No one has ever heard that sentence. Not once in all history. You have to admire a sentence like that. It’s got character.
I have replicated and reproduced your results! Nobel is in the mail!
Demonstrated effect of chewing on jaw size only in young children. And it has to be very tough. We don’t eat meat, or any food, that is very tough. You really want something more like a chew toy.
No demonstrated effect on jaw size in adults. But stressing bones in the right way can make you develop thicker/stronger bones. So although a chew toy won’t give you a “stronger jaw”, it might give you a stronger jaw.
Hey, some of us like our steak well done. 
If chewing grew the jaw, wouldn’t gum have a greater affect than rice?
You don’t understand. Your jaw bone itself doesn’t have to grow bigger to give you the appearance of a bigger jaw. You have muscles on the side of your jaw that you can grow, just like any other muscle.
Maybe if you provided some examples we’d see what you are talking about. Human cheek muscles don’t usually bulge noticeably.
Or maybe not.
Maybe Chinese people secretly do special chewing exercises at night when no one’s looking.
Or maybe not.
Maybe Chinese people only pretend to eat rice, and actually their jaws are bigger because they live on the other side of the earth, where gravity is reversed.
Or maybe not.
I hope you’re being facetious and not serious.
If you are being serious, how many of the ~1.5 billion Chinese people spread across 3,700,000 sq mi (many of which, especially in the North, eat primarily wheat not rice) have you observed to have “bigger jaws and cheekbones”? 
I would hazard a guess that many of those you’ve observed are from a particular part of China whose genetics tends towards that trait.
I’m Japanese, but through personal interactions, movies, TV and pics have seen thousands (possibly tens of thousands) of Chinese faces and while there are certain facial characteristics (which are impossible for me to fully describe), “bigger jaws and cheekbones” are not always a defining factor.
I suggest searching for “Produce 101 China” on Youtube for an example of the diversity of 101 (102 including judge Ella Chan) Chinese beauties vying for a chance to be a Chinese girl pop group.
BTW, Japanese and Koreans probably eat more rice per person compared to those persons in China who do eat rice. Also, it’s primarily short grain rice which is more glutinous and sticky, requiring more chewing that the typical Chinese long grain rice. Do you see lots of Japanese and Koreans with “bigger jaws and cheekbones”?
Just to add a random data point, my former house mate, who is half Chinese, told me he had dental problems because he’d apparently inherited a too small jaw from the Chinese side of the family, and his teeth, which appeared to be from the white British side of the family were too big for it.
His dentist apparently told him that this was common amongst those of mixed Chinese/European descent, because Chinese people’s teeth and jaws were, on average, slightly smaller proportionately than European ones.
Face shapes do vary from place to place.
I have heard anecdotally that the big three cosmetic procedures here in China are: “double eyelid” (i.e. make the eyes larger and more Western shaped), narrowing/lifting of the nose and…buccal fat removal (removing fat from the jaw to make the chin more defined and the face narrower).
So, what I’m saying is, there may be truth to some kinds of wide face shapes being more common in East Asia. However it seems to be largely genetic, and not because of eating rice (which, let’s face it, is among the easiest foodstuffs to chew).
For kicks and giggles, http://alllooksame.comwhile this site has been around for years, it may be new to some of you. And if you’ve already taken the test, take it again since you know the twist…(scroll down for the spoiler).
The site does require to you register to take the test, but it doesn’t require any real info or real email address.
SPOILER:
The people chosen have facial, hair, makeup and pose characteristics that are viewed as (stereo)typical for the nationalities represented. I just took the test again and scored 10 out of 18 because I forced myself not to go with my first guess since I knew the twist.
Chew chew training.
Note: This site supports SPOILER tags, which allow spoilers that require a click to open, without taking up large amounts of space in a thread for scrolling down for spoilers.
It’s not new.
Rice doesn’t require any chewing at all. It breaks up into its little bits and you can just swallow it. Have you eaten rice? Bread on the other hand actually does require chewing.
If heavy chewing caused jaws to get bigger, all grazing animals (cows, horses, giraffes, etc) would have look like Quagmire from Family Guy! 