Arquivo da tag: Dieta

Painel S.A.: Influenciadora que fez vídeo do Bradesco para reduzir carne diz ter ficado frustrada com banco (Folha de S.Paulo)

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Grupo de três irmãs Verdes Marias afirma que conteúdo foi aprovado pela empresa

14.jan.2022 às 8h04 3-4 minutes

As influenciadoras que produziram o vídeo do Bradesco sugerindo redução no consumo de carne dizem que ficaram frustradas com a decisão do banco de remover o conteúdo da internet.

O material, divulgado nas redes sociais no mês passado para promover um aplicativo do banco que calcula pegadas de carbono, foi tirado do ar após irritar o agronegócio e levou o presidente do Bradesco a se retratar.

“Ficamos frustradas”, diz Mariana Prado Moraes, influenciadora que participou do vídeo. Para ela, os churrascos em frente às agências como forma de protesto ajudaram a manter o tema na pauta.

“Foi uma reação de ódio para o convite feito pela segunda-feira sem carne, mostrando como o tema incomoda alguns grupos, mas as mudanças climáticas precisam ser discutidas, independentemente do incômodo gerado”, diz Moraes, que representa o grupo de três irmãs Verdes Marias.

O trio, que tem cerca de 28 mil seguidores no Instagram, publica conteúdos nas redes socias para incentivar a vida sustentável por meio de pequenas mudanças no dia a dia, como reciclagem, consumo de alimentos orgânicos e uso de absorventes e fraldas de pano.

Moraes diz que a sugestão de citar a segunda-feira sem carne no vídeo partiu delas, mas o roteiro e a versão final foram validados e aprovados previamente pelo Bradesco.

“O tema da mudança de hábito em relação à alimentação precisa ser colocado na pauta, e isso aconteceu com o vídeo. O IPCC [Painel Intergovernamental sobre Mudanças Climáticas] deixou claro em seu último relatório que o clima da Terra está mudando e que o ser humano tem interferência nisso. Entre as ações trazidas, o impacto da pecuária é um deles”, diz.

Ela afirma que o Verdes Marias permanece em diálogo com o Bradesco. Mas, ainda em dezembro, o banco escreveu uma carta aberta ao agronegócio, em que tentou se desvincular do conteúdo. No documento, afirmou que tomaria ações administrativas internas por causa do ocorrido.

O Bradesco não comenta.

com Andressa Motter e Ana Paula Branco

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Bradesco se desculpa com agro por vídeo que defende reduzir consumo de carne

Influenciadoras associam produção pecuária a aplicativo que calcula pegada de carbono

Douglas Gavras – 29 de dezembro de2021

Um vídeo sobre consumo sustentável que circulou nas redes sociais na última semana levou o Bradesco a escrever uma carta aberta, se retratando com o agronegócio. No material, um aplicativo oferecido pelo banco —que permite que o cliente calcule sua pegada de carbono— é associado à redução do consumo de carne.

Ele começa com três influenciadoras dando dicas de como o consumidor pode tomar atitudes mais sustentáveis. “Duas atitudes simples que você pode tomar no seu dia a dia para reduzir o seu impacto”, diz uma delas.

Elas, então, dizem que a primeira atitude que o consumidor poderia tomar é reduzir o consumo de carne, optando por pratos vegetarianos uma vez por semana —movimento que ficou conhecido como “Segunda sem Carne”.

“A criação de gado contribui para a emissão dos gases de efeito estufa, então, que tal se a gente reduzir o nosso consumo de carne e escolher um prato vegetariano na segunda-feira?”

O vídeo segue sugerindo que o consumidor também pode começar a usar composteira para o lixo doméstico e que o usuário calcule a quantidade emitida de carbono e use a informação para pensar em outras maneiras de compensar suas emissões.

O vídeo despertou críticas de entidades e políticos ligados ao agronegócio ao longo da última semana. Em nota, o Imac (Instituto Mato-Grossense da Carne) criticou o material, dizendo que a pecuária brasileira, no contexto mundial, é a menos impactante na produção de carbono.

“No Brasil, a nossa pecuária é realizada de forma natural, utilizando-se da pastagem como o principal insumo alimentar (…) e os modelos de produção utilizam pastagens produtivas para a criação de bovinos contribuem positivamente para o balanço de carbono, sequestrando as emissões desse gás que a produção pecuária emite.”

