Short answers, pulled from the story.
The Willandra Lakes in Australia hold the oldest known evidence of cremation, dating back 17,000 years. Archaeologists discovered the remains of a partly burned body there, known as the Mungo Lady.
Ancient Egyptians developed a complex theology about the soul's journey that strictly prohibited burning bodies because they believed the physical form was essential for the afterlife. They embalmed their dead instead to preserve this necessary vessel for the next life.
A movement to reintroduce cremation began in Europe during the 1870s with new furnace technology developed by Sir Charles William Siemens. Professor Paolo Gorini of Lodi and Ludovico Brunetti of Padua published practical reports in 1873 that helped establish the practice.
The process typically takes about 90 minutes for an adult body inside a chamber called a retort. Modern cremators generate temperatures between 1400 and 1800 degrees Celsius to ensure complete disintegration of human remains.
Roughly one million bodies burned yearly in the United States generate more pollution than 22,000 average homes produce. Each cremation consumes roughly 280 liters of fuel releasing about 350 kilograms of carbon dioxide annually.