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7.6 Evidence of Evolution

5 min readjanuary 11, 2023

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Evolution is a scientific theory that is supported by a wide range of evidence from many different disciplines. Key pieces of evidence include: 🦖

  1. : The fossil record provides a historical record of the gradual changes that have occurred in organisms over time. This evidence supports the idea that species have evolved through time and that modern organisms have evolved from ancestral species.

  2. : The distribution of species across the Earth can provide clues about their evolutionary history. For example, similar species are often found in geographically close areas, while dissimilar species are found in distant areas.

  3. and : The similarities and differences in the anatomy and of different species can provide clues about their evolutionary relationships. For example, the similarities between the bones of a bat's wing and a human arm suggest that they share a common ancestor.

  4. and : The similarities in the and of different species can provide clues about their evolutionary relationships. For example, the similarities in the genetic code of different organisms support the idea that all living organisms share a common ancestor.

  5. : mathematical models help to understand how evolution can shape the patterns of genetic and phenotypic diversity observed in natural populations.

In general, the evidence for evolution comes from many different disciplines, and it is strong and consistent. The theory of evolution provides a framework for understanding the diversity of life on Earth and how it has changed over time. In this section, we'll dive deeper into a couple of these disciplines and make comparisons to see how we got to the conclusion scientists have widely agreed upon today!

Fossils

Scientists have been able to date recovered fossils using a variety of methods. They can approximate the age of the rock surrounding the fossil to get a good idea of what era the fossil is from, use relevant geographical data (compared to other fossils found nearby), and even look at the decay of certain isotopes. 🧲

More details on some of the methods used to date fossils include:

  • : This method involves analyzing the layers of rock and soil in which a fossil is found to determine its age relative to other rocks and fossils in the same area. This can provide information about the era in which the fossilized organism lived.

  • Radiometric dating: This method involves measuring the decay of certain isotopes, such as carbon-14 or potassium-argon, in the rock surrounding a fossil. This can provide a more precise age for the rock and, by extension, the fossil.

  • : this method is based on the orientation of the Earth's magnetic field that fluctuates over time. By measuring the orientation of magnetic minerals in the rock, scientists can approximate the age of the rock and thus the fossil.

  • : By analyzing volcanic ash layers and their unique chemistry and mineralogy, scientists can match the ash from one location to another and use that information to build chronologies.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-96KVvnOmNjhv.png?alt=media&token=37f4229a-3f63-46c6-be7f-cdbc0d5fe4d1

Source: Understanding Evolution

All these methods allow paleontologists to piece together the evolutionary history of an organism by comparing its age and characteristics with other fossils found nearby; they can also provide insights into the ancient ecosystems in which these organisms lived and how they evolved over time. Therefore, they are indispensable tools in understand the fossil record and help to support the theory of evolution.

Animals

Evidence of evolution can be found in today’s animals as well. are structures in modern organisms that have lost most or all of their original function due to evolution. The , as well as , , and are examples of . 💸

The is a small pouch located at the beginning of the large intestine. It is believed to have once played a role in the digestive system of our ancestors, possibly as a fermenting chamber for cellulose-digesting bacteria, but in modern humans it has little to no function. Appendicitis, which is an inflammation of the appendix, can be a serious health concern but it is the only function that the appendix have in our bodies.

are a third set of molars that most humans have, but that often do not have enough room in the jaw to fully emerge. They are considered vestigial because they are not necessary for modern human diets and can cause problems if they do not emerge properly.

, similarly, is considered vestigial in humans. Humans have less than other primates, and the hair that we do have is often not as thick or coarse as that of other primates, which is due to the loss of function over time, as humans evolved to better regulate body temperature with sweat glands rather than fur.

The , or coccyx, is the remnant of a tail found in other primates. It has lost most of its original function, but it still serves as the attachment point for some muscles and ligaments.

are another example of a vestigial structure, as birds such as penguins, kiwis and ostrich have lost the ability to fly but still have wings. They are still used for other behaviors such as balance, courtship, and thermal regulation.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-jx4tc4OzvXGT.png?alt=media&token=a6aa2a2d-01ff-49d8-8c2b-af53cb15e7f4

Source: ThoughtCo

All these examples indicate that a structure may not be necessary to survival in today’s environment but they have been inherited from ancestors who found them useful. They serve as a evidence of the change and adaptation in organisms throughout the evolutionary history. 😅

Homologous Structures

are structures or organs that are similar in form or function across different species and suggest a common ancestry. The comparison of the bone structure of the human arm, a dog's leg, a bird's leg and a whale's flipper is a great example of . 🦵

In the case of the forelimbs of these animals, there are some notable differences, such as the bones being specialized for different types of movement, but there are also similarities in the basic structure, such as the presence of a humerus, radius and ulna. This similarity in structure indicates that these animals share a common ancestor who had a similar forelimb structure, and over time these structures evolved to adapt to the different environments and lifestyles of the descendants.

