Neil Shubin Your Inner Fish Analysis
Your Inner Fish
Your Inner Fish by Neil Shubin, delves into the questions of why the human body looks the way it does. Looking at the earliest forms of vertebrate life on land and even to the earliest forms of life on Earth we can trace the evolution of the human body. The creatures, from millions of years ago, have left us with a genetic a imprint that reveals how similar we truly are to the other creatures on Earth. Shubin tells the story of evolution by tracing the skeletal features and organs of the human body back millions of years by examining fossils and DNA, he shows us our inner fish, reptile, and monkey.
What does your inner fish look like? Starting with a human arm a great anatomist, Sir
Richard Owen, discovered that our arms, and legs, hands and …show more content…
feet fit into a larger scheme that is common pattern among other creatures such as bats, birds, frogs and lizards. The pattern that
Owen discovered is one bone in the upper arm, two bones in the forearm, and nine little bones at the wrist, then a series of five rods that make the fingers. Seeing these similarities Owen went on to look at skulls and backbones here he found that there was a fundamental design in the skeleton of all animals which Owen credited to the plan of a creator. His findings were published in a monograph On the Nature of limbs (Shubin, 31-32). However it was Charles Darwin who supplied the reason why human arms and bat wings share common skeletal patterns, this being that they share a common ancestor. Yet, in fish the whole skeleton looks different. For instance, the base of a typical fin has four or more bones, but in the mid 1800s, the discovery of fish that had lungs in the Southern Continents started shedding some light on how fish crawled out of the water and started living on land. This confused anatomist so they named the fish Lepidosmen
Paradova, which means paradoxically scaled amphibian. Other fish were found in Africa and
Australia, which were named lungfish. Perhaps what is most fascinating about these fish was that they had a single bone that attached to the shoulder much like the upper arm of a human.
Anatomists had found a fish with a humerus bone. Around this same time there was the discovery of a fossil that was 380 million years old found on the shores of Gaspe Peninsula in Quebec.
This fish had a surprising mix of features seen in amphibians and fish.
The fish was named Eusthenopteron. This fossil had Owen’s one bone, two bone pattern in its fin skeleton (33), making it another clue to human’s ancient past. But, it was not until 2004 that Shubin and his colleagues found Tiktaalik, a fish with a wrist, elbow and shoulder composed with the same pattern like humans arms. Tiktaalik lived approximately 375 million years ago. Paleontologists say that Tiktaalik represents a transition between non-tetrapod vertebrates (fish) such as Panderichthys, known from fossils 380 million years old, and early tetrapods such as Acanthostega and
Ichthyostega, known from fossils that are 365 million years old. Tiktaalik is a mixture of primitive fish and derived tetrapod characteristics lead Shubin to characterize Tiktaalik as a fishpod
(Wilford). In the PBS video Neil Shubin states, “Here we had the first fish who could do push ups.” How did Tiktaalik become so different from other fish?Another notable difference in Tiktaalik is spiracles on the top of the head that suggest the creature had primitive lungs as well as gills. This may have led the development of a more robust ribcage, which is a key
evolutionary trait of land living creatures. This robust ribcage would have helped support Tiktaalik’s body any time it ventured outside the water. Yet another interesting difference was the fact that Tiktaalik lacked bony plates in the gill area that restrict lateral head movement which makes Tiktaalik the
earliest known fish to have a neck with a pectoral griddle separate from the skull. Having a neck would have given Tiktaalik a better ability to hunt prey either on land or in the shallows
(Holmes). One hypothesis is that large shallow water fish lived in an environment that didn’t have much oxygen in the water so they developed lungs. “Dr Jenkins, who assisted in the interpretation of fossils said, ‘Fish feeding in water readily orient the mouth toward food by maneuvering the entire body’” (Wilford). This caused the first transition from water based life to land based life. However, if an animal spends any time out of water then it would need a true neck that would allow the head to move independently on the body. Thus Tiktaalik is truly a transitional creature that exhibits changes that anticipate the emergence of land animals.
Another very interesting discovery in the field of genetics was the Sonic hedgehog gene.
