek, were the mainstay of the medieval peasant diet.

The research also showed that dairy products, likely the ‘green cheeses’ known to be eaten by the peasantry, also played an important role in their diet.

Dr. Dunne added: “Food and diet are central to understanding daily life in the medieval period, particularly for the medieval peasant.

“This study has provided valuable information on diet and animal husbandry by medieval peasants and helped illustrate agricultural production, consumption and economic life in one of England’s early medieval villages.”

Professor Evershed said “West Cotton was one of the first archaeological sites we worked on when we began developing the organic residue approach – it is extraordinary how, by applying the suite of the latest methods, we can provide information missing from historical documents.”

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How to Eat Like a Viking

Participants at the Slav and Viking Festival in Wolin, Poland tend to be sticklers for authenticity. Many adorn their bodies with tattoos, and some adopt a Viking diet, slaughtering and roasting game.
PHOTOGRAPH BY DAVID GUTTENFELDER, NATIONAL GEOGRAPHIC

Nationalgeographic.com

Historical interpreters bring a reconstructed longhouse to life at the Ribe Viking Center in Denmark. Meals were cooked over an open fire on a hearth, and Viking fare included salted herring, barley porridge, and boiled sheep heads.
PHOTOGRAPH BY DAVID GUTTENFELDER, NATIONAL GEOGRAPHIC

By Catherine Zuckerman

All that marauding must have left the Vikings famished. It’s easy to envision a group of them around a table, ravenous after a long day of ransacking, devouring giant hunks of meat and hoisting horns-full of ale.
But that wouldn’t quite be fair, or accurate.
As tempting as it is to assume that Viking meals were crude and carnivorous, the truth is that everyday Viking fare included a range of foods that a health-minded modern person would applaud.
Picture, for example, that burly, bearded warrior throwing down his sword to enjoy a tart treat similar to yogurt, or refuel with a tangle of fresh greens.
“The Vikings had a wide range of food and wild herbs available to make tasty and nutritious dishes,” says Diana Bertelsen, who helped research and develop recipes for Denmark’s Ribe Viking Center—a reconstructed Viking settlement where visitors can immerse themselves in just about every aspect of Viking culture, including what and how they ate.
“There are no original recipes from the Viking age available,” says Bertelsen, but “we know for certain what crops and animals were available a thousand years ago. Excavations reveal what the Vikings ate and what they imported, for instance peaches and cinnamon.”

Of course a specific Viking’s diet was heavily influenced by his or her location, says medieval scholar Eleanor Rosamund Barraclough. In cold, dry, coastal Scandinavia, for example, fish such as herring and salmon provided a key source of protein and were typically dried and preserved in salt.
This “stockfish,” as it’s called, “is a bit like beef jerky, only fishy,” says Barraclough. “It would have been a valuable food source on long sea journeys.”
Wealth also played a part in determining one’s diet, says Barraclough. “In Greenland, Vikings ate more seals, particularly on the poorer farms, while on the richer farms they ate more caribou.”
Seasons, too, dictated a Viking’s daily provisions. Depending on the time of year, meals might include a wide variety of berries, turnips, cabbage and other greens—including seaweed—barley-based porridge, and flat bread made from rye. Dishes were typically simple, but “we have no reason to believe that the food was bland and tasteless,” says Bertelsen.
Indeed, archaeological evidence suggests that Viking cooks were fond of flavor-enhancing ingredients like onions, garlic, coriander, and dill.
Vikings also prepared special food to celebrate seasonal events. “Boars were said to be sacrificed during the winter Yule celebration, and solemn oaths taken on their bristles,” says Barraclough.
Dairy would have made a frequent appearance in many a Viking diet. The seafaring warriors were farmers, after all, and skilled at animal husbandry. Cows and sheep did provide meat, but they also gave the Vikings a reliable supply of buttermilk, cheese, butter, and other products.
In Iceland, especially, Vikings enjoyed their dairy, and often ate it in the form of skyr, a fermented, yogurt-like cheese that today is sometimes marketed as a dairy “superfood.” Viking lore mentions the creamy substance, says Barraclough, who recalls a “saga where a man hides from his enemies in a vat of skyr—which comes very specifically up to his nipples.”
Like much about the Vikings, their eating habits remain a source of fascination—and inspiration—for many people. In fact, given the Vikings’ physical strength and surprisingly healthy diet, it makes sense to wonder: Could the “Viking Diet” be the next “Paleo?”

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The benefits of food processing

 

Stone Tools

 

Original Article:

eurekaert.org

Harved University

Processing food before eating likely played key role in human evolution, study finds

 

How much time and effort do you spend chewing?

Although you probably enjoy a few leisurely meals every day, chances are that you spend very little time and muscular effort chewing your food. That kind of easy eating is very unusual. For perspective, our closest relatives, chimpanzees, spend almost half their day chewing, and with much greater force.

