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A taste for fat may have made us human, says study (yale.edu)
60 points by sridca 14 days ago | hide | past | web | favorite | 66 comments

Since we’re all throwing out our pet theories today, here’s mine: throwing rocks.

As the forests retreated, smallish apes were forced onto the grasslands and had to compete in a different habitat. No claws to work with, no real fangs to speak of. Just a grasping thumb, an upper body shaped by brachiation, and a habit of flinging feces at other apes challenging them for territory.

Rocks can drive predators off carcasses and kill smaller animals. Getting better at throwing rocks brings in more food. An upright posture helps, a bigger brain for visuospacial processing helps.

Eventually we were bigger apes and picked up persistence hunting, spear making, ax making, and fire. Persistence hunting was a group cooperative effort driving us toward protospeech.

True speech is admittedly a bit of a head-scratcher. Lucky mutation maybe? Fairly confident about the rocks, though. Once you’re throwing rocks, smashing bones open for the marrow is a pretty obvious move.

My personal favourite is the hypothesis that human ancestors had for an extended period lived wading in shallow water, which protected them from climate (i.e. either warm springs in cold climate, or regular water in warm ones; we can see similar behaviour among modern monkeys and apes in some circumstances [0]) and possibly from natural predators.

They were not constrained to the water, often leaving it to forage for food and possibly hunt, but regularly returning to its safety. Eventually the climate changes forced them to leave the wading lifestyle and adapt to steppes and other habitats, using their growing intellect to devise adaptations like clothes, tools and at some point mastery of fire.

This would, in my mind, explain a number of specific development present in humans in a very rare combination:

- nearly complete loss of body hair, except on the head (which is consistent with wading) - adaptations for both swimming/diving and two-legged walk - development of speech and facial expressions as communication tools, which work the best when the rest of the body cannot be used - importance of fish in human diet - increased brain in children, which causes more difficult births, which are offset but giving birth in water

This is a variant of what used to be known as "aquatic ape hypothesis" and widely ridiculed, but more resent research has supported some of its elements [1].

[0] https://www.seejapan.co.uk/where-to-go/outdoors/hot-springs/...

[1] https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis#Related...

> - nearly complete loss of body hair, except on the head (which is consistent with wading)

It's also consistent with running. Running creates a lot of energy. Like a lot. You know when it's sub 10 celsius out and everyone is freezing their butts off? You go for a run in tiny tiny shorts and a tiny little t-shirt and yes it's freezing your nips off but 3 miles later you're sweating balls and wishing the t-shirt was smaller and the shorts even tinier.

They say the perfect temperature for a marathon is around 4 celsius. That's because when you're fast enough, heat dissipation is pretty much the only limiting factor to how fast you can run. Even an amateur runner like me can see huuuuuge gains in speed just from running in temperate winter instead of during summer.

Many animals run and still retain their fur. Pretty much all of the known mammals that have lost most of their fur/hair are either aquatic (whales, dolphins, dugongs...) or regular waders (pigs, hippos, elephants...); the only exceptions live underground or in crevices.

If you haven’t read William Calvin’s “The Ascent of Mind” you might enjoy it: http://williamcalvin.com/bk5/bk5.htm The “throwing theory” features prominently.

selecting good rocks for throwing, collecting them, playing and practicing with them. Breaking up bigger rocks and shaping them to make better ones for throwing. Ouch! Some of those broken off shards are sharp. hmmm.....

Could anybody help me find this theory: humans evolved thanks to timing neurons that helped them throw stuff at prey and enemies. Those neurons also help with dance, all kinds of art and other acts of a civilized creature. I read in in a yellowing book which merges biology and AI.

The brain runs almost entirely on beta-hydroxybuterate, and human mitochondria have a very efficient process to use BHB (instead of glucose) for power.

The most efficient diet for humans is one high in fat, moderate in protein, and low in carbs; which explains the absolutely curable disorder known as Diabetes II (aka chronic insulin resistance).

And before anyone jumps on the "keto is a fad diet" bandwagon: if it is, indeed, a fad, it is a fad that modern humans have eaten for 200,000 years, and our ancestors have eaten for another 2 million before that. If our taste for fat did not make us human, it certainly defines a particular trait of ours that all humans depend on.

