What is the Optimum Temperature with respect to human mortality?

By Indur M. Goklany

It is well known that the risk of mortality increases at both the high and low ends of the temperature range experienced by a particular population.[1],[2],[3] Therefore, there should be a temperature at which that population’s risk of mortality is at a minimum. [There, however, may be more than one “local” minimum in a graph of mortality risk versus temperature as one proceeds from the lowest to highest temperatures.]

Recently, Guo et al. (2014) undertook a systematic evaluation of the variation in the risk of mortality from non-accidental causes as a function of daily mean temperature in 12 countries. The figures below display their results. They used mortality data for multiple years (ranging from 10 years for Thailand to 38 years for Japan) for 306 communities in the 12 countries, and pooled the data for the communities in each country to derive these figures.

Note that the temperature on the x-axis for each graph is measured in terms of the percentile of the temperature range rather than the actual temperature (in °F or °C). Also, their methodology was designed to account for deaths that occurred over the following 21 days, since additional deaths from exposure to hot or cold temperatures are known to occur for several days subsequent to actual exposure. [The period over which these deaths occur is longer for cold temperatures than for hot.] Their methodology also apparently accounted for “mortality displacement” or “harvesting,” which is the concept that temperature-related deaths that occur in a vulnerable population immediately following the temperature exposure would be partially offset by fewer deaths in that population over the following weeks.[4]

These graphs show that:

· The relative mortality risk for each country is at a minimum between the 66th and 80th percentile of mean temperature. Nine of the twelve countries have an “optimum” temperature between the 72nd and 76th percentiles.

· For each country the relative mortality risk is substantially higher at the 1 percentile temperature (cold end) than at the 99th percentile (hot end).

· Remarkably, the above bullet points hold not only for relatively cold countries such as Canada and South Korea but also the relatively warm ones such as Brazil and Thailand.

The study also reports that, “The minimum-mortality temperatures were higher in countries with high temperature or in countries close to equator.”

What all this means is that, first, because (a) there are more days during the year that are cooler than the optimum, and (b) relative risk is higher at the cold end than the warm end, more deaths should be associated with temperatures that are colder than optimum than those that are warmer. Hence, if global warming merely slides each curve to the right wholesale, total mortality during the year should drop. But, in fact, global warming is supposed to warm winters more than summers — even so-called Skeptical Science acknowledges this! Therefore, we should get a double dividend from global warming in terms of reduced global mortality.

clip_image002

Figure 1: Relative risk of mortality (y-axis) as a function of mean daily temperature plotted as the percentile of the entire temperature data. Data for each country was pooled. Source Guo et al. (2014).

In summary, there is an optimum temperature which minimizes mortality for any given population, and it is toward the warmer end of what that population generally experiences. Specifically, it is at about the 70th–75th of the mean temperature to which that population is exposed. Finally, if there is any doubt about it, there is a good health-based rationale for:

· The general preference for warm temperatures,

· For taking winter vacations in warm places and summer vacations in cold places,

· For retiring to warmer climes!


References

 

[1] McMichael, Anthony J., et al. “International study of temperature, heat and urban mortality: the ‘ISOTHURM’project.” International journal of epidemiology 37.5 (2008): 1121-1131.

[2] Keatinge, W. R. “Winter mortality and its causes.” International Journal of Circumpolar Health 61.4 (2002).

[3] Guo, Yuming, et al. “Global variation in the effects of ambient temperature on mortality: a systematic evaluation.” Epidemiology 25.6 (2014): 781-789.

[4] Deschenes, Olivier. “Temperature, human health, and adaptation: A review of the empirical literature.” Energy Economics 46 (2014): 606-619.

Note: an earlier version of this essay rfereenced the”y-axis” corrrected to “x-axis”.  h/t to  “joelobryan on March 2, 2015 at 2:49 am.”

0 0 votes
Article Rating

Discover more from Watts Up With That?

Subscribe to get the latest posts sent to your email.

