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Evolution is the study of how different types of living organisms adapt and change over time. New species continually emerge while others go extinct in response to fluctuating environmental conditions.

Embryology and evolution evidence work in tandem to support the theory that all life evolved from a common ancestor, possibly answering questions like why you had a tail before you were born.

In the mid-1800s, Charles Darwin and Alfred Wallace independently concluded that inherited variations in traits, such as a bird's beak shape, may provide better odds of survival in a given niche. Organisms without the advantageous variation are less likely to survive and pass on their genes.

Since the heyday of Darwinism, considerable scientific evidence has emerged supporting the theory of evolution, including embryology, although the mechanisms of mutation and change are more complex than previously understood.

Theories, such as the theory of evolution, are evidence-based ideas widely held by the scientific community. According to Charles Darwin in Origin of the Species, organisms descend and diversify from one common ancestor. Organisms change and adapt over time as a result of inherited physical and behavioral characteristics that are passed down from parent to offspring.

Through the process of natural selection and survival of the fittest, certain traits are more likely to be inherited than other traits.

Embryology is the study and analysis of embryos. Evidence of an evolutionary common ancestor is seen in the similarity of embryos in markedly different species. Darwin used the science of embryology to support his conclusions.

Embryos and the development of embryos of various species within a class are similar even if their adult forms look nothing alike. For instance, chicken embryos and human embryos look similar in the first few stages of embryonic development.

These early similarities are attributed to the 60 percent of protein-coding genes that humans and chickens inherited from a common ancestor.

Evolutionary developmental biology ("evo-devo") dates back to Alexander Kowalevsky 's discovery in the 19th century that embryonic stages of development aid in the classification of organisms. Kowalevsky suggested that sea squirts called tunicates should be classified as chordates instead of mollusks because tunicate larvae have notochords and form neural tubes, making them more like chordates and vertebrate embryos. DNA analysis of the tunicate genome has since proven Kowalevsky correct.

German scientist Ernest Haeckel is known for the ideas of "biogenetic law" and "ontogeny recapitulates phylogeny." Haeckel's drawings of embryos suggested that an organism recapitulates (repeats) stages of its evolutionary history during embryonic stages of development.

Haeckel's controversial comparative embryology drawings released in 1874 showed a developing human embryo passing through stages that resembled different animals, such as embryonic fish, chickens and rabbits.

The notion of recapitulation drew plenty of critics, notably Karl von Baer, who also took a disliking to Darwin's ideas. Embryologist von Baer stressed the differences between vertebrate and invertebrate embryonic development that refuted Haeckel's conclusions.

Modern evo-devo experts like Michael Richardson agree there are similarities in the embryonic development of related species, but mainly at the molecular level.

Darwin's theory of biological evolution noted that all vertebrates have gill slits and tails in early stages of embryo formation, even though these features may be lost or modified in the adult-form phenotype.

For instance, human embryos have a tail that becomes the tail bone. This pattern indicates that all vertebrates stem from a common ancestor that developed that way, and everything diverged from there.

Many embryology and evolution questions can be answered through the study of comparative anatomy. Homologous structures in embryonic development suggest that ancestral structure was maintained as things diversified.

Examples found in comparative anatomy include the forelimbs of humans and the flippers of a whale, which supports the idea of common descent. Although a human arm and bat wing look different, the process of embryonic development is similar.

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How Does Embryology Provide Evidence for Evolution?

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Studies of embryology and evolution support Charles Darwin's theory of evolution of life from a common ancestor. In fact, early-stage human embryos have a tail and rudimentary gills like a fish. Similarities during the stages of embryonic development help scientists classify organisms in a taxonomy.

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1. What does common decent mean?

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Evolution - Evidence from Embryology. Here's a clip from by buddies at Coldwater Media looking at Animal Embryos as evidence for Evolution. Go to http://www.ColdwaterMedia.com for more clips in this series, Investigating Evolution. Also, try http://www.allaboutscience.org/evolution.htm for more information on Embryology and other traditional proofs for the Theory of Evolution.

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Welcome to CK-12 Foundation | CK-12 Foundation

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Fossils & Evidence For Evolution | Evolution | Biology | FuseSchool

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1. Start with ppt; students follow along on document
(place copy of document in GC)
- compare animals on looks
- learn what a mammal is
- A sort of Seeds Activity Desmos OR technology Desmo
Science 3

Science 4

Science 5

Science 6

Science 7

Science 8

Exit ticket for the day

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Fish or Mammals?

This series of activities explores the ancestry of cetaceans (whales, dolphins, and porpoises). The Case Study document presents data from comparative anatomy, fossils, embryological development, amino acid sequences, and DNA transposons.

The Evidence Organizer helps students follow the path that scientists took to understand the ancestry of cetaceans. Each new piece of evidence led to a more-detailed understanding: first that cetaceans are more similar to mammals than to fish; then that they descended from a four-legged mammal that lived on land; later still that they descended from an even-toed ungulate; and finally that their closest living relative is the hippopotamus.

Tip: If students are still having trouble interpreting tree diagrams, go through the practice with trees extension.

Once students have finished filling in their Evidence Organizers (and they understand the evidence), give them a copy of the Argumentation document. Here they will match the appropriate pieces of evidence with the provided claims and reasoning.

Analyzing & Interpreting Data

Students interpret fossil, anatomical, embryological, and DNA data to determine the ancestry of cetaceans.

Students find patterns in fossil, anatomical, embryological, and DNA data to determine relatedness.

Argumentation from Evidence

Students practice choosing the appropriate evidence that supports a claim and is in line with given reasoning.

90 minutes

Extension Activity: A Tale of Two Pandas

This second case study provides more practice with the evidence for common ancestry. In addition, it explores the scientific process, highlighting the fact that sometimes lines of evidence appear to contradict one another. The reading level and the evidence presented here are more challenging than in the Fish or Mammals case study.

The Tale of Two Pandas video introduces the question, "Is the giant panda a bear or a raccoon?"

The Case Study document presents evidence from behavior, anatomy, fossils, and DNA. Note that different lines of evidence support different conclusions.

The Teacher Guide describes how you can assign the lines of evidence to different groups of students to evaluate. Using the Evidence Organizer, students organize their evidence to support one of three claims.

To wrap up, present the Conclusion (pdf document) to summarize how more recent DNA evidence finally led to a scientific consensus: that the giant panda shares a more recent common ancestor with bears.

Students find patterns in anatomical, fossil, and DNA and protein data to determine relatedness.

Analyzing & Interpreting Data

Students interpret anatomical, fossil, and DNA and protein data to determine the evolutionary relationships of the giant panda.

60 minutes

Evidence for Common Ancestry

With the Fish or Mammals? series, students have seen how multiple lines of evidence can help answer puzzling questions about common ancestry-and how multiple lines of evidence generally point to the same conclusion. This activity is intended to reinforce the idea that lines of evidence tend to corroborate one another, while also making the point that many questions about common ancestry are not so puzzling. Students explore a collection of inferences about the relationships among species, which are based on various lines of evidence.

Have students explore individually or in pairs. An optional guiding worksheet is provided.

Fossils, anatomy, embryos, and DNA sequences provide corroborative lines of evidence about common ancestry, with more closely related organisms having more characteristics in common.

30-40 minutes

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Fish or Mammals? This series of activities explores the ancestry of cetaceans (whales, dolphins, and porpoises). The Case Study document presents data from comparative anatomy, fossils, embryological development, amino acid sequences, and DNA transposons. The Evidence Organizer helps students follow the path that scientists took to understand the ancestry of cetaceans.