Native American disease population crashes before European arrival

Disease could reach Native Americans before Europeans

In the mid-16th century, disease-driven population crashes among Native Americans often happened before Europeans arrived in person. The effects of introduced diseases could therefore come before direct colonial contact.

Most cancer deaths happen after the cancer spreads

Cancer cells can leave the original tumor and grow in other parts of the body. This process is called metastasis. Most cancer deaths are caused by cancer after it has spread rather than by the original tumor alone.

Submarines can navigate without GPS

An inertial navigation system works out a submarine’s position from its motion sensors, without outside information once aligned. Weather and jamming do not disrupt it. But small errors build over time, so the system needs occasional position fixes.

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Native American disease population crashes before European arrival

Disease could reach Native Americans before Europeans

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