Climate change is causing a breed of wild sheep in Scotland to shrink, according to research.

Scientists say milder winters help smaller sheep to survive, resulting in this “paradoxical decrease in size”.

Classic evolutionary theory would predict that wild sheep gradually get bigger, as the stronger, larger animals survive into adulthood and reproduce.

Reporting in Science journal, the team says this shows the “subtle interplay” between evolution and the environment.

Scientists first began studying Soay sheep, on the island of Hirta in the St Kilda archipelago, in 1985.

Since then, the sheep have decreased in size by 5% - their legs getting steadily shorter and their body weight decreasing.

This strange phenomenon was first reported in 2007, but the reason for it remained under debate.

Full Story includes pfotograph of shrunken Hirta’s Soay sheep.

Now, evolutionary theory demands that the Scottish male population’s manhood will shrink as well…

Maybe it isn’t the climate change. Maybe the sheep are just getting rained on and the wool......

Classic evolutionary theory would predict that wild sheep gradually get bigger, as the stronger, larger animals survive into adulthood and reproduce.

No, actually it doesn’t.  “Fitness” in evolution relates to fitness in regards to being best equipped for dealing with its environment, not necessarily “fitness” as in strongest and fastest and such.  It just happens that often strongest and fastest and biggest is the fittest when it comes to dealing with environmental challenges.

But if being bigger means that it’s harder to stay cool and that energy and mass is wasted, then “fitness” would, according to classical evolutionary theory, require a smaller animal.

Is it possible that human intervention has had anything to do with this?  Not just the climate.  If their habitat has shrunk b/c of humans moving into the area…then it’s possible there is more food about for the animals to eat (people keeping their lawns tidy…and providing extra sustenance in the way of foliage they have around their yard)...so that the smaller animals don’t have to forage as far to find food.  They don’t have to fight with the bigger animals?

Or could it be just the opposite?  The food and nutritional sources have gotten smaller, so the sheep don’t grow as big?  Not so much evolution per se, as it would be a sign of a now poorer environment.  (If the locals were to boost their feed a bit, odds are they would once again grow bigger.)

Any change that could be seen as potentially bad is due to climate change, formerly known as global warming.

NEO - 04 July 2009 09:51 PM

Any change that could be seen as potentially bad is due to climate change, formerly known as global warming.

Of course. Regardless of whether it actually exists as postulated or not.

I’m still waiting for the next ice age.  I have my dogsled all ready to go. 

gray - 05 July 2009 01:09 AM

I’m still waiting for the next ice age.  I have my dogsled all ready to go. 

Why are you waiting?  It just came out this past week.  Get on your dogsled and head over to your local theater.

I still say it was the rain…..