Summary of Tu pez interior La ciencia del ser humano capitulo 02

00:00:00 - 00:50:00

The video discusses the 195 million year old human-like creature dubbed "HADROCODON," which has a 50% larger brain than any other prior animal. This creature is considered one of the first mammals and its unique features, such as its large cerebrum, helped it survive in a dangerous world at night. When the dinosaurs went extinct 65 million years ago, humans were able to emerge and prosper. This happened when the dinosaurs went extinct, leaving the mammals free to occupy all the vacant spaces on the earth. With its large brain, humans are still affected by the reptilian inside them.

• 00:00:00 In this video, anatomist Nil Szubin tells the story of how he discovered his reptilian self, and how this has helped him in his work as an anatomist. Szubin shares memories of his old street in Pátzcuaro, Mexico, and describes how his fascination with the human body led him to Harvard University for post-graduate study, where he would lead his first expedition in search of fossils. Szubin and his team were unlucky and lost most of their digging gear in a quick tide. However, their luck changed when the president of a local lion club invited them to judge a beauty pageant. As judges, they were required to stay for the night after the pageant, and when they woke up the next day, Szubin found out that his colleague Bill had disappeared. Szubin goes on to describe how he found Bill the next day, and how his experience at the pageant may have saved his friend's life.
• 00:05:00 In this video, Dr. Maider and her team discuss the anatomy of a reptile that lived 375 million years ago and gave rise to modern animals like mammals. They reveal that at 8 weeks into a person's pregnancy, their reptilian embryo is almost identical to the embryo of a modern mammal. This video might change the way you think about your own pregnancy.
• 00:10:00 This video discusses the evolution of human development, and in particular, the changes that occurred in our ancestors' reproductive system. Around 375 million years ago, vertebrates began to live on land, which posed a new challenge for them; they needed to find ways to store their eggs while they were on land. One solution that these early vertebrates evolved was the development of an egg-containing sac that was protected by a protective outer layer. This innovation allowed for the emergence of new animal types, such as reptiles and birds. Our skin and genes are also written in the history of reproduction, as our ancestors' need for egg-containing sacs began to fade about 100 million years ago. However, some of these "unused" genes still reside in our genome, and can be used to study the evolutionary relationships between different species.
• 00:15:00 This video discusses the evolution of human skin, which is different from the skin of reptiles. Human skin is kept moist by its own special glands and oil capsules, which secrete oil to keep the superficial layer hydrated. Reptiles' skin is dry, while human skin evolved from a long battle against the elements over 3 billion years ago. When our reptilian ancestors broke ties with water, a new path appeared. The coast of Africa is one of the most spectacular landscapes on Earth, but for paleontologists, the true spectacle is found inside the skulls of fossil animals. One of the world's best paleontologists, Roger Smith, found astonishing spines on a fossil site in Africa in the 1990s. I lost a lot of blood this season, and the only way it can come out is if I stretch it. And that's what happens with Roger. He loves this place so much that you can't be with him for more than five minutes without becoming aware of it. He lives and breathes fossils. Fossils found at this site reveal the intense battle between predators and prey that occurred over millions of years. This is one of the best sites for paleontology in the world and it has yielded some of the most valuable
• 00:20:00 This video discusses the importance of teeth, and how they can tell us a lot about the biology of human beings. Baron Georges Cuvier, who lived in Paris in the 19th century, was very important and knowledgeable. He always boasted about his knowledge, and would often show people his animal teeth replicas. Cuvier realized that these teeth were enormous - the size of a human tooth - and belonged to a large animal that masticated plants. This animal was an elephant. From the size and shape of these teeth, it is clear that this creature fed on large, white, fleshy plants. Cuvier also demonstrates an impressive 250 million year old teeth - the oldest of its kind - from a gordonOption, a type of carnivorous reptile that lived during the time of the dinosaurs. This fossil is one of those specimens that when you see it, you know exactly what this creature ate and how it lived. The teeth at the front of the mouth are designed to bite into the fruit, while the back teeth are tiny, sharp needles that are perfect for extracting meat from an animal's skeleton. The differences in the teeth row all have the same basic form, but differ in size, shape, and specialization for feeding
