A research team from the University of Tokyo, Tokyo Metropolitan University, Kyushu University, and others has shown that descendants of the Jomon people may have inherited a “heat-generating physique” that lets them raise their body temperature by burning fat, without shivering.
On 5ch, the finding that people with more Jomon-derived genetic ancestry tend to be more prone to obesity sparked detailed discussion about obesity rates and body types in regions like Hokkaido, Okinawa, and Kagoshima, said to carry stronger Jomon genetic ancestry.
Research conducted at the University of Tokyo, Tokyo Metropolitan University, and Kyushu University in Japan has shown that the ancestors of the Jomon people may have evolved a “heat-generating physique” — the ability to burn fat and warm their bodies without shivering — in order to survive the last ice age.
(details omitted)
Our bodies have two switches for fighting off the cold.
Source: nazology.kusuguru.co.jp / Original article here
7AnonymousAug 24, 2026 20:13
So… what happens once you know that? 🤣
12AnonymousAug 24, 2026 20:15
Re: #7
Think for yourself, lol
15AnonymousAug 24, 2026 20:15
Re: #7
Dressing light in winter as a diet method — now that's revolutionary
21AnonymousAug 24, 2026 20:17
Sweaty fat guys are Jomon descendants?
If that's true, Tohoku, Hokkaido, and Okinawa should be overflowing with fat people, right?
Rejected.
139AnonymousAug 24, 2026 21:57
Re: #21
Actually, obesity rates in Tohoku, Hokkaido, and Okinawa ARE high
23AnonymousAug 24, 2026 20:18
I don't see many fat people in Hokkaido though
31AnonymousAug 24, 2026 20:19
Re: #23
I went to Hokkaido three years ago, and people there seemed less "fat" and more "big-boned." Even the thin ones had sturdy, solid frames.
26AnonymousAug 24, 2026 20:18
So the pervert who's always stripping naked was right all along
43AnonymousAug 24, 2026 20:23
Re: #26
If we're all in this together, maybe we shouldn't be so quick to deny each other's strengths?
35AnonymousAug 24, 2026 20:20
(;゚Д゚) So does that make skinny me… "Yayoiken" (likely meant "Yayoi lineage" — 弥生系 — probably a typo)?
49AnonymousAug 24, 2026 20:26
Re: #35
Baldness is a continental (Yayoi) trait, lol
46AnonymousAug 24, 2026 20:25
If you skimp on heating in winter, you'll have lost weight by early spring.
Though it's not exactly a healthy way to diet.
51AnonymousAug 24, 2026 20:27
So the generally-disliked sweaty fat guys might be the Jomon type.
Maybe the reason the Jomon lineage got wiped out was some kind of genetic aversion response.
A gene everyone hates.
53AnonymousAug 24, 2026 20:30
I see — so I'm not fat, I just have strong Jomon blood
55AnonymousAug 24, 2026 20:31
Re: #53
Be careful
You'll get wiped out
56AnonymousAug 24, 2026 20:31
Re: #53
You're still fat either way though, no?
72AnonymousAug 24, 2026 20:41
The traits everyone hates are probably Jomon characteristics:
Fat
Sweaty
Bald
Coarse body hair
Body odor
Bald
If any of this sounds like you, brace yourself.
The Yayoi won't let you escape.
82AnonymousAug 24, 2026 20:48
Re: #72
Got some kind of grudge against bald guys?
85AnonymousAug 24, 2026 20:51
My arm hair is sparse
Beard only grows around my mouth
Shovel-shaped teeth
Normal shin hair
Flat facial features
Bald
High alcohol tolerance
Curly hair
Pretty much all Yayoi genes
117AnonymousAug 24, 2026 21:33
Re: #85
Same as me, except for the "bald" part.
Middle-aged guy here, 174cm and about 72kg.
110AnonymousAug 24, 2026 21:23
So doesn't that mean I could lose weight just by exercising!?
114AnonymousAug 24, 2026 21:27
You don't need to be a Jomon descendant to figure this out.
Why burn fat to stay warm?
If you gather firewood, there's no need to carry extra fat, and no need to deliberately burn it either.
It's genuinely inefficient.
There must have been a scenario where this trait was advantageous, which is why the ability survived.
A scenario where you're forced to stay in a cold place.
A scenario where you need to consciously raise your body temperature there.
And without moving your body.
So what does that body heat actually do?
It improves physical performance.
Lying in wait for prey.
Hunting.
Re: #110
Exactly.
A constitution that gains fat easily and also burns it easily.
And one more thing —
muscle builds up just as easily too.
119AnonymousAug 24, 2026 21:35
This is amazing.
I wonder if people with high body temperature have more brown fat cells.
If we could someday inject the genes for more brown fat cells, we'd be all set for the next ice age.
125AnonymousAug 24, 2026 21:41
Re: #119
You can't burn calories you never ate.
What you'd actually want for the next ice age is someone who can stay warm through the power of civilization without burning fat —
a low-calorie, eco-friendly human who can survive on scarce food.
That might not be the Jomon people.
It might be you.
120AnonymousAug 24, 2026 21:37
Jomon bodies are surprisingly tough.
They wouldn't even collapse under conditions that would normally cause death from overwork.
But they can't defy the laws of physics.
The payback for that toughness — for all the strain put on the body — always comes due later in life.
Jomon people perform best living "short and intense."
Sprinters of life.
