8 replies to this topic

[Shortpoet-GTD]

I thought this hypothesis was worth discussing, so of course, I wanted to share it, and see
what you guys thought.

(Of course with all the hot air in the halls of congress these days, that would explain
their brain shrinkage, but that's another thread.)

But seriously, what do you think?


"Researchers have uncovered a direct link between global temperatures and body size,
leading them to conclude that future climate change could mean species getting smaller.

A team led by scientists from the University of Florida and the University of Nebraska followed the evolution of the earliest horses about 56 million years ago, and found that as temperatures
increased, their body size decreased.
"Because warming happened much slower during the Paleocene-Eocene Thermal Maximum,
mammals had more time to adjust their body size.
So, it’s not clear that we’re going to see the same thing happening in the near future, but we might."
And, of course, human beings could shrink too."
(full article here)
http://www.tgdaily.c...e-us-all-shrink

[still learning]

Shortpoet-GTD, on 24 February 2012 - 01:57 PM, said:

I thought this hypothesis was worth discussing, so of course, I wanted to share it, and see
what you guys thought.....

But seriously, what do you think?

"Researchers have uncovered a direct link between global temperatures and body size,
leading them to conclude that future climate change could mean species getting smaller.

"Because warming happened much slower during the Paleocene-Eocene Thermal Maximum,
mammals had more time to adjust their body size.
So, it’s not clear that we’re going to see the same thing happening in the near future, but we might."

Who knows?
For one thing we don't know how far climate change is going to proceed.  Will the world get CO2 emissions under control before things get too far along or will business-as-usual continue until things collapse?  Something in between?

For actual evolutionary change to occur it takes both heritable variation (happening all the time) and, in nature, selection, differential reproductive success based on variations.  I think most people are of the view that natural selection doesn't operate on humans in the modern world nearly as much as it did before civilization.  Being stronger or faster or healthier or more heat tolerant or more famine tolerant doesn't mean as much in the modern world as it did 100,000 years ago.
I don't think anybody doubts that tropical climates tend to produce smaller humans than more temperate climates.  Whether from temperature itself or allied effects like tropical diseases, people whose ancestors resided in equatorial regions tend to be a little shorter and a little skinner than those whose ancestors lived in cooler regions.  Pygmys?  Found only in the tropics.

If we lose civilization, then natural selection can go back to work favoring the better adapted and culling the less well adapted.

Evolution by variation and natural selection also takes considerable time to work, takes many generations to have much effect,  The expected fast temperature rise with continued business-as-usual probably will be too fast for evolution to keep up (see figure 2 here http://www.wundergro...limate/PETM.asp )

[inTHEsane]

Well I am not a scientist nor do I have all the data in front of me to even make an educated guess,
which to me when it comes to climate change and things over time frames that long, when we weren't
as good at recording things or really knowing much.

I thought they had many other reasons as to why certain species may have shrank in size over the years
as well as why other ones have adapted or changed due to their environment. That being said to me it
seems like it would be more those reasons and tempature change would be a coincedence, unless
say warmer climate change the environment/ecosystem of the area a certain species mainly lives.

Say for instance giraffes, they're long necks supposively comes from them eating tall plants/trees.
If climate changed an area to where it didn't have high trees and such, making giraffes have to bend
down for food instead of strech/reach for food, would mostly likely cause at least it's height to change.

[jasserEnv]

I would tend to agree that humans would not likely be affected by such changes. I also question whether the rapid nature of the temperature changes would lead to body size reductions so rapidly. Although there has been evidence of rapid evolutionary changes, I think that in many cases, if there are stresses on populations, it can actually cause the number of members of that species to drop rapidly instead. It all depends what the cause of smaller body sizes is. If it is due to food scarcity, it would likely cause drops in populations. If it was to enable life forms to move more easily beneath a thicker jungle canopy, I don't think we would see any changes for example.

[jasserEnv]

Apologies on the double post. The forum software hiccoughed when inTHESane posted at the same time as me...

[joeldgreat]

I prefer to think the opposite of this. One hundred years ago, the average height of people living here in my country is 5 feet 2 inches tall. Now it jumped an inch taller. In my college days, I used to play basket ball with only a 5 feet 7 inches play as center. Now I've seen kids in highchool already in 6 feet. Therefore, I would blame global warming for getting people increase their height than before.

[inTHEsane]

Interesting the forum seems to be having a glitch, it just posted joe's four times as well.
Anyway I agree to and forgot to mention that, we as humans have been growing in size
over the years, and pretty sure we have experienced the same climate as shrinking
horses, so I don't see this to be an accurate connection.

[hunysukle]

it's a possibility, since more oxygen in the atmosphere causes animals to be significantly larger. There's evidence in the prehistoric time period. So, therefore, a lack of oxygen in the atmosphere could eventually cause human beings to become a couple inches shorter. However, this would probably take many centuries for a change to gradually happen.

[Shortpoet-GTD]

hunysukle, on 28 March 2012 - 01:08 PM, said:

it's a possibility, since more oxygen in the atmosphere causes animals to be significantly larger. There's evidence in the prehistoric time period. So, therefore, a lack of oxygen in the atmosphere could eventually cause human beings to become a couple inches shorter. However, this would probably take many centuries for a change to gradually happen.

Oh, I don't know about that. Look how quickly the gop brains have shrunk in recent years?  Down to pea size at present.
(Sorry, off topic-but it fits.)