Timing of the onset of puberty The definition of the onset of puberty depends on perspective (e.g., hormonal versus physical) and purpose (establishing population normal standards, clinical care of early or late pubescent individuals, etc.) The most commonly used definition of the onset of puberty is physical changes to a person's body[citation needed]. These physical changes are the first visible signs of neural, hormonal, and gonadal function changes. The age at which puberty begins varies between individuals and populations. The age at which puberty begins is affected by both genetic factors and by environmental factors such as nutritional state and social circumstances.[1] The average age at which puberty begins is affected by your race. For example, the average age of menarche in various populations surveyed[weasel words] has ranged from 12 to 18 years. The earliest average onset of puberty is for African-American girls and the oldest average onset for high altitude subsistence populations in Asia. However, much of the higher age averages reflect nutritional limitations more than genetic differences and can change within a few generations with a substantial change in diet. The median age of menarche for a population may be an index of the proportion of undernourished girls in the population, and the width of the spread may reflect unevenness of wealth and food distribution in a population. Researchers have identified an earlier age of the onset of puberty. However, they have based their conclusions on a comparison of data from 1999 with data from 1969. In the earlier example, the sample population was based on a small sample of white girls (200, from Britain). The later study identified as puberty as occurring in 48% of African-American girls by age nine, and 12% of white girls by that age.[34] Historical shift The average age at which the onset of puberty occurs has dropped significantly since the 1840s.[35][36][37] Researchers[who?] refer to this drop as the 'secular trend'. In every decade from 1840 to 1950 there was a drop of four months in the average age of menarche among Western European females. In Norway, girls born in 1840 had their menarche at an average age of 17 years. In France the average in 1840 was 15.3 years. In England the average in 1840 was 16.5 years. In Japan the decline happened later and was then more rapid: from 1945 to 1975 in Japan there was a drop of 11 months per decade.
The definition of the onset of puberty depends on perspective (e.g., hormonal versus physical) and purpose (establishing population normal standards, clinical care of early or late pubescent individuals, etc.) The most commonly used definition of the onset of puberty is physical changes to a person's body[citation needed]. These physical changes are the first visible signs of neural, hormonal, and gonadal function changes.
The age at which puberty begins varies between individuals and populations. The age at which puberty begins is affected by both genetic factors and by environmental factors such as nutritional state and social circumstances.[1]
The average age at which puberty begins is affected by your race. For example, the average age of menarche in various populations surveyed[weasel words] has ranged from 12 to 18 years. The earliest average onset of puberty is for African-American girls and the oldest average onset for high altitude subsistence populations in Asia. However, much of the higher age averages reflect nutritional limitations more than genetic differences and can change within a few generations with a substantial change in diet. The median age of menarche for a population may be an index of the proportion of undernourished girls in the population, and the width of the spread may reflect unevenness of wealth and food distribution in a population.
Researchers have identified an earlier age of the onset of puberty. However, they have based their conclusions on a comparison of data from 1999 with data from 1969. In the earlier example, the sample population was based on a small sample of white girls (200, from Britain). The later study identified as puberty as occurring in 48% of African-American girls by age nine, and 12% of white girls by that age.[34] Historical shift
The average age at which the onset of puberty occurs has dropped significantly since the 1840s.[35][36][37] Researchers[who?] refer to this drop as the 'secular trend'. In every decade from 1840 to 1950 there was a drop of four months in the average age of menarche among Western European females. In Norway, girls born in 1840 had their menarche at an average age of 17 years. In France the average in 1840 was 15.3 years. In England the average in 1840 was 16.5 years. In Japan the decline happened later and was then more rapid: from 1945 to 1975 in Japan there was a drop of 11 months per decade.
But I guess no one should be surprised when something is influenced both bu genes and the local environment, after all, what isn't? Peak oil is not an energy crisis. It is a liquid fuel crisis.
How do you separate the effect of genes and different social situations?... *Lunatic*, n. One whose delusions are out of fashion.
