Claim: Global Warming will Shrink Animals

Guest essay by Eric Worrall

Recycled climate wisdom from Seth Borenstein…

Global warming shrank animals in the past. Scientists say it could happen again.

Seth Borenstein, Associated Press

WASHINGTON — Global warming shrank certain animals in the ancient past, and scientists worry it could happen again.

Warm-blooded animals got smaller at least twice in Earth’s history when carbon dioxide levels soared and temperatures spiked as part of a natural warming, a new study says.

University of New Hampshire researcher Abigail D’Ambrosia warned that mammals — but not people — could shrivel in the future under even faster man-made warming.

“It’s something we need to keep an eye out for,” said D’Ambrosia, who led the new work. “The question is how fast are we going to see these changes.”

Read more: https://amp.usatoday.com/story/99345782/

The abstract of the study;

Repetitive mammalian dwarfing during ancient greenhouse warming events

Abigail R. D’Ambrosia1, William C. Clyde, Henry C. Fricke, Philip D. Gingerich and Hemmo A. Abels

Abrupt perturbations of the global carbon cycle during the early Eocene are associated with rapid global warming events, which are analogous in many ways to present greenhouse warming. Mammal dwarfing has been observed, along with other changes in community structure, during the largest of these ancient global warming events, known as the Paleocene-Eocene Thermal Maximum [PETM; ~56 million years ago (Ma)]. We show that mammalian dwarfing accompanied the subsequent, smaller-magnitude warming event known as Eocene Thermal Maximum 2 [ETM2 (~53 Ma)]. Statistically significant decrease in body size during ETM2 is observed in two of four taxonomic groups analyzed in this study and is most clearly observed in early equids (horses). During ETM2, the best-sampled lineage of equids decreased in size by ~14%, as opposed to ~30% during the PETM. Thus, dwarfing appears to be a common evolutionary response of some mammals during past global warming events, and the extent of dwarfing seems related to the magnitude of the event.

Read more: http://advances.sciencemag.org/content/3/3/e1601430.full

Shrinking animals is one of my favourite climate scare stories. The fear of climate shrinking animals has such a camp 1980s science fiction feel, but what they are actually talking about is a very gradual process which took place over a prolonged period – certainly not something a person could “keep an eye on” over any reasonable timeframe.

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michael hart
March 22, 2018 7:07 pm

But is it going to save us from giant insects and reptiles?

Rick C PE
March 22, 2018 7:08 pm

I’ll add this to the very long list of things I’m not worried about.

D. J. Hawkins
March 22, 2018 7:15 pm

Wasn’t this period in proximity to the “dinosaur killer” asteroid? Wasn’t there some discussion not long ago about the Deccan Traps and such? Could there be remnant effects going into the PETM that might better explain shrinking mammals?

tty
Reply to  D. J. Hawkins
March 23, 2018 5:03 am

No, this was 10-15 million years later.

Jones
March 22, 2018 7:18 pm

Napoleon had something to say about leetle peeple…..

willhaas
March 22, 2018 7:20 pm

The reality is that the climate change we have been experiending is caused by the sun and the oceans over which mankind has no control. There is no real evidence that CO2 has any effect on climate and there is plenty of scientific rational to support the idea that the climate sensivity of CO2 is zero. The AGW conjecture is dependent upon a radiant greenhouse effect caused by trace gases with LWIR absorption bands. Such a greenhouse effect has not been observed in a real greenhouse, on Earth, or anywhere else in the solar system for that matter. The radiant greenhoue effect is science fiction as is the AGW conjecture.
Considering what has been learned from the paleoclimate record. we are most likely nearing the end of the current interglacial period. It is very unlikly that temperatures will increase to equal what they were during the previous interglacial period. The next ice age will probably last at least 100K years just like tha last one so we will not have to worry about warmer temperatures shinking animals for at least anothe 100K years. Many of reading this may not be alive to experience the next interglacial period.

