Cambio humano que podemos creer

Montreal – En un reciente simposio sobre evolución en Montreal se planteó la siguiente pregunta a estudiantes de secundaria y a profesores universitarios: “¿Cree usted que los seres humanos aún siguen evolucionando?” Aproximadamente el 80% de la audiencia respondió “no”. De hecho, existe una creencia casi universal sobre que, a través de las culturas multifacéticas y las tecnologías complejas, los seres humanos se han liberado de las presiones de la selección natural.

Hallazgos recientes, sin embargo, demuestran lo contrario. Lejos de proporcionar inmunidad contra las presiones evolutivas, la cultura suele crear otras nuevas. Por ejemplo, los genes asociados con la digestión de la lactosa son más prevalentes en las poblaciones que tradicionalmente se ha dedicado a la cría de ganado y han consumido leche.

En estudios científicos en las revistas Nature Genetics y Proceedings of the National Academy of Sciences of the United States of America, el biólogo evolutivo Stephen Stearns y sus colegas se propusieron demostrar que la selección natural actúa en los seres humanos contemporáneos. Con el apoyo de genealogías extensas, que incluyen siglos de datos registrados en iglesias y registros nacionales de salud, su argumento es convincente.

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