Nature meant no vaccines or antibiotics, living utterly helpless in the face of epidemics that periodically ravaged our populations.
Nature meant illiteracy, not even being able to imagine such a thing as a book.
Nature meant dying in agony at age 30 from a tooth abscess.
Nature meant a 50% infant mortality rate.
Nature meant no contraception. Think about it.
Nature meant no doctor if you broke a bone or got mauled by an animal.
Nature meant constant risk of starvation if rains failed or herds wandered elsewhere or some blight struck the local edible plants.
Nature meant having no idea what those bright dots in the night sky were, or how big the world was, or who lived a mere fifty miles away, or even that there was such a thing as fifty miles away.
Nature meant living in constant fear of the neighboring tribe, or plotting atrocities against them (read up on rates on intergroup violence in hunter-gatherer societies).
Long ago our ancestors lived naturally. The history of agriculture and civilization is a history of thirteen thousand years of determined struggle to escape from that ghastly horror.
So why should we accept "natural" as a guide to what is good or right in any area? I'm wholly unmoved by being told that a way of life or new technology is "unnatural". Almost everything that makes life worth living is "unnatural".