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.
One other condition that is associated with horizontal fingernail lines is arsenic poisoning. Fingernails may be lined and ridged in transverse fashion, and the lines are usually described as white in color. Again, this may not mean anything, but it has been noted as a symptom of long exposure to arsenic.