Heredity and Evolution

Variation is the degree of differences in the progeny and between the progeny and the parent. Variations can be seen either in the morphological appearance (phenotype) or the genetic makeup (genotype) of an organism.

Gregor Johann Mendel, also known as the ‘Father of Genetics’, postulated the Laws of Inheritance. Genetics is the branch of science which studies the different laws that govern inheritance and heredity in living organisms.

Natural selection is the phenomenon wherein nature selects organisms having traits favourable to the environment. The organisms exhibit different characteristics due to different genotypes (variation). If these characteristics are favoured by the natural environment, the organisms with these variations survive and propagate, and may form different species. Thus, evolution is the outcome of natural selection.

Molecular phylogeny is the technique that employs comparison of changes accumulated in the DNA of an organism over generations to establish evolutionary relationships. This approach is based on the idea that organisms which are more distantly related will accumulate a greater number of differences in their DNA.

The set of rules that determine the process by which traits and characteristics are reliably inherited is known as heredity. Heredity is also explained as ‘tendency of the offspring to exhibit certain characters of parents or ancestors’.

Neanderthals are the closest extinct ancestor of modern human beings. They both belong to the same genus (Homo) and shared 99.7% similarity in their DNA.

All copies of a gene are not identical and alternative forms of a gene are called alleles. They lead to the alternative or different forms of one trait.

Common origin of man and chimpanzee is best shown by DNA similarity. According to DNA studies, DNA of humans and chimpanzees is 98% similar. Humans and chimpanzees share a common ancestry.

Variations when combined with geographical isolation ensures that only the organisms that have well-adapted to the changing conditions will survive. This can lead to the emergence of a new species (well-adapted organisms), through a process called speciation.

The preserved traces of living organisms like plants, animals, insects from remote pastare known as fossils. Study of fossils is known as paleontology. Fossils are studied to understand the process of evolution and to establishevolutionaryrelationships.