This gene is responsible for regulating tetrapod limb development. Every limbed animal has the
Sonic hedgehog gene which is one of three proteins in the mammalian signaling pathway family called hedgehog. It plays a key role in regulating growth of digits on limbs and organization of the brain. The hedgehog gene was first identified in the fruit fly Drosophila melanogaster in the classic Heidelberg screens of Christiane Nusslein-Volhard and Eric Wieschaus, as published in
1980. These genes control the segmentation pattern of the Drosophila embryos. If the hedgehog loses its function a mutation causes the embryos to be covered with denticles, which are small pointy projections that resemble a hedgehog. That is how this got its name (Wieschaus). Then in
1993, Philip Ingham, Andrew P. McMahon, and Clifford Tabin start some experiments to find a hedgehog gene equivalent in vertebrates. They ended up finding three homologous genes. Two of these were named after desert and Indian hedgehog species the third was named after Sega’s video game character Sonic the Hedgehog (Shubin 53). The Tabin group used chicken embryos
to see how the Sonic Hedgehog worked. They found that if they injected vitamin A at the site of
Sonic Hedgehog that a mirror image of the wing would grow on top of the normal wing. Dahn did the same kind of experiment on the fins of skates, which also showed a mirror image duplication (Dahn). His findings show that Sonic hedgehog regulation may underlie major morphological changes during appendage evolution.
If you look at the embryos of humans, chickens, and fish they are very similar. All of them have a head with gill arches. In the 1800s natural philosophers looked to embryos to try and find a common plan for life on earth. One of these observers was Karl Ernst von Baer who studies chicken development. In the process he discovered that a chicken make look very different from a fish, but their embryos share striking similarities. Both develop from a single cell into tube-shaped bodies. They share many traits early on, such as a set of arching blood vessels in their necks. Fish keep this vessel arrangement but in chickens and humans, amphibians, reptiles this vessels are reworked into a different anatomy suited to getting oxygen through lungs (Developmental Similarities).
Yet another surprising thing that happens to the gill arches in mammals is they become the three middle ear bones known as the malleus, incus, and stapes. The first arch is stapes and the second arch makes the malleus and incus. Karl Reichert followed the gill arches of different species in 1837. He found that the two ear bones in mammals corresponded to pieces of the jaw in reptiles. Much later a German anatomist Ernst Gaupp in 1910-1912 provides more detail and interprets Reichert’s work in an evolutionary framework. Embryologists and paleontologists didn’t started working together until 1913 before that they worked in isolation. It was W.K. Gregory who saw an important link between Gaupp’s embryos and the African fossils found in the
1840s. As Gregory looked at the successively more mammalian mammal like reptiles, he found a continuum of forms showing beyond doubt that over time the bones at the back of the reptilian jaw got smaller and smaller until they ultimately lay in the middle ear of mammals. So why would mammals need a three-boned middle ear? It allows mammals to hear higher frequency sounds than animals with a single middle ear bone. This shift was accomplished by repurposing existing bones not evolving new bones.
So while there are many differences between fish and humans one can see our relationship to ancient fish ancestors if they look close enough. Through evolution we see how fins become limbs, aquatic life goes to land, and how structures have been repurposed throughout life.
Here in lies the proof that Darwin’s Origin of the species gives a unique insight into our ancestry and answers the question why we look the way we do. One can see that humans did in fact have a fish ancestor that we evolved from. In other words every living thing on the planet has its start with some sort of parent creature that can be traced back to an ancient aquatic ancestor. Anyone who observes humanity for more than a few minutes sees that every living thing is slightly different from their ancestors, but their history and ours can be found, buried in our genes, our features, and in our landscape. We only need look.
Works Cited
Dahn, Randall D., et al. "Sonic hedgehog function in chondrichthyan fins and the evolution of appendage patterning." Nature 445.7125 (2007): 311. Health Reference Center Academic.
Web. 2 May 2015.
Developmental Similarities: Karl Von Baer." Developmental Similarities: Karl Von Baer. Web. 3
May 2015. <http://evolution.berkeley.edu/evolibrary/article/history_10>.
Holmes, Bob. "Meet your ancestor; Fossil hunters searching for the first fish that crawled onto land have struck gold. Bob Holmes reports on the latest missing link." New Scientist.
(September 9, 2006 ): 2673 words. LexisNexis Academic. Web. Date Accessed:
2015/05/02.
Shubin, Neil. Your Inner Fish: A Journey into the 3.5-billion-year History of the Human Body.
New York: Pantheon, 2008. Print.
Wieschaus, Eric, and Christiane Nüsslein-Volhard. "Mutations Affecting Segment Number and
Polarity in Drosophila." Nature 287.5785 (1980): 795-801.
Wilford, John. "Scientists Call Fish Fossil the 'Missing Link '" The New York Times. The New
York Times, 4 Apr. 2006. Web. 2 May 2015.
Your Inner Fish. Dir. Tom Cook. PBS, 2014. DVD.
