Gradualism is an evolutionary model that refers to the tiny variations in an organism or in society that happen over time to make a better fit for animals and humans in their environment. These variations allow them to survive and thrive, resulting in a slow and consistent process of change in the whole population.
Gradualism in biology has to do with the evolution of a species. You can think of it as slow and steady. By definition, gradualism is the small, consistent changes within an organism that take place over time to give a species an advantage.
Gradualism is in direct contrast to the evolutionary theory of punctuated equilibrium. While gradualism is slow and steady, punctuated equilibrium is a large change happening all at once after a long period of no changes. Punctuated equilibrium typically happens through sudden gene mutations.
Gradualism evolution takes time to happen, especially in the animal kingdom. Explore some examples of gradualism in different types of animals.
A species of butterfly is yellow and black in color. However, a butterfly is born that happens to be orange and yellow in color making it difficult to see. Over a long period of time, the yellow and black butterflies die out, because the orange and yellow color combination makes the butterflies less visible to predators.
Small variations occur over time in a population of wolves — larger ears, longer teeth and a heightened sense of smell. Wolves with these helpful traits tend to survive better than those without; as time progresses slowly, the traits gradually become the norm among the population.
Over a period of many, many years, a population of elephants develops larger ears to help protect the elephants from the sun and keep them cool. This larger ear eventually becomes a physical feature of the entire population of elephants.
A group of finches begins to exhibit different features from those in the rest of the population, including shorter beaks and black stripes on their wings. Eventually, the two distinct groups of birds are considered entirely separate species from one another.
Changes occur among a group of tree frogs which include color patterns that help them hide from predators and poisonous skin secretions that deter predators from seeking them out as a food source. As time progresses, these traits become standard in the population of tree frogs.
A bird is born with a longer beak than others in its population, which allows it to more easily forage for insects inside trees, offering it an advantage over its shorter-beaked relatives. As a great deal of time progresses, more and more birds in the population are born with this advantageous feature, eventually resulting in the entire population of birds with longer beaks.
Over a long period of time, tigers develop a combination of orange and black stripes, which allow them to hide in tall grasses as they stalk their prey. This trait eventually becomes one of the distinguishing features of tigers, as the coloring on all future tigers changes to adopt the orange and black stripe coloring.
Small variations appear over a long period of time among a population of penguins, including thicker coats of down that allow them to survive in very cold climates. Penguins with these traits survive much better than those with thinner down coats, leading to the changes becoming standard among all penguins.
Certain moths in one population gradually adopt changes in color and wing shape. After a great deal of time, the two groups of moths develop into entirely distinct species from one another.
Gradualism doesn't just happen in evolution. Gradualism also refers to slow changes in society and politics. Discover a few non-evolutionary examples of gradualism.
- In the United States, African-Americans were originally kept as slaves. Over time, slavery was abolished, and they were afforded the right to vote. In the mid-20th century, segregation was ended and Blacks were integrated into society as individuals with full rights.
- England, originally a full monarchy, gradually became a democracy with the introduction of the House of Lords, a Parliament and a Prime Minister. Today Britain is a democratic society, with the monarchy serving primarily as a figurehead.
- When the Industrial Revolution occurred, it allowed for the gradual creation of a middle class. Poor individuals were now able to work and move up in society whereas before, there was no social mobility.
- Women in America originally lacked many of the rights afforded to men, such as the right to own property and to vote. Over time, with the gradual growth of the suffrage movement, the laws were changed and women were given the same voting rights as their male counterparts.
- In the mid-20th century, women were often paid far less than men for similar jobs, when they were allowed to work. Gradually, as women pushed for equal rights to men, their pay grades and job opportunities began to reach parity with those of men.
- Throughout the world, gay people have historically been denied certain rights and privileges, such as the right to marry. Gradualism in western society has allowed for the slow adoption of rights for gay people. This process is ongoing even today.
- In some eastern nations, women still have very few rights. In some countries, this leads to revolution — however, in others, gradualism has prevailed and women’s rights are slowly becoming the norm.
- Gradualism in American society has led to a greater understanding of the health needs of children, as more and more schools offer healthy lunches in an effort to curb child obesity.
You can think of gradualism as the slow and steady tortoise working on winning the race. Now that you know how animals can evolve gradually, and you have plenty of examples that help to better illustrate the gradualism concept, check out examples of evolution in biology.