The Physical Development of a Human Being.
As defined in Berk's, Development Through the Lifespan, physical development is changes in body size, proportions, appearance, and the functioning of various body systems; brain development; perceptual and motor capacities; and physical health. The physical development of a human being is the unique because of all of the visible changes that every human being goes through. Physical growth results from a continuous and complex interplay between heredity and environment. Humans begin to develop before they are out of their mother's womb. After conception, the zygote is what I consider the earliest development of the human being. The period of the zygote is about two weeks long. The zygote then becomes an embryo. The period of the embryo lasts from the second week on through the eighth week of pregnancy. The embryo then changes to form the fetus. The period of the fetus is from the ninth week until the end of the pregnancy. The zygote, embryo, and fetus all form in the first trimester or pregnancy. By the third trimester, the fetus is around seven and half pounds. .
I weighed about eight and one fourth pounds when I was born. My mother still tells me that when I was born I had enough hair to braid. She says all my hair gave her horrible heartburn. Luckily she did not smoke or use any drugs or alcohol during the time that she was pregnant with me. All of these things can do serious harm to the fetus.
Boys tend to be a little longer and heavier than girls at birth. Babies change faster than older humans do. The human body grows and enlarges at the most rapid rate during the first two years. Weight is gained steadily during this time. By nine months baby fat has usually arrived and is at its highest level. This helps babies to maintain a constant body temperature. Babies become thinner during the second year. This held true for me from what I have seen of my baby pictures.