Evolution

How does natural selection work, and what conditions are needed for it to occur? What is the difference between an adaptation and a random trait that happens to exist? How did classic examples like Darwin’s finches help scientists understand natural selection? How quickly can populations evolve in response to strong environmental pressures? What are some common misconceptions about natural selection and how can we correct them?

How do mutations arise, and how can they create new genetic variation in a population? Why is genetic variation important for a population’s long-term survival? What is genetic drift, and how can it change a population even without natural selection? How do small populations experience evolution differently than large ones? What is the founder effect, and how has it shaped some human and animal populations?

What processes can cause one species to split into two over time? How do geographic barriers contribute to the formation of new species? What is reproductive isolation, and why is it central to many definitions of species? How do adaptive radiations create many new species in a relatively short time? What evidence do we have that speciation is occurring in modern populations right now?

How do fossils help us reconstruct the history of life on Earth? What is a phylogenetic tree, and how do scientists build and interpret them? What kinds of anatomical and genetic evidence support the idea of common ancestry? How do transitional fossils challenge the idea that species are fixed and unchanging? What are some major evolutionary milestones revealed by the fossil record?

What do fossils and genetics tell us about the origins of modern humans? How did early hominins differ from modern humans in anatomy and lifestyle? What is the current understanding of how Homo sapiens spread around the globe? How have culture, technology, and biology interacted during human evolution? What are some common myths about human evolution, and how do we know they are inaccurate?