How Many Equations of Motion Describe a Moving Human?
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Re: How Many Equations of Motion Describe a Moving Human?
#2This is tangentially related. Do you know why we have hair in armpits but not on back of the knees or on inner side of the elbow (between biceps and forearm)? Both knee and elbow can move in a way that skin touches itself (just like armpit), but the knee and elbow have only 1 degree of freedom, no matter how you move them, the skin cannot rub on itself. Skin can only rub on itself in armpit (2 degrees of freedom), groin (2 degrees of freedom), and butt crack (technically 1 degree but they are very close together and fulcrum are hips which are far apart not like single-jointed elbow so it can rub on itself).
Re: How Many Equations of Motion Describe a Moving Human?
#3This is tangentially related. Do you know why we have hair in armpits but not on back of the knees or on inner side of the elbow (between biceps and forearm)? Both knee and elbow can move in a way that skin touches itself (just like armpit), but the knee and elbow have only 1 degree of freedom, no matter how you move them, the skin cannot rub on itself. Skin can only rub on itself in armpit (2 degrees of freedom), gr…
Not sure that holds up to strict scrutiny. It's a fine hypothesis for the armpit but makes no sense with the groin. There the hair is heaviest on skin that touches nothing else and almost indistinguishable from background on the actual sliding surfaces. Same for butt crack.
Re: How Many Equations of Motion Describe a Moving Human?
#4Omg!
You cant derive science from first principles and give up all the physics/maths techniques used in the last 200 years.
They didn't even take into account the error would increase is the you added more time derivatives.
Re: How Many Equations of Motion Describe a Moving Human?
#5This is tangentially related. Do you know why we have hair in armpits but not on back of the knees or on inner side of the elbow (between biceps and forearm)? Both knee and elbow can move in a way that skin touches itself (just like armpit), but the knee and elbow have only 1 degree of freedom, no matter how you move them, the skin cannot rub on itself. Skin can only rub on itself in armpit (2 degrees of freedom), gr…
Because we have sweat glands for pheremones in our armpits. The main theory is that armpit hair serves to waft that.
We don't have those types of glands on the backs of our knees or inner side of elbow, etc. So no extra hair there, and no need for antiperspirant there either.
Re: How Many Equations of Motion Describe a Moving Human?
#6> With animate objects, though, and with humans, in particular, we do not know the cardinality of the set of equations that define their trajectory.
Does it really matter? You can imitate human motion by multiplying a bunch of matrices to the point that the difference with "reality" is negligible. Learning Blender is the hardest part.
Re: How Many Equations of Motion Describe a Moving Human?
#7This is tangentially related. Do you know why we have hair in armpits but not on back of the knees or on inner side of the elbow (between biceps and forearm)? Both knee and elbow can move in a way that skin touches itself (just like armpit), but the knee and elbow have only 1 degree of freedom, no matter how you move them, the skin cannot rub on itself. Skin can only rub on itself in armpit (2 degrees of freedom), gr…
The information content in hair distribution is substantial. The genetic program for facial hair must have dozens of bits. Like eyebrows are a pretty specific shape in a specific place.
Eyebrows may have a practical function (avoiding sweat dripping into the eyes) but I suspect the main evolutionary pressure is through mate selection. People with eyebrows halfway up their forehead or below their eyes were sufficiently unattractive that those combinations of genes didn't propagate.
Since hair for the whole body is presumably encoded by some very non-modular genes, hair distribution on parts that aren't important for function or appearance may just be side-effects of changes that affected parts that are important.
Our species lost most of its body hair fairly recently, so the evolution of hair patterns is relatively incomplete.
Re: How Many Equations of Motion Describe a Moving Human?
#8This is tangentially related. Do you know why we have hair in armpits but not on back of the knees or on inner side of the elbow (between biceps and forearm)? Both knee and elbow can move in a way that skin touches itself (just like armpit), but the knee and elbow have only 1 degree of freedom, no matter how you move them, the skin cannot rub on itself. Skin can only rub on itself in armpit (2 degrees of freedom), gr…
The information content in hair distribution is substantial. The genetic program for facial hair must have dozens of bits. Like eyebrows are a pretty specific shape in a specific place. Eyebrows may have a practical function (avoiding sweat dripping into the eyes) but I suspect the main evolutionary pressure is through mate selection. People with eyebrows halfway up their forehead or below their eyes were sufficientl…
> People with eyebrows halfway up their forehead or below their eyes were sufficiently unattractive that those combinations of genes didn't propagate.
What we find attractive is also genetically determined, though. If very fit (in an evolutionary sense) people started to develop eyebrows half way up their face, that would quickly lead to a population of people who found that hot.
Re: How Many Equations of Motion Describe a Moving Human?
#9This is tangentially related. Do you know why we have hair in armpits but not on back of the knees or on inner side of the elbow (between biceps and forearm)? Both knee and elbow can move in a way that skin touches itself (just like armpit), but the knee and elbow have only 1 degree of freedom, no matter how you move them, the skin cannot rub on itself. Skin can only rub on itself in armpit (2 degrees of freedom), gr…
The information content in hair distribution is substantial. The genetic program for facial hair must have dozens of bits. Like eyebrows are a pretty specific shape in a specific place. Eyebrows may have a practical function (avoiding sweat dripping into the eyes) but I suspect the main evolutionary pressure is through mate selection. People with eyebrows halfway up their forehead or below their eyes were sufficientl…
The main theory I'm aware of is that eyebrows serve to better communicate facial expressions, on top of being a sweat guard.
Our eyebrow region is exceedingly expressive in terms of movement, similar to our mouth when not speaking (think of all the variations of smiles, frowns, smirks, etc.). The bands of hair make it much easier to identify that movement, especially from a few meters away. Eyebrows are for direct emotional signaling.
Re: How Many Equations of Motion Describe a Moving Human?
#10This is tangentially related. Do you know why we have hair in armpits but not on back of the knees or on inner side of the elbow (between biceps and forearm)? Both knee and elbow can move in a way that skin touches itself (just like armpit), but the knee and elbow have only 1 degree of freedom, no matter how you move them, the skin cannot rub on itself. Skin can only rub on itself in armpit (2 degrees of freedom), gr…
Not sure that holds up to strict scrutiny. It's a fine hypothesis for the armpit but makes no sense with the groin. There the hair is heaviest on skin that touches nothing else and almost indistinguishable from background on the actual sliding surfaces. Same for butt crack.
Hair act as mechanical lubricant.