The modern scientific concept of evolution is most closely associated with Charles Darwin , who formulated the theory of evolution by natural selection in the mid‑19th century and presented it in 1859 in his book On the Origin of Species.

However, Darwin was not the first person ever to think about species changing over time:

  • Ancient Greek thinkers like Anaximander and Empedocles suggested that living things might transform from one form to another.
  • In the late 18th and early 19th century, Jean‑Baptiste Lamarck proposed one of the first broad evolutionary theories, arguing that organisms gradually progressed from simpler to more complex forms.
  • Charles Darwin’s grandfather, Erasmus Darwin, also speculated about evolution in his work Zoonomia , though his ideas remained underdeveloped.
  • Alfred Russel Wallace independently conceived the idea of evolution by natural selection around the same time as Charles Darwin; the two jointly presented their ideas in 1858, before Darwin’s full book appeared.

So, if your question is:

  • “Who introduced the modern scientific theory of evolution by natural selection?” → Charles Darwin (with Alfred Russel Wallace independently co‑discovering the mechanism).
  • “Who first ever thought species might change over time?” → That idea traces back to much earlier philosophers and naturalists, but their views were not yet the modern scientific theory.

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