Abstract
Nucleotide difference between human and chimpanzee, the closest living organism to human, is about 1.4%. Therefore, half (0.7%) of this difference accumulated after the human lineage diverged from the chimpanzee lineage. All the genetic changes responsible for “humanness” must reside in those differences.
Human genome consists of about 3 billion nucleotides, thus the 0.7% difference is tantamount to 21 million nucleotide changes. Although 95% of the human genome can be considered as junk DNA, we still have 1 million nucleotide changes located in nonjunk DNA. How many changes are really responsible for creating humanness in those changes? Our very rough guess is only 10, 000.
Draft human genome sequences will be completed within a year or so. It is now the time to sequence ape genomes so as compare them with human sequences nucleotide by nucleotide. Because we are interested in the changes which occurred in the human lineage, we should compare not only chimpanzee but also gorilla and orangutan. We can pinpoint human-specific changes after multiplyaligned those ape and human sequences by applying maximum parsimony principle.
We just started this kind of sequencing “Ape genome” (Ag=silver) by picking up interesting part of the human genome sequences. PCR primers are made based on those sequences, and corresponding orthologous DNAs are amplified for apes, followed by direct sequencing. The determined nucleotide sequences were submitted to the DDBJ/EMBL/GenBank International Nucleotide Sequence Database, and are also be available through web site of this project, as follows: http://sayer.lab.nig.ac.jp/silver/.