I certainly function (mentally and physically) better in a state of ketosis. Notwithstanding my personal anecdote, I want to add to your observation on energy/atp (in the mitochondria) efficiency and BHB/ketones.

A lot of people counter argue that the body/brain run more efficiently primarily on glucose and glycogen rather than ketones. While it is true if you introduce sugar (glucose) into the blood, cells will generally begin to produce energy/atp primarily from glucose over ketones. However, it is not because the glucose is more efficient, in fact ketones are smaller making them the a more efficient fuel source of the cells. For example, bc they are smaller they cross the blood-brain barrier more easily and are more efficiently used by brain cells to be converted into energy/atp (in the mitochondria).

I think there is a reason we call it “getting knocked out of ketosis” because that is our natural state. That is forget high fat/low carb and abstain from all calories and drink only water to stay hydrated and the body will go into ketosis, which is what we are talking about when we discuss “fasting” as a metabolic state (vs say a culturally/religiously defined “fast”).

The body runs more efficiently on glucose when measured in terms of oxygen consumption. That's why very few elite endurance athletes eat ketogenic diets. Their performance is limited by how much oxygen they can metabolize.

I’d say historically (modern history) you didn’t see any athletes eating ketogenic diets, but more and more you are seeing athletes (especially endurance athletes) eating Keto diets. Keto is great for aerobic activity, the idea of a tribe of early man persistence hunting a mammoth for example would have performed better long term in ketosis having unlimited stores of fuel (fat) rather than draining their glucose in 8 or so miles and “hitting a wall”.

It’s anerobic activity (sprinting or bodybuilding/Olympic lifting) where there may be a slight detriment in performance.

I’ve run marathons in both ketosis and running on glucose. I won’t go there because it’s anecdotal but marathoners, body builders and Olympic style lifters are not the norm and have different requirements especially competing for records. No doubt it’s one thing to live in a natural state of ketosis and treat yourself to a performance boost with some fruit when you are about to burn any glucose than what almost the entire modern world does and spikes their insulin levels all day every day and their body/cells basically not even familiar with how to use ketones as a fuel.

Sure it's possible to eat a ketogenic diet and complete a marathon, but we know from basic biochemistry that it takes more oxygen molecules to produce a given amount of energy from fat metabolism than from sugar. So for elite athletes whose performance is limited by how much oxygen they can get to their muscles it makes the difference between winning and losing.

Diabetes II can also be “cured” by a high carb low fat diet. Not all carbs are equal; the problem is refined carbs.

You can cure diabetes with refined rice, fruit, fruit juice, and sugar diet (Kempner rice diet). The problem isn't any particular macronutrient, it's most likely an excess of calories.

> The brain runs almost entirely on beta-hydroxybuterate

This is not true.


Quote: The mammalian brain depends upon glucose as its main source of energy, and tight regulation of glucose metabolism is critical for brain physiology.


Quote: β-Hydroxybutyrate (βOHB), a ketone body, is oxidised as a brain fuel. Although its contribution to energy metabolism in the healthy brain is minimal, it is an interesting metabolite which is not only oxidised but also has other direct and collateral effects which make it a molecule of interest for therapeutic purposes.

> The most efficient diet for humans is one high in fat, moderate in protein, low in carbs;

This is not true.

Scientifically proven best diet: Whole food plant based high carb, low-moderate fat and low protein.

Unless the body is starving, fat and protein are not converted to glucose (the main energy source for cells) to cover energy needs.

Fat Consumption is the Only Cause of Weight Gain (2018-07-14). https://neurosciencenews.com/fat-consumption-weight-gain-957...

Why Doctors Don't Recommend A Vegan Diet | Dr. Michael Greger (2015-05-17). https://www.youtube.com/watch?v=_d1Ca6SsKfE

Dr Garth Davis: Americans have become obsessed with Protein (2015-10-28). https://www.youtube.com/watch?v=XQCt3IhaUtU

Omnivore or Herbivore? https://livinontheveg.com/omnivore-or-herbivore/



>>Fat Consumption is the Only Cause of Weight Gain (2018-07-14). https://neurosciencenews.com/fat-consumption-weight-gain-957...