Segundo a entidade, não é aceitável associar a responsabilidade integral pela emissão de gases de efeito estufa com a pecuária e a sugestão de se reduzir o consumo de carne bovina no Brasil não faz sentido.

Já a ABPA (Associação Brasileira de Proteína Animal) avalia que a carta pública divulgada pelo Bradesco foi importante, ao reconhecer a importância do agronegócio para o país. “Entretanto, o setor espera manifestações mais explícitas deste apoio, com alcance, no mínimo, equivalente à divulgação que gerou esta situação revoltante a que produz alimentos.”

A associação ressalta a importância que o setor tem em gerar segurança alimentar, empregos e segurança econômica para centenas de milhares de famílias.

Por meio de seu perfil no Twitter, o deputado federal José Medeiros (Pode-MT) também criticou a peça. “É isso mesmo @Bradesco? Vocês não pensaram em consultar Embrapa ou alguma instituição séria para saber se o pasto captura carbono na atmosfera e compensa os gases da pecuária?”, questionou.

No último dia 24, o Bradesco publicou uma carta aberta ao agronegócio, em que procurou se desvincular do conteúdo. O banco determinou a remoção do material de suas redes, disse que apoia o setor de “forma plena” e afirmou que tomaria ações administrativas internas severas por conta do ocorrido.

“Nos últimos dias lamentavelmente vimos uma posição descabida de influenciadores digitais em relação ao consumo de carne bovina, associadas à nossa marca. Importante dizer que tal posição não representa a visão desta casa em relação ao consumo da carne bovina“, diz a carta do banco.

Ainda de acordo com o banco, a instituição acredita e promove “direta e indiretamente a pecuária brasileira e por conseguinte o consumo de carne bovina”. Ainda segundo o Bradesco, o material foi retirado do ar no último dia 23. Procurada pela reportagem, a assessoria de imprensa do Bradesco informou que seu posicionamento está detalhado na carta aberta ao agronegócio brasileiro. Veja abaixo. ​

A seguir, a íntegra da carta aberta divulgada pelo banco:

CARTA ABERTA AO AGRONEGÓCIO BRASILEIRO

Ao longo de seus quase 79 anos de história o Bradesco apoiou de forma plena o segmento do agronegócio brasileiro, estabelecendo parcerias sólidas e produtivas. Tal opção é baseada em sua crença indelével nesse segmento enquanto vetor de desenvolvimento social e econômico do país.

Contudo, nos últimos dias lamentavelmente vimos uma posição descabida de influenciadores digitais em relação ao consumo de carne bovina, associadas à nossa marca.

Importante dizer que tal posição não representa a visão desta casa em relação ao consumo da carne bovina.

Pelo contrário.

O Bradesco acredita e promove direta e indiretamente a pecuária brasileira e por conseguinte o consumo de carne bovina.

Diante do ocorrido, medidas foram imediatamente tomadas incluindo a remoção do conteúdo de ambiente público, e, além disso, ações administrativas internas severas.

Dessa forma, reiteramos nossa lamenta pelo ocorrido e reforçamos mais uma vez nossa crença irrestrita na pecuária brasileira.

Rich nations could see ‘double climate dividend’ by switching to plant-based foods (Carbon Brief)

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carbonbrief.org

Ayesha Tandon

10.01.2022 | 4:00pm

Adopting a more plant-based diet could give rich countries a “double climate dividend” of lower emissions and more land for capturing carbon, a new study says.

Animal-based foods have higher carbon and land footprints than their plant-based alternatives, and are most commonly consumed in high-income countries. The study, published in Nature Food, investigates how the global food system would change if 54 high-income countries were to shift to a more plant-based diet.

High-income countries could cut their agricultural emissions by almost two-thirds through dietary change, the authors find. They add that moving away from animal-based foods could free up an area of land larger than the entire European Union.

If this land were all allowed to revert to its natural state, it would capture almost 100bn tonnes of carbon – equal to 14 years of global agricultural emissions – the authors note. They add that this level of carbon capture “could potentially fulfil high-income countries’ CO2 removal obligations needed to limit warming to 1.5C under equality sharing principles”.

The US, France, Australia and Germany would collectively see roughly half of the total carbon benefits, the study notes, because meat and dairy production and consumption are high in these countries.

‘Double climate dividend’

Feeding the world’s population of almost eight billion people is no small task. The global food system is responsible for around one-third of all human-caused greenhouse gas emissions, and half of the planet’s habitable land is used to produce food.

