Tag Archives: hadza

There’s no such thing as an ideal diet, new study suggests

As long as you keep a healthy balance and an active lifestyle, things should generally be okay.

A Tsimane member. Image credits: jambogyuri.

Diversity

In modern times, diet studies are often confusing or even contradictory — some diets focus on proteins, others say you should eat more carbs, others emphasize fruits and veggies, there’s probably a diet for every imagination. But while some things are pretty clear by now (fruits and veggies are good, processed meats are bad), others are hotly debated.

Scientists have long debated whether there’s an ideal food diet, something that we as a species evolved to eat. A team of researchers explored that question by studying the diets, habits and physical activity levels of hundreds of modern hunter-gatherer groups and small-scale societies. These groups have a very similar lifestyle that of ancient human societies.

Right off the bat, there were major differences between these groups. Some groups got up to 80% of their calories from carbohydrates, while others got most of their energy from protein. Some groups such as the Hadza people in Tanzania eat a large amount of sugar in the form of honey, deriving over 15% of their calories from honey (which, for most practical purposes, is similar to sugar).

If anything, the common denominator is diversity.

“Diets in hunter‐gatherer and other small‐scale societies tend to be less energy dense and richer in fibre and micronutrients than modern diets but are not invariably low carbohydrate as sometimes argued,” researchers write.

A complex picture

In any given day, the Hadza eat red meat and honey, but also potato-like roots — not exactly what you’d imagine as a very healthy diet. Meanwhile, the Tsimane, a Bolivian population, eat more complex carbohydrates from plantain, corn, cassava, rice and banana, often complemented by fish and wild game. The percentage of different nutrients varies wildly, but the health effects seem negligible: previous studies have shown that these groups have almost no diabetes and cardiovascular problems. However, there are many examples with Tsimane people developing Type II Diabetes and other health issues after moving to neighboring villages and taking up sedentary jobs.

Here’s where things get really interesting: the calorie intake of people like the Tsimane and the Hadza is comparable to that of the average American. However, they have excellent fitness, extremely low rates of obesity and cancer, and are generally free from any chronic diseases. The reasons for this may not be all that jolly, however.

Infant mortality rates are high, and fatalities from infections and accidents are extremely high. Those who do manage to reach adulthood are more likely to be very healthy. They are active until old age, walking at least 5-10 miles a day, and exhibit very alert and active lifestyles. While calorie-wise this doesn’t make as much of a difference as you might expect, it does wonders for your health.

However, considering that when these people give up their native lifestyles they start to develop disease rates comparable to industrialized countries, the key seems to be in their lifestyle, not their diets. It is possible that genetics and other factors unrelated to lifestyle help protect them from chronic diseases — but there’s still another factor to consider.

Choice and variety

Foods rich in fibers are a staple of a healthy diet. This was one of the very few similarities across all investigated diets. Image credits: Keith Weller, USDA.

Another big difference between peoples like the Hadza and the Tsimane and modern urban people is the amount of variety in the diet. We pretty much take it for granted nowadays, but we have access to an unprecedented culinary variety. For all the obvious advantages that come with this, there’s also a disadvantage: it can make us overeat.

It’s called sensory-specific satiety, and it means that the more you eat a type of food, the less satisfaction you derive decreases in time. As a consequence, your appetite decreases when you keep eating the same type of food and increases when you keep eating different things — that’s why you always have room for dessert after a savoury meal. In truth, however, you don’t have the extra room, and you’re probably overeating.

The bottom line is that we’re not really sure what diets work best, but there seem to be some generally applicable rules: eat fiber-rich foods like fruits and veggies, avoid energy-dense foods (like sweets or meats), and keep an active lifestyle.

“A more integrative understanding of hunter‐gatherer health and lifestyle, including elements beyond diet and activity, will improve public health efforts in industrialized populations,” researchers conclude.

The study “Hunter‐gatherers as models in public health” by Pontzer, Wood, and Raichlen, has been published in Obesity Reviews.

