Selective breeding

People can choose which plants and animals have babies.

They pick the ones with the best traits. This is called selective breeding.

If a plant grows big fruit, people pick it. Then, that plant has babies with big fruit too. This can make more food for us.

People do this with animals, too. They can make dogs of many sizes.

They can even make sheep with soft wool.

This has happened for a very long time. People have done this since long ago. It helps us grow better crops and animals.

Selective breeding is a way people change plants and animals. They choose which parents will have babies. They pick the ones with the best traits. These traits are the special features of a living thing.

This has happened for a very long time. Humans have done this since prehistory. For example, wild teosinte changed into modern maize.

People also bred dogs to be many different sizes.

In the 1700s, a man named Robert Bakewell used this method. He worked with sheep to make them larger. He also made them have better wool. He helped make cattle much bigger too. In 1700, a bull might weigh 370 pounds. By 1786, they could weigh 840 pounds!

Scientists also use this in labs. They can breed plants to have many colors.

Researchers have made carrots in many bright colors. This work helps us grow more food. It also helps us understand how life works.

Selective breeding is a way humans change living things. It is also called artificial selection. People choose specific males and females to have offspring together. They do this to develop certain traits, or special characteristics. These traits might be a specific color or a certain size.

When animals are bred this way, they are called breeds. Plants that are changed by humans are called varieties or cultivars. This process helps people get exactly what they need from nature.

How does this way of working actually happen? A breeder looks for animals or plants with very useful features. They pick the best ones to reproduce. This is sometimes called "breeding the best to the best." They might use a method called inbreeding to keep traits stable. This helps ensure the babies look like the parents.

However, focusing on only one trait can cause problems. For example, some roosters grew so heavy they could not dance. This made it hard for them to interact with hens.

Humans have practiced this since prehistory. Long ago, people changed wild plants into food we recognize today. For instance, teosinte was changed into modern maize.

Dogs have also been changed into many different sizes over time.

The Romans practiced selective breeding thousands of years ago. They used advice from experts like Mago the Carthaginian. Later, in the 11th century, Abu Rayhan Biruni wrote about it too.

Robert Bakewell made breeding a real science in the 1700s. He worked during the British Agricultural Revolution. Bakewell improved sheep to have more wool and better bodies. He also created the Dishley Longhorn cattle. His work made farm animals much larger and better. In 1700, an average bull weighed only 370 pounds. By 1786, that weight grew to 840 pounds!

Charles Darwin studied this in his 1859 book. His book is called On the Origin of Species. Darwin used selective breeding to explain natural selection. He showed how humans direct changes in plants and animals. Today, scientists use these same ideas in many ways. They use it in aquaculture to improve fish and shellfish. They also use it in labs to study how life works.

Selective breeding, often called artificial selection, is a process where humans influence the traits of living things. By choosing specific males and females to reproduce, humans can develop particular phenotypic traits. Phenotypic traits are the observable characteristics of an organism, such as size, color, or behavior.

In the world of animals, these groups are known as breeds. In the world of plants, they are often called varieties, cultivars, or cultigens. This process allows humans to transform wild species into useful resources for food, clothing, and companionship.

The mechanism of selective breeding relies on controlled reproduction. A breeder begins with breeding stock, which is a group of animals or plants used for planned reproduction. The breeder identifies individuals that possess desirable characteristics. They then allow these specific individuals to mate, a process sometimes called "breeding the best to the best." To keep these traits stable across many generations, breeders may use inbreeding or linebreeding. These methods ensure that offspring closely resemble their parents.

However, the process can be unintentional. For example, certain ploughing practices might lead to larger grain seeds without a human ever intending to select for them.

Different methods are used depending on the goal of the breeder. Purebred breeding aims to maintain stable, predictable traits within a single, recognizable breed. This is often managed through breed registries or stud books that record lineages. In contrast, crossbreeding involves mating two different purebreds to create a crossbreed. When plants are crossed this way, they are called hybrids. Sometimes, breeders look for hybrid vigor, which is a phenomenon where a hybrid shows superior qualities compared to its parents.

Humans have practiced selective breeding since prehistory. Key species like wheat, rice, and dogs have changed significantly from their wild ancestors over millennia. In Mesoamerica, humans selectively bred teosinte, a wild grass, into modern maize.

The Romans also practiced these methods, using advice from ancient authorities like Mago the Carthaginian. In the 11th century, the polymath Abu Rayhan Biruni documented examples of selective breeding in his book, *India*. These ancient practices laid the groundwork for modern agriculture.

During the 18th-century British Agricultural Revolution, Robert Bakewell established selective breeding as a scientific practice. He focused heavily on improving sheep, creating the Lincoln Longwool and the New Leicester. The New Leicester was a hornless sheep with a meaty body and straight top lines. Bakewell also revolutionized cattle breeding. He crossed long-horned heifers with a Westmoreland bull to create the Dishley Longhorn. This shift from using cattle as oxen to using them for beef had massive results. In 1700, the average bull weighed 370 pounds. By 1786, that weight had increased to 840 pounds.

While highly effective, selective breeding can lead to unintended consequences. Focusing too heavily on a single trait can cause health or behavioral issues. For instance, some roosters bred for heavy muscle growth lost the ability to perform courtship dances. This caused them to alienate hens, sometimes leading to fatal interactions. In a Soviet study, attempting to breed lab rats for higher intelligence resulted in severe neurosis. These animals became unable to solve problems without the help of drugs.

Selective breeding also plays a role in modern science and industry. Charles Darwin used the concept in his 1859 book, *On the Origin of Species*. He used artificial selection as an analogy to explain his theory of natural selection. Today, scientists use these principles in experimental biology and aquaculture. In aquaculture, breeders work to improve the growth rates and survival of fish and shellfish. This requires careful documentation of genetic gains and control over reproduction cycles to avoid inbreeding depression.