Wow the sugar industry is still at it. Read the abstract. The study concludes that mice are incapable of auto-regulating caloric intake because fat stimulates their pleasure pathways causing them to overeat. Kinda like how sugar behaves in humans. See the graphical abstract[0] for a pictorial depiction the authors have helpfully provided.

[0]: https://www.cell.com/cell-metabolism/fulltext/S1550-4131(18)...

You are right to question this study and the conclusion of the article. Still, the study shows some important points:

- Professor John Speakman, who led the study, said: “The result of this enormous study was unequivocal – the only thing that made the mice get fat was eating more fat in their diets.

- “Carbohydrates including up to 30% of calories coming from sugar had no effect. Combining sugar with fat had no more impact than fat alone. There was no evidence that low protein (down to 5%) stimulated greater intake, suggesting there is no protein target. These effects of dietary fat seemed to be because uniquely fat in the diet stimulated the reward centres in the brain, stimulating greater intake.

Anyway, one has to wonder why the body has a natural tendency to eat carbs (only in plants like healthy fiber) if they are not part of the natural diet: Sweet fruits. Sweet vegetables. Sugar. Starch products. Processed meat with vegetable spices and not just bloody pure meat like carnivores with the appropriate digestive system.

Sugar and Fat Bingeing Have Notable Differences in Addictive-like Behavior https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2714381/

WHY LOW CARB DIETS ARE A SCAM (2016-11-30). https://www.youtube.com/watch?v=1dj-Wmmt0FE&feature=youtu.be...

The Science of Cheese Addiction (2017-03-25) https://www.youtube.com/watch?v=1hE6lhQu7k4

You're wrong about most things but it's definitely cool to see cheese addiction come up in mainstream media. I used to eat whole blocks of the stuff at a time and when I quit I was literally shivering. That stuff might be alright in small doses if you have an eating disorder and need to make food more palatable, but it is not good for adults.

As a Midwesterner, I feel attacked.

EDIT: in all seriousness, I appreciate your anecdote. This thread is convincing me of how little I know.

Don't believe everything you read, even rehashed science journals. You only have to look at what pro cyclists eat to know that fat isn't a cause of weight gain. When I stopped sugar and carbs (but still ate fruit so no ketosis) and started eating high amounts of fat the weight dropped off of me. I was already normal weight (185cm @ 85kg) and I lost 10kg. Fat has absolutely no blame in weight gain.

...for some people anyway.

Fat keeps you satiated for much longer and also helps avoid the sugar spikes that accompany carbs.

Protein and carbs are both more satiating. High-fat diet doesn't necessarily improve blood sugar regulation, since insulin resistance can increase.

https://www.ncbi.nlm.nih.gov/m/pubmed/7498104/ https://www.ncbi.nlm.nih.gov/m/pubmed/26615402/

The study you linked talks about saturated fats.

>A diet very high in fat and saturated fat adversely affects insulin sensitivity and thereby might contribute to the development of type 2 diabetes.

It's well established that sugars are responsible for type 2 diabetes.

>Isoenergetic 1000 kJ (240 kcal) servings of 38 foods separated into six food categories (fruits, bakery products, snack foods, carbohydrate-rich foods, protein-rich foods, breakfast cereals)

This is a badly designed study. It doesn't test the macro level satiety. It says "fat content" which I am going to presume is in the snack foods which are also high in semi-complex sugars.

The thing with all of these studies is that they are easy to try at home on yourself. It's well documented that the sugar industry paid to give fat a bad name but if you eat a high fat, plentiful protein and low carb diet for a month you will now the truth. You can feel it, you can see it.

> The study you linked talks about saturated fats.

True, saturated fat is probably the worst on this front, and unsaturated fat, if it comes packaged with things like vitamin e (to help prevent oxidation) might not be so bad.

> It's well established that sugars are responsible for type 2 diabetes.

No, it's actually not. This is a popular theory, but it's not very well supported. In terms of NAFLD, a strong contributer to insulin resistance, the worst offenders (in the context of a hyper-caloric diet ) are saturated fat and sugar (at 33% of the effect of sat. fat). Sugar only becomes bad when it's converted to fat, which only happens to a significant degree in hyper-caloric diets, when the liver can't dispose of the glucose quickly enough.