Reply to  willhaas
March 22, 2018 7:30 pm

Suprise, the artical said that there were warmings back then, & that they were similar to the presant day warmings.
So how come, where did the man made co2 come from ?.
Mj

willhaas
Reply to  m.j.elliott.
March 23, 2018 1:39 am

There is evidence that the burning of fossil fuels has increased the amount of CO2 in the Earth’s atmosphere but there is no real evidence that this additional CO2 has had any effect on climate.

higley7
Reply to  m.j.elliott.
March 23, 2018 5:08 am

To Willhaas’s Comment.
No, there is no evidence that we have added CO2 to the atmosphere. Our Co2 emissions have gone up logarithmically while CO2 in the atmosphere has risen linearly. We are having no effect.

Samuel C Cogar
Reply to  m.j.elliott.
March 23, 2018 6:02 am

higley7 – March 23, 2018 at 5:08 am

Our Co2 emissions have gone up logarithmically while CO2 in the atmosphere has risen linearly. We are having no effect.

Right you are, higley7, ……. but 80+% of the educated populace avert both their eyes and their mind to that fact.
I had previously compiled the following statistics via reliable sources, to wit:
Increases in World Population & Atmospheric CO2 by Decade
year — world popul. – % incr. — Dec CO2 ppm – % incr. — avg increase/year
1940 – 2,300,000,000 est. ___ ____ 300 ppm est.
1950 – 2,556,000,053 – 11.1% ____ 310 ppm – 3.3% —— 1.0 ppm/year
1960 – 3,039,451,023 – 18.9% ____ 316 ppm – 1.9% —— 0.6 ppm/year
1970 – 3,706,618,163 – 21.9% ____ 325 ppm – 2.8% —— 0.9 ppm/year
1980 – 4,453,831,714 – 20.1% ____ 338 ppm – 4.0% —– 1.3 ppm/year
1990 – 5,278,639,789 – 18.5% ____ 354 ppm – 4.7% —– 1.6 ppm/year
2000 – 6,082,966,429 – 15.2% ____ 369 ppm – 4.2% —– 1.5 ppm/year
2010 – 6,809,972,000 – 11.9% ____ 389 ppm – 5.4% —– 2.0 ppm/year
2012 – 7,057,075,000 – 3.62% ____ 394 ppm – 1.3% —– 2.5 ppm/year
Source CO2 ppm: ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_mm_mlo.txt
Based on the above statistics, to wit:
Fact #1 – In 70 years – world population increased 207% – CO2 increased 31.3%
Fact #2 – Atmospheric CO2 has been steadily and consistently increasing at a rate of 1 to 2 ppm per year for the past 70 years, …… whereas human generated CO2 releases have been increasing exponentially every year for the past 70 years.
Fact #3 – Global Average Temperature calculation results have been steadily and consistently increasing a few hundredths or tenths of a degree for the past 70 years, ……. whereas human created infrastructure, housing, vehicles, etc. (Heat Islands) have been increasing exponentially every year for the past 70 years.
Conclusions:
Given the above statistics, it appears to me to be quite obvious that for the past 70 years there is absolutely no direct association or correlation between:
Increases in atmospheric CO2 ppm and world population increases.
Increases in Average Global Temperature and world population increases.
Increases in Average Global Temperature and Heat Islands construction increases.
Increases in Average Global Temperature and atmospheric CO2 ppm increases.
But then of course, …… I am not looking through Rose Colored Glasses.

Kristi Silber
Reply to  m.j.elliott.
March 23, 2018 2:39 pm

Samuel – So urban heat islands are causing global warming? I guess that means that city-dwellers will be the first to shrivel.
You are aware, aren’t you, that the UHI is taken into effect in temperature measurements?
You don’t seem to be aware of how much CO2 ends up in the ocean or plant material or that temperature is not expected to have a linear correlation with CO2. That kills most of your argument. Nor has there been anything yet discovered to account for the rise in temperature except CO2.
Anything can seem obvious when its based on erroneous assumptions.
Higley: “No, there is no evidence that we have added CO2 to the atmosphere. Our Co2 emissions have gone up logarithmically while CO2 in the atmosphere has risen linearly. We are having no effect.”
You’re kidding, right?

