Infant development experts say that teething usually starts when your baby is around four months old, and continues until he or she is about two years old, at which time you get a reprieve until about five years old when the baby teeth start being replaced by grown-up teeth.
Quick Answer. Meiosis contributes to genetic variation by creating new groups of genes, according to the University of Miami Miller School of Medicine. The new groups are created when chromosomes passed down from a mother and father share instructions encoded into genes.
Meiosis is a process by which we can halve the number of chromosomes. It takes place whenever the organism has to produce daughter cells that have half the number of chromosomes as the parent cells. In humans, meiosis occurs in spermatogonial and oogonial cells to produce sperms and eggs respectively. In higher plants which have a dominant diploid sphorophytic phase, the gametophytic phase is produced by meiosis. Meiosis occurs in almost all the higher living organisms.