system
Given the following post, respond as if you're commenting on Reddit:
human
Why is sitting bad for us and how often would a human/primate sit naturally?

Hm, this might be a strangely-worded question. 
We've been hearing a lot about how sitting is (or can be) causing so many health problems because how stationary our lifestyles have become. 

I guess I'm a bit curious as to why sitting is such a health risk. Is it only because the amount of exercise we get throughout the day is limited? (spending more time watching television, video games, computers, sedentary occupations-less time outside walking, running, exercising)

Or is sitting itself causing issues? 
If humans were not exposed to technology or jobs that require regular sitting, how often would we be sitting? Is there a difference to how and how much we sit now compared to our past ancestors and other primates now? 


As someone who works in animation, I do a lot of sitting which got me thinking. 
Anyway, thanks to any and all answers!
gpt
Sitting, as it turns out, has played an important role in the evolution of our species. In fact, our body structure is well designed for sitting.

Not just us either. Resting is an important part of what all animals do on a day to day basis, and we all have strategies for doing it to our best advantage. Songbird feet, for example, are built in such a way that when weight is placed on the foot, the weight of the bird tightens the tendons of the foot, and the bird can perch without using any muscle strength.

Compared to monkeys, Apes spend less time lying down or hanging and more time sitting. As a result, all apes execpt for humans have what is called an ischial callosity, a large callous on their ass that allows them to sit for long periods of time without getting ass-chap.

Humans take it a step further than the rest of the apes. Because we walk upright, we need large muscles on our ass. We fill these muscles with a lot of fat on purpose because it helps us sit comfortably for long periods without bruising. We are built to sit.

So why is sitting a risk factor for heart disease, stroke, high blood pressure, diabetes, and a whole host of other epidemic conditions? The answer: we spend too much time sitting and not enough time walking. As much as humans are built to sit, we are built to walk, AND RUN! We should naturally spend a good portion of our day walking and running. EVERY DAY! But we don't. Most of us sit too much and eat too much, and that's why the statistics suggest that sitting is a risk factor.

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tl;dr sitting isn't bad, what's bad is not being active enough.   

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PS: There are ways sitting can be bad for you. Especially among elderly, it has been noted that long flights can be a risk factor for thromboembolisms (essentially a blood clot that forms somewhere in your distal arteries, makes its way to your heart and beyond). Such long periods of sitting causes the blood in your legs to circulate less. If the blood pools, it can clot, and those clots can disrupt the function of your heart or brain if they find their way to either of those places. 

However, if you have been getting good exercise lately, this shouldn't be a problem for you, as your strong heart will continue to move the blood through your legs sufficiently for the duration of the flight.

Edit: Breaking up your sitting episodes to walk around a little can certainly go a long way.