Wednesday, April 06, 2005
Monkey Business
American scientists have found a chunk of human chromosome that may have caused the split of hominids from chimpanzees and launched the emergence of the human race five million years ago.
LaDeana Hillier of the Genome Sequencing Center at Washington University School of Medicine in St. Louis said she and her colleagues found on human chromosome 2 what "we think may be remnant of the centromere of one of the two chimp chromosomes that merged to form the human chromosome 2."
A centromere is the "cinched" part of the chromosome where the where the chromatids, the chromosome's two rods, are held together to form an X shape.
Human chromosome 2, the second largest human chromosome, was formed by the merger of two chimpanzee chromosomes recently renamed chimp chromosomes 2a and 2b.
Matt Ridley wrote in his book Genome that such chromosome fusion may have taken place after a small group of chimps got isolated in northern Africa by a cataclysmic flood some five million years ago. Ridley said that when the primates were "becoming inbred, flirting with extinction, exposed to the forces of the genetic founder effect (by which small population can have large genetic changes thanks to chance), this little band of apes shares a large mutation: two of their chromosomes have become fused. Henceforth they can breed only with their own kind, even when the 'island' rejoins the mainland." The rest, he says, is history.
LaDeana Hillier of the Genome Sequencing Center at Washington University School of Medicine in St. Louis said she and her colleagues found on human chromosome 2 what "we think may be remnant of the centromere of one of the two chimp chromosomes that merged to form the human chromosome 2."
A centromere is the "cinched" part of the chromosome where the where the chromatids, the chromosome's two rods, are held together to form an X shape.
Human chromosome 2, the second largest human chromosome, was formed by the merger of two chimpanzee chromosomes recently renamed chimp chromosomes 2a and 2b.
Matt Ridley wrote in his book Genome that such chromosome fusion may have taken place after a small group of chimps got isolated in northern Africa by a cataclysmic flood some five million years ago. Ridley said that when the primates were "becoming inbred, flirting with extinction, exposed to the forces of the genetic founder effect (by which small population can have large genetic changes thanks to chance), this little band of apes shares a large mutation: two of their chromosomes have become fused. Henceforth they can breed only with their own kind, even when the 'island' rejoins the mainland." The rest, he says, is history.
