Homo sapiens sapiens
Homo erectus
Homo sapiens neanderthalensis
Homo sapiens archaic
CO2 ice core record
LEAD Technologies Inc. V1.01Handmade Software, Inc. Image Alchemy v1.12 Handmade Software, Inc. Image Alchemy v1.12 Handmade Software, Inc. Image Alchemy v1.12
domesticated plants & animals
currently:
380 ppm
Siegenthaler et.al. Science 2005