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The size of the human brain had a great deal to do with the food choices of our ancestors. Credit: Shutterstock

The size of the human brain had a great deal to do with the food choices of our ancestors. Credit: Shutterstock

Original Article:

Phys.org

August 31, 2015 by Norman Owen-Smith, The Conversation

 

Much attention is being given to what people ate in the distant past as a guide to what we should eat today. Advocates of the claimed palaeodiet recommend that we should avoid carbohydrates and load our plates with red meat and fat. Its critics, on the other hand, argue that these are the same ingredients that would set us up for heart attacks. Moreover, these animal-derived foods require more space to produce on our crowded planet filled with starving humans.

A factual foundation for the debate is provided by a review of the eating patterns of early humans and how we adapted to digest starches softened by cooking. The researchers contend that it was digestible starches that provided extra energy needed to fuel the energy needs of bigger brains, rather than extra protein from meat to grow these brains.

But the most striking thing about human diets is just how variable they have been and the adaptations that have taken place. Furthermore, the American evolutionary biologist Marlene Zuk in her book Paleofantasy contends that these dietary adaptations are not fixed on what our ancestors ate in caves at some time in the past.

So are our energy, or protein, needs much different from other mammals of similar size? Brains demand a lot of energy but so does the liver and the digestive tract. The extra nutrition that we need for brain work may be counterbalanced, at least partially, by a lesser need for:

a long gut to process poor quality foods, or
a large liver to handle nasty chemicals in these plant parts.
Once built, a large brain does not require extra sources of protein to maintain its activities.

My studies on the dietary requirements of savanna-inhabiting herbivores highlight how these animals must cope with the dry season when most herbage is brown and indigestible even with the aid of microbial symbionts in the gut.

But carnivores do not have this problem because the dry season is when weakened herbivores are most readily killed, especially when they concentrate around scarce waterholes.

The role of carbs among early humans
Meat has long been part of human diets, along with carbohydrates provided by fruits, tubers and grains. We can get by without it, obtaining protein from milk or, with some planning, from legumes.

The early humans that consumed most meat were the Neanderthals, who lived in Europe many thousand years ago, but were not our ancestors. Meat formed the crucial lean-season food for the Neanderthal people during successive winters when plants were seasonally buried under deep snow, but later also for the modern humans who spread through Eurasia and displaced them around 40 000 years ago.

Unlike tropical Africa, meat could be stored during the freezing winters of the far north to provide a reliable food source, especially in the form of large carcasses of elephant-like proboscideans.

This led to a wave of large mammal extinctions as humans spread rapidly into Australia and entered the Americas towards the end of the last Ice Age. By that time hunting technology had been honed and meat routinely supplemented plant food, but the latter remained the dietary staple for African hunter-gatherers like the Bushmen or San people into modern times.

The food journey within evolution

Coping with the intensifying dry season in the expanding African savanna was a critical issue for human ancestors during the evolutionary transition from ape-men to the first humans between three and two million years ago. How did our ape-men ancestors gather sufficient to eat during this time of the year when nutritious fruits and leaves were scarce?

This was when meat, or at least the marrow left within bones, could have become a nutritional fallback, probably acquired by scavenging from animal carcasses not completely consumed by big fierce carnivores, along with underground storage organs of plants.

Obtaining this meat required more walking and hence longer limbs, hands freed to carry, security in numbers and stone weapons to throw at threatening carnivore fangs, but not much expansion in cranial capacity. These were features of the early Australopithicines.

At this early time, another branch of ape-men, placed in the genus Paranthropus, took a different adaptive route. They developed huge jaws to chew on tough plant foods extracted from underground storage organs to get them through the dry season.

The last representative of this genus faded out nearly a million years ago when this strategy eventually became unviable. About that time the lineage leading to early humans discovered cooking, or at least how to use it effectively to make starches stored by plants more readily digestible, according to the article in The Quarterly Review of Biology.

Adding this reliably found source of energy to the proteins acquired more opportunistically by hunting animals or gathering shellfish provided the means to survive through seasonal bottlenecks in food availability and build even bigger brains and the adaptations that followed.

A supporting adaptation was to store more body fat to get through the lean periods, especially among women supporting dependent offspring. This works against us now that foods supplying carbohydrates are plentiful.

