(The absence of natural selection is hard to imagine, though, given that organisms replicate their genetic material, and some genes will replicate better than others in different environments.
Lamarckism and teleologically-driven evolution, however, were once seen as the main drivers of adaptation.) Finally, you could have evolution but not gradualism: every population could experience great saltational leaps in one generation.
The fossil fish Priscacara liops found in sediments dating from the Eocene epoch (55.8 ± 0.2 to 33.9 ± 0.1 mya) in present day Green River, a tributary of the Colorado, USA. Scientific understanding requires both facts and theories that can explain those facts in a coherent manner.
Evolution, in this context, is both a fact and a theory.
Like every other science, there is scientific debate about some aspects of evolution, but none of these debates appear likely to shake the foundations of this field.
There exists no other scientific explanation that can account for all the patterns in nature, only non-scientific explanations that require a miraculous force, like a creator.
For example, you could have evolution without branching: that would mean that only one long-evolved species would be alive today.
Or you could have evolution, but not occurring by natural selection.While progress has been made in this area, the origin of life remains an interesting, but unanswered, question.Biological evolution results from changes over time in the genetic constitution of species.These examples also illustrate the importance of this evidence for science and society more generally.Evolutionary biology is a strong and vigorous field of science.In my general talk on the evidence for evolution, I give a list of seven observations that, if repeated and confirmed, would disprove parts of the theory of evolution described above.