All humans share some common bits of DNA, passed down to us from our African ancestors. Geneticist Spencer Wells talks about how his Genographic Project will use this shared DNA to figure out how we are -- in all our diversity -- truly connected.
meiosis - cell division necessary for sexual reproduction in eukaryotes, such as animals, plants and fungi. The number of sets of chromosomes in the cell undergoing meiosis is reduced to half the original number, typically from two sets (diploid) to one set (haploid). The cells produced by meiosis are either gametes (the usual case in animals) or otherwise usually spores from which gametes are ultimately produced (the case in land plants).