Evolution

An ancient retroviral gene helps human placental cells fuse into a continuous layer. Studies of syncytin reveal how molecular machinery once used by viruses became part of mammalian development, with genetic experiments in mice providing further evidence of its importance.

Laboratory rats learned to play hide-and-seek with humans, switching roles and selecting hiding places. Some even hid again after being found, delaying their playful reward. Two studies reveal how the animals behaved and how their brains tracked the game.

A computer model suggests that conditions favorable to an RNA world may have become persistent around 4.33 billion years ago, as the most destructive asteroid impacts became less frequent and potentially energy-rich environments survived for longer.

Scientists can recreate pieces of prebiotic chemistry and test possible routes from molecules to biology. But even making life in the lab might not reveal the path that actually occurred on early Earth.

Alaskan wood frogs remained frozen for an average of 193 days and survived temperatures as low as −18.1°C. High tissue glucose levels, possibly built up through repeated freeze–thaw cycles, may help protect them.

Trypanosoma congolense affects both sides of transmission: it alters volatile cues from infected hosts and molecular sensory programs in tsetse flies. Field trapping showed that infection-associated odors drew more infected flies.

The reflective layer behind a reindeer’s retina is gold-turquoise in summer but turns deep blue in winter. The change comes from a reorganization of collagen fibres that tunes this biological mirror to Arctic twilight.

Humans have 46 chromosomes while chimpanzees have 48 because two ancestral chromosomes fused to form human chromosome 2. The molecular traces of that event remain visible in our genome today.

A remarkably preserved Archaeopteryx fossil reveals previously unseen feathers near the upper wing. By closing a gap between the wing and body, they may have helped create an effective aerodynamic surface for flight.

An analysis of 953 bacterial and archaeal genomes suggests that LUCA had an incomplete enzymatic metabolism. The study links earlier metabolic chemistry to native metals and phosphite in serpentinizing hydrothermal systems.

Evolution is not a modern ape turning into a human or life marching toward perfection. This guide explains what changes across generations, how natural selection works, and why a scientific theory is not a guess.

An analysis of 87 Homo skulls found that larger braincases and smaller faces fit neutral evolution and stasis better than sustained directional selection.