Oolon Colluphid
01 Apr 2009, 10:22 AM
... at least, it's being raised at a meeting of the Linnaean Society, according to an item on this morning's Today programme (http://news.bbc.co.uk/today/hi/today/newsid_7976000/7976020.stm) (BBC Radio 4).
Bizarrely, I can find nothing else whatever about this online. I wondered if it were an April Fools joke, but it's a very crap one if so, given that it is a perfectly sensible idea and has been suggested before, eg in the 2003 paper:
PNAS June 10, 2003 vol. 100 no. 12 7181-7188
Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: Enlarging genus Homo
What do functionally important DNA sites, those scrutinized and shaped by natural selection, tell us about the place of humans in evolution?
Here we compare ≈90 kb of coding DNA nucleotide sequence from 97 human genes to their sequenced chimpanzee counterparts and to available sequenced gorilla, orangutan, and Old World monkey counterparts, and, on a more limited basis, to mouse.
The nonsynonymous changes (functionally important), like synonymous changes (functionally much less important), show chimpanzees and humans to be most closely related, sharing 99.4% identity at nonsynonymous sites and 98.4% at synonymous sites.
On a time scale, the coding DNA divergencies separate the human–chimpanzee clade from the gorilla clade at between 6 and 7 million years ago and place the most recent common ancestor of humans and chimpanzees at between 5 and 6 million years ago.
The evolutionary rate of coding DNA in the catarrhine clade (Old World monkey and ape, including human) is much slower than in the lineage to mouse. Among the genes examined, 30 show evidence of positive selection during descent of catarrhines.
Nonsynonymous substitutions by themselves, in this subset of positively selected genes, group humans and chimpanzees closest to each other and have chimpanzees diverge about as much from the common human–chimpanzee ancestor as humans do.
This functional DNA evidence supports two previously offered taxonomic proposals: family Hominidae should include all extant apes; and genus Homo should include three extant species and two subgenera, Homo (Homo) sapiens (humankind), Homo (Pan) troglodytes (common chimpanzee), and Homo (Pan) paniscus (bonobo chimpanzee).
Classification of Humans.
Our results with coding DNA provide dates for branch-points in humankind's ape ancestry that agree with the dates found by using noncoding DNA (9, 22). Thus, the coding DNA results support the position of humans in the age-related classification shown in Table 1. In these previous studies, the principle of rank equivalence with other primate clades of the same age required grouping the chimpanzee clade with the human clade within the same genus. An age of <6 Ma for the mrca of Homo's two subgenera, Homo (Pan) and Homo (Homo), is well within the range of ages found in other mammals for intrageneric divergencies (11, 53–56). To have rank equivalence, any fossil species that shares a mrca with humans to the exclusion of chimpanzees should be in the subgenus Homo (Homo). For example, A. afarensis should be called H. (Homo) afarensis (Table 1).
Simpson (1963) provided a precedent for the very close taxonomic grouping of humans and chimpanzees (6). On the basis of his broad knowledge of mammalian systematics, he eliminated the genus Gorilla, grouped gorillas and chimpanzees together in the genus Pan, and grouped Pan and Pongo (the orangutan's genus) into the subfamily Ponginae, which along with the gibbon subfamily Hylobatinae constituted the family Pongidae (6). This taxonomic arrangement captured the cladistic relationships of the living nonhuman apes to one another but not to humans. As already noted, the traditional view advocated by Simpson and others treats humans as outside the ape clade and has the lineage to humans diverge radically from the supposed ancestral pongid state (2–4, 6, 57). In contrast to this traditional view, the results we obtained by using a sample of functionally important DNA depict humans to be as conservative as chimpanzees, gorillas, and orangutans. We argue that if it is valid from the standpoint of mammalian systematics to place gorillas and chimpanzees in the same genus, it is even more valid in light of findings such as 99.4% identity between humans and chimpanzees at nonsynonymous DNA sites to place these two closely related genetic relatives in the same genus.
The evidence both from cladistic analyses and from simply measuring degrees of genetic correspondence call for grouping chimpanzees and humans together as sister subgenera of the same genus and justify believing that chimpanzees can provide insights into distinctive features of humankind's own evolutionary origins. Chimpanzees use tools, have material cultures, are ecological generalists, and are highly social (58–63). Their anatomical inability to produce most of the sounds of human speech long obscured the fact that chimpanzees are also capable of understanding and using rudimentary forms of language, as shown by recent studies on communication via sign language and lexigrams (64–66).
It is of course entirely possible that once the genetic underpinnings of “human-important” phenotypic features are uncovered, these particular underpinnings will be seen to have diverged more in the terminal human lineage than in the terminal chimpanzee lineage. But it might also be speculated with regard to the genetic underpinnings of “chimpanzee-important” phenotypic features that those particular underpinnings will be seen to diverge more in the terminal chimpanzee than in the terminal human lineage.
Looking to the future, once the DNA sequences of complete genomes from chimpanzees, gorillas, orangutans, and some other primates are known, it will be relatively straightforward to identify among the 20,000–30,000 or more genes of each genome those coding sequences that evolved under the force of positive selection. Eventually it should also be possible to similarly identify the positively selected changes in cis-acting regulatory DNA elements. As such molecular genetic data are integrated with organismal phenotypic data, humans will continue to gain a much better understanding of their place in evolution.
