Final answer:
In the absence of crossing over, human meiosis can result in over 8 million different chromosomal combinations, calculated by the formula 2^23, due to independent assortment.
Step-by-step explanation:
In the absence of crossing over, meiosis can produce a large number of different chromosomal combinations due to a process called independent assortment. In humans, the number of possible combinations is calculated using the formula 2n, where n is the haploid number of chromosomes. Since humans have 23 chromosome pairs, the equation 223 yields over 8 million (8,388,608 to be exact) different combinations for how chromosomes can align during metaphase I of meiosis. This calculation is specific to the random orientation and segregation of chromosomes during the formation of gametes and contributes significantly to genetic variation.