There's also evidence on a molecular level, such as and , that can be used to compare the relatedness of different species. By comparing the sequences of similar genes across different species, scientists can determine if they share a common ancestor. This is one of the methods used to infer evolutionary relationships among species.

It is also important to note that all living organisms share a common genetic code, use the same set of to make proteins, and have similar processes for . This is further evidence of the common ancestry of all living organisms, which supports the theory of evolution. 🧬

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F512px-Homology_vertebrates-en.png?alt=media&token=74334fb2-361c-4fe6-a9aa-de7605a9f602

Source: WikiMedia Commons.

Key Terms to Review (22)

Fossil Evidence

: Fossil evidence refers to the remains or traces of organisms from the past, preserved in geological formations. This evidence provides a historical record of life on Earth and is used to support theories about evolution.

Comparative Anatomy

: Comparative anatomy is the study of similarities and differences in the anatomy of different species. It provides evidence for evolution, as similar structures may indicate common ancestry.

Biogeography

: Biogeography is the study of how species are distributed geographically across Earth, both in present times and throughout history. It provides insight into species' evolution, extinction, and migration patterns.

Biochemistry

: Biochemistry is the branch of science that explores chemical processes within and related to living organisms.

Physiology

: Physiology is the branch of biology that studies the functions and mechanisms at work in living organisms, whether they are plants, animals, or humans.

Molecular Biology

: Molecular biology studies the structure and function of molecules essential for life, including DNA, RNA, and proteins.

Radiometric Dating

: Radiometric dating is a technique used by scientists to date rocks and other materials by comparing the abundance of parent isotopes with daughter isotopes. This method relies on our knowledge about radioactive decay rates.

Mathematical Modeling

: Mathematical modeling is the process of using mathematical structures and concepts to represent real-world situations or phenomena.

Stratigraphy

: Stratigraphy is the study of rock layers (strata) and layering (stratification). It is primarily used in geology for dating and understanding geological events.

Tephrochronology

: Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from specific volcanic eruptions—to create a chronological framework in which paleoenvironmental or archaeological records can be placed.

Vestigial Structures

: Vestigial structures are anatomical features or behaviors that no longer seem to have a purpose in the current form of an organism. These often functioned in a way that was important for the organism's ancestors.

Paleomagnetism

: Paleomagnetism is the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials.

Wisdom Teeth

: Wisdom teeth are the third and final set of molars that most people get in their late teens or early twenties. They're also considered vestigial organs because they're not necessary for chewing modern diets.

Human Appendix

: The human appendix is a small, tube-shaped sac attached to the lower end of the large intestine. It's considered a vestigial organ, meaning it has lost most of its original function through evolution.

Body Hair

: Body hair is hair that grows on various parts of our bodies besides our head. Its primary functions include providing warmth and enhancing touch sensation but much like other vestigial traits, body hair isn't as important to humans today as it was to our ancestors.

Wings on Flightless Birds

: Wings on flightless birds are examples of vestigial structures. They're remnants from when their ancestors could fly but now serve little to no purpose for flight.

Homologous Structures

: Homologous structures are parts of different organisms that have similar structure but not necessarily the same function, indicating a common ancestry.

Tailbone

: The tailbone, or coccyx, is a small, triangular bone at the base of the spinal column in humans and certain other primates. It's a vestigial structure, meaning it's a remnant of an organ or structure that had a function in our evolutionary past.

Amino Acids

: Amino acids are organic compounds that combine to form proteins. There are 20 standard amino acids used by cells to synthesize proteins based on genetic instruction from our DNA.

DNA Sequences

: A DNA sequence is the precise order of nucleotides within a DNA molecule. It represents the genetic information in genes that is used to produce proteins.

Protein Sequences

: A protein sequence is the order in which amino acids are arranged in a protein. This sequence determines the structure and function of the protein.

DNA Replication

: DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules.

