Five differences between the primate hand and the human hand!

Primates have ‘human-like’ short, flat fingernails! Did you know that far most primates have ‘human-like’ short, flat fingernails? Except for marmosets and tamarins, all primates have flat fingernails and toenails instead of claws. What are the major differences between the hands of primate species and the human hand? • 1 – Primates usually have a shorter thumb than humans – the thumb of the macaque (see photo on the left) does not rearch out behond the distal border of the handpalm. • 2 – Primates usually have a lower ‘2D:4D digit ratio’ than humans – the hand of the macaque is featured with a much longer ring finger (digit 4) than the pointer finger (digit 2). • 3 – Primates usually have more fingerprint- and palmar whorls than humans – the hand of the macaque is featured with 5 palmar whorls. • 4 – Primates always have a lower ‘ridge density’ than humans. • 5 – Primates usually have (various) palmar transversal hand creases, a.k.a. ‘simian lines’ – the hand of the macaque has one ‘simian line’. SUGGESTIONS FOR FURTHER READING: • PRIMATE HANDS – Finger length linked with social behavior! • Understanding our past: the human hand vs. the primate hand! • The Monkey Palmist! • Hands in the perspective of evolution! • More interesting stories about the hands of primates! PHOTO: Impression from the hand of a chimpanzee:

FINGERNAILS – 3 Signs of Health Problems: Beau’s lines, yellow fingernail syndrome & nail pitting!

Your fingernails can provide clues to your overall health. But do you know how to read the signs? MayoClinic presented a slideshow of various signs of possible health problems: Learn about some nail conditions that might require medical attention. If you have a nail problem that doesn’t seem to be going away, or is associated with other signs and symptoms, make an appointment with your doctor to get it checked out. 3 IMPORTANT FINGERNAIL PROBLEMS: Causes & remedies of Beau’s lines: Beau’s lines are indentations that run across your nails. They can appear when growth at the area under your cuticle is interrupted by injury or severe illness. Diseases or illnesses associated with Beau’s lines include: • Circulatory diseases, such as peripheral artery disease; • Illness associated with a high fever, caused by pneumonia, scarlet fever, mumps or measles; • Uncontrolled diabetes; • Malnutrition. Causes & remedies of yellow fingernails: Yellow nail syndrome concerns the yellow discoloration in your fingernails may result from a respiratory condition, such as chronic bronchitis, or from swelling of your hands (lymphedema). In yellow nail syndrome, nails thicken and new growth slows, resulting in discoloration. Nails affected with this condition may lack a cuticle and may detach from the nail bed in places. Although this condition is often a sign of respiratory disease, it’s possible to have yellow nails and not have a respiratory condition. Yellow nails may also result from any condition that causes the growth of your nails to slow down. Causes & remedies of nail pitting: Small depressions in the nails are common in people with psoriasis — a skin condition that produces scaly patches. They may also result from nail injuries. Pitting may cause your nails to crumble. Pitting is also associated with conditions that can damage your nail’s cuticle, such as chronic dermatitis of your fingers or alopecia areata, an autoimmune disease that causes hair loss! MORE RELATED SOURCES: • Nail disorders in the hands of children! • Nail disorders in the hands of the elderly! • More news & facts about fingernails!