Change over Time (Evolve) — Characteristics of Life

What Does Change Mean?

All living things are able to change over time. Of all the characteristics of life, this one requires the most careful explanation.

We know that all organisms grow and develop and respond to changes in their environment.

Let's consider some examples:

These are all ways that an individual organism can change during its lifetime.

Changes in Populations

There are also changes that occur on the population level. A population is a group of the same type of organism living in the same place.

Here are some example populations:

• All of the prairie dogs in one grassland
• All of the black ants in the same patch of forest
• All of the humans in your town

When populations change over time, we call this evolution.

So, to repeat, populations evolve; individual organisms change and develop.

Evolution involves changes in the genetic makeup of a population. If we see more or less of a particular trait in a population over time, the population is likely evolving.

Let's look at some examples of this:

Wings of Peppered Moths

In this example, the smoke and smog from British industrialization caused a layer of soot to cover most of the trees in London. This made the tree bark appear darker, so the lighter colored moths resting on it were easier for predators to find. Natural selection began to favor darker moths as a result, so the prevalence of dark-winged moths began to grow while white-winged moths grew to be less common.

Note that the wings of an individual moth did not change from white to black over its lifetime. Instead, the proportion of white and black wings in the entire moth population changed over about 50 years' time. This is evolution in action.

Beaks of Finches

Here's one more example:

Once again, you'll notice the beak of an individual finch did not change from medium to small over its lifetime. As with the moths, the changes here were in the proportions of finches with small beaks and those with medium beaks throughout the entire population.

Key Vocabulary:

1. Organism
2. Growth and development
3. Population
4. Evolve

Adapting to Changes

For an organism to continue to survive, it must be able to adapt to changes in its environment. These responses are closely related to homeostasis, but they are slightly different in that they are more permanent and often result in behavioral changes.

This is not to be confused with evolution, which is change that occurs within an entire population over multiple generations rather than in individual organisms.

Examples of adaptations include:

• A change in a wolf's hunting habits in response to the movement of prey
• The darkening of skin pigmentation in response to sun exposure (tanning)
• Acclimation to pressure change when traveling to higher altitudes (ears popping)

Evolution, on the other hand, is what happens to populations over a long time. You won't be able to see a single organism evolve. The only way to measure it is to look at how traits in a population have changed over hundreds of years.

Videos: Adaptations, Evolution, and Changing Over Time

It can be hard to understand evolution. Here are three videos explaining what evolution and adaptation are and how organisms change over time.

(Video) What Is Evolution?

by Stated Clearly

How and why do changes happen in a population? The answer has to do with small variations in DNA that get passed down from generation to generation. In this video, you will see examples of how some species have changed over time and also learn about the theory of natural selection.

(Video) Adaptations and Evolution

by Science Box

How much do you know about dinosaurs? This cute video uses dinosaurs to explain adaptations and evolution.

(Video) Living Things Change

by Crash Course Kids

Living things have to keep up with their environments. How does this happen? This video explains how an organism's adaptations helps it live in its ecosystem and how evolution changes species over long periods of time.