7.6 Evidence of Evolution

5 min readjanuary 11, 2023

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Evolution is a scientific theory that is supported by a wide range of evidence from many different disciplines. Key pieces of evidence include: 🦖

  1. : The fossil record provides a historical record of the gradual changes that have occurred in organisms over time. This evidence supports the idea that species have evolved through time and that modern organisms have evolved from ancestral species.

  2. : The distribution of species across the Earth can provide clues about their evolutionary history. For example, similar species are often found in geographically close areas, while dissimilar species are found in distant areas.

  3. and : The similarities and differences in the anatomy and of different species can provide clues about their evolutionary relationships. For example, the similarities between the bones of a bat's wing and a human arm suggest that they share a common ancestor.

  4. and : The similarities in the and of different species can provide clues about their evolutionary relationships. For example, the similarities in the genetic code of different organisms support the idea that all living organisms share a common ancestor.

  5. : mathematical models help to understand how evolution can shape the patterns of genetic and phenotypic diversity observed in natural populations.

In general, the evidence for evolution comes from many different disciplines, and it is strong and consistent. The theory of evolution provides a framework for understanding the diversity of life on Earth and how it has changed over time. In this section, we'll dive deeper into a couple of these disciplines and make comparisons to see how we got to the conclusion scientists have widely agreed upon today!

Fossils

Scientists have been able to date recovered fossils using a variety of methods. They can approximate the age of the rock surrounding the fossil to get a good idea of what era the fossil is from, use relevant geographical data (compared to other fossils found nearby), and even look at the decay of certain isotopes. 🧲

More details on some of the methods used to date fossils include:

  • : This method involves analyzing the layers of rock and soil in which a fossil is found to determine its age relative to other rocks and fossils in the same area. This can provide information about the era in which the fossilized organism lived.

  • Radiometric dating: This method involves measuring the decay of certain isotopes, such as carbon-14 or potassium-argon, in the rock surrounding a fossil. This can provide a more precise age for the rock and, by extension, the fossil.

  • : this method is based on the orientation of the Earth's magnetic field that fluctuates over time. By measuring the orientation of magnetic minerals in the rock, scientists can approximate the age of the rock and thus the fossil.

  • : By analyzing volcanic ash layers and their unique chemistry and mineralogy, scientists can match the ash from one location to another and use that information to build chronologies.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-96KVvnOmNjhv.png?alt=media&token=37f4229a-3f63-46c6-be7f-cdbc0d5fe4d1

Source: Understanding Evolution

All these methods allow paleontologists to piece together the evolutionary history of an organism by comparing its age and characteristics with other fossils found nearby; they can also provide insights into the ancient ecosystems in which these organisms lived and how they evolved over time. Therefore, they are indispensable tools in understand the fossil record and help to support the theory of evolution.

Animals

Evidence of evolution can be found in today’s animals as well. are structures in modern organisms that have lost most or all of their original function due to evolution. The , as well as , , and are examples of . 💸

The is a small pouch located at the beginning of the large intestine. It is believed to have once played a role in the digestive system of our ancestors, possibly as a fermenting chamber for cellulose-digesting bacteria, but in modern humans it has little to no function. Appendicitis, which is an inflammation of the appendix, can be a serious health concern but it is the only function that the appendix have in our bodies.

are a third set of molars that most humans have, but that often do not have enough room in the jaw to fully emerge. They are considered vestigial because they are not necessary for modern human diets and can cause problems if they do not emerge properly.

, similarly, is considered vestigial in humans. Humans have less than other primates, and the hair that we do have is often not as thick or coarse as that of other primates, which is due to the loss of function over time, as humans evolved to better regulate body temperature with sweat glands rather than fur.

The , or coccyx, is the remnant of a tail found in other primates. It has lost most of its original function, but it still serves as the attachment point for some muscles and ligaments.

are another example of a vestigial structure, as birds such as penguins, kiwis and ostrich have lost the ability to fly but still have wings. They are still used for other behaviors such as balance, courtship, and thermal regulation.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-jx4tc4OzvXGT.png?alt=media&token=a6aa2a2d-01ff-49d8-8c2b-af53cb15e7f4

Source: ThoughtCo

All these examples indicate that a structure may not be necessary to survival in today’s environment but they have been inherited from ancestors who found them useful. They serve as a evidence of the change and adaptation in organisms throughout the evolutionary history. 😅

Homologous Structures

are structures or organs that are similar in form or function across different species and suggest a common ancestry. The comparison of the bone structure of the human arm, a dog's leg, a bird's leg and a whale's flipper is a great example of . 🦵

In the case of the forelimbs of these animals, there are some notable differences, such as the bones being specialized for different types of movement, but there are also similarities in the basic structure, such as the presence of a humerus, radius and ulna. This similarity in structure indicates that these animals share a common ancestor who had a similar forelimb structure, and over time these structures evolved to adapt to the different environments and lifestyles of the descendants.