Your anecdotal evidence is nice and all, and may work for you, but is no substitute for meta-analysis of controlled studies.


The diet you describe is what I am using to treat my AS. It's not cured it by any stretch but it has done wonders and is improving my health steadily the deeper I go into this dietary journey.

I have understood that saturated fats are bigger culprit for type 2 diabetes than high carb intake. Also sugars are larger risk than carbs in general.

Type 2 is insulin resistance. In other words your body produces insulin to clear sugar from the blood but the body no longer responds (actually clears the sugar from the blood) to insulin.

The resistance (type 2) is built up over time (historically it was “adult onset”) to insulin spikes. I don’t believe saturated fats introduce sugar into the blood, so they don’t cause insulin spikes, which means they don’t contribute to resistance (at least not directly).

In a roundabout way they may contribute to a surplus of calories and the storage of fat, ultimately causing obesity, which does seem to speed up the resistance to insulin. But all things being equal the same surplus of calories on a high carb diet will be more detrimental because there will be insulin spikes and the insulin will also enlarge fat cells allowing the body to store more fat (ie become obese more efficiently).

Yes the study suggest high fat diets may effect insulin sensitivity....so long as the test subjects are consuming carbs ALSO and triggering insulin. In other words the didn’t test effects of high fat diets while subjects were otherwise avoiding insulin spikes.

So yes eating fats is an issue while eating carbs and spiking insulin. You won’t find a single medical case of T2D where the subject hasn’t repeatedly spiked insulin with carbs/sugar.

High fat diets can cause insulin resistance. So can high protein diets. Overall blood sugar regulation remains similar across most macronutrient ratios as long as calories are controlled, as cells scale their receptivity to insulin to maintain homeostasis. The number one controllable factor is calorie intake (minus calorie expenditure), not macronutrient breakdown, and there isn't any one priveledged breakdown that universally works for everyone to control calorie intake.

The energy density table on Wikipedia [0] says it all really. Sort it by specific energy, and marvel at how animal fat is baaasicaly jet fuel.

Also take a moment to appreciate exactly what nuclear power implies in terms of bang-for-buck mining and transport costs.

[0] https://en.wikipedia.org/wiki/Energy_density

> marvel at how animal fat is baaasicaly jet fuel

Fat seems to be with the rest of the hydrocarbons in this regard, which is not surprising since it's one of them.

Fatty acids are not hydrocarbons as they all contain a carboxyl group. Fats have distinctly lower free energy than hydrocarbons.

Also, animal fat is a tissue, not an organic molecule, so there's a little bit more complexity here.

I never was really good at chemistry, but I'm sure I've heard lipids being referred to as "hydrocarbons". Aren't they mostly long chains of hydrogen and carbon? Is it fair to call them "hydrocarbons" in this case?

Hydrocarbons are C_nH_m

Antimatter specific energy: 24,965,421,631,578 Wh/kg!

Twenty four thousand nine hundred and sixty five billion watt-hours per kilogram.


Trillion even. At least when using the short scale.


Cooking unlocks a lot of calories and nutrients, especially starchy food like potatoes and other root vegetables.

These are usually not eaten by most animals, and are available almost everywhere close to year-long, plus they can be stored for later in a dry place.

The human brain consumes a huge amount of calories, so cooking which was done millions of years before homo sapiens arrived as definitively a lot to do with becoming a modern human.

A more intriguing question is, how did cooking start, and how did apes became intelligent enough in order to know how to cook?

Cooking is so straightforward that it would be astonishing if it weren't discovered. There is a fire in the jungle; hungry humans discover a cooked chicken near the perimeter and realize it was the hot fire that caused it to smell and taste so good. Next time, they go to a fire, capture it and control it to cook some meat. From here, it's monkey see monkey do and the rest is history.

Why would it smell and taste unusually good before cooking was invented? Isn't it more likely that appreciation for the taste of cooked food evolved because cooked food is safer and more nutritious? If there's no cooked food there's no reason for this preference to evolve.