Bizarrely, I can find nothing else whatever about this online. I wondered if it were an April Fools joke, but it's a very crap one if so, given that it is a perfectly sensible idea and has been suggested before, eg in the 2003 paper:
PNAS June 10, 2003 vol. 100 no. 12 7181-7188
Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: Enlarging genus Homo
What do functionally important DNA sites, those scrutinized and shaped by natural selection, tell us about the place of humans in evolution?
Here we compare ≈90 kb of coding DNA nucleotide sequence from 97 human genes to their sequenced chimpanzee counterparts and to available sequenced gorilla, orangutan, and Old World monkey counterparts, and, on a more limited basis, to mouse.
The nonsynonymous changes (functionally important), like synonymous changes (functionally much less important), show chimpanzees and humans to be most closely related, sharing 99.4% identity at nonsynonymous sites and 98.4% at synonymous sites.
On a time scale, the coding DNA divergencies separate the human–chimpanzee clade from the gorilla clade at between 6 and 7 million years ago and place the most recent common ancestor of humans and chimpanzees at between 5 and 6 million years ago.
The evolutionary rate of coding DNA in the catarrhine clade (Old World monkey and ape, including human) is much slower than in the lineage to mouse. Among the genes examined, 30 show evidence of positive selection during descent of catarrhines.
Nonsynonymous substitutions by themselves, in this subset of positively selected genes, group humans and chimpanzees closest to each other and have chimpanzees diverge about as much from the common human–chimpanzee ancestor as humans do.
This functional DNA evidence supports two previously offered taxonomic proposals: family Hominidae should include all extant apes; and genus Homo should include three extant species and two subgenera, Homo (Homo) sapiens (humankind), Homo (Pan) troglodytes (common chimpanzee), and Homo (Pan) paniscus (bonobo chimpanzee).
Classification of Humans.
Our results with coding DNA provide dates for branch-points in humankind's ape ancestry that agree with the dates found by using noncoding DNA (9, 22). Thus, the coding DNA results support the position of humans in the age-related classification shown in Table 1. In these previous studies, the principle of rank equivalence with other primate clades of the same age required grouping the chimpanzee clade with the human clade within the same genus. An age of <6 Ma for the mrca of Homo's two subgenera, Homo (Pan) and Homo (Homo), is well within the range of ages found in other mammals for intrageneric divergencies (11, 53–56). To have rank equivalence, any fossil species that shares a mrca with humans to the exclusion of chimpanzees should be in the subgenus Homo (Homo). For example, A. afarensis should be called H. (Homo) afarensis (Table 1).
Simpson (1963) provided a precedent for the very close taxonomic grouping of humans and chimpanzees (6). On the basis of his broad knowledge of mammalian systematics, he eliminated the genus Gorilla, grouped gorillas and chimpanzees together in the genus Pan, and grouped Pan and Pongo (the orangutan's genus) into the subfamily Ponginae, which along with the gibbon subfamily Hylobatinae constituted the family Pongidae (6). This taxonomic arrangement captured the cladistic relationships of the living nonhuman apes to one another but not to humans. As already noted, the traditional view advocated by Simpson and others treats humans as outside the ape clade and has the lineage to humans diverge radically from the supposed ancestral pongid state (2–4, 6, 57). In contrast to this traditional view, the results we obtained by using a sample of functionally important DNA depict humans to be as conservative as chimpanzees, gorillas, and orangutans. We argue that if it is valid from the standpoint of mammalian systematics to place gorillas and chimpanzees in the same genus, it is even more valid in light of findings such as 99.4% identity between humans and chimpanzees at nonsynonymous DNA sites to place these two closely related genetic relatives in the same genus.
The evidence both from cladistic analyses and from simply measuring degrees of genetic correspondence call for grouping chimpanzees and humans together as sister subgenera of the same genus and justify believing that chimpanzees can provide insights into distinctive features of humankind's own evolutionary origins. Chimpanzees use tools, have material cultures, are ecological generalists, and are highly social (58–63). Their anatomical inability to produce most of the sounds of human speech long obscured the fact that chimpanzees are also capable of understanding and using rudimentary forms of language, as shown by recent studies on communication via sign language and lexigrams (64–66).
It is of course entirely possible that once the genetic underpinnings of “human-important” phenotypic features are uncovered, these particular underpinnings will be seen to have diverged more in the terminal human lineage than in the terminal chimpanzee lineage. But it might also be speculated with regard to the genetic underpinnings of “chimpanzee-important” phenotypic features that those particular underpinnings will be seen to diverge more in the terminal chimpanzee than in the terminal human lineage.
Looking to the future, once the DNA sequences of complete genomes from chimpanzees, gorillas, orangutans, and some other primates are known, it will be relatively straightforward to identify among the 20,000–30,000 or more genes of each genome those coding sequences that evolved under the force of positive selection. Eventually it should also be possible to similarly identify the positively selected changes in cis-acting regulatory DNA elements. As such molecular genetic data are integrated with organismal phenotypic data, humans will continue to gain a much better understanding of their place in evolution.