Chimp
Reply to  m.j.elliott.
March 23, 2018 2:51 pm

Kristi Silber March 23, 2018 at 2:39 pm
When GISS was finally forced by FOIA suits to reveal its previously secret UHI adjustments, it was discovered that the bogus book cooking made the adjusted temperatures hotter rather than cooler.

MarkW
Reply to  m.j.elliott.
March 23, 2018 2:53 pm

Kristi, we have examined the studies where they claim to be taking UHI into account.
They aren’t. UHI is way underestimated.

Samuel C Cogar
Reply to  m.j.elliott.
March 24, 2018 4:03 am

Kristi Silber – March 23, 2018 at 2:39 pm

Samuel – So urban heat islands are causing global warming? I guess that means that city-dwellers will be the first to shrivel.

Kristi, ….. iffen the above post was your 1st attempt at trying to impress everyone with your recently acquired “educational expertise”, ……. me thinks you surely have impressed them, ….. but CONTRARY to what you were hoping for.
Kristi, ….. iffen you want to claim that UHIs are causing global warming, …. then that is testimony of your science ignorance, …… and it was disingenuous of you to be asking me if I agree with you.
March 23, 2018 at 2:39 pm

You are aware, aren’t you, that the UHI is taken into effect in temperature measurements?

Kristi, iffen I rule out your lack of “educational expertise”, ….. then I hafta say that I truly believe that you have posted on the wrong forum than what you intended to post on. Apparently you don’t realize that one of the primary reasons that this web site exists is that US government agencies were including the extremely high “local” UHI recorded temperatures as being the “normal” near-surface temperature in order to justify their “junk-science” claims in support of CAGW.

peanut gallery
March 22, 2018 7:25 pm

Hmm… tiny Liberal-Communists. What’s not to love?

3¢worth
March 22, 2018 7:34 pm

“Shrivel”? Doesn’t that happen when something wrinkles and contracts due to lost of moisture, like when flowers shrivel up? Are all mammals in the future going to be tiny and shrivelled?

Kristi Silber
Reply to  3¢worth
March 22, 2018 8:04 pm

“Shrivel”! Odd word, huh? Like grapes!
“There is no real evidence that CO2 has any effect on climate and there is plenty of scientific rational to support the idea that the climate sensivity of CO2 is zero. The AGW conjecture is dependent upon a radiant greenhouse effect caused by trace gases with LWIR absorption bands. Such a greenhouse effect has not been observed in a real greenhouse, on Earth, or anywhere else in the solar system for that matter. The radiant greenhoue effect is science fiction as is the AGW conjecture.”
Another VERY broken record. How many times do people have to say the same things? Sounds like you are trying to convince yourselves. Helps if you have no knowledge of what you’re talking about. “Such an effect has not been observed in a real greenhouse” – true! That’s because “greenhouse” is a metaphor. CO2 has three major absorption bands, one in near IR, one in IR and one in LWIR.
This site talks about the atmosphere of Venus, which is mostly CO2, But there’s also a nice wee demonstration of how CO2 can trap heat.
https://scholarsandrogues.com/2011/05/06/venus-climate-v-co2-heating/

mikebartnz
Reply to  Kristi Silber
March 22, 2018 8:49 pm

Quote *Helps if you have no knowledge of what you’re talking about*.
Said like a good little narcissist.

Tsk Tsk
Reply to  Kristi Silber
March 22, 2018 9:32 pm

And what is the Venusian temperature at the equivalent Earth sea-level pressure? About 350K? Huh.
For a discussion, see here.
Or we could go to the master of BEELLIONS and BEELLIONS

Hugs
Reply to  Kristi Silber
March 23, 2018 7:41 am

But Luboš is a well-known misogyne writing a blog, so we can ignore him. Besides, he’s not a climate scientist so he’s not competent. Wikipedia tells Venus is hot due to the greenhouse effect, so we can safely ignore this denler. Actually his blog should be blocked from google for continuous dissemination of untruths. I’ll check my facts at the SkS. They told me Luboš is just a paid oil shill whom they banned already.
Do I need tags?