172AnonymousAug 24, 2026 23:34
Re: #120
To begin with, the short lifespan of Jomon people wasn't purely a physical issue
141AnonymousAug 24, 2026 22:00
So does that mean I can lose weight by just blasting the AC?
145AnonymousAug 24, 2026 22:18
Re: #141
(°∀°) Skip dinner and you'll slim right down. What's the point of eating right before bed? Though personally I still eat and drink booze anyway.
(°∀°)つ Black oolong tea
(/◎＼) *glug glug*
148AnonymousAug 24, 2026 22:21
Why are there so many overweight people in Hawaii?
171AnonymousAug 24, 2026 23:13
Re: #148
Well, not just Hawaii — people living on Pacific island nations could catch plenty of fish, so they got animal protein easily.
On the other hand, sugary fruit was scarce, so genes efficient at absorbing what little sugar there was survived and spread.
…But once modern society brought in lots of sugary food, that same genetic efficiency meant they absorbed too much sugar,
making them prone to weight gain, apparently. Same goes for Japanese people — basically, human food environments have changed drastically in a short span of time,
and it feels like our bodies and genes just haven't caught up.
149AnonymousAug 24, 2026 22:28
People from Honshu outside Tohoku only carry about 10% Jomon genes, so it's not that relevant.
Now that you mention it, people from Kagoshima and Okinawa, where Jomon ancestry is strong, do tend to be sturdy and a bit stocky.
200AnonymousAug 25, 2026 01:35
Re: #149
By Y-haplogroup it's actually 40%.
Trying to downplay indigenous genetic ancestry
is a form of discrimination against indigenous peoples —
and that includes denying your own ancestors.
168AnonymousAug 24, 2026 22:55
Published in Nature on November 12, 2024 — BioBank Japan (BBJ) genome analysis of Japanese people by region (171,287 individuals)
The study found that a "triple structure" broadly applies to the genetic origins of modern Japanese people, with the proportion of Jomon ancestry varying significantly by region and individual.
The proportion of Jomon ancestry strongly correlated with modern obesity risk and elevated BMI.
Within the Ryukyu Islands (26.1%), Jomon ancestry levels are elevated, with the highest proportion observed on Yoron Island (Figure 2b).
It's even higher in the Hokkaido subpopulation (mixed Ainu) at 31.6% (Figure 2c), a subpopulation drawn mainly from a subset of 139 individuals from Hokkaido.
The Kinki region shows a relatively low level of Jomon ancestry (9.8%). This reflects the region's long-standing role as a political center, suggesting more frequent interaction with people arriving from the Asian continent than in other regions.
177AnonymousAug 25, 2026 00:04
But in winter, Westerners seem oddly prone to dressing lightly, don't they?
181AnonymousAug 25, 2026 00:14
Re: #177
In cities, winters are often hot indoors because of the heating.
Even I often feel like stripping down to just a T-shirt on the subway.
179AnonymousAug 25, 2026 00:12
> As for Europe, it's a mere 8%.
Even the Europeans like Erik the Red who reached Greenland
ultimately failed to establish a lasting settlement there.
It's Danish territory now, but
90% of the population is Inuit, with very few white people.
But the Inuit — or Eskimo, whatever you call them — being a people closely related to us, are incredibly resistant to cold.
Well, even Hokkaido was something Japanese people avoided; serious settlement there didn't really start until the Meiji era, lol
180AnonymousAug 25, 2026 00:14
Re: #179
It's less that Honshu people "disliked" Hokkaido, and more that it was remote, already had indigenous people living there, and was too cold for farming to be practical, no?
Background and Key Points
Japan’s population genetics has long rested on the “dual structure” model proposed in the 1990s: Jomon hunter-gatherers, present in the archipelago from roughly 16,000 to 3,000 years ago, mixed with Yayoi-period rice farmers who arrived from the continent starting around the 3rd century BCE, and modern Japanese are a blend of the two. The BioBank Japan analysis cited in the thread (Nature, November 2024, 171,287 individuals) refined this into a “triple structure” and, crucially, quantified regional variation: Jomon ancestry runs around 26% in the Ryukyus, over 31% in the Hokkaido subpopulation, but only about 10% in Kinki, the historic seat of government where continental contact was heaviest. The physiological claim — that Jomon-associated variants support non-shivering thermogenesis, burning fat via brown adipose tissue rather than shivering — is presented as an ice-age cold-adaptation, with the tradeoff being higher modern obesity/BMI risk, a “thrifty gene” pattern similar to what’s documented in Pacific Islander and Inuit populations.
The thread’s actual disagreement wasn’t over the genetics but over lived observation: posters initially doubted the obesity link because Hokkaido “doesn’t look full of fat people,” only for others to push back with actual regional obesity-rate data supporting the correlation, and a separate dispute over whether Jomon ancestry in Honshu is ~10% (autosomal) or ~40% (Y-haplogroup) — different methods measuring different things, a distinction no one in the thread actually resolved.
What’s likely misunderstood: “Jomon ancestry” here is a statistical genome-wide component, not an ethnic or indigenous identity marker, and the thread’s casual Jomon/Yayoi physical stereotyping (baldness, body odor, sturdiness) has no basis in the actual study, which only ties ancestry proportion to obesity/BMI risk.
*This article is excerpted and summarized from the 5ch (News Speed+) thread “[Study] Jomon People Could Burn Fat to Warm Their Bodies — a “Heat-Generating Physique”; The More Jomon Genetic Ancestry a Person Has, the More Prone to Obesity They Tend to Be“.