142 Comments
Inline Feedbacks
View all comments
March 2, 2015 1:20 am

Similar conculsions by Heald e.a. about parts of Europe: more mortality by cold snaps than by warm snaps and warm mortality is compensated by less mortality in the months after the hot spell, not so after a cold spell.
See Heald e.a.:
http://www.bmj.com/content/321/7262/670.full
Similar for cities in the US:
http://aje.oxfordjournals.org/content/155/1/80.abstract

ferdberple
Reply to  Ferdinand Engelbeen
March 2, 2015 6:33 am

Canada has the flattest mortality graph. Obviously the invention of the touque has saved many lives.

urederra
Reply to  ferdberple
March 2, 2015 7:48 am

Those are not absolute mortality graphs. They just show that it is more likely to die on a cold spell than in a warm spell.

george e. smith
Reply to  ferdberple
March 2, 2015 11:30 am

The essay describes such a litany of “we fixed this and adjusted that” changes in the data that I doubt that the results mean anything at all.
Looks like the authors found another way to fold an origami paper.
At the moment, it is not at all clear what it is supposed to look like; except it is not supposed to be a crane, or a swan.
Do people get paid to do this stuff ??

george e. smith
Reply to  ferdberple
March 3, 2015 4:57 pm

We’re supposed to believe that people can tie someone’s death to global Temperatures when the entire range of the risk involved is from 1.0 to 1.3.
How many death certificates ever state the cause of death was either global warming or global cooling.
Why is it risky to be in the middle where all the countries have a bump upwards.
I think you could get better results just by playing darts. Specially if you do it in a pub over a couple of tankards.
I think there must be a competition going on in academia, to see which school can devise the most idiotic proposition to present for a research grant.
Earth Temperature is generally in the range of -90 deg. C to + 60 deg. C, and there are lots of people living and surviving over a good bit of that range.
A shift of a half a deg. C over a century is not likely to have any measurable effect on global mortality rates.

Rob
March 2, 2015 1:29 am

Heart attacks are much more frequent in cold weather.

Hugh
Reply to  Rob
March 2, 2015 3:58 am

Accidental reasons like drowning and wrecking one’s car are very much more common when the temperatures are good for convertibles and open-air swimming with a beer bottle at hand.
I mean, yeah, you can be dead as a victim of global warming, but at least you were enjoying it.

george e. smith
Reply to  Rob
March 3, 2015 5:01 pm

Because of what people do; not because of the weather.
If you go swimming in the southernmost point of the Ross Sea, then you deserve to have a heart attack.

March 2, 2015 1:39 am

So why is there are relative rise in mortality around the 50th percentile?
Most boring weather causes ennui and thus a rise in suicides? That seems unlikely but is the best I can come up with.
It’s particularly noticeable on the UK chart but seems common to many of the countries.

mikewaite
Reply to  M Courtney
March 2, 2015 2:55 am

It would be interesting to follow up some of the refs to see if the causes of death , eg cardiac v disease v dehydration etc are available in a similar analysis .
I wonder if the peak at 50th percentile in the UK is associated with the fairly mild , humid, windless and cloudy weather that a friend always calls “bug breeding weather”.

Reply to  mikewaite
March 2, 2015 3:23 am

Yes, that makes sense.
The median temperature for the area is the temperature that flora and fauna have evolved to thrive in.
That includes man’s predators, viruses and bacteria.
We face a greater challenge in the middle temperature. And the misty, humid UK is particularly vulnerable to diseases.

Bill_W
Reply to  M Courtney
March 2, 2015 3:26 am

Because temperatures are near the median more often? So just a statistical feature? Did not read the details of how they did the study so this is just an educated guess.

steveta_uk
Reply to  Bill_W
March 2, 2015 4:15 am

Exactly – for UK, temp spread is approx. 0 to 35C – but vast amounts of the year are between 15 and 20C.

george e. smith
Reply to  Bill_W
March 3, 2015 5:05 pm

Half of the pedestrians killed on the roads in the USA, are killed on pedestrian crossings when they had the right of way.
No it has nothing to do with “that’s where everyone crosses the road.”
It’s because that is the widest part and cars can get you from four directions at once.
If the rule was; “Either cars move, or pedestrians move, but NEVER both at once”, then nobody would be killed on a pedestrian crossing.

Duster
Reply to  M Courtney
March 2, 2015 11:00 am

The extremes are periods of lower activity. People stay inside or in the shade and minimize activity. The median range however is where activity peaks, so you expect more deaths due to accidents. Whereas the extremes are the weather itself is lethal.

