Evolutionary Explanations for Variation amongst Humans in the Frequency of Phenotypic Traits

Evolutionary Explanations for Variation amongst Humans in the Frequency of Phenotypic Traits

Introduction

In instances, when a human envisions a human body, they see typically the skin, which primarily forms the body's straight interface with the environmental surroundings, and conveys a human's state of personal identity as well as his health. The human skin is primarily composed of a sheet - like installation that guards the body from a potential threat and any attack by physical, chemical and other microbial agents (Pandolf, Gange, Latzka, Blank, Kraning & Gonzalez, 2002, 189 - 193).

The human skin forms that organ of the human body, which helps in the regulation of the body temperature through the regulation of the blood flow in the body surface and by the process of sweating. The skin is also responsible for detecting and the conveying of significant information regarding the ambient surroundings and other objects that an individual touches (Henderson, Dunnigan, McIntosh, Abdul - Motaal, Gettinby & Glekin, 2007, 413 - 425).

The Dynamics of Human Skin Color and their Differences across Various Regions

Melanin is a pigmented substance characteristically found in the skin of vertebrates including that of all human races. It is produced by specialized cells called melanocytes. The functional state of these cells is primarily genetic and hormonal controls, and establishes the level of constitutive skin pigmentation (the basic color of protected, unexposed skin). Facultative skin color (inducible), or tan, is the intensified skin color produced by exposure to sunlight. The ability of facultative skin color to change is related to constitutive skin color (Williams, Dunkerley, De Deckker, Kershaw & Stokes, 2003, 91 - 103).

This means that capability of light - skinned persons to tan when exposed to ultraviolet light ( UVL ) is largely dependent on the gene action expressed in constitutive skin color. Color would seem to be only a superficial difference, but differences in skin color are also related to the biology and biochemistry of the skin as well as to the whole individual and can provide clues to a variety of internal problems (Kollias, Sayre, Zeise & Chedekel, 2001, 135-160). Physicians, for example, have long used skin color as an indicator of the health of different individuals, throughout the world (Wauters & Soesbergen, 1999, 593-597).

The Evolutionary Explanations for Variation amongst Human Skin Color

People, since time immemorial, were interested why different nations' skin varies by pigmentation intensity. Even ancient Greeks knew that darker skin was typical for people from southern regions and in some way it was connected with solar radiation intensity (Pandolf, Gange, Latzka, Blank, Kraning & Gonzalez, 2002, 189 - 193). Modern science knows incomparably more about skin color biology then ancient Greeks had knew; although there are a lot of blank spots. In the beginning, scientists believed that dark skin pigmentation occurred as means of organism protection against ultraviolet (UV) radiation causing skin cancer. Although all skin cancer forms occur, as a rule, after puberty, which significantly ...