Humans are the highest energy apes, making us smarter but also fatter | Hacker News Reader

Humans are the highest energy apes, making us smarter but also fatter

sciencemag.org

95 pointsPetiver22 comments

The Science magazine article seemed to me scarce on a number of critical details which are made clear in the abstract: http://www.nature.com/nature/journal/vaop/ncurrent/full/natu...

Of particular interest is the fact that the study tries to account for the effects of activity, which is obviously widely variable across human societies and individuals (e.g. French professional cyclist versus Khomani San tracker versus Japanese Sumo wrestler). The abstract specifies that they found an elevated basal metabolic rate, which is activity independent. There is the important and interesting issue of variance. A closer look at Figure 1 one might help in this regard (alas, a paywall...).

I see in Table 1 that their average human female is 6 kg heavier than their average human male. Strange!

Might this be because of the higher % body fat in women?

I don't think so - men are heavier than women on average, e.g. https://en.wikipedia.org/wiki/Human_body_weight . Is it a mistake in the table or a weird sample?

They did select "relatively sedentary humans"; perhaps in that subset, women are heavier than men?

- Men tend to do more muscle-increasing sport than women; meaning a sedentary man isn't gaining that muscle weight.

- Women tend to do more cardio activities to burn fat; meaning an active women may be losing weight.

I suspect you're right about it being a misprint though.

>men aren't gaining that muscle weight they already have >Women tend to do more cardio activities to burn fat; meaning an active women may be losing weight.

The muscle weight is a metabolic load that requires constant caloric intake to support, sedentary women do more cardio to compensate for their otherwise low metabolism. May not be a misprint.

Women seem to heavier in my part of the world

Higher body fat is one of the reasons women are lighter than men. Muscle is higher density than fat.

Estrogen and fat are entangled.

Does that mean we would live shorter lifespans than other apes without medicine, sanitation (and all the other stuff the Romans did for us)?

I remember something about the metabolic rate being tied to lifespan.

> I remember something about the metabolic rate being tied to lifespan.

The "rate of living" theory of ageing? https://en.wikipedia.org/wiki/Rate-of-living_theory

Or possibly the free-radical one, which indirectly links metabolism to ageing via metabolic production of free radicals?

The question is whether that's cause or effect - and regardless, the correlation between metabolic rate and lifespan clearly isn't very strong (as in there are many other factors that probably matter).

In the big scheme of things, a mere 27% difference isn't all that great. I mean, heck, hummingbirds can live to be 10 which is more than twice as long as even record-breaking genetically engineered mice, despite hummingbirds having an unusually high metabolism.

The 27% difference more remarkable if you consider how similar we are to other apes. Regardless, I can't imagine that simplistically extrapolating lifespan from metabolism is particularly accurate, even if it gets you in the right ballpark.

The homo genus needs a new species: Homo Sapiens Corpulentus

There are other factors impacting one's body composition not mentioned in the article - things like testosterone levels, growth hormone levels etc.

higher energy use does not mean fatter, if you /use/ all of that energy.

Animals don't operate on the principle of "run the tank until it's empty". If they did, they would frequently die for no good reason by getting caught out at an inopportune moment. Imagine if, whenever a car ran out of gas, it exploded. You'd probably keep your car close to full, and that is what animals do too. In normal health, you can go several weeks without needing to eat.

Higher energy use means we store more energy than other animals need to. We do balance energy intake against energy output, very precisely. But we still need greater reserves, and those reserves are fat.

As long as a some specific crowd doesn't use the article as another excuse for being morbidly overweight, I'm fine with that.

The study abstract says greatest body fat percentage which isn't really the same as fatter, but when it is true across individuals it points to humans having more tissue devoted to energy storage.

http://www.nature.com/nature/journal/vaop/ncurrent/full/natu...

Agreed.

However, "making us fatter" implies causality. I don't think the paper substantiates that.

My post was more about who cares what mistakes the popularizer blog made.

It's unfortunate how poorly things get translated into the public eye, but it's also so bad that specific instances of it are pretty ignorable.

Makes sense to me

Do you mean "it made sense to me" as in "I understood it, having read it" or "I knew that already, it's obvious"

If it's the former, then good for you, you understood the text

If it's the latter then good for you, you're a genius

Either way, your understanding of it is a great contribution to the discussion. Thanks.

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