Final answer:
In 'Human Nature After Darwin', J.R. Richards identifies three dimensions of Darwinism encompassing genetic, behavioral, and cultural aspects of evolution option (a).
Step-by-step explanation:
J.R. Richards discusses three different 'depths' of Darwinism about the evolution of life and the adaptations of organisms. Darwin's theory of natural selection underlies all of them, as an inevitable outcome of three principles:
- Variation in traits among individuals within a population
- More offspring are produced than can survive due to limited resources
- Competition for resources among offspring leads to survival of the fittest
Ranging from physical characteristics to behaviors, and extending to cultural evolution, these aspects together sculpt the adaptive landscape of organisms on Earth. The inheritance of characteristics allows for the potential spread of advantageous traits across generations.
In other words, traits that enhance an organism's ability to compete for limited resources are more likely to be passed down, leading to changes in populations over time—a process Darwin termed "descent with modification."
Ultimately, adaptive evolution is reflected at all levels of biological organization, promoting diversity and complexity in species, organisms, and even molecular structures.
This perspective is crucial to understanding biological anthropology, providing insights into why living things are the way they are and how humanity has evolved to thrive in diverse environments.