Noah Sinclair
Fingernails are one of the features that distinguish primates, including humans, from other mammals. They are essentially flattened forms of claws. Nails provide a rigid backing to fingertips, improving our ability to grasp objects. They also help us to pick up small objects, open things, and scratch itches. The shape of our nails, which are wide, flat, and shield-shaped, is better suited to our needs than claws, which would have been a nuisance when trying to grasp smaller branches or objects.
| Characteristics | Values |
|---|---|
| Reason for having finger nails | Help in picking things up, holding things and controlling grip, scratching an itch, and picking up tiny objects |
| Alternative to finger nails | Claws |
| Reason for not having claws | Long claws get in the way when grasping and are not suitable for larger-bodied primates trying to grasp smaller branches |
| Reason for having flat nails | Better for locomotion |
| Other uses of nails | Painting nails, visual advertisement of a person's health |
| Medical conditions associated with nails | Clubbing, Schamroth's sign, lung cancer, other lung and heart-related conditions |
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What You'll Learn
Evolution from claws to nails
Humans and other primates are outliers among mammals for having nails instead of claws. The evolution from claws to nails in primates has been a contentious issue. However, fossils of ancient primates, including Teilhardina brandti, one of the oldest known, suggest that they had specialised grooming claws as well as nails. These grooming claws were likely used to remove parasites and debris, which would have been an evolutionary advantage.
The transition from claws to nails in primates may have been influenced by changes in movement and social behaviour. As primates evolved to climb, leap, and grasp more, nails may have become more practical than claws, which could snag or get in the way. Additionally, the development of more complex social networks and increased social grooming may have reduced the reliance on grooming claws for self-grooming.
Genetic mutations may also have played a role in the evolution from claws to nails. Selective pressures may have favoured nails over claws, causing the trait of having nails to persist. Nails provide a rigid backing to fingertips, improving the ability to grasp and hold objects. They also allow for more precise movements, such as picking up small objects or scratching an itch.
While the exact reasons for the evolution from claws to nails in primates are still not fully understood, it is clear that nails offer advantages over claws in terms of dexterity and social behaviour. The evolution of nails has likely contributed to the development of tool use and other complex behaviours in primates, including humans.
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Nails help with picking things up
The human body is full of wonders and mysteries, and one of these is the presence of fingernails and toenails. Our nails, which are made of a protein called keratin, are wide, flat, and shield-shaped, differing from the pointed ends of claws.
Nails are incredibly useful for picking things up, especially small objects. They also help us to pick things off, such as bugs, and to hold on tightly to items. Imagine trying to open a can without your fingernails; it would be a lot more difficult! Nails provide a rigid backing to our fingertips, improving our ability to grasp objects.
Claws would likely get in the way when trying to pick up small items or hold onto branches. This is why most primates, including our closest primate cousins (gibbons, bonobos, chimpanzees, gorillas, and orangutans), have nails on all their fingers and toes. While our primate cousins still use their toes to pick things up, humans generally do not. However, our toenails are a remnant of a time when our early ancestors used their feet to grasp objects.
The shape of our nails, as opposed to claws, is likely due to a genetic mutation that occurred in our early ancestors. This mutation was not selected against because it did not cause harm and may have even conferred advantages for survival and reproduction.
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Nails help with locomotion
The human body is an incredibly intricate system, and even the smallest parts, such as fingernails, serve specific purposes. One of the key functions of fingernails is to aid in locomotion and provide advantages in movement.
Fingernails are a distinctive feature of primates, including humans, setting them apart from other mammals. They are essentially modified claws, having evolved from the claws possessed by our common ancestors with other mammals. This evolutionary transition from claws to nails was influenced by selective pressures favoring traits that aided our primate ancestors' arboreal lifestyle.
Climbing and grasping onto branches high in the tree canopies would have been challenging with long claws, which would have hindered their ability to grasp smaller branches and fruits. Nails, on the other hand, provide a rigid backing to the fingertips, enhancing their grasping capabilities. This allowed our primate ancestors to navigate through trees more efficiently, reaching for food and safety.
The shape of human nails is particularly suited to this purpose. Their wide, flat, and shield-shaped form, positioned at the back of the fingertips, is ideal for gripping and climbing. This shape is in stark contrast to the pointed, cone-shaped claws of dogs or cats, which are designed for digging and scratching. The dense keratin fibers in nails give them the necessary hardness and durability to withstand the forces exerted during locomotion and manipulation tasks.
