Okay, here's my shot...
In 1515, an ingenious weaver in London invents a device they call the "Flying Shuttle," a device that allows a weaver to use a loom with far superior speed and quality. This device is soon spread throughout England, leading to lower priced clothing and an increased demand for such clothes. This demand does lead to the price of wool skyrocketing, however.
The demand for wool leads many to go into sheparding, but the current Open Field system (Less dominant in England than other parts of Europe, but still dominant) leads to disagreements of ownership and upsets communities with a shepard/farmer split. Land reform and local Enclosure acts speed up throughout England, culminating in the "Inclosure Act" of 1592 (OTL 1801, 70 years after the invention of the Flying Shuttle)
Under this system farming is streamlined, revealing the up until then "Hidden Unemployment" which is then forced to move into the cities. The enclosed farms allow farmers to experiment with ideas such as crop rotation without having to put their entire livelihood on the line. With farm animals in pens and gives farmers more opportunities to attempt selective breeding. The Average size of food animals and sheep grows astoundingly.
The increased population in the cities leads to increased unemployment but higher economic productivity since communal farms led to hidden unemployment by employing everybody in the communal production, despite increasingly diminishing returns. As goods and services become cheaper, the slowly emerging middle class starts reinvesting in the country. Production and technological development starts aproaching that of the Industrial Revolution about a century and a half earlier (Less than, but ITTL they will say the Industrial Revolution started in about 1600). These technological results will spread to Europe, especially the Netherlands.
As the agrarian and industrial revolution spreads through Europe, populations explode. As colonies are founded in the New World, Europeans flood into the land more than OTL, which compounds the population expansion. In 1750 an ingenious American plantation owner in Virginia writes up a book on a study of inheritance and genetics. Unlike Gregor Mendel's studies, the paper is immediately adopted by American thinkers and farmers who are continuously struggling for an edge on the frontier world.
Many new strains of plants are developed over time, many strengthening resistance to pests. But the most useful development was the invention of a strain of wheat known as Dwarf Wheat which grew shorter than traditional wheat while still growing the same amount of seeds. Wheat production grows by 60% and it's just the first of several High Yield varieties of crops. With cheap food widely available, the world population continues to explode, especially in less developed areas like Africa and Asia. By 1900 the population had reached 3 billion (1.4 Billion more than OTL) and is continuing to skyrocket.
New technologies continue to be developed ahead of OTL, leading to cheap medicines, new genetics breakthroughs, and improved sanitary conditions. Increased productivity means that underdeveloped regions get increased investment, improving the infrastructure and life expectancy/quality. Population booms continue throughout the 20th century. By the year 2000 there are an estimated 10.5 billion people in the world and there are serious efforts to create permanent habitations in space.