Sophia Delgado
Humans grow nails, or fingernails and toenails, as an evolutionary variation from claws, which were used by primates to climb trees, grab objects, and dig holes. Nails are made of a protein called keratin, which is also found in hair, hooves, horns, and claws. While nails are not essential for human existence, they serve several purposes, including enhancing grip, protecting the delicate tissues, nerves, blood vessels, and muscles underneath, and providing a visual indication of a person's health.
| Characteristics | Values |
|---|---|
| Purpose | Protection, grip, balance, and motor functions |
| Structure | Nail plate, nail bed, cuticle, nail folds, matrix |
| Composition | Keratin, a type of protein |
| Growth | Fingernails: 3.47-3.5 mm per month; Toenails: 1.6 mm per month |
| Health Indicators | Malnutrition, psoriasis, subungual melanoma |
| Evolution | Transitioned from claws to nails for better grip and support for broader fingertips |
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What You'll Learn
Humans evolved from clawed primates
Humans are a species of the hominid family of primates, which also includes all the great apes. The earliest fossils of Homo erectus were discovered in 1891 on the Indonesian island of Java. The study of human origins is a vibrant field, with new discoveries continually adding to our understanding of how we became human.
Primates diverged from other mammals about 85 million years ago, with their earliest fossils appearing over 55 million years ago. The evolutionary history of primates can be traced back 65 million years, and one of the oldest known primate-like mammal species, the Plesiadapis, came from North America. Primates produced successive clades, leading to the ape superfamily, which gave rise to the hominid and gibbon families. African and Asian hominids, including orangutans, diverged about 14 million years ago. Hominins, including Australopithecine and Panina subtribes, parted from the Gorillini tribe between 8 and 9 million years ago.
The view that humans descended from clawed primates is supported by the fact that nails are considered modified claws. Large mammals used claws to climb large tree trunks, grab things, and dig holes. As mammalian ancestors grew larger, claws became a hindrance as they scrambled across tree canopies and tried to grasp small branches in search of fruit. Thus, the transition from claws to nails occurred as a result of evolutionary pressures and the need for firmer grip.
Humans gradually developed traits such as bipedalism, dexterity, complex language, and interbreeding with other hominins, indicating that human evolution was not linear but weblike. The development of nails supported the evolution of broad fingertips, which enhanced grip strength. This allowed early humans to strike stones together to make tools and carve out useful items for their homes. Nails also serve a protective function, shielding the delicate soft tissues, nerves, blood vessels, and muscles beneath.
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Nails support broad fingertips
Human nails are made of a protein called keratin, which is also found in hair, hooves, horns, claws, and the horns of cows and sheep. Nails are flattened versions of claws, which were used by ancient primates to climb trees, grab things, and dig holes. As primates, humans inherited broad fingertips, which are even wider than those of chimpanzees and orangutans.
The evolution of nails supported the development of broad fingertips. Without a firm structure to support them, broad fingertips would be useless, but fingernails enable the fingertips to develop a very important function: grip. Members of the animal kingdom with a firm grip have broad fingertips. For example, our primate cousins, lemurs, have broad fingertips and strong grips.
Around 2.5 million years ago, human ancestors moved from living in trees to living in caves. As a result, fingertips became broader, facilitating the ability to grip stone tools. Early people were able to create useful items for the home, and over time, this skill was honed into the ability to assemble flat-pack furniture.
Nails also have a protective function. Their hard surface prevents injury to the delicate soft tissues, nerves, blood vessels, and muscles underneath. Toenails, in particular, protect the tops of the toes, which are vulnerable to injury and infection. Additionally, there is some evidence that toenails assist in balance, possibly by ensuring that the sensors on the bottom of the toes are applied to the floor in a consistent manner.
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They help with grip and motor functions
Humans grow nails, or more specifically, fingernails, as they help with grip and motor functions. Our fingernails are flattened versions of claws, which our ancient primate ancestors used to support their broad fingertips. These claws allowed them to climb large tree trunks, grab things, and dig holes.
As primates, we have inherited broad fingertips, which are even wider than those of our closest relatives, such as chimpanzees and orangutans. The reason for this dates back to the earliest days of human tool use: striking stones together to make tools requires a powerful grip. Thus, our fingernails enable our fingertips to have a very important function: grip.