GJK
Reply to  M Courtney
March 2, 2015 6:41 pm

The subsidiary peak occurs for all the countries shown, even Canada [albeit only very slight].
Possibly people feel comfortable at the 50 percentile and engage in more outside activities with an accompanying rise in accidents/deaths……bicycle riding for instance, or playing around with powerboats or water skiing ??
Maybe.

thingadonta
March 2, 2015 1:45 am

Warmer temperatures also generally means more precipitation on a world wide basis, meaning more food, better health, better malnutrition and less starvation.

Brute
Reply to  thingadonta
March 2, 2015 2:10 am

You must mean “better nutrition” or “less malnutrition”.

Brian
Reply to  thingadonta
March 2, 2015 10:29 am

If you go to the warmest extreme the microorganisms get rather virulent.

JKnapp
March 2, 2015 1:50 am

This analysis doesn’t say anything about Global Warming mortality. For that, one would have to test if a population such as UK with its existing temp/mortality curve were to be slowly transferred to an Italy (for example) temp/mortality curve would there be more or less deaths. I.e. is there a systematic difference in the curves in populations in warm versus cold climates. (I’m assuming that it is the climate that is the independent variable not the population).
Especially the way the study is done, with temperature given as a % of temperature data. If the average increases why would one assume that the curve would change shape rather than just slide up a comparable amount.
People are adaptable after all.

Ian
Reply to  JKnapp
March 2, 2015 2:06 am

This study could be done now, my family emigrated from England to Australia in the 70’s, along with significant numbers of similar families. Someone just has to sought the data and ask the right questions.

Jimbo
Reply to  JKnapp
March 2, 2015 2:59 am

JKnapp
March 2, 2015 at 1:50 am
…..People are adaptable after all.

Yep, people have mostly adapted to the cold by wearing clothes and better shelters. Humans are basically tropical animals. It is also pointed out that our optimal air temperature on land is 27°C.

A naked person will start to feel cold if the surrounding temperature drops below around 25°C (77°F). Physiological responses such as shivering and diverting blood away from the extremities and surface of the skin will then kick in.

The IPCC acknowledges that ‘warmer’ winters should result in a “decrease cold-related mortality”. I may be mistaken but I vaguely recall that under global warming most of the ‘warming’ will be felt at night, in winter and as you head away from the equator and towards the poles.
You now have to wonder why global warming will kill more people.

Jimbo
Reply to  Jimbo
March 2, 2015 3:02 am

I forgot the link for the quote: “…..below around 25°C (77°F)….”
http://www.coolantarctica.com/Antarctica%20fact%20file/science/cold_humans.htm

Reply to  Jimbo
March 2, 2015 4:24 am

You now have to wonder why global warming will kill more people.

You have to remember: these fanatics don’t care about people, just victims. They also place a high value on animal life.

ferdberple
Reply to  Jimbo
March 2, 2015 6:24 am

Below about 82F (28C), which is the temperature of the tropical jungles, the naked human cannot generate enough energy to overcome radiated heat loss (about 150 watts). We died of exposure.
This suggests that we originally evolved in the jungles, and that the tropical jungles are about the same temperature today as they have been for the past couple of million years.

Eliza
March 2, 2015 1:55 am

Also the warmer it is (and humid), the happier are the people see here
http://www.google.com/#q=happiest+people+paraguay LOL

Editor
Reply to  Eliza
March 2, 2015 6:44 am

Perhaps Paraguay people are happier, but my 75% Swedish genes detest dew points over 70°F and aren’t real fond with them over 60°F. Then again, my idea of a good time is hiking in the mountains or a long bicycle ride, not lying on a beach.

Admin
March 2, 2015 2:04 am

Too right – here in tropical Hervey Bay, where the daytime temperature rarely drops below 60F, and is usually a lot higher, the gravest risk to my life is the risk of being run down by a pensioner in a souped up mobility scooter!

Bloke down the pub
March 2, 2015 2:15 am

In the UK, our bog standard weather tends to occur when the wind is blowing in off the Atlantic. Our extremes of hot and cold are most likely when there is little wind or it’s blowing in off the continent. I suspect that the UK mortality figures are affected by the wind direction in addition to the temps.