However, not all calories have an equal impact on the planet. On average, animal-based foods produce 10-50 times more emissions than plant-based foods. Meanwhile, livestock takes up nearly 80% of global agricultural land, despite producing less than 20% of the world’s supply of calories.

Individuals in high-income nations currently have the greatest potential to reduce greenhouse gas emissions through their dietary choices, because their diets are usually the most meat-orientated. Animal-derived products drive 70% of food-system emissions in high-income countries but only 22% in low–middle-income countries.

(In 2019, Carbon Brief produced a week-long series of articles on food systems, including a discussion of the climate impacts of meat and dairy, and expert views on how changing diets are expected to affect the climate.)

The study explores how the carbon footprint of food production could change if 54 high-income countries were to adopt the EAT-Lancet planetary health diet. This is a mainly plant-based diet that is “flexible by providing guidelines to ranges of different food groups that together constitute an optimal diet for human health and environmental sustainability”. 

Dr Paul Behrens from Leiden University, an author on the paper, tells Carbon Brief that the diet varies between countries to account for their “local production and food cultures”.

The study investigates the immediate reduction in emissions from adopting the EAT-Lancet diet using a dataset from the 2010 Food and Agriculture Organization’s statistical Database, linked at the national level to the Food and Agriculture Biomass Input–Output dataset (FABIO).

The authors also determine how much land could be spared by a shift in diet. They use global crop and pasture maps – combined with soil carbon and vegetation maps – to quantify how much extra carbon could be drawn down by soil and vegetation if this surplus land were allowed to revert to its natural state of mixed native grassland and forest. 

As well as investigating changes in the 54 high-income countries, the study follows the trade of food between nations to see how dietary shifts in one country can affect the food-related land and carbon footprints around the world.

The analysis is performed for the 54 high-income countries available in FABIO. For example, Chile is considered a high-income country, while India is not.

The map below shows the drop in greenhouse gas emissions from global agriculture if the 54 high-income countries were to shift to the EAT-Lancet planetary health diet. Dark red shading indicates the largest reductions. Changes in lower-income countries are due to knock-on impacts for food trade.

According to the study, high-income nations could reduce their agricultural emissions by 62% by shifting to a more plant-based diet. Dr Sonja Vermeulen is the lead global food scientist at WWF, and is not involved in the study. She helped to put this figure into perspective:

“To put this in perspective, it’s about the same positive impact as all countries signing up to and implementing the COP26 declaration on the transition to 100% zero emission cars and vans globally by 2040.” 

Freeing up land

The study finds that moving away from animal-based foods could free an area of land larger than the entire European Union. If this area were allowed to revert to its natural state, it would capture around 100bn tonnes of carbon – equal to 14 years of global agricultural emissions from 2010 – by the end of the century, the authors find.  

The map below shows the potential carbon sequestration from surplus land if the 54 high-income countries were to shift to the EAT-Lancet planetary health diet, with dark green shading indicating the largest potential. Changes in lower-income countries are due to knock-on impacts for food trade. 

Approximately half of the carbon benefit from cutting emissions and increasing carbon sequestration could be seen collectively in the US, France, Australia and Germany, the study says.

The authors also highlight that, according to past research, limiting warming to 1.5C above pre-industrial levels requires the 54 high-income countries in this analysis to achieve cumulative CO2 removals of 85-531bn tonnes of CO2 by the end of the century. This range comes from uncertainty in the amount of CO2 removal required, and in the amount that should be allocated to each country.

Based on these numbers, the study concludes that the 100bn carbon sequestration “could potentially fulfil high-income countries’ CO2 removal obligations needed to limit warming to 1.5C under equality sharing principles”.

The study finds that many low and mid-income countries – such as Brazil, India and Botswana – would export less food to high-income nations if they consumed less meat. This would reduce their own agricultural emissions and free up land for drawing down carbon, despite no dietary changes in their own countries, the researchers say. (The study does not assess the economic impact of this reduced trade.)

Around two-thirds of the carbon sequestration potential from dietary changes in high-income countries is domestic, the study finds. Meanwhile, almost a quarter is located in other high-income countries and around an eighth is from low and middle income countries.

