Pumpkin puree, most frequently used to make pumpkin pies during the holidays, can also serve as an egg substitute in baked goods. It works especially well in dense, moist items, such as sweet breads and muffins. Trade 1/4 cup of pumpkin puree for each egg in the recipe.
Our Earth is also considered as an ecosystem on a much larger scale. When we introduce external factors such as too much carbon dioxide or methane, it destroys the balance of the ecosystem which in turn affects those who live in it. The result is global warming, water shortage, extinction of species, etc. These impacts every living thing on the planet, which includes us.
Population seems to have fallen. The cause could have been climate changes, diseases, deforestation and soil exhaustion. There is evidence that there may have been floods and earthquakes due to shift in tectonic plates. People abandoned cities for farming due to lack of surplus food in more urban areas.