Posts tagged ‘genetic mutation’

June 29th, 2012

Neo-Darwinism

by Max Andrews

Evolution has many meanings.

  • Change over time
    • Evolution of the cosmos
    • Evolution of living things
    • Evolution of culture, technology, etc.
  • Changes within existing species
    • Morphological (anatomical)
    • Genetic (change in gene frequencies)
  • Common ancestry
    • Within a species
    • Descent of all species from a common ancestor
  • Darwinian evolution

Darwinism: Descent with modification through unguided processes

  • Descent:  “I view all beings not as special creations, but as the lineal descendants of some few beings which lived long ago.”
  • Modification:  “The preservation of favorable individual differences of variations, and the destruction of those which are injurious (natural selection).”
  • Unguided processes:  “There seems to be no more design in the variability of organic beings, and in the action of natural selection, than in the course which the wind blows. So I am inclined to look at everything as resulting from designed laws, with the details, whether good or bad, left to the working out of chance.”
    read more »

February 6th, 2012

Darwinian Whale Evolution

by Max Andrews

When evaluating population drift/evolution one must keep in mind a pattern/process distinction.

  • To be explained:  A pattern of a sequence of ancestors to present (a phylogenetic sequence)
  • Explanation:  High random mutation rates + high selection coefficients –> Incremental genetic change over time (“evolution”)

We now know that the majority of anatomical changes unique to fully aquatic cetaceans (Pelagiceti) appeared during just a few million years.

Here are only a few of the changes that had to have occurred during the transition to a fully marine whale

  • Counter-current heat exchanger for intra-abdominal testes
  • Ball vertebra
  • Tail flukes and musculature
  • Blubber for temperature insulation
  • Ability to drink sea water (reorganization of kidney tissues)
  • Reverse orientation of fetus in the uterus
  • Nurse young underwater (modified mammae)
    read more »