The Greatest Show on Earth

Lesson 1. Artificial selection has produced different breeds of dogs.

Did you know that dogs have descended from the wolf? It is pretty interesting because despite having evolved from the same species, there are different breeds of dogs that look starkly different. 

The differentiation into various breeds is the result of artificial breeding of dogs by humans. For thousands of years, humans have selected and bred dogs having similar and desirable characteristics, so that their descendants have only those desirable traits. This process where you selectively breed only those animals with desirable traits is called artificial selection. 

This process is applied to plants as well. For example, tastier varieties of cabbage are developed through artificial selection. 

The traits that an organism manifests is determined and controlled by their respective genes. It is the genes that control whether the dog will have short legs, or whether the cabbage will be tastier. Actually, it is these desirable genes which are selected and preferred, not the characteristics.

During reproduction, the parental genes are passed onto the offspring. The offspring gets half of its genes from the mother and the remaining half from the father, thereby having a unique genetic constitution. 

During artificial selection, the parents with the desirable characters are chosen so that they can pass on the genes for those traits to their offsprings. This process paved the way for differentiation of dogs into different species.      

Lesson 2. All species have evolved from a common ancestor.

Earth today houses thousands of different species of organisms. These species however have common links. If we go back in history far enough, we can find the common ancestors to several of these species which are now starkly different from each other. So how did this differentiation take place? 

In fact, descendants of common ancestors got separated and developed differently under different situations. The separation created separate gene pools that evolved through thousands of years, independently.

What caused these separations? There may have been several reasons, including massive earthquakes, floods and changes in the landscape. Movement of tectonic plates have broken apart continents, and consequently separated organisms. Similar fossils have been found in areas as disparately located as South America, Africa, Australia, India and Antarctica, which prove the  existence of one ‘supercontinent’ millions of years in the past. 

Organisms themselves sometimes end up in a different place, which becomes their new home. For example, green Iguanas landed up in the Caribbean island of Anguilla around 1995. They didn’t exist on that island prior to