Smooth fitness landscapes are a necessary and fundamental outcome of evolution.

Judged against evolutionary biology as of 2007. TRUE: the literature as of 2007 (on evolvability, robustness and genotype-phenotype maps, e.g. Wagner, Kirschner & Gerhart) treats it as established that evolution itself produces smoother fitness landscapes (modular, robust genotype-phenotype maps where small mutations have small effects), and that this smoothing is fundamental and needed for continued adaptation. MOSTLY TRUE: the literature broadly supports that evolution produces smoother landscapes and that this matters a great deal for evolvability, but 'necessary' is somewhat stronger than the evidence. MIXED: one part is supported and the other is not. For example, smoothness is shown to matter for evolvability, but whether evolution produces it (the 'evolution of evolvability') is still openly debated. MOSTLY FALSE: the claim states as established what was in 2007 a contested or largely theoretical hypothesis without solid empirical support. FALSE: the evidence shows that evolution does not tend to produce smoother landscapes, or that smoothness is neither necessary nor fundamental. For example, landscapes are shown to be mainly rugged, with adaptation going ahead without any evolved smoothing.

Set before the research began.

1. E1 PERSPECTIVE: COMPLEX ADAPTATIONS AND THE EVOLUTION OF EVOLVABILITY Evolution (Oxford Academic, Society for the Study of Evolution) · 1 June 1996

   “While our current knowledge is insufficient to assess the plausibility of these models, they form the beginning of a framework for understanding the evolution of the genotype‐phenotype map.”

2. E2 PERSPECTIVE: COMPLEX ADAPTATIONS AND THE EVOLUTION OF EVOLVABILITY Evolution (Oxford Academic, Society for the Study of Evolution) · 1 June 1996

   “Such a design is expected to improve evolvability by limiting the interference between the adaptation of different functions.”

3. E3 Evolution favors protein mutational robustness in sufficiently large populations arXiv · 14 April 2007

   “Whether the evolutionary process somehow promotes the acquisition of mutational robustness and evolvability therefore remains a major question”

4. E4 Evolution favors protein mutational robustness in sufficiently large populations arXiv · 14 April 2007

   “Our work is the first experimental demonstration of the general tendency of evolution to favor mutational robustness and protein stability in highly polymorphic populations.”

E2, a 1996 review, states that such a design is expected to improve evolvability, which supports the view that this kind of structure matters for adaptation. But E1 says knowledge was insufficient to judge models of how the genotype-phenotype map evolves. E3, from 2007, says it "remains a major question" whether evolution promotes robustness and evolvability. E4 reports a first experimental demonstration that evolution tends to favour mutational robustness, but only in large populations with many variants. That is early and conditional support, not established fact. This fits the criteria's mixed case: smoothness was expected to matter for evolvability, but whether evolution produces it was still an open question in 2007.