Your Inner Fish by Neil Shubin, delves into the questions of why the human body looks the way it does. Looking at the earliest forms of vertebrate life on land and even to the earliest forms of life on Earth we can trace the evolution of the human body. The creatures, from millions of years ago, have left us with a genetic a imprint that reveals how similar we truly are to the other creatures on Earth. Shubin tells the story of evolution by tracing the skeletal features and organs of the human body back millions of years by examining fossils and DNA, he shows us our inner fish, reptile, and monkey.
What does your inner fish look like? Starting with a human arm a great anatomist, Sir
Richard Owen, discovered that our arms, and legs, hands and …show more content…
feet fit into a larger scheme that is common pattern among other creatures such as bats, birds, frogs and lizards. The pattern that
Owen discovered is one bone in the upper arm, two bones in the forearm, and nine little bones at the wrist, then a series of five rods that make the fingers. Seeing these similarities Owen went on to look at skulls and backbones here he found that there was a fundamental design in the skeleton of all animals which Owen credited to the plan of a creator. His findings were published in a monograph On the Nature of limbs (Shubin, 31-32). However it was Charles Darwin who supplied the reason why human arms and bat wings share common skeletal patterns, this being that they share a common ancestor. Yet, in fish the whole skeleton looks different. For instance, the base of a typical fin has four or more bones, but in the mid 1800s, the discovery of fish that had lungs in the Southern Continents started shedding some light on how fish crawled out of the water and started living on land. This confused anatomist so they named the fish Lepidosmen
Paradova, which means paradoxically scaled amphibian. Other fish were found in Africa and
Australia, which were named lungfish. Perhaps what is most fascinating about these fish was that they had a single bone that attached to the shoulder much like the upper arm of a human.
Anatomists had found a fish with a humerus bone. Around this same time there was the discovery of a fossil that was 380 million years old found on the shores of Gaspe Peninsula in Quebec.
This fish had a surprising mix of features seen in amphibians and fish.
The fish was named Eusthenopteron. This fossil had Owen’s one bone, two bone pattern in its fin skeleton (33), making it another clue to human’s ancient past. But, it was not until 2004 that Shubin and his colleagues found Tiktaalik, a fish with a wrist, elbow and shoulder composed with the same pattern like humans arms. Tiktaalik lived approximately 375 million years ago. Paleontologists say that Tiktaalik represents a transition between non-tetrapod vertebrates (fish) such as Panderichthys, known from fossils 380 million years old, and early tetrapods such as Acanthostega and
Ichthyostega, known from fossils that are 365 million years old. Tiktaalik is a mixture of primitive fish and derived tetrapod characteristics lead Shubin to characterize Tiktaalik as a fishpod
(Wilford). In the PBS video Neil Shubin states, “Here we had the first fish who could do push ups.” How did Tiktaalik become so different from other fish?Another notable difference in Tiktaalik is spiracles on the top of the head that suggest the creature had primitive lungs as well as gills. This may have led the development of a more robust ribcage, which is a key
evolutionary trait of land living creatures. This robust ribcage would have helped support Tiktaalik’s body any time it ventured outside the water. Yet another interesting difference was the fact that Tiktaalik lacked bony plates in the gill area that restrict lateral head movement which makes Tiktaalik the
earliest known fish to have a neck with a pectoral griddle separate from the skull. Having a neck would have given Tiktaalik a better ability to hunt prey either on land or in the shallows
(Holmes). One hypothesis is that large shallow water fish lived in an environment that didn’t have much oxygen in the water so they developed lungs. “Dr Jenkins, who assisted in the interpretation of fossils said, ‘Fish feeding in water readily orient the mouth toward food by maneuvering the entire body’” (Wilford). This caused the first transition from water based life to land based life. However, if an animal spends any time out of water then it would need a true neck that would allow the head to move independently on the body. Thus Tiktaalik is truly a transitional creature that exhibits changes that anticipate the emergence of land animals.
Another very interesting discovery in the field of genetics was the Sonic hedgehog gene.
