I remember a program many years ago on CBC radio about heritage breeds. Their point was that traditional animal breeds with minor selectivity were a fairly diverse lot. The average farmer did not have hundreds to animals to measure and cull, and did nto trot their animals miles and miles across the country to selectively breed them. (Except maybe race horse, but then, that’s not farm animals). With the massively selective breeding done in the last century, we have produced pigs and cows and chickens intensely targeted for what we want them to produce; but in return, we’ve lost an immense amount of other good characteristics. Modern pigs may be massive rapid meat producers, but they are so stupid they have to be restrained so the mother does not roll over on her piglets. Animals have lost a lot of the smarts that used to allow them to survive. You often hear that race horses of fancy dog breeds are “high strung” - i.e. they have lost a certain amount of self-control, have a tendency to some OCD habits. Some dog breeds, along with the looks that win awards, also have a propensity for arthritis or hip problems.
the point is that slow and steady selective pressure will produce whatever is useful but survivable. Forced breeding isolates one characteristic but does not give mutation a chance to adapt other characteristics. The adaptions for a giraffe, for example, are remarkable- but that took millennia to evolve, so the increasing height went along with the appearance of characteristics that mitigated the health problems of height, such as blood circulation issues. The selectiv advantage was apparently more food.
Our typical humans, bred to 10-foot status, need to evolve bigger, thicker bones and better circulation, a tendency to avoid obesity, etc. to survive. This is not already present in one simple genetic package. people who are 8 feet tall but very prone to ankle or broken leg problems, were less likely to survive in the hunter-gatherer environment up until a few millennia ago.
Similarly, our big brain gives us some advantage (we hope). However, our existing brain uses about 1/3 of our caloric intake, I understand. It also fits through a woman’s hip-bones. Smart people do not necessarily have more children than dumb people - in fact in our current social situation, it sometimes seems the opposite is true; but then, if malnutrition causes poor brain development, then it’s possible there’s a form of bias in that differential reproduction. However, a slower, longer term breeding program allows all the necessary pieces of the genetic puzzle to converge in whatever is being selected for, in a way that rapid forced selection will not.
Nitpick. That’s always been true. It’s not something that has been breed into pigs. My Grandpa’s hog barn built in the 50’s had pens with spaces only the piglets could get into so they could avoid the sow.
ETA. Never heard of restraints either but not real familiar with modern confinement farms. Every thing I’ve seen is some variation of a barrier that only the piglets can get under. Which is probably as old as the domestication of pigs. Before that we didn’t care or notice if an wild pig rolled over on her piglets.
I think the article may be accurate is here is why.
They mention chickens in 1957 weighed 905 grams. Chickens now weigh 4202 grams.
If you assume 1 SD for chicken weight back in 1957 is about 100 grams (which I suppose is reasonable as that is 11% of bodyweight) that means that chickens have increased in mass by 33 standard deviations. I have no idea what 1 sigma for chicken weight is, but a chicken today is arguably 30 sigma to the right of where a chicken was in the 1950s. Even if you assume 1 sigma for chicken weight in the 1950s is 20% of body weight, so 181 grams, that still means weights now are 18 SD to the right compared to the 1950s.
Of course the current arguments over factory farming generate a lot of hyperbole, so as someone whose food comes wrapped in plastic, I can only go by what I hear… Pigs used to be at least as smart as (smart) dogs. By forced selective breeding, i.e. pushing the envelope too fast for one characteristic, what has resulted is essentially a breed of oversized morons. After all, what do we care how smart our meat is? Not sure how far back this goes - your anecdote suggests it was a problem by the 1950’s. Current veggie propaganda mentions that sows are kept in cages too small to turn around or roll over so they don’t flatten the piglets - a symptom of stupidity and excessive weight overriding maternal instinct. Certainly centuries ago when pigs were kept in a pen and basically roamed free in there, this was not a problem.
I think that you are on the right track here and perhaps it is another human-selected species which may get us such a huge difference over a natural trait. Some other ideas:
Chicken egg laying (broiler size was mentioned above but this is a size + time comparison)- how many more eggs can a chicken pump out today than its ancestor or birds as a whole?
Cow milk - they are regularly pumping out gallons more per day for much longer periods of time. There is some hormone work here but certainly a lot of selective breeding as well.
Bee honey production - giving them a protected home near lots of crop flowers certainly maximizes production
corn and soy yields - these yields per acre for Iowa and Missouri today are off the charts compared to even a few decades back. Genetics are a large part of it but so are optimization of agrichemicals.
But there are two that more naturally evolved traits without as much human manipulation that probably put the current genetic abilities in the 20 SD units:
Yeast with ethanol production- There are now yeast that can produce ethanol at levels that were deemed impossible due to toxicity. Natural yeast (and most microbes) are killed at the low single digit concentrations. Ethanol Red was at 22% and I know there are strains well above that now.
Bacteria with betalactam (penicillins) resistance- penicillin derivatives were lethal at micromolar concentrations, but through selection and evolution of the bla and other genes, Molar concentrations of betalactams can now be used as carbon sources by these bacteria.