Evolution and survival of the fittest are not the same thing. Evolution refers to the cumulative changes in a population or species through time. Survival of the fittest is a popular term that refers to the process of natural selection, a mechanism that drives evolutionary change.
Most doctors recommend that you wait until the first day of your missed period before taking a home pregnancy test. A missed period is usually one of the first signs of pregnancy. This is usually around two weeks after conception. However, some tests are more sensitive than others and can be taken earlier. Concentrations of hCG are reported in milliInternational Units (mIU) or amounts equal to 1/1000th of an IU per milliliter.
Home pregnancy tests come in many different types. Most stores sell them over the counter (without a doctor's prescription). The cost varies depending on the brand and how many tests come in the box. Accuracy. Most tests can be taken as soon as you miss your period. Some newer, more expensive tests say they can be used 4 or 5 days before your period.