When and how did eating become so easy? And what were its consequences?

According to a new Harvard study, our ancestors between 2 and 3 million years ago started to spend far less time and effort chewing by adding meat to their diet and by using stone tools to process their food. The researchers estimate that such a diet would have saved early humans as many as 2.5 million chews per year, and made possible further changes that helped make us human. The study is described in a March 9 paper published in Nature.

One of the biggest puzzles in human evolution is how species such as Homo erectus evolved smaller teeth, smaller faces, and smaller guts, and yet managed to get more energy from food to pay for their bigger brains and bodies before cooking was invented. “What we showed is that…by processing food, especially meat, before eating it, humans not only decrease the effort needed to chew it, but also chew it much more effectively” said Katie Zink, the first author of the study, and a lecturer working in the lab of Daniel Lieberman, the Edwin M. Lerner II Professor of Biological Sciences.

By changing their diets to include just 33 percent meat, and processing their food – slicing meat and pounding vegetables – before eating, Zink and Lieberman found that the muscular effort required per chew and the number of chews required per day was reduced by almost 20 percent. They also found that by simply slicing meat with the sorts of simple tools available more than 2 million years ago, humans were able to swallow smaller, more easily digestible pieces than would have been possible without using tools.

“Eating meat and using stone tools to process food apparently made possible key reductions in the jaws, teeth and chewing muscles that occurred during human evolution,” Zink said.

But testing a process as basic as chewing isn’t as easy – or as attractive – as it might sound.

“What Katie did was creative but sometimes, frankly, a little stomach-churning,” Lieberman said. “Not only did she have people come into the lab, chew raw meat and other foods, and spit them out, but then she had to analyze the stuff.”

It wasn’t just any food – or any meat – that subjects noshed on.

To approximate the toughness and texture of the game that early humans ate, Zink and Lieberman (after much experimentation) settled on using goat – which subjects chewed raw while Zink used instruments attached to their jaw to measure the effort involved.

In each trial, volunteers were given, in random order, a selection of foods prepared in several ways – raw, sliced, pounded and cooked goat, as well as several vegetables, including carrots, beets and yams. After chewing each morsel until they would normally swallow, subjects spit out the food. Zink then spread the individual food particles out onto a tray, photographed them, and digitally measured their sizes.

“What we found was that humans cannot eat raw meat effectively with their low-crested teeth. When you give people raw goat, they chew and chew and chew, and most of the goat is still one big clump – it’s like chewing gum,” Lieberman said. “But once you start processing it mechanically, even just slicing it, the effects on chewing performance are dramatic.”

But why study chewing at all?

“Chewing is one of the key characteristics of being a mammal,” Lieberman explained. “Most other animals, like reptiles, barely chew their food — they just swallow it whole. The evolution of the ability to chew food into smaller particles gave mammals a big boost of extra energy because smaller particles have a higher surface area to volume ratio, allowing digestive enzymes to then break food down more efficiently.”

Most mammals, however, eat a relatively low-quality diet- think of cows eating grass and hay – that they need to spend most of the day chewing. Even humans’ closest ape relatives, with a diet that consists mainly of fruit, must spend nearly half their day chewing to extract enough energy from their food, Lieberman said.

“But we humans have done something really remarkable,” he said. “We eat even higher-quality foods than chimpanzees, and spend an order of magnitude less time chewing them.”

Making that change, however, presented early humans with a new challenge.

One of the critical components of that higher-quality diet is meat, which – despite being calorically dense – is very difficult for humans to chew effectively.

“Meat has a lot of nutrients, but it is also very elastic. You can think of it as being like a rubber band,” Zink said. “So the problem is that we can’t break it down with our flat, low-cusped teeth. But if you slice it up, then you do not need to use your teeth to break it down as much, and you swallow much smaller particles. Cooking makes chewing even easier.”

That pre-processing, and the reductions in chewing effort that came with it, Zink and Lieberman said, may have opened the door to one of the most important lifestyle changes in human evolution – the emergence of hunting and gathering.

“With the origin of the genus Homo…we went from having snouts and big teeth and large chewing muscles to having smaller teeth, smaller chewing muscles, and snoutless faces” Lieberman said. “Those changes, and others, allowed for selection for speech and other shifts in the head, like bigger brains. Underlying that, to some extent, is the simplest technology of all: slicing meat into smaller pieces, and pounding vegetables before you chew them.”

The impact that higher-quality diets and easier chewing could have on early humans is clear if you imagine what day-to-day life might have been like millions of years ago.

“Suppose you go out hunting for antelopes like impala or kudu, but at the end of the day you come back empty-handed, which happened fairly often for early humans,” Lieberman said. “Chimps couldn’t survive that way – they would then have to spend all night eating.

