Evolution

Researchers struggle to incorporate ongoing evolutionary discoveries into an animal classification scheme older than Darwin.

Contrary to popular belief, bacteria have organelles too. Scientists are now studying them for insights into how complex cells evolved.

Viruses and other parasites may sync with their host’s biological clock — or reset it — to gain an advantage.

Surviving fragments of genetic material preserved in sediments allow scientists to see the full diversity of past life — even microbes.

For more than six decades, the influential biologist Edward O. Wilson has drawn connections between evolution, ecology and behavior, often sparking controversies inside and outside of science.

Skyrocketing animal diversity a half-billion years ago was linked to spikes and dips in marine oxygen levels, according to a detailed geological study.

The rainbow of pigments that animals use for blood illustrates a central truth of evolution.

Researchers are beginning to understand the ways in which viruses strategically manipulate and cooperate with one another.

New studies revise ideas about the symbiosis that gave mitochondria to cells and about whether the last common ancestor of all eukaryotes was one cell or many.