Our ancient primate ancestors also used their claws for grooming, removing parasites from their hair and skin. Similarly, our fingernails are useful for removing lice, ticks, and other pests from our skin and hair.
Fingernails also help with fine motor functions. They help us judge how to hold things, detecting pressure changes and increasing the sensitivity of our fingertips. The hard surface of our fingernails provides protection for the delicate soft tissues, nerves, blood vessels, and muscles beneath.
Nails are made of a protein called keratin, which is also found in our hair, as well as in the horns of cows and sheep, and the hooves of horses, among other animals. The cells in our nail matrix, called keratinocytes, produce the protein keratin, which forms the nail. The nail is composed of layers of dead, compacted cells, along with keratin, which makes it strong, rigid, and flexible.
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Nails are made of dead, compacted cells
Human nails are made of dead, compacted cells. This is because the cells that make up the nail contain keratin, a type of hardened protein that is also found in hair, horns, hooves, and claws. Keratin is a tissue type made up of amino acid proteins. While the cells that produce keratin are living and require nutrients and proteins to survive, the keratin cells in the nail are no longer living, which is why trimming your nails does not hurt.
The nail is composed of three layers of keratin of varying softness and hardness, which come together to create a protective shield. The outermost layer of the nail, the nail plate, is made of a modified form of keratin. This is the hard, visible surface of the nail. Beneath the nail plate is the nail bed, a layer of skin, and the cuticle, a thin, waterproof membrane that seals the nail plate to the fingertip and acts as a barrier to infections. The matrix is the hidden part of the nail that lies under the cuticle, where nail cells are compacted and pushed out over the nail bed as the nail grows.
Human nails are believed to have evolved from claws, which were used by ancient primates to clutch tree bark and remove parasites from their hair and skin. As primates evolved and began to use tools, nails provided a better grip on branches and smaller, thinner objects. Nails also supported the development of broader fingertips, which improved grip strength.
In addition to their evolutionary advantages, human nails serve several practical purposes. They protect the delicate soft tissues, nerves, blood vessels, and muscles beneath, and assist in balance and mobility. Nails can also be used for scratching, peeling fruits, and removing pests from the skin and hair.
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They can indicate health issues
Human nails, though not vital for existence, serve protective and supportive functions. They also provide clues about our health. Changes in nail appearance can indicate vitamin deficiencies, chronic conditions, or other underlying health issues.
Nail health is closely associated with overall bodily health. Dr Sara Norris, a naturopathic doctor, states that "brittle, weak, and peeling nails are the most common concerns I see in my practice, and these symptoms are more often the result of a poor diet than of systemic disease." Nails that are dry, cracked, or brittle are often due to dryness on the nail plate. Discolouration, such as yellow nails, can be a sign of ageing, nail products, smoking, or an underlying disorder. Yellow nail syndrome, for example, is associated with respiratory issues and limb swelling.
Horizontal lines on the nails, known as Muehrcke's lines, can indicate low albumin levels, a potential sign of malnutrition or inflammatory bowel disease. Vertical black lines, on the other hand, could be a sign of subungual melanoma, a type of melanoma that occurs in the fingernail.
Nail pitting, or small dents on the nail surface, may be indicative of psoriasis, a chronic skin condition. Additionally, "spoon nails", or concave-shaped nails, can be a sign of iron deficiency anaemia.
Clubbing of the nails, characterised by swollen fingertips and curved nails, can sometimes indicate liver, kidney, lung, or gut issues. While rare, it is important to consult a healthcare professional if such changes occur.
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Frequently asked questions
Human nails are made of a protein called keratin, which is also found in hair, horns, hooves, claws, and talons. Nails are an evolutionary variation of claws, which were used by primates to climb trees and grab things.
Fingernails help enhance grip and improve fine motor functions. They also protect the delicate soft tissues, nerves, blood vessels, and muscles underneath.
Toenails protect the toes from injury and infections. They may also assist in balance.
Fingernails can be used to remove lice, ticks, and other pests from the skin and hair. They also help us judge how to hold things, detecting pressure changes and increasing the sensitivity of our fingertips.
While not necessary for survival, nails are certainly useful for many tasks.
