Data from even earlier ice-cores going as far back as 800,000 years ago suggest probable cyclicity of interglacial length and an inverse correlation with the maximum temperature of each interglacial, but Ruddiman argues that this results from a false alignment of recent insolation maxima with insolation minima from the past, among other irregularities that invalidate the criticism.
[6] Archaeological data indicates that various forms of plants and animal domestication evolved in separate locations worldwide, starting in the geological epoch of the Holocene[7] around 12,000 14C years ago (12,000–7,000 BP).
Consequently, in explaining those eras in which CO2 did not rise due to a significant drop in the production of agriculture caused by death, [Ruddiman] likens the plague in Medieval Europe to the decimation of 90 percent of the Indigenous peoples of the Americas, referring to it simply as a 'pandemic' rather than genocide.
Accordingly, the unprecedented drop in CO2 levels from 1550 to 1800—due to a population collapse of more than fifty million people with causal links to colonization, slavery, war, displacement, containment, and outright ethnic cleansing—is attributed to smallpox.
Once Native American agriculture is studied alongside the Early Anthropocene Hypothesis, it becomes clear that such land change and greenhouse gas emissions take place in the Americas only after European colonization.