Final answer:
The European population increased from about 35 million to 80 million from 1000 to 1300, an approximate 128.6% increase. This growth was driven by improved agricultural techniques, better climate, the decline of invasions, and socioeconomic transformations leading to urbanization and decline of feudalism.
Step-by-step explanation:
The percentage of increase in the European population from 1000 to 1300 was significant, with rough estimates indicating that the population grew from approximately 35 million to 80 million. This equates to an approximate increase of 128.6%.
Several factors contributed to this population growth, including improved agricultural techniques, the decline of slaveholding, a more clement climate during the Medieval Warm Period, and the lack of invasions that had previously disrupted societal stability and growth.
During the High Middle Ages, the increase in population was accompanied by significant social and economic transformations. There was a notable rise in the number of cities reaching substantial sizes, such as Venice, Florence, and Milan with over 100,000 inhabitants.
The movement from rural areas to these urban centers was spurred by an agrarian revolution that increased food production and a development in commerce that created new wealth and opportunities, leading to the decline of feudalism.