Have you ever wondered why we have hair and why it varies so much from person to person? Let’s dive into the world of hair and uncover some interesting facts about it!
Hair is a natural part of being human. While we often think of hair as being on our heads, it’s actually all over our bodies. In fact, humans have about five million hairs, just like chimpanzees! Hair and fur are essentially the same thing, made from a protein called keratin.
Our skin has layers, with the outer layer called the epidermis and the layer beneath it called the dermis. In the dermis, cells are constantly dividing, pushing older cells out of follicles to create hair. For chimpanzees, hair helps protect their skin from the sun and keeps them warm. For us, hair still protects our heads from the sun and helps sweat evaporate to cool us down, but it doesn’t keep us warm like it used to.
There are different types of hair that grow on our bodies. Before we’re born, we have a type of hair called lanugo, which usually disappears before birth. After birth, we grow soft, fine hair called vellus hair all over our bodies. The thicker, pigmented hair on our heads, eyebrows, and eyelashes is called terminal hair.
During puberty, some vellus hair changes to terminal hair or androgen hair, influenced by hormones. This happens on the face and chest for men and in the armpits and pubic areas for both men and women. The type of hair you have is mostly determined by your genes, with studies showing that hair traits are 85 to 95 percent inherited.
Hair can be curly or straight depending on the shape of the hair follicle. Oval-shaped follicles produce curly hair, while circular follicles produce straight hair. A special receptor in our cells, called the epidermal growth factor receptor, helps regulate hair growth. If it adds more keratin to one side of the hair shaft, the hair becomes curly!
Hair is a trait passed down from our ancient ancestors. As humans evolved, hair became thinner in some areas, but the reasons for this are still a mystery. Some scientists think hair might have lessened to improve social interaction by making facial expressions more visible. Others suggest it might have helped reduce friction as humans became more mobile.
Hair might also protect sensitive areas from dirt and UV rays or help spread pheromones for mating. Interestingly, some theories suggest that hairlessness in women might have been seen as attractive, influencing human evolution.
Maintaining some body hair might help us detect parasites. A study from the University of Sheffield found that people with more body hair could detect bed bugs more quickly. As humans started wearing clothes over 170,000 years ago, this helped them stay warm during colder times but also increased the risk of parasites.
Hair is indeed a complex and fascinating topic, with many aspects still being studied by scientists!
Use clay or playdough to create a model of a hair follicle. Include the epidermis, dermis, and hair shaft. Label each part and explain how hair grows from the follicle. This hands-on activity will help you visualize the structure of hair and understand its growth process.
Conduct a survey among your classmates to identify different hair types (straight, wavy, curly) and discuss the role of genetics in determining hair type. Create a chart to display your findings and explore how the shape of hair follicles affects hair texture.
Participate in a class debate on the theories of why human hair evolved the way it did. Discuss the potential reasons for hair thinning and the role of hair in social interaction and protection. This will help you understand the evolutionary significance of hair.
Design a simple experiment to test how body hair might help detect parasites. Use small objects to simulate parasites and see if having more or less “hair” affects detection speed. This activity will give you insight into the practical functions of body hair.
Research the protein keratin and its role in hair structure. Create a presentation to share with the class, explaining how keratin contributes to hair strength and texture. This will deepen your understanding of the biological composition of hair.
Here’s a sanitized version of the provided YouTube transcript:
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Give me a head with hair, long beautiful hair, shining, gleaming, steaming flaxen waxen. HAIR! It’s Monday, so we’re answering viewer questions today, and on our “Why Do We Have Warts” video, Saihan, Elyse, and TheGamingWookiee all had questions about hair! Different types, why do some have more than others, and why do we even need it!
Firstly, hair is a natural part of being human. We tend to associate it with our head, face, armpits, pubic regions, and legs; but it’s actually everywhere. We like to think of ourselves as a naked ape, but we have the same number of hairs on our body as a chimpanzee—around five million hairs. Before you ask, hair and fur are the same thing. You and your furry pets all have hair made of the same substance: keratin.
Your skin is made of layers—the epidermis, then the dermis underneath. In the dermis, cells are constantly dividing, and the older cells are pushed out of follicles, creating hair all the time. On chimpanzees, hair protects skin from the sun and provides warmth. When you take into account thermoregulation, hair was a way to keep body warmth naturally! Though, in modern humans, it still protects our head from the sun’s rays and allows sweat to travel along hair shafts and evaporate, cooling us down, but it doesn’t keep our bodies warm anymore.