It may be the stronger smell or the faster delivery of particulates of burnt fat through the air.

Dogs, wolves, and bears can’t cook or start fires but all of them are attracted to the smell of cooked food as well. You could argue that dogs and maybe wolves co-evolved that preference alongside ours, but that doesn’t hold up for bears.

Are bears attracted to the smell of cooked food? Or just attracted to the smell of food, and cooking is how most people treat food out in the wilderness?

Why come did bears evolve to steal my pickinickbasket them?

This is the classic HN comment about how easy it was to invent something in retrospect, but applied to fire.

(If it's so easy, why do none of the other ape species do it? How long before you get an accidental cooked chicken, not an incinerated one?)


Chimps are also omnivorous and eat other mammals.

> The paper argues that this theory does not make nutritional sense. “The meat of wild animals is lean,” Thompson says. “It actually takes more work to metabolize lean protein than you get back.” In fact, eating lean meat without a good source of fat can lead to protein poisoning and acute malnutrition. Early Arctic explorers, who attempted to survive on rabbit meat exclusively, described the condition as “rabbit starvation.”

What? It's simply not true that lean protein takes more energy to digest than it produces -- it takes 20-30% of the energy to digest it, not >100% [1]. It's not celery -- and even the idea that celery is a "negative-calorie food" turns out to be a myth [2], so it's basically ridiculous to suggest that meat could be.

And while wild animals can have somewhat leaner meat, there's plenty of fat, see the table in [3], and seeing as animals really were abundant back then, it would be easy to eat as much fat as you wanted (remember, it comes in big chunks) and throw away any excess super-lean muscles.

And to be clear, despite the name, "rabbit starvation" is about vitamin deficiency, not calorie deficiency. [4]

Since these quotes are coming from the paper's author, I'm finding the whole thing highly suspect... intriguing, but hard to take seriously with such factual inaccuracies.

[1] https://www.precisionnutrition.com/digesting-whole-vs-proces...

[2] https://en.wikipedia.org/wiki/Negative-calorie_food

[3] https://news.psu.edu/story/186616/1997/12/10/fat-and-cholest...

[4] https://en.wikipedia.org/wiki/Protein_poisoning

Take away fire and starches/grains and you take away civilization. Grazing is for extracting calories from marginal land. Prime land isn't given to animals to graze on - it's given to plants. Once we knew how to harvest corms and tubers and cooked them we became more starvation proof. (Hunting is more hit or miss).

Starch granule are found in the teeth of many hominid fossils. We produce amylase in our saliva which breaks down cooked starches when it hits our tongues. Other omnivores do not have this adaptation.

You cannot have a high fat diet hunting (deer and small game simply do not have high amounts of fat). We moved on to agriculture because it provided plenty of calories and didn't run away from us when we tried to kill it.

While we may have eaten fat opportunistically - it's starches and fire that got us to where we are.

The study explores the possible way to sustain a bigger brain well before invention of tools, and controlled fire. It's also absolutely not about hunting.

It's always hit or miss when one tries to comment after reading just a headline ;-)

Human != civilized

The crucial driver for the emergence of an utterly and uniquely distinct intelligence is a source of nutrition available to countless other predators for hundreds of millions of years? Makes perfect sense... unless you believe in natural selection.

Natural selection tells us the process typically works in the reverse order: environmental pressures create a situation where the emergence of increased intelligence grants the individual an ability to leverage the calorie source to their distinct reproductive advantage; not just relative to lions but relative to those in their group. So the marginally improved intelligence mutation occurs first, and it has to be so advantageous that it can overcome counterveiling selective pressures such as more aggressive individuals simply taking the calorie rich source. Were it otherwise we'd be living in Planet of the Apes, or more likely would never have existed.

Whatever evolutionary strategy our ancestors found themselves pursuing, it almost certainly must have been unique and special. The notion that we developed intelligence because intelligence intrinsically provides a reproductive advantage doesn't make any more sense than the notion that we developed intelligence because we could eat fat. Such simple strategies are immediately, incrementally, and perpetually available to countless species, now, then, and prior. If it were true it would imply that evolution is a simple escalator for traits like intelligence, but we see no such evidence of that.

