Comparative Anatomy Comparative anatomy is the study of similarities and differences in the physical structures of organisms.
Comparative Anatomy At some point in our pasts, humans, frogs, bats, birds, and cats all shared a common ancestor.
Homologous Structures Homologous structures are parts of organisms that are similar in BOTH ancestral origin and structure. - are the result of evolution - can indicate how closely two or more species share common ancestors
Homologous Structures - The humerus bones in the upper limbs of these animals are homologous structures.
Analogous Structures Analogous structures appear similar, but have different ancestral origins. - the wings of birds and insects - result from similar environmental conditions that produced similar natural selection outcomes
Vestigial Structures Another source of evidence for evolution is vestigial structures: structures that have no function in their present-day form.
Vestigial Structures Scientists hypothesize that the structures once functioned in an ancestor.
Vestigial Structures in Humans Appendix Nictitating Membrane Wisdom Teeth Tailbone from our large-jawed ancestors with bad dental hygiene from our herbivore ancestors from our tailed primate ancestors present when we are embryos
Vestigial Structures in Humans The recurrent laryngeal nerve goes from the brain to your voice box. It helps us speak and swallow. It takes a very long course, looping from the brainstem down around the aorta and then back up to the larynx. WHY?
Vestigial Structures in Humans We evolved from very different ancestors. That’s why our bodies are full of glitches, and this nerve is one of them. The nerve used to line up with a blood vessel, and both serviced the gills of our fishy ancestors.
Vestigial Structures It takes a 15 FOOT detour in giraffes! It takes a 92 FOOT detour in supersaurus!