Where Do Our Traits Come From?

When somebody says that a newborn baby has “his mother’s eyes” or “her father’s smile,” what are they trying to say?

Physical characteristics like eye color, hair color, and dimples are called traits. All of your traits are given to you by your parents. But how?

You inherit something called genes (information) from your parents. These genes (information) determine your traits. When a new baby is made, they inherit 50% of their genes from their mother and 50% of their genes from their father. That's why you might hear people say you look like one of your parents, maybe having your mom's eyes or your dad's smile.

Like humans, most animals also inherit traits from their parents. The diagram below shows two dog parents with their offspring.

Genetic Variations

How many different hair colors can you think of?

Some of your friends and family may have red, brown, black, or blonde hair. As humans, we’re all part of the same species. So how can hair color in the same species have a lot of variety?

A species is a group of organisms that share similar characteristics.

Our hair color is an example of genetic variation. Genetic variation is the variety of genes and traits within a population. Everyone inherits a unique combination of genes (information) and traits from each of their parents. This explains why people have different traits like hair color, eye color, and skin color.

Genetic variation also exists in animals and plants. Tulip petals can be different colors, moths can have different colored wings, snakes can have different scale patterns and colors, and finches can have different beak sizes.

What is an Adaptive Trait?

Frogs are known for their long, sticky tongues that help them catch prey. But what would happen if a frog had a shorter tongue?

Scenario:

Two hungry frogs are sitting in a pond. They love to eat flies, and their pond has a bunch of them! But flies move fast, so the frogs have to stick their tongues out quickly to catch them. Luckily, frogs can stick their tongues out five times faster than the blink of an eye.

But one frog has a longer tongue and one has a shorter tongue. Who is more likely to catch more flies? In other words, who had the advantage?

The frog with the longer tongue would be able to catch more flies, which means it gets the energy it needs to survive. That means that having a long tongue is an adaptive trait for this frog.

Natural selection explains how a population of species evolves over time in response to their environment.

Let’s analyze an example showing the process of natural selection.