age of discovery archaea bacteria bonobo chimpanzee chromosomal crossover coalescent theory common descent cousin digital object identifier eukaryote exponential growth fertilisation gene genealogical dna test genealogy genetic distance genetic genealogy genetic recombination genetics gorilla human human evolution human migration identical ancestors point language last universal ancestor leaf node linguistics meiosis mendelian inheritance mitochondrial dna mitochondrial eve nuclear dna orangutan organism patrilineality phylogenetic tree population bottleneck proto-language richard dawkins sexual reproduction timeline of evolution timeline of human evolution upper paleolithic western europe y-chromosomal adam