Duster
Reply to  Bloke down the pub
March 2, 2015 11:05 am

AN interesting a viable suggestion. In southern California they get the Santa Anas, which are miserable winds that blow off the deserts, over the San Gabriels and out to sea. Homicide rates are roughly doubled during Santa Anas.

March 2, 2015 2:25 am

I recall Richard Tol claiming in one blog debate that there is an optimum climate and it is the climate of Florence. At first I thought he was joking. The relativism of this result makes more sense to me, and it is just one more thing making it hard to take seriously the cost/benefit analysis of the economists.

Hugh
Reply to  berniel
March 2, 2015 4:19 am

“At first I thought he was joking”
He was. The optimum is the climate of Madeira.

David Chappell
Reply to  Hugh
March 2, 2015 7:33 am

especially when accompanied by its namesake beverage.

ferdberple
Reply to  berniel
March 2, 2015 6:26 am

Regardless of country the optimum temperature is around the 75th percentile. what this shows is that human adapt to a wide range of regional temperatures without the slightest regard for global temperatures.

Ben Palmer
March 2, 2015 2:29 am

“Results and Conclusions: Three of the studied meteorological factors (daily average temperature, atmospheric pressure and relative humidity) all have relevant and significant influences on ACS incidences for the entire population. However, the ACS incidence for the population over 65 is only affected by daily average temperature, while the ACS incidence for the population under 65 is affected by daily average pressure and humidity. In terms of ambient temperature, the overall findings of our study are in line with the findings of the majority of contemporary European studies, which also note a negative correlation. The results regarding atmospheric pressure and humidity are less in line, due to considerable variations in results. Additionally, the number of available European studies on atmospheric pressure and humidity is relatively low. The fourth studied variable—season—does not influence ACS incidence in a statistically significant way.”
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4245633/

Dodgy Geezer
March 2, 2015 2:36 am

One comment might be that mortality increase occurs when a population encounters UNUSUAL weather. But you need to look at the culture to predict what kind of unusual weather would be worst.
A population is (we assume) adapted to living in a particular temperature range – this adaptation includes physiological features, environmental features such as house type, and behavioral features such as methods of working and relaxation. All these will be optimised for the local weather conditions.
You need to look at these adaptations and predict how well they will stand either higher or lower temperatures. For instance, igloos can probably withstand extreme cold, but may collapse in a hot spell. A culture where the young girls go out night-clubbing with minimal clothing is likely to suffer if the weather gets cold.

Reply to  Dodgy Geezer
March 2, 2015 2:43 am

Dodgy, ++++

Reply to  Dodgy Geezer
March 2, 2015 2:55 am

A culture where the young girls go out night-clubbing with minimal clothing is likely to suffer if the weather gets cold.
You can easily disprove this theory by going to Newcastle-upon-Tyne, UK (Newcastle NSW may be different).
There, on any winter weekend, you can see girls in minimal clothing and men in T-shits, complaining that the snow is too hot.
The only physiological change I can determine is that the girls legs, if not fake-tanned, are a rather fetching blue colour.

Hot under the collar
Reply to  soarergtl
March 2, 2015 4:30 am

In Newcastle-upon-Tyne have you factored in the ‘warming effect’ of “Newcastle Brown” ale? : )

AndyG55
March 2, 2015 2:40 am

I’m near Newcastle, NSW Australia. and I can tell you that the only reason anyone here takes summer in a colder place is for the skiing.
Long weekend in summer, everyone is heading up the coast, especially from Sydney, roads are jam packed !!
(heading north means warmer down here)
Even in summer, most people from somewhere as nice and warm and ideal as the mid coast of NSW….
STILL seek somewhere warmer. !!

Admin
Reply to  AndyG55
March 2, 2015 4:29 am

NSW coast – BRRRR. Try Queensland coast 😉

Leonard Lane
Reply to  Eric Worrall
March 2, 2015 10:42 pm

Spot on! But Sunshine Coast is better than Gold Coast, IMO. Toowoomba is nicest in summer though.

