Human-Chimp DNA Difference Trebled

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We are more unique than previously thought, according to new comparisons of human and chimpanzee DNA.

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It has long been held that we share 98.5 per cent of our genetic material with our closest relatives. That now appears to be wrong. In fact, we share less than 95 per cent of our genetic material, a three-fold increase in the variation between us and chimps.

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The new value came to light when Roy Britten of the California Institute of Technology became suspicious about the 98.5 per cent figure. Ironically, that number was originally derived from a technique that Britten himself developed decades ago at Caltech with colleague Dave Kohne. By measuring the temperature at which matching DNA of two species comes apart, you can work out how different they are.

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But the technique only picks up a particular type of variation, called a single base substitution. These occur whenever a single "letter" differs in corresponding strands of DNA from the two species.

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But there are two other major types of variation that the previous analyses ignored. "Insertions" occur whenever a whole section of DNA appears in one species but not in the corresponding strand of the other. Likewise, "deletions" mean that a piece of DNA is missing from one species.

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Read the rest of the article here at New Scientist

Hmmm? What was I making it out to be? Anyway, it highlights what previous measurements of the difference were based on-only single based substitutions between the two.

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But the technique only picks up a particular type of variation, called a single base substitution. These occur whenever a single "letter" differs in corresponding strands of DNA from the two species.

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As they only compared about 0.3% of the DNA, they only glanced at the differences. Also, there are much greater differences in gene expression and other epigenetic factors.