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This has shaped human evolution for many years, but reasons why humans choose their mates are not fully understood. Sexual selection is quite different in non-human animals than humans as they feel more of the evolutionary pressures to reproduce and can easily reject a mate. [ 2 ]
Recent human evolution refers to evolutionary adaptation, sexual and natural selection, and genetic drift within Homo sapiens populations, since their separation and dispersal in the Middle Paleolithic about 50,000 years ago. Contrary to popular belief, not only are humans still evolving, their evolution since the dawn of agriculture is faster ...
Professor of biology Jerry Coyne sums up biological evolution succinctly: [3]. Life on Earth evolved gradually beginning with one primitive species – perhaps a self-replicating molecule – that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection.
Understanding the changes that have occurred during an organism's evolution can reveal the genes needed to construct parts of the body, genes which may be involved in human genetic disorders. [242] For example, the Mexican tetra is an albino cavefish that lost its eyesight during evolution.
Fisher's principle is an evolutionary model that explains why the sex ratio of most species that produce offspring through sexual reproduction is approximately 1:1 between males and females. A. W. F. Edwards has remarked that it is "probably the most celebrated argument in evolutionary biology". [1]
This can be due to any number of factors, including improved nutrition resulting in rapid body growth, increased weight and fat deposition, [19] or exposure to endocrine disruptors such as xenoestrogens, which can at times be due to food consumption or other environmental factors.
Sex differences in human physiology are distinctions of physiological characteristics associated with either male or female humans. These differences are caused by the effects of the different sex chromosome complement in males and females, and differential exposure to gonadal sex hormones during development.
The human Y chromosome showing the SRY gene which codes for a protein regulating sexual differentiation. Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following gonadal determination. [1]