Kristi Silber
Reply to  Kristi Silber
March 23, 2018 4:27 pm

mikebartnz March 22, 2018 at 8:49 pm
Quote *Helps if you have no knowledge of what you’re talking about*.
Said like a good little narcissist.
Narcissist? That’s odd. I wasn’t saying anything about myself. I can see “catty,” “rude” or “obnoxious,” but narcissist?
(I am sorry for that. I just get so sick of hearing that same thing over and over. Is there nothing original to say?)
tsk tsk
“And what is the Venusian temperature at the equivalent Earth sea-level pressure? About 350K? Huh.”
The surface temperature of Venus is 735 K. I don’t know what you mean by “at the equivalent…” How is that relevant?
Sagan apparently didn’t know the atmospheric composition when he wrote his paper since he didn’t know the correction for CO2. Frankly I don’t understand how an adiabatic process would apply.
Doesn’t that refer to the change in temperature with pressure? Physics wasn’t my strong point.
If the whole atmosphere of Venus were N2, how would the surface retain heat? What difference woul pressure make if N2 doesn’t absorb IR? Even though the rotation of Venus is 200+ days, the whole surface is hot because the atmosphere holds so much heat in.
The other paper looks sketchy to me. “So CO2 and N2, treated as ideal gases, have the same molar heat. ” They don’t have the same molar heat, but more important, they don’t absorb energy the same. …I don’t know, I’m not qualified to assess the whole thing, but it seems like there are some assumptions made, and I’m always wary of those unless I understand them. Besides, I’ve looked at half a dozen astronomy sites and they all say greenhouse effect.

mikebartnz
Reply to  Kristi Silber
March 23, 2018 5:12 pm

Quote *That’s odd. I wasn’t saying anything about myself.*
You don’t have to be saying anything about yourself to be a narcissist. Narcissists will often put others down to make themselves look better.

Kristi Silber
March 22, 2018 7:37 pm

Now this even I think is silly! It may happen, but over the course of at least hundreds of years (maybe thousands, depending on many factors) in the case of large mammals, and it’s not something to worry about.
DJ Hawkins: “Wasn’t this period in proximity to the “dinosaur killer” asteroid? Wasn’t there some discussion not long ago about the Deccan Traps and such?”
What are Deccan Traps?
This would have been after the dinosaur extinction.
Size in mammals is related to their ability to dissipate heat. After the “dinosaur killer” asteroid, the Earth cooled, allowing the radiation of mammals into new niches as well as their increase in size. It makes sense that populations exposed to significant warming would experience decreasing body size, too. But there is nothing I can think of that is very scary about this.
“University of New Hampshire researcher Abigail D’Ambrosia warned that mammals — but not people — could shrivel in the future under even faster man-made warming.” I wonder why not humans?

Kristi Silber
Reply to  Kristi Silber
March 22, 2018 7:40 pm

…Oh, Deccan Traps…got it.

Reply to  Kristi Silber
March 22, 2018 8:23 pm

“I wonder why not humans?”
A protein rich rich diet in childhood and teen years ensures full growth potential. Human populations do shrink under war-time like deprivations of calories and protein. The Japanese male height was considerably constrained between to 1950 by Imperial decrees and maintenance of strict meat rationing. After WW2, look what happened by 1950 onward…comment image
Yes, Animals are tasty. Yum. Just finished my T-bone steak dinner and the puppy dogs are in the backyard enjoying the bones and some remaining bovine flesh.