This gene is responsible for regulating tetrapod limb development. Every limbed animal has the
Sonic hedgehog gene which is one of three proteins in the mammalian signaling pathway family called hedgehog. It plays a key role in regulating growth of digits on limbs and organization of the brain. The hedgehog gene was first identified in the fruit fly Drosophila melanogaster in the classic Heidelberg screens of Christiane Nusslein-Volhard and Eric Wieschaus, as published in
1980. These genes control the segmentation pattern of the Drosophila embryos. If the hedgehog loses its function a mutation causes the embryos to be covered with denticles, which are small pointy projections that resemble a hedgehog. That is how this got its name (Wieschaus). Then in
1993, Philip Ingham, Andrew P. McMahon, and Clifford Tabin start some experiments to find a hedgehog gene equivalent in vertebrates. They ended up finding three homologous genes. Two of these were named after desert and Indian hedgehog species the third was named after Sega’s video game character Sonic the Hedgehog (Shubin 53). The Tabin group used chicken embryos
to see how the Sonic Hedgehog worked. They found that if they injected vitamin A at the site of
Sonic Hedgehog that a mirror image of the wing would grow on top of the normal wing. Dahn did the same kind of experiment on the fins of skates, which also showed a mirror image duplication (Dahn). His findings show that Sonic hedgehog regulation may underlie major morphological changes during appendage evolution.
If you look at the embryos of humans, chickens, and fish they are very similar. All of them have a head with gill arches. In the 1800s natural philosophers looked to embryos to try and find a common plan for life on earth. One of these observers was Karl Ernst von Baer who studies chicken development. In the process he discovered that a chicken make look very different from a fish, but their embryos share striking similarities. Both develop from a single cell into tube-shaped bodies. They share many traits early on, such as a set of arching blood vessels in their necks. Fish keep this vessel arrangement but in chickens and humans, amphibians, reptiles this vessels are reworked into a different anatomy suited to getting oxygen through lungs (Developmental Similarities).
Yet another surprising thing that happens to the gill arches in mammals is they become the three middle ear bones known as the malleus, incus, and stapes. The first arch is stapes and the second arch makes the malleus and incus. Karl Reichert followed the gill arches of different species in 1837. He found that the two ear bones in mammals corresponded to pieces of the jaw in reptiles. Much later a German anatomist Ernst Gaupp in 1910-1912 provides more detail and interprets Reichert’s work in an evolutionary framework. Embryologists and paleontologists didn’t started working together until 1913 before that they worked in isolation. It was W.K. Gregory who saw an important link between Gaupp’s embryos and the African fossils found in the
1840s. As Gregory looked at the successively more mammalian mammal like reptiles, he found a continuum of forms showing beyond doubt that over time the bones at the back of the reptilian jaw got smaller and smaller until they ultimately lay in the middle ear of mammals. So why would mammals need a three-boned middle ear? It allows mammals to hear higher frequency sounds than animals with a single middle ear bone. This shift was accomplished by repurposing existing bones not evolving new bones.
So while there are many differences between fish and humans one can see our relationship to ancient fish ancestors if they look close enough. Through evolution we see how fins become limbs, aquatic life goes to land, and how structures have been repurposed throughout life.
Here in lies the proof that Darwin’s Origin of the species gives a unique insight into our ancestry and answers the question why we look the way we do. One can see that humans did in fact have a fish ancestor that we evolved from. In other words every living thing on the planet has its start with some sort of parent creature that can be traced back to an ancient aquatic ancestor. Anyone who observes humanity for more than a few minutes sees that every living thing is slightly different from their ancestors, but their history and ours can be found, buried in our genes, our features, and in our landscape. We only need look.
Works Cited
Dahn, Randall D., et al. "Sonic hedgehog function in chondrichthyan fins and the evolution of appendage patterning." Nature 445.7125 (2007): 311. Health Reference Center Academic.
Web. 2 May 2015.
Developmental Similarities: Karl Von Baer." Developmental Similarities: Karl Von Baer. Web. 3
May 2015. <http://evolution.berkeley.edu/evolibrary/article/history_10>.
Holmes, Bob. "Meet your ancestor; Fossil hunters searching for the first fish that crawled onto land have struck gold. Bob Holmes reports on the latest missing link." New Scientist.
(September 9, 2006 ): 2673 words. LexisNexis Academic. Web. Date Accessed:
2015/05/02.
Shubin, Neil. Your Inner Fish: A Journey into the 3.5-billion-year History of the Human Body.
New York: Pantheon, 2008. Print.
Wieschaus, Eric, and Christiane Nüsslein-Volhard. "Mutations Affecting Segment Number and
Polarity in Drosophila." Nature 287.5785 (1980): 795-801.
Wilford, John. "Scientists Call Fish Fossil the 'Missing Link '" The New York Times. The New
York Times, 4 Apr. 2006. Web. 2 May 2015.
Your Inner Fish. Dir. Tom Cook. PBS, 2014. DVD.