Generosity may be contagious, new study suggests

A new study carried on a hunter-gatherer society in Tanzania gives a surprising insight into why people help each other — it’s “contagious”.

At first glance, being generous doesn’t really make much sense. From an evolutionary standpoint, it seems like being selfish would be the best idea. But for a social creature like Homo sapiens, things are rarely simple, and recent studies suggest that generous people are happier and fare better in society. However, that still doesn’t explain why we give.

This is where the new study comes in. Researchers found that the Hadza, a hunter-gatherer people, are generally willing to share — but that doesn’t mean they always do. In fact, whether they are willing to share something or not depends not so much on the individual, but rather on the group they were living with at the time.

“We found that year after year, willingness to share with others clustered within residence groups or what we call ‘camps,'” says lead author Coren Apicella of the University of Pennsylvania. “People were living with other people who were similar to them in levels of generosity.”

In other words, people were more generous when they were in the company of other generous people — not the other way around.

“We also found individual willingness to share changed from year to year to match their current campmates and found no evidence that people preferred living with more cooperative people,” adds Kristopher Smith, the study’s first author. Importantly, those trends persisted even as the Hadza people changed campmates about every couple of months.

The Hadza, or Hadzabe, are an indigenous ethnic group in north-central Tanzania, near the Serengeti plateau. There are, as of 2015, between 1,200 and 1,300 Hadza people living in Tanzania, although the increasing impact of tourism and encroaching pastoralists pose serious threats to the continuation of their traditional way of life.

Studies like this are particularly important because they are carried out on a society that greatly resembles a subsistence lifestyle similar to that occurring throughout most of human evolution. Furthermore, since they gain most of their calories through hunting and plant gathering, which are both fairly scarce resources, sharing is really generous — not something to be treated lightly.

“The Hadza are one of the last populations left on the planet who live a similar lifestyle to how our ancestors lived for millions of years,” says co-author Ibrahim Mabulla. “They offer insight into how cooperation evolved.”

“Food is unreliable and people often worry about there being enough food to feed themselves and their families,” Apicella says. “To counteract this, the Hadza share their food with their campmates. High levels of cooperation help to ensure survival in this unpredictable setting.”

The methodology of the study was almost just as intriguing as the study itself. Obviously, it’s not easy to study this type of population — especially since researchers need to pay special attention not to disturb them in any significant way. So to test their theories out, researchers visited 56 camps in Tanzania over the course of six years.

During the visits, nearly 400 Hadza adults of all ages were asked to play a public goods game. The game is normally played by asking people to decide whether they share money with the group or keep it for themselves — but since that wouldn’t have made much sense here, the money was substituted for straws of honey, the Hadza’s favorite food.

In the game, each person starts out with four straws. If they decide to keep them, they keep them. But if they share them with the group, the number of straws get tripled. If everyone shares, everyone wins — however, there’s also an incentive to keep the straws for yourself.

The data showed that Hadza individuals living in certain camps were consistently more generous than others were. Moreover, individuals behaved differently over time, modifying their behavior to match the norms of the camp they were currently living in.

“You have some camps in which everyone is contributing and some where people are contributing very little,” Smith says. “In a random population, you’d expect all the camps to contribute similar amounts.”

“We were surprised to find that people do not have a stable tendency to cooperate and are instead influenced by those around them,” Apicella says. “Our results show that there is no such thing as good guys and bad guys,” challenging a swath of evolutionary models for explaining cooperation that assume dispositional types: cooperators and defectors.

Lastly, this also shows the fluid nature of human collaboration — it can change over time, and it can be influenced.

So if you feel like the people around you are selfish and self-centered, the best way to change that is to start being more generous yourself — who knows, you might be giving them the generosity contagion.

Journal Reference: Current Biology, Smith et al.: “Hunter-Gatherers Maintain Assortativity in Cooperation despite High Levels of Residential Change and Mixing” https://www.cell.com/current-biology/fulltext/S0960-9822(18)30994-1

Scientist gives himself Fecal Transplant from Hunter-Gatherer from Tanzania… to See how it Goes

A field researcher from America has transplanted fecal microbiome from a Tanzanian tribesman to his own gut. Why? Well… to see what happens, basically.

