What research method is used in order to establish what causes a behavior? an experiment What is the first step of the scientific method? pose a question In the science of human development, &quot;nurture&quot; refers to: environmental influences.
Vertical lines on one's nails, like those the writer seems to have, are a common phenomenon that often get more pronounced with age. There are many reasons for ridged nails but the most common is aging, says Dr. Phoebe Rich, M.D., FAAD, clinical adjunct professor of dermatology at Oregon Health Science University.
Cause of Vertical Ridges on Fingernails. According to the Mayo Clinic, the nails are composed of laminated layers of a protein called keratin. This same protein is also found in the hair and skin. The nails are made up of several parts, including the nail beds, folds, cuticles and lunula.