Charles Darwin (1809-1882) and Alfred Russel Wallace (1823-1913) are jointly credited with coming up with the theory of evolution by natural selection, having co-published on it in 1858. However, Darwin has generally overshadowed Wallace since the publication of On the Origin of Species in 1859. The Natural history Museum’s Library holds the world’s largest concentration of Darwin works, with 478 editions of On the Origin of Species in 38 languages.
Natural selection is a mechanism of evolution. Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success. This process causes species to change and diverge over time.
Natural selection is one of the ways to account for the millions of species that have lived on Earth.In Darwin and Wallace’s time, most believed that organisms were too complex to have natural origins and must have been designed by a transcendent God. Natural selection, however, states that even the most complex organisms occur by totally natural processes.
How it works?
In natural selection, genetic mutations that are beneficial to an individual’s survival are passed on through reproduction. This results in a new generation of organisms that are more likely to survive to reproduce.
For example, evolving long necks has enabled giraffes to feed on leaves that others can’t reach, giving them a competitive advantage. Thanks to a better food source, those with longer necks were able to survive to reproduce and so pass on the characteristic to the succeeding generation. Those with shorter necks and access to less food would be less likely to survive to pass on their genes.
If you take 1,000 giraffes and measured their necks, they’re all going to be slightly different from one another. Those differences are at least in part determined by their genes.
The ones with longer necks may leave proportionally more offspring, because they have fed better and have maybe been better in competing for mates because they are stronger.
Then, if you were to measure the necks of the next generation, they’re also going to vary, but the average will have shifted slightly towards the longer ones. The process carries on generation after generation.