When were gravestones invented?

Answer Archeologists have discovered that the use of gravestones or headstones dates back to between 20,000 and 75,000 years ago. Neanderthal graves have been discovered that used stacked rocks or fieldst... Read More »

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When were cell phones invented&who were they made by?

Martin Cooper invented the cell phone in 1973, and Motorola was its maker. The phone was much bigger and heavier than today's models. Called the DynaTAC, the phone did not go one sale until 10 year... Read More »

When were screws invented?

The standard flat-headed screw was invented around 700 BC, reports History For Kids. According to American Heritage, the Phillips-head screw was invented some time in the 1930s by Henry F. Phillips... Read More »

When were arrowheads invented?

The earliest arrowhead is believed to be one made of bone, discovered at Sibudu Cave on the north coast of South Africa. It dates from the Paleolithic Era and is believed to be over 61,000 years ol... Read More »

When were bar codes invented?

The concept of a bar code dates back to the early 20th century, but did not take shape for many decades. The patent for the technology that the bar code is based upon was granted in 1949, and the f... Read More »