Fecal bacteria, magnified 10,000x Fecal transplant is increasingly accepted as a medical treatment for some diseases. Eric Erbe, digital colorization by Christopher Pooley

Fecal bacteria, magnified 10,000x Fecal transplant is increasingly accepted as a medical treatment for some diseases. Eric Erbe, digital colorization by Christopher Pooley

“AS THE SUN set over Lake Eyasi in Tanzania, nearly thirty minutes had passed since I had inserted a turkey baster into my bum and injected the feces of a Hadza man – a member of one of the last remaining hunter-gatherers tribes in the world – into the nether regions of my distal colon.”

It’s not every day you get the chance to read an essay which starts like this, isn’t it? Yet that’s exactly how Jeff Leach, the man behind this research, starts his story. He has been part of a team working in Tanzania and living side by side with the Hadza, a group of hunter gatherer people. The Hadza live now the same way their ancestors have for thousands or even tens of thousands of years; they are the last full-time hunter-gatherers in Africa. What’s interesting is that the Hadza are not genetically related to any other people, and their language is unique.

The Hadza are also at the mercy of the local weather and climate. Leach’s team has collected numerous (over 2000) samples from humans, animals, and the environment in order to observe how the microbial communities in and around the Hadza change as a result of the weather patterns – especially the six month variation (dry season – wet season).

A Hadza hunting party. Image via The Telegraph

“[The question is] what a normal or healthy microbiome might have looked like before the niceties and medications of late whacked the crap out of our gut bugs in the so-called modern world,” Leach writes.

For this purpose, the Hadza are indeed ideal subjects. They are not stone-age or isolated people – they’ve had plenty of contact with other humans, but they still have the same diet and lifestyle they’ve had for millennia, and almost never use modern medication.

The microbiome in the colon is starting to receive more and more attention – and rightfully so. The health impact it has on our bodies is huge, and has been widely ignored in Western medicine, until recently. Eating “probiotics” and similar foods is a good step, but this just “scratches the surface”. Meanwhile, fecal transplant has been used more and more to treat various afflictions.

“Recent research suggests that use of antibiotics may be fundamentally altering our gut biomes for the worse, increasing rates of allergies, asthma and weight gain. In one recent lab study, introduction of genetically altered gut bacteria prevented mice from getting fat. In another, artificial sweetners altered gut microbes and contributed to obesity and other metabolic disorders in mice, and some correlation to the same effect was found in people”, Popular Science writes.

So understanding how our biome changed as a result of a modern lifestyle could have huge implications for future medicine… but is a fecal transplant really necessary? Leach and his team believe it will greatly accelerate the study. Their results are already interesting, but they want to find out as soon as possible if modern humans can survive with ancient fecal biome.

“On the original question of whether or not the gut microbiome composition of the Hadza changes between wet and dry seasons, our initial – though unpublished data – suggest yes. To our knowledge this is the first study in the world to document this pattern among rural and remote populations. Ecologically speaking, this suggests there may not be one steady state – or equilibrium – for the human gut. It’s moving target with multiple steady states.”, Leach writes further.

Another reason why he is doing this is to test his theory: that we have conducted a biome genocide, basically wiping out most of the bacteria that inhabits our gut. He wants to see what will happen when you get that biome back.

“Microbial extinction [is] something I believe we all suffer from in the western world and may be at the root of what’s making us sick.”

Is there truth to his theories? The fact that he would risk inserting a hunter-gatherer’s feces inside of him seems to indicate that at the very least, he’s very confident in his ideas. Personally, I think what he says makes a lot of sense. Most of what we are is actually bacteria or other foreign bodies – it seems extremely unlikely for those elements to not have any particular impact; wiping them out (as we are doing today, with modern drugs and the modern diet) likely has serious consequences. We’ll keep you posted on how the situation develops.

Source: (Re)Becoming Human: what happened the day I replaced 99% of the genes in my body with that of a hunter-gatherer, by Jeff Leach.