page_title: List of common misconceptions
section_title: Evolution
hierarchical_section_title: List of common misconceptions / Science / Biology / Evolution
caption_attribution_description: Tyrannosaurus rex, Palais de la Découverte, Paris
context_page_description: This is a list of popular wrong ideas and beliefs about notable topics. Each has been discussed in published literature.
context_section_description: The word theory in the theory of evolution does not imply scientific doubt about its validity. The concepts of theory and hypothesis have specific meanings in science. While theory in colloquial usage may denote a hunch or conjecture, a scientific theory is a set of principles that explains observable phenomena in natural terms. "Scientific fact and theory are not categorically separable", and evolution is a theory in the same way as gravitation, or plate tectonics are theories.
  Humans did not evolve from chimpanzees or any other modern-day primates. Humans and chimpanzees share a common ancestor that lived about seven million years ago. Humans are part of the Hominidae (great ape) family, that also includes chimpanzees, gorillas and orangutans. The common ancestor of humans and chimpanzees, which lived between 6 and 8 million years ago, evolved into two lineages. One line eventually became modern humans, and the other became the two living chimpanzee species.
  Evolution is not a progression from inferior to superior organisms, because the words inferior and superior are undefined value judgements. Evolution also does not necessarily result in the evolution of complexity, though overall it has done so. A population can evolve to become simpler, having a smaller genome.
  According to the California Academy of Sciences, only 59% of U.S. adults know humans and dinosaurs did not coexist. However, the last of the non-avian dinosaurs died 65.5 million years ago, after the Cretaceous–Tertiary extinction event, whereas the earliest Homo Genus (humans) evolved between 2.3 and 2.4 million years ago.
  Evolution does not "plan" to improve an organism's fitness to survive. For example, an incorrect way to describe giraffe evolution is to say that giraffe necks grew longer over time because they needed to reach tall trees. Evolution does not see a need and respond to it. A mutation resulting in longer necks would be more likely to benefit an animal in an area with tall trees than an area with short trees, and thus enhance the chance of the animal surviving to pass on its longer-necked genes. Tall trees could not cause the mutation nor would they cause a higher percentage of animals to be born with longer necks. In the giraffe example, the evolution of a long neck may also have been driven by sexual selection. The idea would be that long necks evolved as a secondary sexual characteristic, giving males an advantage in "necking" contests over females. It is common for an adaptation to have more than one function.
  Mammals did not evolve from reptiles, just as humans have not evolved from chimpanzees (above). Soon after the first vertebrate land-dwellers appeared, they split into two branches. The line leading to mammals (Synapsids) diverged from the line leading to reptiles (Sauropsids) about 320 million years ago, in the mid Carboniferous period. Only much later did the modern reptilian groups (lepidosaurs, turtles and crocodiles) emerge. Mammals are the only survivors of the synapsid line. The confusion over the origin of mammals comes from conflicting definitions of "Reptile". Under Linnaean taxonomy reptiles are all amniotes except mammals and birds, thus including the synapsids as well as the first basal amniotes. With the rise of classification based on phylogeny, the Sauropsida excludes basal amniotes and the synapsid line. The synapsids are popularly known as "mammal-like reptiles". An example is Dimetrodon, which is often thought of as a dinosaur, but is in fact neither a dinosaur nor closely related to modern reptiles.
caption: Tyrannosaurus. Non-avian dinosaurs died out in the Cretaceous–Tertiary extinction event at the end of the Cretaceous period.
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