Madison Crego’s Reviews > Your Inner Fish: a Journey into the 3.5-Billion-Year History of the Human Body > Status Update

Fossils show humans came from earlier fish because they reveal transitional forms with a mix of old and new traits. Tiktaalik, "fish with a wrist," was a major breakthrough because it bridged the gap between fish and land animals. It had fish traits like scales and gills, but also land-animal traits such as a neck, flat head, lungs, and limb-like fins that could support weight. Found in the right rock layers, Tiktaalik helps scientists see the progression from fish to land animals, showing that human-like features evolved slowly over time, not all at once.

There’s a basic design in the skeletons of all animals. Frogs, bats, humans, and lizards are just variations on this design. Their limbs share a common pattern, which Darwin explained as evidence of a common ancestor. It shows how evolution modifies a single blueprint for different animals.