Population growth is the increase in the number of people in a population or dispersed group. The global population has grown from 1 billion in 1800 to 8.2 billion in 2025. Actual global human populat
The logistic growth of a population
The Black Death was a plague pandemic that occurred in Europe from 1346 to 1353. It was one of the most fatal pandemics in human history, leading to the death of up to 50 million people, around 30% to
Population growth
…challenged many recent population projections as having underestimated population growth. The world human population has been growing since the end of the Black Death, around the year 1350. A mix of technological advancement that improved agricultural productivity and sanitation and medical advancement that reduced…
Yersinia pestis (200 × magnification), the bacterium that causes plague
The Oriental rat flea (Xenopsylla cheopis) engorged with blood. This species of flea is the primary vector for the transmission of Yersinia pestis, the organism responsible for spreading bubonic plague in most plague epidemics. Both male and female fleas feed on blood and can transmit the infection.
Oriental rat flea (Xenopsylla cheopis) infected with the Yersinia pestis bacterium which appears as a dark mass in the gut. The foregut (proventriculus) of this flea is blocked by a Y. pestis biofilm; when the flea feeds on an uninfected host Y. pestis is regurgitated into the wound, causing infection.
Skeletons in a mass grave from 1720 to 1721 in Martigues, near Marseille in southern France, yielded molecular evidence of the orientalis strain of Yersinia pestis, the organism responsible for bubonic plague. The second pandemic of bubonic plague was active in Europe from 1347, the beginning of the Black Death, until 1750.