19세기부터 현재까지 산업화된 국가들을 중심으로 출산율이 급락하고 있는 전세계적인 현상은 진화적인 관점에서 선뜻 이해하기 어렵다. 왜 자원이 더 풍부해진 현대에 들어서 사람들은 자식수를 자발적으로 줄이는가? 본 논문은 현대의 저출산 현상을 설명하는 다양한 진화적 접근들을 요약하고, 이를 토대로 우리 사회의 저출산 문제를 해결할 실마리를 얻고자 한다. 1) 현대의 극히 낮은 출산율은 수렵-채집 생활에 맞추어진 우리의 심리적 적응이 진화적으로 낯선 환경과 불협화음을 일으킴에 따른 부적응적인 부산물이라는 가설, 2) 사회적으로 성공한 사람들이 자녀를 적게 낳는 행동이 전파되거나, 가족 중심의 네트워크가 붕괴하여 출산의 중요성이 덜 강조됨에 따라 저출산이 야기되었다는 유전자-문화 공진화 가설, 그리고 3) 부모가 자녀에게 투자하는 양이 대단히 많이 요구되는 현대의 환경에서 극심한 저출산은 부모의 장기적인 적합도를 최대화하는 적응적인 형질이라는 가설을 차례대로 검토한다. 저출산에 대한 진화적 관점은 저소득층의 출산을 지원하는 정책보다는 모든 사회경제적 계층에서 자녀를 장차 경쟁력 있는 성인으로 키우기 위한 비용을 줄이는 정책을 추진하는 것이 더 효과적임을 시사한다.
The sharp decline of fertility in industrialized countries since the 19th century constitutes a major problem for evolutionary approaches to human behavior. Why would people voluntarily reduce their total number of offspring, despite the fact that resources are so abundant in modern times? Here I review three evolutionary hypotheses for low fertility in modern societies, and discuss how the evolutionary perspective could shed new light on solving the problem of low fertility in Korea. Low fertility may be 1) a maladaptive outcome from the mismatch between our ancestral environments and evolutionarily novel environments, 2) a consequence of gene-culture coevolution where traits that reduce genetic fitness can still spread through a population as a result of imitation, especially if the traits are expressed by high-status people, or 3) an adaptation that maximize parents' long-term genetic fitness in knowledge- based industrialized societies where high parental investment is required for rearing competitive offspring. Based on these considerations, I suggest how the evolutionary explanations of low fertility can be applied to increasing the birth rate in Korea.
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