Dr Nynke Schulp is an associate professor of land use, lifestyle and ecosystem change at the Vrije Universiteit Amsterdam, and was not involved in the study. She tells Carbon Brief that existing studies “tend to work from the assumption that the whole world adopts a specific dietary change”, and so “this study’s focus on dietary change in high-income nations is an important nuance, both from a mitigation potential perspective and from a climate justice perspective”.

Capturing carbon

The study assumes that any land freed up by a change in diet would be allowed to revert to its natural state through a “natural climate solution” called passive restoration, in which land is allowed to revert to its past state. Behrens explains in a press release that this technique has a range of co-benefits, including “water quality, biodiversity, air pollution and access to nature, to name just a few”.

The study breaks down the carbon sequestration potential of passive restoration into three categories: aboveground biomass carbon (AGBC), belowground biomass carbon (BGBC) and soil organic carbon (SOC) stocks. These refer to carbon held in plant matter above the soil, plant matter below the soil, and the soil itself, respectively.

The plot below shows the total carbon sequestration (left) and emissions reductions (right) potentials from a range of different food types. The red lines on the left and right mark fixed values to make comparisons between the charts easier. Note that carbon sequestration is shown as a total over the 21st century, while the reduction in emissions is shown per year.

The plot shows that animal-based products – most notably beef – have high carbon and land footprints. The authors highlight that the US and Australia in particular would see benefits from reducing their beef intake, due to their high domestic production and consumption. 

Vermeulen tells Carbon Brief that changing diets in these countries could “transform” them:

“The term ‘food system transformation’ is perhaps often used too lightly – but there can be no doubt that the changes in these places would constitute total transformation of local economies, landscapes and cultures. Imagine the vast cattle ranches of the US and Australia replaced with equally vast rewilded or repurposed lands – would these be used for biomass and bioenergy, or conservation and biodiversity, and how would rural communities create new livelihoods for themselves?”

Dietary choices

High-income countries could see the largest per-capita carbon reductions by shifting to a planet-friendly diet, the study concludes. However, asking individuals to take charge of their personal carbon footprints can be a controversial area of discussion.

For example, the authors note that alcoholic beverages and “stimulants” including coffee, cocoa products and tea comprise 5.8% of dietary greenhouse gas emissions. These “luxury, low-nutrition crops” are predominantly consumed in high-income countries and present a “non-negligible” opportunity for cutting emissions and capturing carbon, according to the study. However, “sociological and policy complications” would make it difficult to reduce consumption of these products in practice, the authors say.

They also highlight that eating more offal – a co-product of meat production – could be a good way for individuals to reduce their meat-related carbon footprints. However, the authors say that offal is “not typically consumed in high-income nations due to convention and consumer preference”.

Dr Matthew Hayek is an assistant professor in the Department of Environmental Studies at NYU arts and science, who was not involved in the study. He tells Carbon Brief how governments could incentivise individuals to eat more sustainably: 

“Folks in developed countries eat far more meat and dairy than the global average… Reducing emissions from food consumption in rich countries is critical. For consumers who have ample food choices, these choices play a sizable role in contributing to our climate goals. Our policies must reflect this by making healthy and sustainable food choices more prevalent, convenient, and inexpensive.”

And Behrens tells Carbon Brief that “the onus is on high-income nations to transform food systems”. In the press release, he adds:

“It will be vital that we redirect agricultural subsidies to farmers for biodiversity protection and carbon sequestration. We must look after farming communities to enable this in a just food transition. We don’t have to be purist about this, even just cutting animal intake would be helpful. Imagine if half of the public in richer regions cut half the animal products in their diets, you’re still talking about a massive opportunity in environmental outcomes and public health.”

Sun, Z. et al. (2022) Dietary change in high-income nations alone can lead to substantial double climate dividend, Nature Food, doi: 10.1038/s43016-021-00431-5

Neanderthals carb loaded, helping grow their big brains (Science)

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sciencemag.org

By Ann GibbonsMay. 10, 2021 , 3:00 PM 5-7 minutos

A reconstruction of Neanderthal mealtime Mauricio Anton/Science Source

Here’s another blow to the popular image of Neanderthals as brutish meat eaters: A new study of bacteria collected from Neanderthal teeth shows that our close cousins ate so many roots, nuts, or other starchy foods that they dramatically altered the type of bacteria in their mouths. The finding suggests our ancestors had adapted to eating lots of starch by at least 600,000 years ago—about the same time as they needed more sugars to fuel a big expansion of their brains.

