How has natural selection affected humans?

Answer 1

Natural Selection

Natural Selection

Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with artificial selection, which in his view is intentional, whereas natural selection is not.

Answer 2

There is strong evidence that all human beings have their origins in central Africa, and that migrations out of Africa starting roughly 100,000 years ago can account for the spread of humanity across the globe. These migrations can be genetically traced. If this is so, then natural selection might help account for many if not all of the major physical differences between different racial groups. People who migrated away from the equator lost the ability to produce large amounts of melanin in the skin. Changes in over-all stature/structure happened with groups that migrated very far north; these changes make it easier to endure the extreme cold conditions there. These are two examples of many that can be examined. These are not 'proofs' that natural selection has played a role in these differences. The question is asking for possibilities, not proofs. The Genographic Project link will bring you to an absolutely wonderful site describing the genetic mapping of the human journey out of Africa starting roughly 100,000 years ago. Send them a genetic sample (order the kit through them) and get some amazing information about your deep ancestry. The information you get tells you nothing about current family ties-- only the general path of either your maternal line (through mitochondrial DNA) or your paternal line (through Y chromosome analysis). I do not work for and I do not represent the National Geographic Society, or the Genographic Project.

Answer 3

In nature

By avoiding changes in the environment, by removing invasive species, or by relocating endangered species to new habitats, humans can affect the survival of species that would ordinarily become extinct due to competition for resources. Genetic engineering can improve crop species to give them improved survival traits.

In humans

The study of "eugenics" seeks to improve the human species by better natural selection, e.g. breeding for desirable traits rather than undesirable ones (which ones are desirable may be subjective). The extension of this concept to ethnic groups has led to terrible crimes.

The only current way to improve human natural selection is through planned selective marriage. But on a practical scale, this is unlikely to make any measurable change in the population as a whole, due to the billions of non-selective marriages.

A possible example of the "reverse" of eugenics is vision problems. Because eyeglasses and other vision aids allow those with genetically poor vision to have as many offspring as those with better vision, the proportion of the population with imperfect vision could remain the same or even statistically increase. Under normal natural selection, those with better vision (a survival trait) would likely have predominated over time.

Answer 4

Natural selection affects humans in the same way it does to all other animals - survival of the fittest - the only difference being that humans have the technology to help the less fit, allowing them to pass on those genes some of the time, so natural selection in humans just has a less profound affect.

Answer 5

The most conspicuous ways in which natural selection has affected our lineage is that is has caused us to become bipedal animals with huge brains, flat faces, long legs and shorter arms, highly dexterous fingers and opposable thumbs.

Answer 6

Natural selection has the effect of promoting traits that allow their bearers to raise more fertile offspring. The result of this is that these traits become more numerous in the population.

Answer 7

There is only one effect of natural selection: an increase in average fitness.

Answer 8

Not all people are equally susceptible to any disease organism.

Some people are smarter than others.