Simplify the following text for a Grade 11 native English-speaking person.
Original: By that time the ideas were widespread in progressive social circles , one proponent being the novelist Harriet Martineau whose circle of acquaintances included Charles Darwin , and the ideas of Malthus were a significant influence on the inception of Darwin 's theory .
Simplified: One supporter was the novelist Harriet Martineau whose circle of acquaintances included Charles Darwin . The ideas of Malthus were a significant influence on the inception of Darwin 's theory .