Rather, we will look at the type of evidence, the inferences and the assumptions that are being made. Consequently, the argument will be accessible to non-scientist and scientist alike. Many more animals produce large numbers of offspring - consider, for example, the number of caterpillars coming from a cabbage white butterfly, or reflect on the population of tadpoles appearing in the local pond. Observation 2 Species numbers remain approximately constant. There are good years and bad years for all the animals we know - but we are not being overrun by robins or cabbage white butterflies or frogs.
Some offspring die without descendants of their own.
There are losers in the game of life. Observation 3 Individuals differ in small ways, and many of these differences are inherited from parents. The observation applies to people, as we can confirm by looking at parents and children known to us. In fact, it applies to all organisms - wherever we can look closely enough. Those individuals whose variations adapt them to their environment will be the most likely to survive and reproduce.