> And the only things that could crack open these containers, she adds, were the bone-cracking jaws of hyenas or a clever ape wielding a rock.

The authors do mention that. It was written by three professors of evolution and anthropology at Yale, Oxford, and Uni Chicago, but the first comment here is dismissive snark.

>We propose that the regular exploitation of large-animal resources—the “human predatory pattern”—began with an emphasis on percussion-based scavenging of inside-bone nutrients, independent of the emergence of flaked stone tool use. This leads to a series of empirical test implications that differ from previous “meat-eating” origins scenarios.

My bone to pick isn't with the scholarship on the particulars of human hunting patterns. It's with the conclusions related to the evolution of intelligence.

There's a tendency to think that human intelligence arose because of a series of serendipitous adaptations that permitted intelligence to blossom--eating marrow, eating meat, having opposable thumbs, bipedalism, complex vocalizations, etc. But every time a researcher tries to differentiate humans along an axis, we later discover that these adaptations are actually quite pervasive.

Tool use, communication, calorie sources, etc... whatever early humans did we eventually find to actually be quite pervasive in the sense of independently arising. Which suggests that none of these alone is any sort of bottleneck to intelligence. And if such adaptations are incrementally available then why is it human intelligence exploded so? What's the bottleneck? The only response, again, is some sort of cosmic serendipity along the whole chain, but that's conclusory without any evidence (i.e. showing the bottleneck that prevents all these other species from continuing down the same path and, most importantly, why humans are uniquely capable of squeezing through these bottlenecks time and again).

The scholarship in the article is interesting and useful, but as it regards intelligence it doesn't even begin to answer the critical questions.

Exactly. Personally I find the argument that it was cooking that enabled us to evolve a lot more compelling. It's certainly not something any other species does and it unlocks a lot of new calories.

Have you heard of a book titled "the mating mind"?

If you use a rock to smash up a bone to get to the marrow, I wonder if you also get, as a side-effect, a bunch of bone flakes, some of which are sharp enough to be used as a cutting implement. Maybe primitive hominids were smashing bones for sharp flakes before they started flaking rocks to make cutting tools.

Before you get there, the bones would have been used as clubs and sharp broken bones used as proto-spears or knives.[1] Then after some period of time, it would seem reasonable that already recognizing the utility of the bones that a slightly more evolved creature would start to put the pieces together (pun intended) and find uses for bone chips/flakes for ever more effective tools. I can't even imagine how much time must have passed before this came together to get early us even that far.

[1] Which in turn would have come about after a long period of time just using rocks before those evolving primates discovered their advantages as tools/weapons.

Some years ago, I came across a paper suggesting something similar, except that the key dietary change was when an ancestor hominin (I don't recall which, if they identified a specific one) switched from a largely fish-based diet to one of land mammals. The paper seemed to take as as established fact that there was, at one time, a hominin with a fish-based diet.

I have not been able to track down this paper again, but the idea that adopting an aquatic diet was a step in the evolution of homo sapiens seems to be 'in the air'; this paper seemed to be saying that a subsequent switch away from that diet was also important. IIRC, it included both a nutritional argument, and the point that it allowed this hominin to spread beyond lake-shores and coastlines.

“It actually takes more work to metabolize lean protein than you get back.”

Is this correct? I've never heard this position before.

Sounds like a reference to "rabbit starvation", which is real but a pretty difficult situation to get yourself into.

Now it is a good time to stop then. Both consumption and production (by organism).

Carnivores like lions first eat internal organs like liver & kidney. Apparently these contain a nice mix of fat and protein. Even orcas preying on whales just eat the liver and leave the rest.

Question is why.

My brief research after reading this article showed that cats can't produce their own fat or proteins. And are poor in taking energy from carbohydrates.

Since they can't get their energy from carbs, they eat fat along with proteins.

Say our ancestors couldn't farm. Or were carnivores then it makes sense that they'd seek fat source by instinct just to stay alive.

The argument that fat eating made us human is fiction.

Liver is generally high in vitamins (notable A) and minerals.

Even in countries like Japan, organ meats are relished along with the muscle meats.

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