Additionally, the presence of nails, as opposed to claws, may have offered social and reproductive advantages. For example, the absence of long claws may have reduced the risk of injury during social interactions, and nail characteristics could have been subject to sexual preference or used as a visual indicator of health and genetic fitness.
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Nails indicate health
Human beings have nails instead of claws due to a genetic mutation. Nails are wide, flat, and shield-shaped, and present on the back of the fingertips and toes. They are useful for picking things up, scratching an itch, and holding things tightly. Nails also provide a rigid backing to improve our grip while grasping objects.
Nails can be indicators of health and reveal clues about one's overall health. Healthy nails are typically smooth and free of discoloration. Changes in the colour or texture of one's nails may indicate a disease in the body. For example, white nails, or leukonychia, could indicate trauma, anemia, dietary deficiencies, heart or kidney disease, or poisoning. Nails with white tips and darker rims can be a sign of liver problems like hepatitis. Yellow nails are commonly caused by a fungal infection, but in rare cases, they can indicate severe thyroid disease, lung disease, diabetes, or psoriasis. Bluish nails suggest oxygen deprivation, which could be linked to emphysema or heart problems. Rippled or pitted nails are early signs of psoriasis or inflammatory arthritis.
Additionally, nail abnormalities can be linked to vitamin deficiencies and chronic conditions. For instance, brittle, weak, and peeling nails often result from a poor diet or poor digestion. Hypothyroidism or iron deficiency may also cause brittle nails. Horizontal lines on the nails may indicate a lack of vitamins and minerals in the body.
Nail biting or picking has been associated with anxiety and obsessive-compulsive disorder. While nail changes are usually not the first sign of a health issue, it is important to consult a healthcare professional if you notice persistent or concerning changes in your nail colour or texture.
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Nails are made of keratin
The presence of nails instead of claws in humans is attributed to a genetic mutation that occurred during evolution. Selective pressures may have favoured nails over claws, making it a trait that persisted. Nails are wide, flat, and shield-shaped, and they are located at the back of the fingertips and toes. This shape and positioning enable humans to grasp objects, pick up small items, and hold things securely.
Nails are made of a hardened protein called keratin, which is also found in hair, skin, and animal hooves, claws, and horns. Keratin is produced in the matrix, the area where the nail is tucked into a pouch in the skin, known as the proximal nail fold. The matrix constantly generates new keratin, which accumulates at the nail plate, gradually hardening and pushing out of the skin to form the nail. This process causes the nail to grow, with fingernails growing at a rate of about 3 millimetres per month and toenails growing slightly slower.
The structure of the nail comprises several parts, including the nail plate, the visible portion of the nail; the nail bed, the underlying tissues containing tiny blood vessels; the cuticle, a thin, clear membrane that seals the nail plate to the fingertip and acts as a barrier against infections; and the lunula, a whitish, half-moon shape at the nail's base.
The formation of a nail begins in the nail root or sinus, located a few millimetres behind the cuticle. Here, the cells that will form the nail plate undergo a process of death, hardening, and outward protrusion from the skin. As older cells are compacted and pushed out by newer cells, they take on the flattened, hardened form of the fingernail or toenail.
The presence of nails is not merely a cosmetic feature but serves important functions in daily life. Nails provide a rigid backing to improve the grip and facilitate grasping, which is essential for climbing and holding objects. Additionally, nails protect the sensitive tips of the fingers and toes from injuries and provide a surface for activities like scratching and picking up small objects.
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Frequently asked questions
We have fingernails because we are primates. Nails are one of the features that distinguish primates, including humans, from other mammals. They help us pick things up, scratch an itch, and hold things tightly.
Fingernails are made of a protein called keratin. Keratin is also found in hair and the top layer of skin, but nails are harder because the keratin fibres are packed more closely together.
Humans have fingernails instead of claws due to a genetic mutation. Nails are better suited to our needs as they help with locomotion and grasping smaller branches and objects.
Fingernails can serve as a visual advertisement of a person's health. For example, malnutrition can change nail colouring, and small pits in fingernails can signal the skin condition psoriasis. Clubbed nails, which become red, swollen, and sponge-like, can be a sign of a serious condition such as lung cancer or other lung and heart-related issues.