Pop Piasa
Reply to  Joel O’Bryan
March 22, 2018 9:25 pm

Joel, I wonder if Lysenko managed to shrink any Russians during his reign as ‘minister of genetics’…

Craig
Reply to  Joel O’Bryan
March 23, 2018 8:55 am

I’m 6″ taller than my dad, and my son is 6″ taller than me, and none of us ever lacked for good nutrition.

Kristi Silber
Reply to  Joel O’Bryan
March 23, 2018 4:37 pm

Joel, nutrition wouldn’t explain why humans wouldn’t evolve in response to heat – that’s what “adaptation” means here. We can sweat, unlike other animals, but that doesn’t help when the heat and humidity are too high…hmmm, maybe there’s a cost of losing surface area even if surface area/volume goes up.

Samuel C Cogar
Reply to  Kristi Silber
March 24, 2018 6:28 am

Kristi Silber – March 22, 2018 at 7:37 pm

This would have been after the dinosaur extinction.
Size in mammals is related to their ability to dissipate heat/b<. After the “dinosaur killer” asteroid, the Earth cooled, allowing the radiation of mammals into new niches as well as their increase in size. It makes sense that populations exposed to significant warming would experience decreasing body size, too.

Kristi Silber, …… your mimicry of “tripe n’ piffle” is making you look as foolish as most any other learning disabled person, so best you cease n’ desist before your creditability is completely destroyed.
Kristi S, didn’t you know that the currently calculated Global Average Temperature is accepted to be 57.2 degrees F (11.5 degrees C)?
Kristi S, it’s obvious that you didn’t know that the proxy calculated Global Average Temperature during the Age of the Dinosaurs, 252 mya – 66 mya, is accepted to be 77 degrees F (25 degrees C.
So “DUH”, during the Age of the Dinosaurs when the earth was populated with gigantic size land animals the average temperature was 19.8 degrees F warmer than it has been during the past 200,000+ years.

eyesonu
March 22, 2018 7:40 pm

Shrinking critters ….. so opossums will become rats, rats become mice, and mice will now infest your cat and maybe cross breed with the fleas. And to top it all off, we’ll never be able to find the elephant in the room! Got it!

Editor
March 22, 2018 7:42 pm

… scientists worry …

Dear heavens, save me from the “worries” of snowflake scientists …
w.

Pop Piasa
Reply to  Willis Eschenbach
March 22, 2018 8:46 pm

A worried scientist is usually waiting for the latest grant to be approved.

RicDre
Reply to  Pop Piasa
March 23, 2018 9:17 am

+100

MarkW
March 22, 2018 7:47 pm

1) The association between pertubations in carbon and changes in temperatures are assumed, not proven. Especially given the extremely poor correlations between the timing of the two events.
2) There are many things that affect animal evolution. Once again they are assuming the poor correlation between two events proves causation.
This isn’t science.

Tom Halla
March 22, 2018 7:54 pm

I would have thought fifties bad science fiction, or did that just run to giant bugs caused by fallout?

Reply to  Tom Halla
March 22, 2018 8:05 pm

tty
Reply to  Tom Halla
March 23, 2018 5:36 am

Really big insects/spiders require more oxygen in the atmosphere. So no amount of radiation can do it.
It also has to do with the amount of predation. There were lots of very big insects in New Zealand until the maori brought the Polynesian Rat Rattus exulans. Not many left now. Google “Giant Wetas”.

RicDre
Reply to  Tom Halla
March 23, 2018 9:22 am

For fifties bad science fiction related to this topic see “The Incredible Shrinking Man” (1957)

March 22, 2018 8:01 pm

Just more of the old “correlation” equals “causation” when it suits the agenda.

March 22, 2018 8:08 pm

Are these people actually getting paid for this stuff???

Reply to  Mike
March 22, 2018 8:27 pm

Yes, and quite well I might add. On your tax dollar.