March 2, 2015 2:49 am

Note that the temperature on the y-axis for each graph is measured in terms of the percentile of the temperature range rather than the actual temperature (in °F or °C).
Should read “x-axis.”
[please verify it is now properly edited. .mod]

ren
March 2, 2015 2:53 am

It will be difficult days in the north-eastern US. First, freezing rain, frost later come back.
http://vortex.accuweather.com/adc2004/pub/includes/columns/newsstory/2015/650x366_03020044_hd30.jpg
“The milder and more spring-like weather headed to the Midwest and Northeast will only be brief. Fresh arctic air will quickly return Wednesday through Thursday.
While slowing down the snow melt and easing the flood threat, the arctic blast will arrive fast for any wet or slushy areas to freeze and turn icy.
The arrival of the colder air will also coincide with when a new batch of rain will spread from the southern Plains to the East Coast. As the cold air slams into the rain, a changeover to treacherous ice or snow will occur in a large swath from Texas and the lower Mississippi Valley to the mid-Atlantic and potentially a part of the Northeast.”

Robertv
March 2, 2015 2:54 am

Isn’t human mortality 100 % ? I never met one older than 120 .

Hugh
Reply to  Robertv
March 2, 2015 5:02 am

Mortality rate is not expressed as per person, but person and per unit time.
Like, how many people out of 100,000 are expected to die during a year (and in this article, accidental causes were excluded).

RoHa
March 2, 2015 2:59 am

An optimum temperature to be dead? From whose point of view? The dead people might prefer to be warm, while those dealing with them would probably prefer the dead too be too cold to get smelly.

RoHa
March 2, 2015 3:03 am

“the risk of mortality increases at both the high and low ends of the temperature range”
Does that mean that somewhere in the middle of the range the risk of mortality is zero?

richardscourtney
Reply to  RoHa
March 2, 2015 3:06 am

RoHa
Why on Earth would you think a local minimum must equal zero?
Richard

RoHa
Reply to  richardscourtney
March 2, 2015 8:07 am

Not “must”, but I hope that it does. Then if I stay at the right temperature, I will be immortal!

Bernd Palmer
Reply to  RoHa
March 2, 2015 3:19 am

Stupidity also increases the risk of mortality.

Bob Boder
Reply to  Bernd Palmer
March 2, 2015 5:13 pm

Not in the U.S.

Duster
Reply to  RoHa
March 2, 2015 11:09 am

Look at the charts. There is no “zero” mortality. Some locations, particularly Britain see a third peak in the 50 percentile.

icouldnthelpit
March 2, 2015 3:09 am

(Another wasted effort by a banned sockpuppet. Comment DELETED. -mod)

Reply to  icouldnthelpit
March 2, 2015 3:20 am

Er, no. The weather changes and that affects people – this about weather.
You have got confused with weather and climate.
Climate changes too and that’s not proven to be controlled by man either.

icouldnthelpit
Reply to  M Courtney
March 2, 2015 3:26 am

(A wasted posting effort by a banned sockpuppet. Comment DELETED. -mod)

Reply to  M Courtney
March 2, 2015 3:37 am

icouldnthelpit
?
Not sure how to reply to that. It’s too early here in the UK for drinking. But Cheers to you anyway.
Now, are you implying that you do think that weather is controlled by man?
Or are you saying that you think weather is not controlled by man but climate is?
Either way I think you need to be a little clearer in your communication.

icouldnthelpit
Reply to  M Courtney
March 2, 2015 3:50 am

(A wasted posting effort by a banned sockpuppet. Comment DELETED. -mod)

richardscourtney
Reply to  icouldnthelpit
March 2, 2015 4:20 am

icouldnthelpit
“Can be” and “is” are not the same thing.
Yet again you evade the issue when someone questions what seems to be nonsense from you.
M Courtney asked you to clarify your words when he wrote

Now, are you implying that you do think that weather is controlled by man?
Or are you saying that you think weather is not controlled by man but climate is?

Your reply to that request provides an untrue ad hom. then says

To answer your questions, I think the climate can be influenced by man.