There are many different types of hair. Fetuses in the womb grow hair called lanugo; though it usually recedes from the body before birth, it doesn’t always. A comforting reminder of our primate history, perhaps? After birth, we humans grow soft, fine, unpigmented vellus hair all over our bodies, though thicker, pigmented hair on the head, eyebrows, eyelashes, and so on, is called terminal hair. During puberty, some of the vellus hair transitions to terminal hair or androgen hair—named for the sex hormones that cause them. This occurs on the face and chest for men and in the armpits and pubic regions for both men and women. What hair you get depends a lot on your genes. A 2009 Cambridge study found that the genes for hair were 85 to 95 percent inherited, though some can be affected by the environment.
Hair curls for two reasons. First, an asymmetrical or oval-shaped follicle will force a curvy hair to emerge; circular follicles produce straight hair. A specific cellular receptor called epidermal growth factor receptor regulates the growth of hair. If the EGFR puts too much keratin on one side of the hair shaft as it grows, it will come out curly!
Hair is a holdover from our ancient ancestors. As we evolved, our genes mutated, and hair thinned on some parts of the body, but the reason for this variation is an evolutionary mystery! Perhaps hair lessened for social interaction, to better see the eyes and face; or as we became more upright and mobile, evolution favored those with just enough to reduce skin-on-skin friction in certain areas; or perhaps ancient humans spent more time in the water, and hair wasn’t as useful there except on the exposed parts of the head.
Perhaps hair remains in certain regions to block dirt and other particles or to keep UV rays away from sensitive areas. Or maybe it allows pheromones to spread from the body for mating! The Economist suggests that perhaps mature women are more visibly hairless, on average, than men because, at some point, hairlessness was selected by men as a sexually attractive trait; a similar theory as to why human males have the largest average size of all primates. Again, we don’t exactly know.
What we do know is that maintaining some, but not all, body hair may be due to parasite detection. A study from England’s University of Sheffield found that people with more body hair could detect bed bugs more quickly than those with less. By tracing the evolution of lice alongside humans, scientists determined we started wearing clothing more than 170,000 years ago. This was beneficial for the cooler temperatures of the coming ice age and when we began to move from Africa into Europe. More clothing, like thicker hair, means more parasites, which can be problematic.
This is indeed a complex topic!
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This version removes any inappropriate language and maintains a professional tone while preserving the original content’s essence.
Hair – Hair is a threadlike structure that grows from the skin of mammals, including humans, and is made of a protein called keratin. – Example sentence: The hair on a mammal’s body helps to keep it warm and can also serve as camouflage in its environment.
Genes – Genes are units of heredity made up of DNA that determine specific traits or characteristics in an organism. – Example sentence: Genes passed down from parents to offspring can influence traits like eye color and height.
Evolution – Evolution is the process by which different kinds of living organisms develop and diversify from earlier forms over generations. – Example sentence: The theory of evolution explains how species adapt to their environments over time.
Follicles – Follicles are small sacs in the skin from which hair grows. – Example sentence: Each hair on your head grows from its own follicle, which is located in the skin.
Protein – Proteins are large, complex molecules that play many critical roles in the body, including building tissues and organs. – Example sentence: Proteins are essential for the growth and repair of cells in all living organisms.
Keratin – Keratin is a type of protein that makes up the structure of hair, nails, and the outer layer of skin. – Example sentence: Keratin helps protect the skin and makes hair strong and resilient.
Traits – Traits are characteristics or features of an organism that can be inherited from its parents. – Example sentence: Traits such as fur color and leaf shape can help organisms survive in their environments.
Puberty – Puberty is the stage of development in humans and other animals when they become capable of reproduction. – Example sentence: During puberty, humans experience many physical changes, including growth spurts and the development of secondary sexual characteristics.
Receptors – Receptors are proteins on the surface of cells that receive signals from the environment or other cells. – Example sentence: Receptors on nerve cells help organisms detect changes in their surroundings, such as temperature or light.
Parasites – Parasites are organisms that live on or inside another organism, called the host, and benefit at the host’s expense. – Example sentence: Some parasites, like ticks and fleas, can cause harm to their hosts by feeding on their blood.