Karl Baumgarten
March 22, 2018 8:14 pm

When they bring back a T-Rex, they can just leave it outside to shrink, before bringing it inside to eat them.

petermue
March 22, 2018 8:22 pm

Seth Boahahahahahaahaaa…. SCNR

Bryan A
Reply to  petermue
March 22, 2018 8:47 pm

I thought it was Bore N Stein

BallBounces
March 22, 2018 8:24 pm

I have a friend. One of his eyeballs shrank, and had to be reinflated, actually, re-lubricated. Now I realize man-made climate change was behind my friend’s shrunken eyeball. I don’t know if it will affect his other eyeball, but I’m gonna keep an eye out for it, I can tell ya.

Sara
March 22, 2018 8:28 pm

Gee whizzikers, how do these guys account for mammoths and mastodons, giant sloths and them there big ol’ short-faced cave bears? And what about the buffalo?
Doom on you! Doom on you! Doom on you!
I can’t believe these people get paid to make these pronouncements. Why don’t they tell us what their REAL issue is….? I’m breathless with anticipation over the answer to that one.

Bryan A
Reply to  Sara
March 22, 2018 9:06 pm

Twas Climate Change spelled the end of the Mega Fauna.
And as it has warmed since the great prairie herds of 1850, obviously Climate Change is to blame for Buffalo reductions.
The climate has changed so radically since 1850 that every person alive at that time couldn’t survive to today. Climate Change must be stopped so people can start living longer lives again.

Sara
Reply to  Sara
March 23, 2018 4:31 am

Wouldn’t have anything to do with humans eating them, now, would it? Nah! that’s too easy!
Still doesn’t explain how horses went from eohippus, the size of a cat with five toes, to the Shire, the largest draft horse breed at 18 to 22 hands with hooves the size of dinner plates.

tty
Reply to  Sara
March 23, 2018 5:30 am

It is much more common for animal lineages to grow gradually larger than gradually smaller. The largest forms however also tend do become extinct more often than small ones, so it starts all over again. Nobody knows quite why.

Kristi Silber
Reply to  Sara
March 23, 2018 4:47 pm

tty – sexual selection leading to unsustainable mass during geological periods of stress? I can see how climate or other environmental changes might be harder on animals that need larger areas for a sustainable population. If size is correlated with age of reproduction or negatively with birthrate it might take larger animals longer to adapt to change. Just some ideas.

tty
Reply to  Sara
March 24, 2018 1:57 am

Sexual selection is probably part of the answer. However in that case one would expect marked sexual dimorphism. This is true for some large animals (e. g. Sea elephants and Sealions), but not for most large animals.

Kristi Silber
Reply to  Sara
March 25, 2018 2:13 am

“Sexual selection is probably part of the answer. However in that case one would expect marked sexual dimorphism. This is true for some large animals (e. g. Sea elephants and Sealions), but not for most large animals.” I would have thought otherwise, if not in morphology at least in behavior. Actually, I would think most large mammals are at least the former. Think of all the antlers and horns, and the size dimorphisms.

WR
March 22, 2018 8:45 pm

I’m sure there’s a “study” out there that posits that “climate change” (I don’t think they even know what that means anymore) will make animals bigger too. Just like CC will cause more droughts yet more rain, more cold yet more heat, etc. In other words, if more or less of something can conceivably be bad, then they will find a way to show that CC will make the bad things happen.

John F. Hultquist
March 22, 2018 9:11 pm

I’m going to wake during the night, with this in my head:
I’m worried now but I won’t be worried long
“Worried Man Blues”

Reply to  John F. Hultquist
March 22, 2018 9:30 pm

Hah!
You remind me of…

Pop Piasa
Reply to  Leo Smith
March 22, 2018 9:52 pm

Thanks Leo, I’m too lazy to be crazy too. Jammin’ blues with fiddle.

Pop Piasa
Reply to  John F. Hultquist
March 22, 2018 9:34 pm

Here John, this will get it out of your head…

MarkW
Reply to  Pop Piasa
March 23, 2018 6:34 am

Don’t worry, be happy.