That is NOT what was asked.
Please answer M Courtney’s request for clarification or apologise for trolling the thread.
Richard

icouldnthelpit
Reply to  richardscourtney
March 2, 2015 4:39 am

(Another wasted effort by a banned sockpuppet. Comment DELETED. -mod)

richardscourtney
Reply to  richardscourtney
March 2, 2015 4:41 am

icouldnthelpit
So, as usual, you refuse to clarify your nonsense and you refuse to apologise for your trolling. No surprise there.
Richard

icouldnthelpit
Reply to  richardscourtney
March 2, 2015 4:50 am

(Another wasted effort by a banned sockpuppet. Comment DELETED. -mod)

Reply to  richardscourtney
March 2, 2015 7:55 am

icouldnthelpit,
Ah right. So on your scale you are at point 1. It’s Not Happening.
Climate might be influenced by man – just like it might be influenced by a butterfly’s wing…. but we do agree that man does not have a controlling influence on weather or climate.
So certainly not more than 50%.
I’m a little less sceptical than the position you have found yourself in but at least I am clear.

icouldnthelpit
Reply to  richardscourtney
March 2, 2015 9:39 am

(Another wasted effort by a banned sockpuppet. Comment DELETED. -mod)

Hugh
Reply to  icouldnthelpit
March 2, 2015 4:53 am

It’s Happening, But It’s Good.

Well, I have still +16K to go before my neighbourhood reaches Madeira levels, so Arctic amplification gogo. 🙂

icouldnthelpit
Reply to  Hugh
March 2, 2015 4:57 am

(Another wasted effort by a banned sockpuppet. Comment DELETED. -mod)

Hugh
Reply to  Hugh
March 2, 2015 5:04 am

After you.
(I can’t do anything. China burns coal as much as it wants, so even if I believed the scariest scenarios, I would be a spectator / passenger only.)

rh
Reply to  icouldnthelpit
March 2, 2015 5:02 am

Don’t ya just love it when someone says cheers, when they really mean FU.

icouldnthelpit
Reply to  rh
March 2, 2015 5:05 am

(Another wasted effort by a banned sockpuppet. Comment DELETED. -mod)

Bob Boder
Reply to  icouldnthelpit
March 2, 2015 5:15 pm

1. I’ll say anything <— you are here
2 I say anything <— and here
3 I have said anything <— and here
4 I say nothing <— and here

ren
March 2, 2015 3:09 am

Winter in the US. 03/02/2015.
http://oi59.tinypic.com/2gwbaf9.jpg

March 2, 2015 3:14 am

joelobryan on March 2, 2015 at 2:49 am is correct — the “y-axis” should be “x-axis”. Thanks Joel, and my apologies to all.

Walt D.
March 2, 2015 3:19 am

Since humans evolved with very little body hair and fat, it would seem that as a species, we are not naturally adapted to live in any climate where we would not be able to survive year round, outside, wearing only swimming trunks or a bikini.

Reply to  Walt D.
March 2, 2015 3:25 am

We are naturally adapted to wear clothes.
That is why we have evolved to experience a sense of shame.

Jimbo
Reply to  Walt D.
March 2, 2015 3:56 am

On evolution of humans some argue that Turkana Basin and the Danakil (Afar) Depression were central to early human evolution. It is pointed out that the Danakil Depression is among the hottest, permanently inhabited places on Earth. Could this be why we are hairless? Maybe an expert here would like to chime in.

Abstract – 2010
Benjamin H. Passeya et al
High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates
Many important hominid-bearing fossil localities in East Africa are in regions that are extremely hot and dry. Although humans are well adapted to such conditions, it has been inferred that East African environments were cooler or more wooded during the Pliocene and Pleistocene when this region was a central stage of human evolution. Here we show that the Turkana Basin, Kenya—today one of the hottest places on Earth—has been continually hot during the past 4 million years. The distribution of 13C-18O bonds in paleosol carbonates indicates that soil temperatures during periods of carbonate formation were typically above 30 °C and often in excess of 35 °C……
http://www.pnas.org/content/107/25/11245.short
======
Letters to Nature – 1998
A one-million-year-old Homo cranium from the Danakil (Afar) Depression of Eritrea
One of the most contentious topics in the study of human evolution is that of the time, place and mode of origin of Homo sapiens1, 2, 3. The discovery in the Northern Danakil (Afar) Depression, Eritrea, of a well-preserved Homo cranium with a mixture of characters typical of H. erectus and H. sapiens contributes significantly to this debate……
http://dx.doi.org/10.1038%2F30954

Gamecock
Reply to  Jimbo
March 2, 2015 4:36 am

Humans are not hairless, our body hair is just minimal. I have known people with heavy body hair.
There is no reason to believe we didn’t have heavier hair in prehistoric times.

