==Taxonomic relationships==
The genus ''Pan'' is now considered to be part of the subfamily [[Homininae]] to which [[human]]s also belong. [[Theory of evolution|Evolutionary]] [[Biology|biologists]] believe that the two species of chimpanzees are the closest living [[evolution|evolutionary]] relatives to [[human]]s. It is thought that humans shared a common ancestor with chimpanzees and gorillas as recently as [[Pliocene|four]] to [[Miocene|seven million years ago]]. Groundbreaking research by [[Mary-Claire King]] in 1973 AD found 99% identical [[DNA]] between human beings and chimpanzees,<ref>Mary-Claire King, ''Protein polymorphisms in chimpanzee and human evolution'', Doctoral dissertation, University of California, Berkeley (1973).</ref> although research since has modified that finding to about 94%<ref name=ns>{{cite web | url = http://www.sciam.com/article.cfm?chanID=sa003&articleID=9D0DAC2B-E7F2-99DF-3AA795436FEF8039 |date = 2006-12-19 | title = Humans and Chimps: Close But Not That Close | publisher = Scientific American | accessdate = 2006-12-20}}</ref> commonality, with at least some of the difference occurring in 'junk' DNA. It has even been proposed that ''troglodytes'' and ''paniscus'' belong with ''sapiens'' in the genus ''[[Homo (genus)|Homo]]'', rather than in ''Pan''. One argument for this is that other species have been reclassified to belong to the same genus on the basis of less genetic similarity than that between humans and chimpanzees. Indeed cladistic taxonomy, based on both genetic difference and date of likely divergence, is very clear in placing both extant species of ''Pan'' in the genus ''Homo'', mainly because the genus ''Homo'' takes precedence on account of being coined first. It is very important, however, to consider where the differences in the genome appear. {{fact}}<ref>http://www.sciencedaily.com/releases/2006/12/061219201931.htm</ref>
A study published by Clark and Nielsen of [[Cornell University]] in the December 2003 AD issue of the journal ''[[Science (journal)|Science]]'' highlights differences related to one of humankind's defining qualities — the ability to understand [[language]] and to communicate through speech. These macro-phenotypic differences, however, may owe less to physiology than might be assumed given that ''Homo sapiens'' developed modern cultural features long after the modern physiological features were in place and indeed competed averagely against other species of ''Homo'' with regard to tools, etc for many millennia. Differences also exist in the genes for smell, in genes that regulate the metabolism of amino acids and in genes that may affect the ability to digest various proteins.