• 00:25:00 In this video, zoologist Roger Scruton discusses the importance of teeth fitting properly, and how we can often break a tooth or something similar until we eventually suffer from a broken tooth. He then looks at the teeth of some incredibly complex animals, which allow us to give good bites but come with a price--a tooth's transition to a mammalian life results in the need for dentists. This is true even for reptiles, who don't need dentists because they produce their own teeth over the course of their lifetime. However, Scruton points out that our human teeth are inextricably linked to our psychological well-being. We can develop a very precise bite thanks to our teeth's alignment, but we often neglect the importance of this until we suffer a broken tooth. For Scruton, this tragic event is a reminder of the fragility of life and the importance of understanding our own evolution through the study of fossils.
• 00:30:00 Roger believes that living underground may have helped our ancestors survive in harsh climates and that the hair on our heads may have developed as a result. In this video, he shows how two of our body's most important features--hair and teeth--are related to ancient predators who lived in lost lands. Our skin is also related to these creatures, as are our complex dentition and skin layers.
• 00:35:00 The passion of Abby is to explore the mystery of how human organs, such as teeth, are formed. We'll use a tooth as an example, and see how an embryo rat's lower jaw is removed, and eventually turns into a tooth. This type of work requires a lot of dexterity, and here I'm using a tungsten needle, but for a very small tissue, we use a glass rod and use it as a very fine knife. Almost there. This is here we are seeing a tooth in its first stage, although it looks like teeth, it was a flat sheet of tissue, and now it has sunk into it, achieving this shape of cap. After putting the tooth in an incubator, Abby can observe how it grows. And what's remarkable is that the skin folds over itself, like papiroflexia, and we can now see that a tooth has been formed, and it's not any particular molar, but all of our organs of the skin, from hair to glands, develop in a similar way. We believe that this is a primitive principle, and these skinfoldings were one of the first steps in being able to continue forward, and form a very simple skin, and then something different will happen
• 00:40:00 Michael talks about the importance of the skin and how it affects our health. He demonstrates this by showing how a person with healthy skin looks different from someone with bad skin. The idea has been important in the formation of our bodies over evolution, and it's especially important today because of new technologies like hearing aids. Michael talks about how reptiles only have one ear bone, while we humans have three. This is one of the reasons why we hear better than reptiles. The development of our ears and the ability to hear a wide range of sounds started with three tiny bones in our middle ear, which all mammals have. However, reptiles only have one of these bones- the hammer and anvil. This simple puzzle has been a mystery to scientists for nearly 2 centuries. What they've discovered is that when you look at an embryo's ear bones from early development to adulthood, you essentially see a reptilian ear. And this is just one of many discoveries that have been made in recent years about the amazing anatomy of mammals. Karen Sears, an old student of Michael's, talks about how she studies ear development in zarigüeyas- a species of mammal that has recently become more popular in laboratories. She explains that during early development, the ear bones
• 00:45:00 In this video, Dr. Löw discusses the development of human bones and teeth. He explains how over the course of millions of years, bones that used to form the jawbone and mandible gradually became smaller and moved to their final position in mammals. We have reptiles today with one bone, and mammals with three bones, due to the embryo providing an anatomical link between the two. We can see this transition happening in embryos as early as zebrafish, and eventually see it in fossilized animals from 200 million years ago onwards. In recent years, one of the foremost scientists involved in the study, my colleague Hello, found a fossilized skull in China that is of particular interest. The lower jawbone was very different from ours, containing teeth instead of bones that carry them. This suggests that over the course of millions of years, the old jawbone bones gradually shrunk and eventually disappeared. But in their place, teeth-bearing bones took on a new function in the ear. This fascinating transition can be difficult to detect, as the diminutive bones in the ear are scattered throughout the skull and are not often found together with the rest of the body. However, by painstakingly reconstructing the skull from various angles using 3D printing, my colleague was able
• 00:50:00 The video discusses the 195 million year old human-like creature dubbed "HADROCODON," which has a 50% larger brain than any other prior animal. This creature is considered one of the first mammals and its unique features, such as its large cerebrum, helped it survive in a dangerous world at night. When the dinosaurs went extinct 65 million years ago, humans were able to emerge and prosper. This happened when the dinosaurs went extinct, leaving the mammals free to occupy all the vacant spaces on the earth. With its large brain, humans are still affected by the reptilian inside them.