The modern day dilemma

The problems we currently face are that we retain a craving for sugar, which was scarce the past, while most of the starchy carbohydrates we eat are highly refined. This means losing out on the other nutrients in plant parts like minerals and vitamins, and most basically fibre.

A meat-based diet could have a role to play for people who have a propensity to store fat by filling the gut for longer and alleviating desires to snack on sweets between meals. More important generally is the need to exercise so that we are hungry enough to consume sufficient food to provide the scarce micronutrients that we also require for healthy bodies.

The best advice is to eat lots of things: meat if you can afford it and justify its planetary costs to produce, but also all kinds of good food, as least refined and processed as you can obtain (apart from wines).

Explore further: Hunger for meat pushing food security to the edge

This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).

 

 

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Topic: Original Palaeo diet
Research led by the University of Southampton has found that early humans were driven by a need for nutrient-rich food to select ‘special places’ in northern Europe as their main habitat. Evidence of their activity at these sites comes in the form of hundreds of stone tools, including handaxes.

A study led by physical geographer at Southampton Professor Tony Brown, in collaboration with archaeologist Dr Laura Basell at Queen’s University Belfast, has found that sites popular with our early human ancestors, were abundant in foods containing nutrients vital for a balanced diet. The most important sites, dating between 500,000 to 100,000 years ago were based at the lower end of river valleys, providing ideal bases for early hominins – early humans who lived before Homo sapiens (us).

Professor Brown says: “Our research suggests that floodplain zones closer to the mouth of a river provided the ideal place for hominin activity, rather than forested slopes, plateaus or estuaries. The landscape in these locations tended to be richer in the nutrients critical for maintaining population health and maximising reproductive success.”

The project was funded by English Heritage and the University of Southampton’s Faculty of Social and Human Sciences. It involved academics from Geography and Environment and Medicine at Southampton, together with Archaeology at Queen’s.

The researchers began by identifying Palaeolithic sites in southern England and northern France where high concentrations of handaxes had been excavated –for example at Dunbridge in Hampshire, Swanscombe near Dartford and the Somme Valley in France. They found there were fewer than 25 sites where 500 handaxes or more were discovered. The high concentration of these artefacts suggests significant activity at the sites and that they were regularly used by early hominins.

Professor Brown and his colleagues then compiled a database of plants and animals known to exist in the Pleistocene epoch (a period between 2.6 million to 11,700 years ago) to establish a potential list of nutrient resources in the landscape and an estimation of the possible diet. This showed that an abundance of nutritious foods were available and suggests this was likely to have been the dominant factor driving early humans to focus on these sites in the lower reaches of river valleys, close to the upper tidal limit of rivers.

Over 50 nutrients are needed to sustain human life. In particular, it would have been essential for early humans to find sources of protein, fats, carbohydrates, folic acid and vitamin C. The researchers suggest vitamins and protein may have come from sources such as raw liver, eggs, fish and plants, including watercress (which grows year round). Fats in particular, may have come from bone marrow, beaver tails and highly nutritious eels.

The nutritional diversity of these sites allowed hominins to colonise the Atlantic fringe of north west Europe during warm periods of the Pleistocene. These sites permitted the repeated occupation of this marginal area from warmer climate zones further south

Professor Brown comments: “We can speculate that these types of locations were seen as ‘healthy’ or ‘good’ places to live which hominins revisited on a regular basis. If this is the case, the sites may have provided ‘nodal points’ or base camps along nutrient-rich route-ways through the Palaeolithic landscape, allowing early humans to explore northwards to more challenging environments.”

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The paper ‘Site Distribution at the Edge of the Palaeolithic World: A Nutritional Niche Approach’ will be published online by the journal PLOS ONE after the above embargo time: http://dx.plos.org/10.1371/journal.pone.0081476

Original article:
eurekalert.org
Dec 10, 2013

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Topic Stone Age Diet

Analyses of Stone Age settlements reveal that the hunters were healthy and would gladly eat anything they could get their hands on, including carbohydrates – contrary to the modern definition of the Paleolithic, or Stone Age diet.

The Stone Age hunter’s food contained large amounts of protein from fish, lean mean, herbs and coarse vegetables and has formed the basis of one of today’s hottest health trends: the paleo diet.

The modern version of the Stone Age diet excludes foods rich in carbohydrates. This exclusion of carbs is based on the idea that Stone Age hunters didn’t have access to bread, rice or pasta.

But is it true that Stone Age hunters and gatherers didn’t eat any carbohydrates at all?

