Comets are one of the most important created factors of life on the Earth. Planets beside proper distance from their sun, having atmosphere with proper density and pressure; must have some organic matters like Hydrogen, Carbon and Oxygen because these are base of genetic tissues of life and #comet include abundant supplies of them because most of them consist of dust and water ice that probably bring organic atoms and molecules to the Earth.
Hyrcanian forests in north of Iran are one of the oldest creatures surviving from the ice edge and after that expands through Europe and Siberia, you can see both beside.

Canon EOS 5D Mark IV