“Following the invention of hunting and gathering, though, humans can benefit from a division of labor,” he continued. “Someone else may have come back with an impala, or some tubers you could eat. And instead of spending all night eating it, you’d spend a lot less time, energy and effort to chew it by pounding it or cutting it with just a few stone stone tools. What a dramatic shift!”

Though many aspects of our biology changed when the genus Homo evolved, Zink and Lieberman said that processing food before eating almost surely played a significant role.

“One of the innovations that helped make us human is cutting up and pounding our food,” Lieberman said. “Extra-oral processing first by using stone tools and then by cooking played a very important role in human evolution because it released selection for big faces and big teeth, which then enabled selection for shorter faces which were important for speech, and enabled us to grow big brains and have large bodies. We are partly who we are because we chew less.”

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Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

 

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How modern humans ate their way to world dominance



The Batwa hunter-gatherers collect and roast wild yams in the Bwindi Impenetrable Forest in Uganda.

The difference between humans and their closest relatives is partly a matter of taste. Yams, pumpkins, and squash are as bland as potatoes to our tongues today, but to a chimp and our ancestors, wild varieties were bitter and yucky. Now scientists have pinpointed some of the genetic changes that allowed our ancestors to diversify their palates, potentially allowing them to take better advantage of a wide range of foods—and conquer the world.

As humans adapted to new habitats, they had to become open to new culinary experiences. They ate more starchy tuberous roots, learned to cook their meat and bitter root vegetables, and eventually domesticated plants and animals. Those dietary revolutions helped make us human, giving our bodies the extra calories that enlarged our brains, while allowing our guts, jaws, and teeth to shrink as we ate softer, more easily digestible food.

To figure out how these changes evolved, anthropological geneticist George Perry of Pennsylvania State University, University Park, and his colleagues compared the genomes of modern humans and chimpanzees to the newly published genomes of a Neandertal and one of its close relatives, a mysterious human ancestor known as a Denisovan, known only from a few bones found in a Russian cave. All three groups of humans had lost two bitter taste genes, TAS2R62 and TAS2R64, that are still present in chimpanzees, the team reports this month in the Journal of Human Evolution.

Two million years ago, our early ancestors such as Australopithecus or early members of Homo likely found wild yams and other tubers bitter. But as humans began to cook, they could roast tuberous root vegetables long enough that they weren’t as bitter. (Today, hunter-gatherers still rely on roasted tubers as a major source of calories.) At the same time, hominins—members of the human family—lost those two particular bitter taste genes, so they were presumably able to eat a wider range of tuberous plants. Modern humans, Neandertals, and Denisovans all lost the ability to detect the bitter flavor in some wild plants and eventually modern humans bred varieties of squashes, gourds, and yams that are less bitter than the wild types.

The team also found some intriguing differences between modern humans, who arose in Africa in the past 200,000 years or so, and our archaic human relatives, such as Neandertals and Denisovans. Our lineage, for example, carries an average of six copies, and as many as 20 copies, of the salivary amylase gene, AMY1. The gene produces the enzyme amylase in our saliva, which has been thought to help digest sugars in starchy foods, although its role in human digestion is still unproven. By contrast, chimps, Neandertals, and Denisovans carry only one to two copies of the salivary amylase gene, which suggests they got fewer calories from starchy veggies than modern humans. This confirms an earlier finding that Neandertals didn’t have extra copies of the amylase gene and is “definitely a surprise,” says biological anthropologist Richard Wrangham of Harvard University, who was not a co-author on this paper.

Wrangham has proposed that a key human ancestor, H. erectus, relied on cooking starchy tuberous roots to get enough calories to expand its brain. But if so, that distant ancestor wasn’t using extra copies of the amylase gene to extract more calories from these plant foods. He and Harvard postdoctoral researcher Rachel Carmody suggest the amylase copies may have had other functions, such as helping prevent cavities.

And although researchers have proposed earlier that this adaptation took place with the invention of agriculture, Perry and his colleagues have found that hunter-gatherers also carry the extra copies of the salivary amylase gene. This suggests that this adaptation took place in modern humans, after the split with the ancestor they shared with Neandertals about 600,000 years ago but before plants were domesticated 10,000 years ago. “This doesn’t mean that earlier hominins weren’t eating more starch, but perhaps they weren’t getting all of the same benefits as modern humans,” Perry says.

One sign that cooking shaped our ancestors’ genomes as well as our guts is that humans, Neandertals, and Denisovans all have lost a masticatory myosin gene, MYH16, that helps build strong chewing muscles in the jaws of chimps. This may be one result of learning to cook, which softens food, Perry says. This fits with evidence that some early hominins were chefs—Neandertals in the Middle East cooked barley porridge, for example.

Now, Perry and his colleagues are trying to figure out when this gene was lost in the human lineage. The loss of the gene for muscular jaws in Neandertals, Denisovans, and moderns suggests that cooking arose in their common ancestor, H. erectus, he says.

Original article:

By Ann Gibbons 

News.sciencemag.org

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