The idea of evolution is that the species change over time. The proposed mechanism of evolution is natural selection. Natural selection favors inheritable traits, suitable (adapted) for survival and reproduction. Organisms with such traits will tend to leave more offspring than others, and thus will evolve over time.
Some of the people that influenced Darwin are:
• Lamarck who first proposed that humans evolved from a lower species through adaptations over time
• Malthus, economist who explained that population grows faster than food production could sustain. So, Darwin proposed that only individuals that have favorable adaptations would survive.