Edited for ease of reading. Re: hunter-gatherers being skinny- South Asians also have relatively skinny limbs but "fat" torsos, which like their higher risk of heart disease is thought to be due to their AASI ancestry.

I'm actually not sure about this either... I earlier on assumed this (and supported this assumption with Bergmann's rule). 

But I recall existing data stating the contrary (Mongols with longer limbs as well as narrower shoulders than northern Han, but Guangxi Han with wider shoulders). I may post the raw data here if I am able to find it sometime. Mongolian body types may be influenced by Indo-European steppe-related admixture, but I also dont find eastern tungusic groups (with less caucasoid admixture) particularly larger etc. in upper body compared to Mongols. Many northern han, korean, japanese body types may be characterized as not really resembling actual "northern" asians...



You may look at the body types of Udeges in this video.

And even if Bergmann's rule is valid, it probably would not apply as a strict rule to human populations for overall body morphology because humans simply wear thicker clothing in colder weather. Cold adaptation perhaps might apply to hands/feet and face however, as actual "tungids" do seem to have less prominent facial features (eg. smaller nose and eyes) as well as shorter-digited but fatter hands and feet. Examining data on feet size by ethnicity seems to correspond to an increasing trend from Mongolia to TW Han and Filipinos. This makes sense as these regions are exposed to cold more often (moreso hands and face, but hand and feet growth/morphology may be linked). The thin limbs of Siberians is probably related to their lifestyle being more mobile as well as less taxing on eg. fast twitch muscles of limbs than rice farming groups. 

The girl can definitely pass in Vietnam, though my experience with Vietnamese phenotypes is rather limited.

For China, I'll give 2 yes and 4 maybes. Yunnan yes she can pass, Guangxi yes, Guangdong maybe (western parts of Guangdong), Hainan maybe, Guizhou maybe, and Hunan maybe (the southern and southwestern parts of Hunan). Outside of the aforementioned yes and maybe regions, I don't think she could pass elsewhere.

Yes the guy handing her the money can definitely pass as Vietnamese or Southern Chinese, in fact he might even be able to pass as Central or Northern Chinese.

Except Chang isn't a Cantonese surname, it's most likely Taiwanese.

If no more details were provided, then there's no way for you to know for certain that everyone in that photo was Cantonese. These guys don't look that Cantonese to me but rather Pan Chinese or Pan East Asian, and there're 2 guys in the front row that look hyper northern.

Maybe the Cantonese that I'm more familiar with are from Western GD or GX, whereas they could be from the Pearl River Delta. Anyways, they don't look Cantonese to me.

Hunter-gatherers living in tropical regions tend to be skinny that I largely agree, but those from polar or subpolar regions aren't skinny at all. The Tungusic peoples, the Mongols, the Inuits, and certain North American natives are quite stocky and strong and it would be lying to say that they're all skinny. Neither their limbs nor their torso are skinny.

You and throway2 need more reality check.

LOL, you definitely need some reality check. Mongols have narrow shoulders and longer limbs? What are you smoking? And GX people don't have wide shoulders or frames either, on the contrary they probably have the smallest frame out of all Chinese, along with people from Guizhou, Yunnan, Guangdong, and Hainan. Ask any Chinese and they'll likely tell you the same thing as what I said.

Northern populations (Mongols, Tungusic peoples, Korean, Japanese, and Northern Chinese, etc.) tend to have longer torsos but shorter limbs, whereas southern populations tend to have shorter torsos and longer limbs. The Nilotic people of tropical Africa have the longest limbs in proportionate to their bodies, proving what I said is true. SE Asians have higher Manouvrier's skelic index/Stem-leg length index than East and North Asians, again proving my point.

I think both Bergmann's rule and Allen's rule apply to humans.