30% Gorillas

30% of the Gorilla Genome Contradicts the Supposed Evolutionary Phylogeny of Humans and Apes
Casey Luskin March 13, 2012 2:13 PM

A whopping 30% of the gorilla genome -- amounting to hundreds of millions of base pairs of gorilla DNA -- contradicts the standard supposed evolutionary phylogeny of great apes and humans. That's the big news revealed last week with the publication of the sequenceof the full gorilla genome. But there's a lot more to this story.
Eugenie Scott once taught us that when some evolutionary scientist claims some discovery "sheds light" on some aspect of evolution, we might suspect that's evolution-speak for 'this find really messed up our evolutionary theory.' That seems to be the case here. Aylwyn Scally, the lead author of the gorilla genome report, was quotedsaying, "The gorilla genome is important because it sheds light on the time when our ancestors diverged from our closest evolutionary cousins around six to 10 million years ago." NPR titled its story similarly: "Gorilla Genome Sheds Light On Human Evolution." What evolutionary hypothesis did the gorilla genome mess up?
The standard evolutionary phylogeny of primates holds that humans and chimpsare more closely related to one-another than to other great apes like gorillas. In practice, all that really means is that when we sequence human, chimp, and gorilla genes, human and chimp genes have a DNA sequence that is more similar to one-another's genes than to the gorilla's genes. But huge portions of the gorilla genome contradict that nice, neat tidy phylogeny. That's because these gorillagenes are more similar to the human or chimp version than the human or chimp versions are to one-another. In fact, it seems that some 30% of the gorilla genome contradicts the standard primate phylogeny in this manner. New Scientist explains:
But despite the ancient split, the remaining 30 percent of [the gorilla's] genome turned out to be more closely related to humans or chimp than thosespecies are to one another...
(Sara Reardon, "DNA from the last of the great apes decoded," New Scientist, March 10-16, 2012, p. 12)
Nature news put it this way:
But the genome sequencing has thrown up surprises, too. The standard view of the great-ape family tree is that humans and chimps are more similar to each other than either is to the gorilla -- because chimps and humans diverged morerecently. But, 15% of human genes look more like the gorilla version than the chimp version.
Scally's interview with NPR stated:
And what we see that as is in fact this 15 percent figure that you may have mentioned or that people might have seen, which is that humans are actually closer to gorillas in 15 percent of their genome, of the human genome. So overall we're closer to chimpanzees, and 70percent of our genome is closer to chimpanzees. That's consistent with the speciation of the species tree.
But there are these regions all across the genome where the ancestry is different, and that amounts to 15 percent where humans and gorillas are closest and then another 15 percent where chimpanzees and gorillas are closest.
Likewise, the technical paper in Nature stated: "In 30% of thegenome, gorilla is closer to human or chimpanzee than the latter are to each other." As a result, now they must qualify assertions that chimps are our "closest" relatives, as the paper stated "Molecular studies confirmed that we are closer to the African apes than to orangutans, and on average closer to chimpanzees than gorillas." (emphasis added) "On average," of course, is wiggle-language, becausehuge portions parts of our genomes don't fit with the standard evolutionary phylogeny. As one of the researchers put it, "We can't just conform to a simple tree on a gene-by-gene basis."
As always, they try to explain why hundreds of millions of base pairs in the gorilla genome contradict the standard phylogeny. As we saw in an ENV post from last year titled, "Study Reports a Whopping '23% of...