Sabine Karg, an external lecturer at Copenhagen University’s Saxo Institute, specialises in archaeobotany. She says that Stone Age hunters, unlike many followers of the modern Stone Age diet, joyfully munched away at carbs when the opportunity presented itself.

“Carbohydrates have been part of their diet. In flooded settlements from the Palaeolithic and Mesolithic periods, traces of roots and seeds from various aquatic plants and wild grasses have been found.”

Stone Age hunters were not picky

The modern version of the paleo diet forsakes everything that’s reminiscent of bread, rice, pasta, legumes and milk.

But according to Karg, the Stone Age hunters were nowhere near that fastidious about their food.

Easily digestible food with high energy content is a welcome feature if you have to make the effort of finding the next meal yourself, and traces of foods containing carbohydrates have also been found in the old settlements.

“What archaeologists find in their excavations is dependent on both the preservation conditions and how the people had prepared their food,” says Karg. “For us, the conditions are particularly good in flooded settlements where organic material is well preserved, or in burn layers or fireplaces where we can find charred plant residues,” she says, giving an example:

“We have found seeds of wild grasses, aquatic plants and root vegetables, all of which have formed part of the hunters’ diet. Especially after an unsuccessful hunt, they had to go out and dig up roots.”

Paleo diet for 9,000 years

The Stone Age menu was widely different depending on the region, climate and season. In Denmark, people lived by hunting and gathering for more than 9,000 years until they changed their ways and became farmers.

During the course of these 9,000 years, Denmark presented the hunters with terrains ranging from frozen landscapes similar to today’s Greenland to warm islands with temperatures like those in today’s Southern European holiday destinations.

The starch sources that the archaeologists have so far found include acorns and sea beet, the latter of which is the ancestor of both the beetroot and the sugar beet.

Compared to today, the Palaeolithic and Mesolithic diets included lots of proteins, less fat and fewer, though some, carbohydrates.

You are what you eat

A healthy diet was as important to Stone Age hunters as it to modern man. But since we can’t just send a Stone Age hunter to hospital for a fitness test, if we are to find out about the health of the hunters, we need to make do with what’s available to us – bones and teeth.

So ScienceNordic asked Pia Bennike, a biological anthropologist and lecturer at Copenhagen University, to bring out the boxes of Neolithic bones and tell us about their condition.

“The hunters’ dental health was excellent,” she says. “There is very little tooth loss and no caries. That’s understandable because they didn’t consume many sugary carbohydrates. The only sweet food available at the time was honey. The advantage with the starch sources they had, e.g. root vegetables, is that it’s coarse food, which actually helps clean the teeth.”

Stone Age food was less prepared than today’s food

Bennike explains that the Stone Age hunters made good use of their healthy teeth:

“The skulls reveal that they had a strong chewing system and that their teeth were worn. The very heavy tooth wear shows that they have had a coarse diet, but also that perhaps they didn’t prepare their food as much as we do today.”

When it comes to tooth decay, she says, it’s not only about the contents of the food, but also about how it’s prepared:

“Caries emerges at the beginning of the Neolithic period and increases in the Iron Age and the Viking Age. This occurs in line with people starting to eat more carbohydrates, but also much more finely processed food.”

The hunters had strong bones

From the bones, we see that the general health condition of the Stone Age hunters wasn’t all that bad. Their life expectancy, however, was a lot shorter than it is for modern man.

“There are only few visible signs of diseases on the bones, but that could be put down to the low average age at the time. Those who survived into adulthood could expect an average lifespan of around 35-40 years,” says Bennike.

“Bone quality was generally better than today, but the question is whether that’s due to diet or exercise. Both factors have probably played a part, but the level of physical activity in particular makes a difference. It may also be an evolutionary feature because the further we go back in time, the stronger the bones.”

Stone Age people got their calcium from shellfish

Calcium is crucial to the quality and strength of our bones. Today we are advised to drink milk because of its high calcium content. But milk was not featured in the Stone Age diet, so the hunters must have found their calcium elsewhere.

“Calcium is found in many other foods, e.g. shellfish, so I think they got the calcium they needed,” says Bennike.

Stone Age hunters had strong bones and strong teeth. They lived active lives and ate a coarse diet, consisting of anything edible that they could get their hands on.

Original article:
sciencenordic.com
Jan 4, 2013

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