Artificial Selection Examples- When Selection Goes Wrong
What Is Artificial Selection (And Why It Often Goes Sideways)
Artificial selection is when humans decide which plants or animals get to reproduce based on traits we want. Unlike natural selection, where survival decides, humans play matchmaker with a specific goal in mind.
The problem? We're really bad at seeing the big picture. We pick what looks good, what produces more, what grows faster. We ignore what happens two generations down the line.
This article shows you real examples where artificial selection went wrong. Not to depress you. To show you what happens when you optimize for one thing and forget everything else.
The Basics: How Artificial Selection Works
You select parents with desired traits. You breed them. You repeat. Over generations, you get animals or plants that look, produce, or behave exactly how you want.
Charles Darwin used pigeon breeding to explain this. Dog breeding is another obvious example. Farmers have done it with crops for thousands of years.
It works. That's not in dispute. The question is: works for what? And at what cost?
When Artificial Selection Goes Wrong: Real Examples
1. English Bulldogs: A Breathing Disaster
English bulldogs look nothing like their ancestors. The original bulldogs were agile, healthy working dogs. Today's bulldogs are genetic disasters.
Breeders selected for:
- Flattened faces
- Wrinkled skin
- Wide chests
- Short stature
What they got was a dog that can't run more than a few minutes without overheating. Their airways are so compressed that many bulldogs struggle to breathe. The average lifespan dropped significantly. Many require expensive surgeries just to function.
A 2016 study found that if bulldog breeding continues as-is, the breed could become unviable within decades.
2. Milk Production: The Dairy Cow Problem
Modern dairy cows produce an absurd amount of milk. Holstein cows average about 6-7 gallons per day. Their ancestors produced maybe one gallon.
This happened through aggressive selection for milk volume. The consequences:
- Metabolic disorders like ketosis and milk fever
- Reproductive problems — many cows can't calve without assistance
- Lameness from carrying oversized udders
- Shortened lifespan — many dairy cows are slaughtered after 3-4 years when natural lifespan is 20+ years
The industry knows. They just accept it as the cost of production.
3. Broiler Chickens: Growth Rate Gone Nuclear
Broiler chickens (meat chickens) are bred to put on weight fast. Really fast. A modern broiler reaches market weight in 6-7 weeks. In the 1950s, it took 12-16 weeks.
The selection worked. Too well. Problems include:
- Organ failure — hearts and lungs can't keep up with rapid growth
- Skeletal problems — legs break under the weight
- Inability to walk properly in many birds
- Ascites (fluid buildup) kills millions of birds annually
These chickens are essentially engineered to die young. They reach slaughter weight before their bodies give out.
4. Corn: The Inbred Weakling
Modern corn looks nothing like its wild ancestor, teosinte. We've selected for larger ears, more kernels, and uniform appearance.
The result: genetic uniformity. Most corn in the US is so genetically similar that a single disease could wipe out massive portions of the crop. The Irish Potato Famine is a historical example of what happens when you breed genetic uniformity into food crops.
Farmers now deal with corn that requires heavy pesticide and fertilizer use to survive. It can't compete with weeds or handle drought without human intervention.
5. Bananas: The Complete Failure
The banana you eat today is a Cavendish. The banana your grandparents ate was a Gros Michel. The Gros Michel was bigger, had better flavor, and shipped better.
It went extinct. Panama Disease, a fungal infection, wiped it out completely. Why? Because all Gros Michel bananas were genetically identical clones. No variation meant no resistance.
The Cavendish replaced it. Now the Cavendish is facing the same disease. Same solution: find a new variety and repeat the cycle.
6. Racehorses: Breeding for Speed, Dying for It
Thoroughbred racehorses are bred for speed. Generations of selection for fast runners. But this selection ignores everything else.
Common problems from this artificial selection:
- Fragile legs — catastrophic injuries are common
- Small hearts relative to body size
- Respiratory issues from selective breeding for nostril size
- Many Thoroughbreds are euthanized before age 5 due to injury
The racing industry knows horses break down. They breed more anyway.
7. Wheat: The Lodging Problem
Modern wheat varieties are short-stalked to resist lodging (falling over). Short stalks mean less energy goes to the stalk, more to the grain.
Except short-stalked wheat is more susceptible to:
- Root diseases
- Drought stress
- Certain pest damage
Each "improvement" creates new vulnerabilities. Farmers now need more inputs to compensate.
Comparing Artificial Selection Outcomes
| Species | Desired Trait | Unintended Consequences |
|---|---|---|
| English Bulldog | Flat face, wrinkles | Respiratory failure, overheating, birth problems |
| Holstein Cow | High milk yield | Metabolic disease, lameness, 4-year lifespan |
| Broiler Chicken | Rapid weight gain | Organ failure, broken legs, sudden death |
| Corn | High yield, uniformity | Genetic vulnerability, input dependency |
| Banana (Cavendish) | Consistent fruit, shipping durability | Complete disease vulnerability |
| Thoroughbred | Race speed | Fragile legs, catastrophic injury, early death |
Why Does This Keep Happening?
Three reasons artificial selection consistently produces problems:
Single-trait focus. Breeders pick one thing and optimize for it. Everything else gets ignored or actively degraded. A dairy cow produces more milk. Whether she can walk, breathe, or live past four years is someone else's problem.
Short-term economics. If you can sell more milk this quarter, you breed for more milk. Future health problems don't show up on quarterly reports. The next guy deals with it.
Ignoring genetic diversity. Uniformity is efficient. It makes processing easier, results more predictable. It also makes everything fragile. One pathogen, one environmental shift, and the whole system collapses.
Getting Started: How to Recognize Bad Artificial Selection
You don't need a genetics degree. Look for these signs:
- Extreme physical features. Flat faces, oversized udders, legs too short for the body. If it looks uncomfortable to live in, it probably is.
- Health guarantees. If a breeder offers a health guarantee, that's a red flag. Healthy animals shouldn't need guarantees — they're supposed to be healthy.
- Low genetic diversity. If every example of the plant or animal looks identical, that's a warning sign.
- Performance data without health data. "Gains 20% faster" is nice. "Lives 60% shorter" should come with it.
For crops: if a variety requires constant pesticide, fertilizer, and irrigation to survive, the artificial selection created a plant that can't exist without industrial support.
The Bottom Line
Artificial selection works. It produces more milk, faster growth, prettier flowers. But every gain comes with a cost. The question is who's paying it.
Usually not the breeder. Usually not the consumer. Usually the animal, plant, or system itself.
This isn't a call to abandon artificial selection. It's a call to be honest about tradeoffs. When you select for one thing, you're selecting against others. Ignoring that doesn't make the problems disappear. It just means they show up later, in worse form.