What do you see as the prime movers of sociocultural change

In this forum, we will discuss the ecological and evolutionary approaches we have read about this week. First, define what is meant by a) an ecological approach and b) an evolutionary approach. Avoid using quotations but show that you understand the terms. Then, choose one specific variant of these theories as discussed in our textbook, chapters 11 and 12 specifically. Summarize the theory and discuss what earlier theory (or theories) it build upon. This is to say: these modern theories find their ancestors amongst the theories discussed previously. Identify a theory discussed earlier in the course that addresses similar issues or makes similar theoretical assumptions, and discuss how the two theories are similar and different.
What do you see as the prime movers of sociocultural change? Do you see any long-term direction to such change? Are any of the ideas put forward by these approaches applicable to cultural change in the 21st century?
Be sure to support your points with examples from the text, required and recommended material, and/or other scholarly articles. Avoid reliance on quotes but rather show in your own writing that you master the concepts.