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.
1 Thisholds particularly true if the black lines on fingernails are vertical in nature. 2  As opposed to this, horizontal lines are an indication of an underlying health problem, such as cardiac problems or elevated stress levels. 3  Vertical lines may or may not have a definite cause.