“Because of your complex evolutionary history, you are not adapted for any single diet, habitat, social environment, or exercise regime. From an evolutionary perspective, there is no such thing as optimal health.”

Lieberman’s text is dependent on the idea that natural selection favors reproductive success over individual health or happiness. This idea conflicts with modern trends in health, which often suggest that certain practices can provide optimal health. This assertion arises through the discussion on natural selection, which is commonly associated with the phrase “survival of the fittest”; however, this phrase is misleading because natural selection impacts reproductive success rather than individual fitness.

“If there was any one key initial adaptation, a spark that set the human lineage off on a separate evolutionary path from other apes, it was likely bipedalism, the ability to stand and walk on two feet.”

Evolution experts posit that bipedalism was the catalyst for the eventual development of humans. Bipedalism, as with other evolutionary traits, is a context-dependent adaptation. It made humans physically slower and weaker, but it provided other advantages, including making some foods easier to forage and allowing hominin species the use of their hands to carry food and tools. This passage reflects The Evolution of the Human Body and Health.

“It is impossible to ever know for sure why natural selection favored adaptations for bipedalism, but I think the evidence most strongly supports the idea that regularly standing and walking upright was initially selected to help the first hominins forage and obtain food more effectively in the face of major climate change that was occurring when the human and chimpanzee lineages diverged.”

Lieberman acknowledges that the fossil record of early hominins is limited; this reflects the difficulty of studying past events, particularly prehistoric events. However, he uses a broad perspective and multiple factors to draw plausible conclusions. His choice to directly address the limitations of the evidence displays academic integrity.