Complete the text with the words below.
All life forms on earth are evolving 1) ... . Changes in the genetic material of animals, insects and plants can eventually lead to the 2) ... of new species.
In most species, two sets of 3) ... from the parents combine at the reproduction stage to create a unique offspring that is not 4) ... to its parents.
Genetic variation happens randomly. This is important in order to increase the 5) ... of survival and further reproduction. The species 6) ... itself to environmental changes in this way. Over time, helpful characteristics become more common and unhelpful ones disappear. This is part of the process of natural selection.
We all 7) ... our characteristics from our parents. How this happens is of constant interest to evolutionary biologists who 8) ... the work of developing and testing theories of evolution.