The study is “groundbreaking,” says Harvard University evolutionary biologist Rachel Carmody, who was not part of the research. The work suggests the ancestors of both humans and Neanderthals were cooking lots of starchy foods at least 600,000 years ago. And they had already adapted to eating more starchy plants long before the invention of agriculture 10,000 years ago, she says.

The brains of our ancestors doubled in size between 2 million and 700,000 years ago. Researchers have long credited better stone tools and cooperative hunting: As early humans got better at killing animals and processing meat, they ate a higher quality diet, which gave them more energy more rapidly to fuel the growth of their hungrier brains.

Still, researchers have puzzled over how meat did the job. “For human ancestors to efficiently grow a bigger brain, they needed energy dense foods containing glucose”—a type of sugar—says molecular archaeologist Christina Warinner of Harvard and the Max Planck Institute for the Science of Human History. “Meat is not a good source of glucose.”

Researchers analyzed the bacterial DNA preserved in dental plaque of fossilized teeth, such as this one from a prehistoric human. Werner Siemens Foundation/Felix Wey

The starchy plants gathered by many living hunter-gatherers are an excellent source of glucose, however. To figure out whether oral bacteria track changes in diet or the environment, Warinner, Max Planck graduate student James Fellows Yates, and a large international team looked at the oral bacteria stuck to the teeth of Neanderthals, preagriculture modern humans that lived more than 10,000 years ago, chimps, gorillas, and howler monkeys. The researchers analyzed billions of DNA fragments from long-dead bacteria still preserved on the teeth of 124 individuals. One was a Neanderthal who lived 100,000 years ago at Pešturina Cave in Serbia, which produced the oldest oral microbiome genome reconstructed to date.

The communities of bacteria in the mouths of preagricultural humans and Neanderthals strongly resembled each other, the team reports today in the Proceedings of the National Academy of Sciences. In particular, humans and Neanderthals harbored an unusual group of Streptococcus bacteria in their mouths. These microbes had a special ability to bind to an abundant enzyme in human saliva called amylase, which frees sugars from starchy foods. The presence of the strep bacteria that consume sugar on the teeth of Neanderthals and ancient modern humans, but not chimps, shows they were eating more starchy foods, the researchers conclude.

Finding the streptococci on the teeth of both ancient humans and Neanderthals also suggests they inherited these microbes from their common ancestor, who lived more than 600,000 years ago. Although earlier studies found evidence that Neanderthals ate grasses and tubers and cooked barley, the new study indicates they ate so much starch that it dramatically altered the composition of their oral microbiomes.

“This pushes the importance of starch in the diet further back in time,” to when human brains were still expanding, Warinner says. Because the amylase enzyme is much more efficient at digesting cooked rather than raw starch, the finding also suggests cooking, too, was common by 600,000 years ago, Carmody says. Researchers have debated whether cooking became common when the big brain began to expand almost 2 million years ago or it spread later, during a second surge of growth.

The study offers a new way to detect major shifts in diet, says geneticist Ran Blekhman of the University of Minnesota, Twin Cities. In the case of Neanderthals, it reveals how much they depended on plants.

“We sometimes have given short shrift to the plant components of the diet,” says anthropological geneticist Anne Stone of Arizona State University, Tempe. “As we know from modern hunter-gatherers, it’s often the gathering that ends up providing a substantial portion of the calories.”

Humans were apex predators for two million years (Eureka Alert!)

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News Release 5-Apr-2021

What did our ancestors eat during the stone age? Mostly meat

Tel-Aviv University

IMAGE
IMAGE: Human Brain. Credit: Dr. Miki Ben Dor

Researchers at Tel Aviv University were able to reconstruct the nutrition of stone age humans. In a paper published in the Yearbook of the American Physical Anthropology Association, Dr. Miki Ben-Dor and Prof. Ran Barkai of the Jacob M. Alkov Department of Archaeology at Tel Aviv University, together with Raphael Sirtoli of Portugal, show that humans were an apex predator for about two million years. Only the extinction of larger animals (megafauna) in various parts of the world, and the decline of animal food sources toward the end of the stone age, led humans to gradually increase the vegetable element in their nutrition, until finally they had no choice but to domesticate both plants and animals – and became farmers.

