ANATOMY

Detailed explanation-1: -It is known as Luca, the Last Universal Common Ancestor, and is estimated to have lived some four billion years ago, when Earth was a mere 560 million years old.

Detailed explanation-2: -Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time.

Detailed explanation-3: -Individual organisms don’t evolve. Populations evolve. Because individuals in a population vary, some in the population are better able to survive and reproduce given a particular set of environmental conditions.

Detailed explanation-4: -One example is the evolution of the horse. The horse can be traced to an animal the size of a dog having several toes on each foot and teeth appropriate for browsing; this animal, called the dawn horse (genus Hyracotherium), lived more than 50 million years ago.