Jimbo
Reply to  Jimbo
March 2, 2015 5:30 am

Gamecock
March 2, 2015 at 4:36 am
Humans are not hairless, our body hair is just minimal. I have known people with heavy body hair.

I know we have hair but I should have phrased it better. So let me re-phrase.
“Could this be why we have so much less hair than other apes?”
Your hairy friend should go seek a good hair removal cream at his (or her) local pharmacy. 😉

There is no reason to believe we didn’t have heavier hair in prehistoric times.

At some point in time we lost most of our hair for one reason or another. It’s a minor point a per my point and the focus of my reference was on high temperatures and human evolution.
From my top reference in their full paper version I see this:

Implications for Human Thermophysiology.
This temperature record is relevant to the evolutionary origin or maintenance of a unique suite of adaptations that permit humans to remain active under high ambient heat loads. For example, upright posture in hot, open environments confers thermophysiological advantages to bipedal hominins owing to reduced interception of direct solar radiation and to displacement of the body away from the near-surface environment, which may be excessively hot due to solar heating (29). Derived human traits such as very little body hair, high sweating capacity, and high surface area to volume ratio are also advantageous for daytime activity in hot, arid climates (30), and temperature is a central variable in hypotheses of behaviors such as long-distance scavenging and persistence hunting (31). However, the thermoregulatory advantages of these adaptations arise primarily under very hot, sunny conditions (29, 32, 33). Our results suggest that such conditions were relevant to human ecology in the Turkana Basin, either directly within or at the spatial or temporal margins of human-preferred habitats….

It is likely that numerous independent factors were involved in the evolutionary origin and maintenance of traits such as bipedal locomotion, slender body form, reduction of functional body hair, and high sweating capacity……
http://www.pnas.org/content/107/25/11245.full

ferdberple
Reply to  Jimbo
March 2, 2015 6:42 am

Human beings ability to shed heat allows us to continue to expend energy in hot climates where other animals would overheat. Thus, in a hot climate a human can run down faster animals, because we can continue running longer.

cedarhill
March 2, 2015 3:35 am

This confirms if you can’t grow tomatoes, humans shouldn’t grow either.

March 2, 2015 3:41 am

There are two correlations that need to be kept in mind when considering these results and what they mean for energy and climate policy.
Correlation 1. Infant mortlity is strongly negatively correlated to Per capita GDP.
http://commons.m.wikimedia.org/wiki/File:Infant_deaths_vs_GDP_per_capita_(PPP).png
Correlation 2. Energy useage per capita is positively correlated to per capita GDP.
http://notrickszone.com/wp-content/uploads/2012/06/Caryl1.gif
The Congo (tropics) will never have the climate of Lichtenstein, but denying the people of sub-Saharan Africa affordable energy consigns their families to high infant mortality, and that drives much higher population fertility rates (and world population growth). So while the Greenie watermelons of the world believe that to “Save the Planet” we must eliminate inexpensive carbon-forms of energy, the effect of doing so actually may (likely) have the opposite consequence.

Jimbo
Reply to  Joel O’Bryan
March 2, 2015 5:48 am

Joel, I often explain to Malthusians that if they really want us to slow down population growth then cheap, abundant energy is one of the important keys. The other is economic growth (from that energy). Global fertility was higher back in the 1960s than today, even in Africa. There are many (well off) countries where they are below the replacement level.

