Evolution of Complexity

Why do some species eat others? Life began as microscopic single-celled organisms making their own energy from sunlight and other chemical resources. At some point, some of these creatures found it less effort just to eat their neighbors and acquire the energy they had gone...

Evolution of Behavior

What role does behavior play in evolution? Most adaptations ultimately require some level of genetic change, but genetic change depends in part on the availability of sufficient genetic variation within the population—or, at the very least, the chance to produce new mutations. If the environmental...

Evolution and Genetics

Why was the discovery of genetics so important for our understanding of evolution? Despite the fact that Darwin’s theory of evolution was widely acclaimed by his scientific contemporaries, it had a central weakness that left it open to criticism. Neither Darwin nor anyone else had...

Evolution of Humans

Who were our earliest ancestors? Our lineage can be said to have started when the African great apes of the late Miocene gave rise to a new, more terrestrial group, the australopithecines, some six or seven million years ago. Two important things had happened at...

Evolution of Species

What is a species? Having some way of classifying the natural world is important. That is the starting point of all science. For biology, it is also important for undertaking the kinds of very sophisticated statistical analyses that involve comparisons across different species and genera—the...

Evolution of Life

Can we say how life on earth started? The origins of life on earth must predate the earliest fossils, and presumably must be simpler in form than even those earliest fossils. It is very unlikely that we will ever know what these life forms were,...

Evolution and Adaptation

How do species adapt to their environments? Darwin argued that species became increasingly adapted to their environments as variants (or what we would now call genetic mutants) that exhibited a slightly better fit to their environment survived better and were able to reproduce more successfully....

Evolution of Sociality

Why do some animals live in groups? The ancestral mammals were small (we can tell that from their fossils) and almost certainly solitary (as suggested by reconstructing their likely behavior from the social arrangements of living species using statistical analyses that take species evolutionary...

Evolution of Culture

Does culture evolve? Culture is defined as those aspects of our behavior and beliefs that are learned—passed on from parents to children or between two unrelated individuals, by copying and instruction. Given that evolution simply means the way traits change over time, and all cultural...

Evolution and Natural Selection

Why do we need a theory of evolution? We live in a world of immense diversity. There are around 5,500 species of mammals and some 10,000 species of birds. But even that pales into insignificance beside the 12,000 species of roundworms, about half of whom...