“So far, attempts to reconstruct the diet of stone-age humans were mostly based on comparisons to 20th century hunter-gatherer societies,” explains Dr. Ben-Dor. “This comparison is futile, however, because two million years ago hunter-gatherer societies could hunt and consume elephants and other large animals – while today’s hunter gatherers do not have access to such bounty. The entire ecosystem has changed, and conditions cannot be compared. We decided to use other methods to reconstruct the diet of stone-age humans: to examine the memory preserved in our own bodies, our metabolism, genetics and physical build. Human behavior changes rapidly, but evolution is slow. The body remembers.”

In a process unprecedented in its extent, Dr. Ben-Dor and his colleagues collected about 25 lines of evidence from about 400 scientific papers from different scientific disciplines, dealing with the focal question: Were stone-age humans specialized carnivores or were they generalist omnivores? Most evidence was found in research on current biology, namely genetics, metabolism, physiology and morphology.

“One prominent example is the acidity of the human stomach,” says Dr. Ben-Dor. “The acidity in our stomach is high when compared to omnivores and even to other predators. Producing and maintaining strong acidity require large amounts of energy, and its existence is evidence for consuming animal products. Strong acidity provides protection from harmful bacteria found in meat, and prehistoric humans, hunting large animals whose meat sufficed for days or even weeks, often consumed old meat containing large quantities of bacteria, and thus needed to maintain a high level of acidity. Another indication of being predators is the structure of the fat cells in our bodies. In the bodies of omnivores, fat is stored in a relatively small number of large fat cells, while in predators, including humans, it’s the other way around: we have a much larger number of smaller fat cells. Significant evidence for the evolution of humans as predators has also been found in our genome. For example, geneticists have concluded that “areas of the human genome were closed off to enable a fat-rich diet, while in chimpanzees, areas of the genome were opened to enable a sugar-rich diet.”

Evidence from human biology was supplemented by archaeological evidence. For instance, research on stable isotopes in the bones of prehistoric humans, as well as hunting practices unique to humans, show that humans specialized in hunting large and medium-sized animals with high fat content. Comparing humans to large social predators of today, all of whom hunt large animals and obtain more than 70% of their energy from animal sources, reinforced the conclusion that humans specialized in hunting large animals and were in fact hypercarnivores.

“Hunting large animals is not an afternoon hobby,” says Dr. Ben-Dor. “It requires a great deal of knowledge, and lions and hyenas attain these abilities after long years of learning. Clearly, the remains of large animals found in countless archaeological sites are the result of humans’ high expertise as hunters of large animals. Many researchers who study the extinction of the large animals agree that hunting by humans played a major role in this extinction – and there is no better proof of humans’ specialization in hunting large animals. Most probably, like in current-day predators, hunting itself was a focal human activity throughout most of human evolution. Other archaeological evidence – like the fact that specialized tools for obtaining and processing vegetable foods only appeared in the later stages of human evolution – also supports the centrality of large animals in the human diet, throughout most of human history.”

The multidisciplinary reconstruction conducted by TAU researchers for almost a decade proposes a complete change of paradigm in the understanding of human evolution. Contrary to the widespread hypothesis that humans owe their evolution and survival to their dietary flexibility, which allowed them to combine the hunting of animals with vegetable foods, the picture emerging here is of humans evolving mostly as predators of large animals.

“Archaeological evidence does not overlook the fact that stone-age humans also consumed plants,” adds Dr. Ben-Dor. “But according to the findings of this study plants only became a major component of the human diet toward the end of the era.”

Evidence of genetic changes and the appearance of unique stone tools for processing plants led the researchers to conclude that, starting about 85,000 years ago in Africa, and about 40,000 years ago in Europe and Asia, a gradual rise occurred in the consumption of plant foods as well as dietary diversity – in accordance with varying ecological conditions. This rise was accompanied by an increase in the local uniqueness of the stone tool culture, which is similar to the diversity of material cultures in 20th-century hunter-gatherer societies. In contrast, during the two million years when, according to the researchers, humans were apex predators, long periods of similarity and continuity were observed in stone tools, regardless of local ecological conditions.

“Our study addresses a very great current controversy – both scientific and non-scientific,” says Prof. Barkai. “For many people today, the Paleolithic diet is a critical issue, not only with regard to the past, but also concerning the present and future. It is hard to convince a devout vegetarian that his/her ancestors were not vegetarians, and people tend to confuse personal beliefs with scientific reality. Our study is both multidisciplinary and interdisciplinary. We propose a picture that is unprecedented in its inclusiveness and breadth, which clearly shows that humans were initially apex predators, who specialized in hunting large animals. As Darwin discovered, the adaptation of species to obtaining and digesting their food is the main source of evolutionary changes, and thus the claim that humans were apex predators throughout most of their development may provide a broad basis for fundamental insights on the biological and cultural evolution of humans.”