March 22, 2018 10:31 pm

March 22, 2018 11:12 pm

What continent has most of the large animals?
Answer – Africa (elephants, rhinos, hippos, giraffes, etc).
Is Africa hot or cold?
Answer – hot.
So why haven’t all of the large African animals shrunk? They have had millions of years to shrink, but they haven’t done so. Were the large African animals even bigger in the past (maybe they have already shrunk). Imagine elephants the size of dinosaurs.
P.S I want a poodle sized elephant when they find one.

mikebartnz
Reply to  Sheldon Walker
March 22, 2018 11:28 pm

The other thing is that you have like pocket pooches and then you have dogs as big as miniture ponies and they disipitate heat via their tongues. So I see that as a crock of shit.
The only way to prove that would be to clone an animal and put them in two different extremes under the same care.

tty
Reply to  Sheldon Walker
March 23, 2018 5:27 am

Actually some african animals have “shrunk”. But the effect is weak in the Tropics where temperature changes relatively little between glacials and interglacials.

Tom Judd
March 22, 2018 11:15 pm

And then they wonder why people don’t buy this crap. Yep, give up your car, your AC, your single family suburban home to protect against … mammalian shrinkage.

Bill Murphy
Reply to  Tom Judd
March 23, 2018 12:29 am

RE: “…to protect against … mammalian shrinkage.”
That fad came and went in the ’60s. Remember Twiggy?

johchi7
March 23, 2018 12:09 am

BS and hogwash. Size is relative to genetics and calories, and visa versa. The more calories or less, the larger or smaller a species becomes and causes an effect on genetics. The environment therefore has an effect on the size and genetics of the species, as well as cross breeding of species that creates new species.
Many species that were able to cross breed created what humans today look like. With many different genetic differences, broken into species we call races, to separate ourselves from common animals. As species of humans migrated globally they reduced their gene pool and “bottlenecked” to create subspecies. It is that mixture of genetics that create the differences in every human. The smaller the gene pool the more the population resembles each other. The environment in which they live, or inflict upon themselves, changes their mass by the calories, water and availability of sustenance from birth to death. A species that has a long history of food shortage will genetically become smaller. Where if they moved to an area that has more food, they begin to increase in size over generations. Or if their environment changes from poor to good, or good to poor over generations will cause mutations.
I know this is not a detailed explanation and I’ll get criticism for it. If you open your perspectives you can read between the lines. The proof is all around you… if you look at people around the world. The stature difference between North and South Koreans is a great example, that has only taken several generations. The high mountain people of Peru and their lowlands relatives where the Carbon and Oxygen differences created genetic differences as much as the foods they consumed or the atmospheric pressure variations. Then you have to wonder about the tribes in the Amazon where food is lacking for them and their small stature, compared with the Pygmy people in the Central African Rainforest, and other areas of the earth. Some scientist attribute the lack of B3 from reduced ultraviolet light under the canopies contribute to reductions of calcium uptake in their bones, causing the evolution of a small skeletal size…as well as their diets calcium? Yet, nowhere is it mentioned; that in rainforests, there are high Carbon Dioxide and Oxygen percentages, as related to non-rainforests, effects on human stature. How do we compare hunter gatherers to the more sedate lives of civilization in stature, where calories are burned to what is not, plays a role in genetics?
It is these types of issues that there is no real answer. You cannot compare what happened to a few species millions of years ago, in secluded areas, to make any theory of what may happen in the future. Which is why I said this is BS and hogwash.

Non Nomen
March 23, 2018 12:26 am

The irrational fear of AGW already shrinks the brains of alarmists like D’Ambrosia, Boringstein et al.

Rah
Reply to  Non Nomen
March 23, 2018 12:38 am

I think “shrivels” would be the best word to describe it.

Non Nomen
Reply to  Rah
March 23, 2018 12:50 am

I wish their reproductive organs to shrivelshrink to a size that makes a natural reproduction of alarmists impossible and they’ll have to do it in vitro. I want these funny alarmists not to go extinct completely. Good for a laugh, occasionally.