Beaks are one of the most diversified features in these birds and are well adapted to the type of food they eat; ranging from fine needle-like beaks in warbler finches that are perfect for picking up insects; long, sharp and pointed beaks in cactus finches for probing into cactus or deep, broad and blunt beaks in large …

1: Darwin’s Finches: Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources.

Darwin’s finches are a classical example of an adaptive radiation. Their common ancestor arrived on the Galapagos about two million years ago. During the time that has passed the Darwin’s finches have evolved into 15 recognized species differing in body size, beak shape, song and feeding behaviour.

Mutations are essential to evolution. Every genetic feature in every organism was, initially, the result of a mutation. The new genetic variant (allele) spreads via reproduction, and differential reproduction is a defining aspect of evolution.

The most reproductively successful

Does evolution go only in one direction? No, it does not. There is no such thing as a goal of evolution at making things fly or at making things intelligent or whatever. There is no intrinsic directionality.

Early human fossils and archeological remains offer the most important clues about this ancient past. These remains include bones, tools and any other evidence (such as footprints, evidence of hearths, or butchery marks on animal bones) left by earlier people.

The story of human evolution is not one of neat, linear progression with a concrete beginning and end. Instead, it is a tale of a family tree whose complex and bushy branches stretch over many millennia and continents. It features a changing cast of ancient hominin relatives, evolutionary dead-ends and many unknowns.

From museum displays to editorial cartoons, evolution is depicted as a linear progression from primitive to advanced. You’ve certainly seen the pictures of a chimpanzee gradually straightening up and progressing through various hominids all the way to a modern human being.

Evolution is progressive improvement of species The process of evolution leads to a branching pattern of relationships among organisms, not a linear progression. As the late evolutionary biologist Stephen J. Gould put it, “evolution is a bush, not a ladder.”

Orthogenesis, also called straight-line evolution, theory that successive members of an evolutionary series become increasingly modified in a single undeviating direction.