Explore evolutionary mechanisms from early life to humans, including natural selection, mutation, drift, and speciation. Understand biodiversity over time and trace key milestones from early life forms to modern humans.

Evolution refers to changes in allele frequencies within populations, not individuals. It’s about adaptation, not purpose or progress. Understanding evolution requires a focus on population changes over generations.

Evolution by natural selection requires variation, heritability, differential reproduction, and time. Traits that enhance survival and reproduction become more common over generations.

Mutations introduce new alleles. Most are neutral, some harmful, few beneficial. They are random and can lead to adaptations when combined with natural selection, e.g., lactase persistence in humans.

Natural selection, a non-random process, increases advantageous traits. It includes directional, stabilizing, and disruptive selection. Antibiotic resistance exemplifies strong selection.

Genetic drift causes random allele frequency changes, especially in small populations. Concepts like bottleneck and founder effects illustrate its impact, leading to genetic diversity loss.

Speciation arises from reproductive isolation and genetic divergence. Allopatric and sympatric speciation explain how new species form. Darwin’s finches are a classic example of speciation in action.

From the last universal common ancestor (LUCA) to multicellular life, key events include endosymbiosis, the Cambrian explosion, and vertebrate land colonization, setting the stage for human evolution.

Humans evolved from primates through traits like bipedalism and tool use. The genus Homo experienced branching evolution, with migrations out of Africa influencing genetic diversity globally.

Human evolution continues through genetic variation, selection, and drift. Recent adaptations include lactase persistence and high-altitude tolerance. Evolutionary biology informs medicine and conservation.