Israeli Archaeologists Present Groundbreaking Universal Theory of Human Evolution (Haaretz)

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Tel Aviv University archaeologists Miki Ben-Dor and Ran Barkai proffer novel hypothesis, showing how the greed of Homo erectus set us careening down an anomalous evolutionary path

Ruth Schuster, Feb. 25, 2021

Why the human brain evolved as it did never has been plausibly explained. Apparently, not since the first life-form billions of years ago did a single species gain dominance over all others – until we came along. Now, in a groundbreaking paper, two Israeli researchers propose that our anomalous evolution was propelled by the very mass extinctions we helped cause. Or: As we sawed off the culinary branches from which we swung, we had to get ever more inventive in order to survive.

As ambling, slow-to-reproduce large animals diminished and gradually went extinct, we were forced to resort to smaller, nimbler animals that flee as a strategy to escape predation. To catch them, we had to get smarter, nimbler and faster, according to the universal theory of human evolution proposed by researchers Miki Ben-Dor and Prof. Ran Barkai of Tel Aviv University, in a paper published in the journal Quaternary.

In fact, the great African megafauna began to decline about 4.6 million years ago. But our story begins with Homo habilis, which lived about 2.6 million years ago and apparently used crude stone tools to help it eat flesh, and with Homo erectus, which thronged Africa and expanded to Eurasia about 2 million years ago. The thing is, erectus wasn’t an omnivore: it was a carnivore, Ben-Dor explains to Haaretz.

“Eighty percent of mammals are omnivores but still specialize in a narrow food range. If anything, it seems Homo erectus was a hyper-carnivore,” he observes.

And in the last couple of million years, our brains grew threefold to a maximum capacity of about 1,500 cranial capacity, a size achieved about 300,000 years ago. We also gradually but consistently ramped up in technology and culture – until the Neolithic revolution and advent of the sedentary lifestyle, when our brains shrank to about 1,400 to 1,300cc, but more on that anomaly later.

The hypothesis suggested by Ben-Dor and Barkai – that we ate our way to our present physical, cultural and ecological state – is an original unifying explanation for the behavioral, physiological and cultural evolution of the human species.

Out of chaos

Evolution is chaotic. Charles Darwin came up with the theory of the survival of the fittest, and nobody has a better suggestion yet, but mutations aren’t “planned.” Bodies aren’t “designed,” if we leave genetic engineering out of it. The point is, evolution isn’t linear but chaotic, and that should theoretically apply to humans too.

Hence, it is strange that certain changes in the course of millions of years of human history, including the expansion of our brain, tool manufacture techniques and use of fire, for example, were uncharacteristically progressive, say Ben-Dor and Barkai.

“Uncharacteristically progressive” means that certain traits such as brain size, or cultural developments such as fire usage, evolved in one direction over a long time, in the direction of escalation. That isn’t what chaos is expected to produce over vast spans of time, Barkai explains to Haaretz: it is bizarre. Very few parameters behave like that.

So, their discovery of correlation between contraction of the average weight of African animals, the extinction of megafauna and the development of the human brain is intriguing.

From mammoth marrow to joint of rat

To be clear, just this month a new paper posited that the late Quaternary extinction of megafauna, in the last few tens of thousands of years, wasn’t entirely the fault of humanity. In North America specifically, it was due primarily to climate change, with the late-arriving humans apparently providing the coup de grâce to some species.

In the Old World, however, a human role is clearer. African megafauna apparently began to decline 4.6 million years ago, but during the Pleistocene (2.6 million to 11,600 years ago) the size of African animals trended sharply down, in what the authors term an abrupt reversal from a continuous growth trend of 65 million years (i.e., since the dinosaurs almost died out).

When Homo erectus the carnivore began to roam Africa around 2 million years ago, land mammals averaged nearly 500 kilograms. Barkai’s team and others have demonstrated that hominins ate elephants and large animals when they could. In fact, originally Africa had six elephant species (today there are two: the bush elephant and forest elephant). By the end of the Pleistocene, by which time all hominins other than modern humans were extinct too, that average weight of the African animal had shrunk by more than 90 percent.

