How many people died in 1492

The trees and flora that repopulated that unmanaged farmland started absorbing more carbon dioxide and keeping it locked in the soil, removing so much greenhouse gas from the atmosphere that the planet's average temperature dropped by 0. Typically, experts look to the Industrial Revolution as the genesis of human-driven climate impacts. But this study shows that effects may have began some years earlier. Experts have long struggled to quantify the extent of the slaughter of indigenous American peoples in North, Central, and South America.

That's mostly because no census data or records of population size exist to help pinpoint how many people were living in these areas prior to To approximate population numbers, researchers often rely on a combination of European eyewitness accounts and records of "encomienda" tribute payments set up during colonial rule.

But neither metric is accurate — the former tends to overestimate population sizes, since early colonizers wanted to advertise riches of newly discovered lands to European financial backers. The latter reflects a payment system that was put in place after many disease epidemics had already run their course, the authors of the new study noted.

So the new study offers a different method: the researchers divided up North and South America into regions and combed through all published estimates of pre-Columbian populations in each one.

In doing so, authors calculated that about Once Koch and his colleagues collated the before-and-after numbers, the conclusion was stark.

That means about 55 million people perished because of violence and never-before-seen pathogens like smallpox, measles , and influenza.

Using these population numbers and estimates about how much land people used per capita, the study authors calculated that indigenous populations farmed roughly 62 million hectares , square miles of land prior to European contact. Over time, trees and vegetation took over that previously farmed land and started absorbing more carbon dioxide from the atmosphere.

Julia Pareci of the indigenous Pareci community stands iin front a corn field planted within an Indian reservation, near the town of Conquista do Oeste, Brazil. Carbon dioxide CO2 traps heat in the planet's atmosphere it's what human activity now emits on an unprecedented scale , but plants and trees absorb that gas as part of photosynthesis. So when the previously farmed land in North and South America — equal to an area almost the size of France — was reforested by trees and flora, atmospheric carbon-dioxide levels dropped.

War and violence. While epidemic disease was by far the leading cause of the population decline of the American indigenous peoples after , there were other contributing factors, all of them related to European contact and colonization.

One of these factors was warfare. But with the arrival of the first European settlers, waves of new diseases, along with warfare, slavery and other brutality would kill off around 56 million people, or around 90 percent of the indigenous population.

Warfare and enslavement also contributed to disease transmission. Because their populations had not been previously exposed to most of these infectious diseases, the indigenous people rarely had individual or population acquired immunity and consequently suffered very high mortality.

But by rejecting these claims and focusing on colonial records instead, extremely low population estimates were published in the early 20th century which counted the population after disease had ravaged it.

On the other hand, liberal assumptions on, for example, the proportion of the indigenous population that was required to pay tributes or the rates at which people had died led to extraordinarily high estimates.

Our new study clarifies the size of pre-Columbian populations and their impact on their environment. By combining all published estimates from populations throughout the Americas, we find a probable indigenous population of 60m in The large pre-Columbian population sustained itself through farming — there is extensive archaeological evidence for slash-and-burn agriculture, terraced fields , large earthen mounds and home gardens.

By knowing how much agricultural land is required to sustain one person, population numbers can be translated from the area known to be under human land use. This changed in the decades after Europeans first set foot on the island of Hispaniola in — now Haiti and the Dominican Republic — and the mainland in Europeans brought measles, smallpox, influenza and the bubonic plague across the Atlantic, with devastating consequences for the indigenous populations. One explanation is that multiple waves of epidemics hit indigenous immune systems that had evolved in isolation from Eurasian and African populations for 13, years.