Human height or stature is the distance from the bottom of the feet to the top of the head in a human body, standing erect. It is measured using a stadiometer, in centimetres when using the metric system, or feet and inches when using United States customary units or the imperial system.In the early phase of anthropometric research history, questions about height techniques for measuring nutritional status often concerned genetic differences.Height is also important because it is closely correlated with other health components, such as life expectancy. Studies show that there is a correlation between small stature and a longer life expectancy. Individuals of small stature are also more likely to have lower blood pressure and are less likely to acquire cancer. The University of Hawaii has found that the "longevity gene" FOXO3 that reduces the effects of aging is more commonly found in individuals of small body size. Short stature decreases the risk of venous insufficiency.When populations share genetic backgrounds and environmental factors, average height is frequently characteristic within the group. Exceptional height variation (around 20% deviation from average) within such a population is sometimes due to gigantism or dwarfism, which are medical conditions caused by specific genes or endocrine abnormalities.The development of human height can serve as an indicator of two key welfare components, namely nutritional quality and health.
Certain studies have shown that height is a factor in overall health while some suggest tallness is associated with better cardiovascular health and shortness with longevity. Cancer risk has also been found to grow with height. Moreover, scientists have also observed a protective effect of height on risk for Alzheimers disease, although this fact could be a result of the genetic overlap between height and intracraneal volume and there are also genetic variants influencing height that could affect biological mechanisms involved in Alzheimers disease etiology, such as Insulin-like growth factor 1 (IGF-1).Nonetheless, modern westernized interpretations of the relationship between height and health fail to account for the observed height variations worldwide. Cavalli-Sforza and Cavalli-Sforza note that variations in height worldwide can be partly attributed to evolutionary pressures resulting from differing environments. These evolutionary pressures result in height-related health implications. While tallness is an adaptive benefit in colder climates such as those found in Europe, shortness helps dissipate body heat in warmer climatic regions. Consequently, the relationships between health and height cannot be easily generalized since tallness and shortness can both provide health benefits in different environmental settings. In the end, being excessively tall can cause various medical problems, including cardiovascular problems, because of the increased load on the heart to supply the body with blood, and problems resulting from the increased time it takes the brain to communicate with the extremities. For example, Robert Wadlow, the tallest man known to verifiable history, developed trouble walking as his height increased throughout his life.