Economist – Oct 22nd 2011
Odd though it seems, however, the growth in the world’s population is actually slowing. The peak of population growth was in the late 1960s, when the total was rising by almost 2% a year. Now the rate is half that.
http://www.economist.com/node/21533364

http://media.economist.com/images/20091031/CFB000.gif
http://media.economist.com/images/20091031/CFB987.gif

Jimbo
Reply to  Jimbo
March 2, 2015 6:02 am

This is what we are facing at around 2060. Some people talk of ‘over-population’ – let’s say they are correct. This century you will hear about population alright, but it won’t just be ‘over-population’. Elderly care and lack of labour could pose problems too.
http://cdn.static-economist.com/sites/default/files/imagecache/original-size/images/2014/11/articles/main/20151101_inc011.png

Reply to  Jimbo
March 2, 2015 3:28 pm

In old age Karl Malthus was starting to recognize the creativity of humans, that we conserve and substitute. IOW, he was headed toward reversing his beliefs.
Of course the negative mentality that repeats his fallacious claims doesn’t dig into such.
The book The Doomsday Myth reports on a number of cases where conservation and substitution in response to economic pressure avoided shortages, even in the face of government force.
Rubber is a particularly interesting case of government force:
– Brazil forbid export of rubber plants, to conserve and maximize the price of rubber. Of course that didn’t work, someone got plants to SE Asia where people farmed them, giving much greater supply.
– England and Holland then tried to corner the market, discouraging development of natural rubber for example. But the war restricted supply. Fortunately Americans developed an artificial substitute, helping win the war.

Reply to  Joel O’Bryan
March 2, 2015 3:19 pm

Indeed, “joelobryan”.
.
Alex Epstein covers some of that in his book “The Moral Case for Fossil Fuels”.
(Being the one source of energy that is abundant and affordable.)

Reply to  Keith Sketchley
March 2, 2015 10:04 pm

Agreed Keith. And thanks for the book suggestion. I’ll look for it on my Amazon Kindle account.
Regards. J
It is quite sad that the Eco-Greens of our western culture want to deprive the mother’s developing world of the energy they need to raise their families. That is, Energy you and I had and took for granted.

March 2, 2015 4:15 am

The shape of those lines (flatness versus curviness) has at least a partial explanation in this graph.
http://en.m.wikipedia.org/wiki/Energy_intensity#/media/File:Gdp-energy-efficiency.jpg
My interpretation: Canada and the USA get those flatter lines by being less energy efficient (i.e. our big SUVs and trucks are a lot safer than a mini when we get hit by that lorry. And gas powered 10 hp snow blowers saves many heart attacks over the shovel powered snow removal where petrol is 4X higher.).

commieBob
Reply to  Joel O’Bryan
March 2, 2015 5:20 am

Is something wrong with the graph? It shows a GDP per capita of less than $15,000 for Saudi Arabia. Wiki gives GDP (PPP) per capita as nearly $54,000. There’s no way Saudi belongs in the same bubble as Russia and the Ukraine

Hugh
Reply to  Joel O’Bryan
March 2, 2015 6:36 am

There might be an error.
Saudi Arabia is probably hard to measure with traditional numbers. There are about 20 million citizens plus maybe nine million people as foreign labour. The numbers in Wikipedia are not to be taken literally.
Anyway, there is some support in the net for a low, under $25,000 value:
http://data.worldbank.org/indicator/NY.GDP.PCAP.CD/countries/SA?display=graph

ferdberple
Reply to  Joel O’Bryan
March 2, 2015 6:47 am

Is something wrong with the graph?
==========
yes, it labels efficient and inefficient incorrectly. Canada at about $80/million btu is much MORE efficient than Bangladesh at $450/million btu.
Countries with a high price of energy are hardly efficient. If they were, they would be able to use their efficiency to get their energy costs down. It is the inefficiency in their economies that keeps prices high.

Reply to  Joel O’Bryan
March 2, 2015 9:40 am

You confuse “efficient” with better. An advanced country farmer can cultivate and harvest a 100 acre plot by himself using modern machinery — but uses many million BTUs of fossil carbon energy to do so. In Bangladesh, that same level of agricultural production is human or animal powered, using far fewer BTUs of carbon energy. Clearing a driveway of 10 cm of snow with a shovel over hrs of labor is much more carbon energy efficient than using a gas powered snow blower, but there’s no doubt in my opinion which is better. But GreenPeace would rather in throw-out my back shoveling than releasing 2 additional Kg of carbon to the atmosphere with a gas snowblower.

CR Carlson
March 2, 2015 4:29 am

When Greens, enviro-mentals and Obama finally outlaw fossil fuels or force reductions and cause an unstable power grid resulting in massive black-outs at the worst times, take a wild guess which will result in greater mortality- severe freezing or balmy Summer.

1 2 3