And during the Pleistocene, as the African animals shrank, the Homo genus grew taller and more gracile, and our stone tool technology improved (which in no way diminished our affection for archaic implements like the hand ax or chopper, both of which remained in use for more than a million years, even as more sophisticated technologies were developed).

If we started some 3.3 million years ago with large, crude stone hammers that may have been used to bang big animals on the head or break bones to get at the marrow, over the epochs we invented the spear for remote slaughter. By about 80,000 years ago, the bow and arrow was making its appearance, which was more suitable for bringing down small fry like small deer and birds. Over a million years ago, we began to use fire, and later achieved better control of it, meaning the ability to ignite it at will. Later we domesticated the dog from the wolf, and it would help us hunt smaller, fleet animals.

Why did the earliest humans hunt large animals anyway? Wouldn’t a peeved elephant be more dangerous than a rat? Arguably, but catching one elephant is easier than catching a large number of rats. And megafauna had more fat.

A modern human can only derive up to about 50 percent of calories from lean meat (protein): past a certain point, our livers can’t digest more protein. We need energy from carbs or fat, but before developing agriculture about 10,000 years ago, a key source of calories had to be animal fat.

Big animals have a lot of fat. Small animals don’t. In Africa and Europe, and in Israel too, the researchers found a significant decline in the prevalence of animals weighing over 200 kilograms correlated to an increase in the volume of the human brain. Thus, Ben-Dor and Barkai deduce that the declining availability of large prey seems to have been a key element in the natural selection from Homo erectus onward. Catching one elephant is more efficient than catching 1,000 rabbits, but if we must catch 1,000 rabbits, improved cunning, planning and tools are in order.

Say it with fat

Our changing hunting habits would have had cultural impacts too, Ben-Dor and Barkai posit. “Cultural evolution in archaeology usually refers to objects, such as stone tools,” Ben-Dor tells Haaretz. But cultural evolution also refers to learned behavior, such as our choice of which animals to hunt, and how.

Thus, they posit, our hunting conundrum may have also been a key element to that enigmatic human characteristic: complex language. When language began, with what ancestor of Homo sapiens, if any before us, is hotly debated.

Ben-Dor, an economist by training prior to obtaining a Ph.D. in archaeology, believes it began early. “We just need to follow the money. When speaking of evolution, one must follow the energy. Language is energetically costly. Speaking requires devotion of part of the brain, which is costly. Our brain consumes huge amounts of energy. It’s an investment, and language has to produce enough benefit to make it worthwhile. What did language bring us? It had to be more energetically efficient hunting.”

Domestication of the dog also requires resources and, therefore, also had to bring sufficient compensation in the form of more efficient hunting of smaller animals, he points out. That may help explain the fact that Neolithic humans not only embraced the dog but ate it too, going by archaeological evidence of butchered dogs.

At the end of the day, wherever we went, humans devastated the local ecologies, given enough time.

There is a lot of thinking about the Neolithic agricultural revolution. Some think grain farming was driven by the desire to make beer. Given residue analysis indicating that it’s been around for over 10,000 years, that theory isn’t as far-fetched as one might think. Ben-Dor and Barkai suggest that once we could grow our own food and husband herbivores, the megafauna almost entirely gone, hunting for them became too energy-costly. So we had to use our large brains to develop agriculture.

And as the hunter-gathering lifestyle gave way to permanent settlement, our brain size decreased.

Note, Ben-Dor adds, that the brains of wolves which have to hunt to survive are larger than the brain of the domesticated wolf, i.e., dogs. We did promise more on that. That was it. Also: The chimpanzee brain has remained stable for 7 million years, since the split with the Homo line, Barkai points out.

“Why does any of this matter?” Ben-Dor asks. “People think humans reached this condition because it was ‘meant to be.’ But in the Earth’s 4.5 billion years, there have been billions of species. They rose and fell. What’s the probability that we would take over the world? It’s an accident of nature. It never happened before that one species achieved dominance over all, and now it’s all over. How did that happen? This is the answer: A non-carnivore entered the niche of carnivore, and ate out its niche. We can’t eat that much protein: we need fat too. Because we needed the fat, we began with the big animals. We hunted the prime adult animals which have more fat than the kiddies and the old. We wiped out the prime adults who were crucial to survival of species. Because of our need for fat, we wiped out the animals we depended on. And this required us to keep getting smarter and smarter, and thus we took over the world.”