Have you ever wondered what makes your hair the way it is? Hair is more than just something on your head; it’s a complex and intriguing part of our biology. Let’s dive into the story of hair and uncover some cool facts about it!
Hair is primarily made of a protein called keratin, which is also found in your fingernails. The color of your hair comes from pigments called melanin. There are two types: eumelanin, which is brown-black, and pheomelanin, which is red-yellow. The mix of these pigments gives your hair its unique color. Whether your hair is curly or straight depends on the shape of your hair follicles, which is determined by your DNA.
Blondes, brunettes, and redheads all have different levels of melanin. Blondes have less pigment, while brunettes have more eumelanin, and redheads have more pheomelanin. This variation in pigment is controlled by a gene that also affects skin color. As humans moved away from sunny regions, our hair and skin colors began to vary more.
Did you know that even Neanderthals had different hair colors? Some had red hair due to variations in their genes. As humans evolved, we lost much of our body hair to help us stay cool while running in hot climates. Hair can also be a home for parasites like lice. There are three types of lice that can live on humans: head lice, body lice, and pubic lice. Each type has its own unique history with us.
We have about the same number of hair follicles as our ape ancestors, but hair is only thick in specific areas. One reason we lost our fur is to help us cool down more effectively. Hair in certain areas, like the face and underarms, becomes coarser during puberty due to hormonal changes. This type of hair is called “androgenic” hair and is influenced by sex hormones. It also helps trap and project odors and pheromones.
As we get older, the cells that produce pigment in our hair follicles decrease, leading to gray hair, which is simply hair without color. It’s normal to lose 40 to 50 hairs a day, as new ones grow in their place. However, if hair follicle stem cells become inactive, it can lead to hair loss. This can happen due to aging or damage from treatments like chemotherapy.
If you’re experiencing hair loss, don’t worry too much. Science is always working on solutions, and hair loss is something humans have adapted to over millions of years. So, keep exploring and stay curious about the amazing world of hair!
Using materials like clay or playdough, create a model of a hair strand. Include the cuticle, cortex, and medulla layers. Label each part and explain its function. This will help you understand the structure of hair and how it contributes to its strength and appearance.
Research and create a chart showing different hair colors and the levels of eumelanin and pheomelanin present in each. Use colored pencils to illustrate the variations. This activity will help you visualize how melanin affects hair color.
Create a timeline that shows the evolution of hair in humans and our ancestors. Include key points such as the development of different hair colors and the reasons for hair loss in certain areas. This will give you a historical perspective on how hair has changed over time.
Participate in a class debate about the role of hair in human evolution. Discuss topics such as why humans lost body hair and the significance of hair in different cultures. This will enhance your understanding of the biological and cultural aspects of hair.
Interview a hairstylist or dermatologist to learn about hair care and common hair issues. Prepare questions about hair growth, hair loss, and treatments. This will provide you with practical insights into the science of hair and how it applies to everyday life.
This episode is supported by Curiosity Stream. The story of our hair, or “hair-story” if you will, is quite complex. Scientists are still sorting out the facts, examining questions, and getting to the root of this biological tale. We must ask: What’s the deal with hair?
Hair is a significant part of our culture – it’s been featured on Broadway, celebrated in songs, and has even inspired its own musical genre. But what exactly is it? Hair is made of keratin, the same protein that forms your fingernails, along with a few additional components. Its color comes from two types of melanin: brown-black eumelanin and red-yellow pheomelanin. These pigments are produced in the hair follicle, and whether each strand is curly or straight depends on the angle of the follicle itself. Your DNA determines whether you resemble a Thor, a Loki, or perhaps a Weasley.
Blondes might have more fun, but they have lower levels of pigment. They have a mix of the two hues, but at reduced levels. Eumelanin is predominant in brunettes, while redheads primarily have reddish pheomelanin. This pigment ratio is controlled by a gene that also influences the melanin in our skin. In Africa, this pigment gene remains relatively stable, which makes sense for UV ray absorption. However, as we moved away from tropical regions, we observed more variation in skin and hair.
Ancient DNA indicates that even some Neanderthals had variations in their MC1R genes that led to red hair as they adapted to northern climates. So why does our hair grow where it does and not where it doesn’t? We actually have about the same number of hair follicles as our ape ancestors, and while some hair grows almost everywhere, it is only thick in certain areas.
One theory is that we lost our fur to stay cool. Running across the savannahs is a hot endeavor, and bare skin sheds heat more effectively. Additionally, hair can provide a habitat for parasites. There are three types of lice that can live on humans: head lice, body lice, and pubic lice. Head lice have been with us for a long time, possibly since we diverged from chimps. The story of pubic lice is more unusual; they are closely related to gorilla lice and likely appeared more recently, possibly due to interactions with gorillas or from butchering bushmeat.
Body lice, despite their name, live in clothing and joined us around 42,000 to 72,000 years ago, likely when we transitioned from fig leaves to leather clothing.
As for why hair in certain areas feels coarser, such as facial hair and underarm hair, it’s because these hairs emerge due to hormonal changes during puberty. This “androgenic” hair is influenced by the production of sex hormones, which is why men tend to have more of it. This hair also contains more eumelanin, which is why the color may differ from head hair. Hair in the underarms and genital area helps trap and project odors and pheromones that become prominent during puberty.
As we age, the pigment-producing cells in our follicles diminish, leading to hair that grows without color. Grey hair isn’t a color; it’s simply a lack of pigment. Typically, we lose 40 to 50 hairs per day, which is normal as we grow new ones. However, when hair follicle stem cells become inactive due to aging or are damaged, such as from chemotherapy, it results in hair loss.
If you’re experiencing hair loss, don’t worry; science is likely to find solutions. Besides, it’s a trend we’ve been embracing for millions of years. Stay curious!
Hair – A threadlike structure that grows from the skin of mammals, composed mainly of keratin. – Hair helps to protect the scalp from sun damage and provides insulation against cold temperatures.
Keratin – A type of protein that is a key structural component of hair, nails, and the outer layer of skin. – Keratin is what gives hair its strength and resilience, allowing it to withstand environmental stress.
Melanin – A natural pigment found in most organisms, responsible for the color of skin, hair, and eyes. – The amount of melanin in the skin determines how light or dark a person’s complexion is.
Eumelanin – A type of melanin that is dark brown or black, contributing to the color of hair and skin. – People with black or brown hair have higher levels of eumelanin in their hair follicles.
Pheomelanin – A type of melanin that is reddish-yellow, contributing to the color of red and blonde hair. – Pheomelanin is more abundant in individuals with red hair, giving it its distinctive hue.
Genes – Units of heredity made up of DNA that determine specific traits and characteristics in living organisms. – Genes inherited from parents play a crucial role in determining an individual’s hair color and texture.
Follicles – Small secretory cavities in the skin from which hair grows. – Each hair follicle is connected to a sebaceous gland that secretes oils to keep the hair moisturized.
Lice – Small, wingless, parasitic insects that live on the skin of mammals, feeding on blood. – Head lice infestations are common in schools and can be treated with special shampoos.
Hormones – Chemical substances produced in the body that regulate and control the activity of certain cells or organs. – Hormones like testosterone and estrogen can influence hair growth and distribution on the body.
Aging – The process of becoming older, which involves a gradual decline in physical and sometimes mental capacity. – As part of the aging process, hair may turn gray due to a decrease in melanin production.