There's also evidence on a molecular level, such as and , that can be used to compare the relatedness of different species. By comparing the sequences of similar genes across different species, scientists can determine if they share a common ancestor. This is one of the methods used to infer evolutionary relationships among species.

It is also important to note that all living organisms share a common genetic code, use the same set of to make proteins, and have similar processes for . This is further evidence of the common ancestry of all living organisms, which supports the theory of evolution. 🧬

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F512px-Homology_vertebrates-en.png?alt=media&token=74334fb2-361c-4fe6-a9aa-de7605a9f602

Source: WikiMedia Commons.

Key Terms to Review (22)

Fossil Evidence

: Fossil evidence refers to the remains or traces of organisms from the past, preserved in geological formations. This evidence provides a historical record of life on Earth and is used to support theories about evolution.

Comparative Anatomy

: Comparative anatomy is the study of similarities and differences in the anatomy of different species. It provides evidence for evolution, as similar structures may indicate common ancestry.

Biogeography

: Biogeography is the study of how species are distributed geographically across Earth, both in present times and throughout history. It provides insight into species' evolution, extinction, and migration patterns.

Biochemistry

: Biochemistry is the branch of science that explores chemical processes within and related to living organisms.

Physiology

: Physiology is the branch of biology that studies the functions and mechanisms at work in living organisms, whether they are plants, animals, or humans.

Molecular Biology

: Molecular biology studies the structure and function of molecules essential for life, including DNA, RNA, and proteins.

Radiometric Dating

: Radiometric dating is a technique used by scientists to date rocks and other materials by comparing the abundance of parent isotopes with daughter isotopes. This method relies on our knowledge about radioactive decay rates.

Mathematical Modeling

: Mathematical modeling is the process of using mathematical structures and concepts to represent real-world situations or phenomena.

Stratigraphy

: Stratigraphy is the study of rock layers (strata) and layering (stratification). It is primarily used in geology for dating and understanding geological events.

Tephrochronology

: Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from specific volcanic eruptions—to create a chronological framework in which paleoenvironmental or archaeological records can be placed.

Vestigial Structures

: Vestigial structures are anatomical features or behaviors that no longer seem to have a purpose in the current form of an organism. These often functioned in a way that was important for the organism's ancestors.

Paleomagnetism

: Paleomagnetism is the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials.

Wisdom Teeth

: Wisdom teeth are the third and final set of molars that most people get in their late teens or early twenties. They're also considered vestigial organs because they're not necessary for chewing modern diets.

Human Appendix

: The human appendix is a small, tube-shaped sac attached to the lower end of the large intestine. It's considered a vestigial organ, meaning it has lost most of its original function through evolution.

Body Hair

: Body hair is hair that grows on various parts of our bodies besides our head. Its primary functions include providing warmth and enhancing touch sensation but much like other vestigial traits, body hair isn't as important to humans today as it was to our ancestors.

Wings on Flightless Birds

: Wings on flightless birds are examples of vestigial structures. They're remnants from when their ancestors could fly but now serve little to no purpose for flight.

Homologous Structures

: Homologous structures are parts of different organisms that have similar structure but not necessarily the same function, indicating a common ancestry.

Tailbone

: The tailbone, or coccyx, is a small, triangular bone at the base of the spinal column in humans and certain other primates. It's a vestigial structure, meaning it's a remnant of an organ or structure that had a function in our evolutionary past.

Amino Acids

: Amino acids are organic compounds that combine to form proteins. There are 20 standard amino acids used by cells to synthesize proteins based on genetic instruction from our DNA.

DNA Sequences

: A DNA sequence is the precise order of nucleotides within a DNA molecule. It represents the genetic information in genes that is used to produce proteins.

Protein Sequences

: A protein sequence is the order in which amino acids are arranged in a protein. This sequence determines the structure and function of the protein.

DNA Replication

: DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules.