Squirrels Evolving to Suit Global Warming?

Gavinsblog writes "New Scientist is reporting that using a technique called quantitive genetics, researchers have found that due to the effects of global warming, female squirrels now give birth on average 18 days earlier in the year than their great-great-grandmothers. Is global warming also affecting human evolution?
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Comments

causality or correlation?

[jo-do-cus]

What i dont get: where did they get the information that these changes are "due to global warming" ?? It's not like you can interrogate a squirrel to ask them why his genes are different.

Probably the scientists saw the correlation with the changing climate and wrote that this would be 'a possible cause for that'. Journalists normally twist the meaning and content of scientific reports to make a nice headline, eventuakky becoming "Squirrels Evolving to Suit Global Warming".

Generally, one cannot claim that species evolve for some purpose, and even if it would be so, then how do you prove that any change in genes is due to some cause??? It's all just correlations and some hopeful guesses, if you ask me.

Re:causality or correlation?

[e8johan]

"It's not like you can interrogate a squirrel to ask them why his genes are different."

Can you do that to a human? I think that I know the basic mechanisms generating my genome from my parents, but I don't know why they are different.

As I understand it gene changes are not fit a certain problem, but completely random. As a random change may be a change to the better, the survival of the fittest will make this change spread to more individuals in the next generation than a less fit gene.

This does not rule out that the change in birth rate and pregnancy time has been fitter due to a change in the climate. But sience based on correlation is dangerous. It has been used before to "prove" lies.

Re:causality or correlation?

[Sgt York]

I was skeptical about this at first, as well. But there is a bit of logic to it (just a bit). If it is warmer earlier in the year, it is possible for the pups to survive when born earlier. Typically, animals that are born prior to the last freeze don't have a good survival ratio. If the last freeze comes earlier in the year, pups born at earlier times have a better chance. It's logical, but there are holes.

It is possible that this is a response to warming, but not an evolutionary response. Perhaps the squirrels mate earlier due to increased temperature. Also, this would be an easily saturable effect. Plants don't bloom in response to temperature, they bloom in response to ammount of sunlight. Since the Earth's tilt is still the same, the plants will still bloom at the same time. This means the pups may be alive & toasty warm, but with little/no food in the early stages of life. This would yeild smaller (or no) adults

Although you are correct that evolution does not have a purpose, it does occur in response to change in the environment. It does not have the "intent" of adapting to he environment, but that is what winds up happening.

Besisdes, this is probably popular media exaggerating a scientitst's claims again. I haven't read the real paper, but I would wager that the scientist worded things in less absolute terms. He probably said it appears to be due to global warming, or was strongly correlated with increased temperature.

Re:causality or correlation?

[perljon]

The general problem with concluding a casual relationship from a correlational study is that it's not objective. the author can create any logic to explain the causal relationship.

ie, take these facts. There are more computers produced every year.
When computers are on, they create heat.
The Earth is warming every year.
Therefore, The increased existance of computers is causing global warming.

This may seem insane, but it follows the same logic pattern as this story or any causaality based on a correlational study.
Causality can only be determined with causal expirements.

Evolution of human?

[Gadzinka]

Is global warming also affecting human evolution?

There ain't no such thing as human evolution (anymore).

The evolution is a trials and errors process. During the duplication of DNA sometimes something goes wrong and the result isn't a perfect copy of the original.

This is called a mutation.

As a result some function of the organism is different. The change may be beneficial for the organism or it may render it handicaped. For every positive mutation there are houndreds of thousands negative mutations.

Who's to tell which mutations are positive and which are negative?

Natural selection.

If/when a particular mutation has some features that allow it to dominate gene pool it is positive. If the mutation causes premature death, sterility etc the faulty genes do not enter the gene pool. This is negative.

In order for humans to evolve we would have allow natural selection to work. We don't do this. It is not the survival of the fittest for a long time.

Robert

Re:Evolution of human?

[jazznjava]

There ain't no such thing as human evolution (anymore).

I agree that natural selection is past its prime in developing countries, but I don't believe evolution has stopped, or that evolution will ever stop. I think people are evolving more by societal selection than natural selection.

In other words, now it comes down to who has more children, not who has children and who gets killed before they get the chance to (except those lucky Darwin Award laureates).

So geeks are currently on the road to extinction! It is up to those who can to breed like rabbits to prevent this!

Re:Evolution of human?

[bill_mcgonigle]

There ain't no such thing as human evolution (anymore).

This statement assumes a static environment model, which is uncertain at best.

Maybe we wipe out the ozone layer, and everybody with light skin dies young from skin cancer.

Or maybe we blanket the earth with a nuclear winter or there's an mega-killer asterioid hit and everybody with dark skin dies from Vitamin D deficiency. Everybody in temperate climates dies too because it's too cold to grow crops, so only those smart/clever/ruthless enough to migrate south and grow food survive.

For instance. There may not be any environmental pressures on human evolution at the moment, but that equalibrium is subject to being upset.

Human Evolution...

[jsimon12]

"Is global warming also affecting human evolution?"

The envionment really stopped effecting human evolution once we started to manipulate it, so it is unlikely that you will see any similar effects in humans. If it gets to hot for us, we just crank up the AC.

Breaking News?

[gi-tux]

I remember seeing this in gray squirrels growing up on the farm 30+ years ago. If food is available early then the squirrels had their litters early. If there were bad rains late in the season and the first litter was drowned, etc. then a second litter was usually delivered.

I wouldn't call this anything evolutionary. It is interesting that their instinct takes care of this for them, but it isn't any kind of change. We have been lucky over the last few years and have had short winters (at least in the southern US) and that has changed the beginning of spring and most likely the birth dates of some animals.

I bet that they spent a ton of federal money on that study too. Just another waste of taxpayer money trying to prove that God doesn't exist.

Re:Global Warming?--Right...

[MarkGriz]

Agreed.

I must say I'm a bit surprised that most of the comments here seem to be in the "not global warming" camp. Must be that the doom-n-gloomers are still asleep?

You miss the point (but I am not surprised)

[jsimon12]

The point is the fact that humans change their environment rather then adapt to it, whether it be with AC, buffalo skin tents, white clothing or even a simple structure made from fallen branches. The last major physical thing we "adapted" to would probably be UV radiation and the production of vitamin D (hence the reason people have different skin colors).