Evidence of Shared Heritage Between Humans and Primates
Published August 2003
Li Jin, PhD, professor of environmental health at the UC College of
Medicine, and his colleagues from the Chinese Human Genome Center at
Shanghai and Fudan University recently confirmed in a continuing study
that chimpanzees are our closest genetic relatives. By sequencing the
coding and regulatory regions of 127 known genes on human chromosome 21
in DNA samples from humans and chimpanzees, the researchers compared
the differences. Their findings support the presence of natural
selection in the evolution of the human genome. The study also revealed
that the relative evolution span between humans and chimpanzees is 4.93
Using DNA samples from humans, chimpanzees, gorillas,
orangutans, and macaques allowed for a direct comparison among the
species. In the last 20 years, DNA sequencing has strengthened the
notion that despite their phenotypic differences, the genomes of humans
and primates are strikingly similar.
"By implementing a bioinformatics based approach, we
show that the identification of genetic variants specific to the human
lineage might lead to an understanding of the mechanisms that are
attributable to the phenotypes that are unique to humans, by changing
the structure and/or dosage of the proteins expressed," said Dr. Jin.
The comparison between humans and chimpanzees yielded
that the difference in the coding and regulatory regions is
significantly lower than that observed in random genomic regions, which
suggests the presence of natural selection in the human genome. Another
benefit of the study is that by sequencing human chromosome 21, the
smallest chromosome in the human genome, a better understanding of
regions corresponding to mental retardation may emerge.
Other revelations have included that some primates,
such as chimpanzees and bonobos share nearly 99 percent of human
sequences. This has led some scientists to argue that knowing the
complete genome of at least one of these species will aid in
identifying the genes that contribute to what makes us human.
The study, which began two years ago, started as a
collaborative project between the Chinese Human Genome Center at
Shanghai, Fudan University and the Center for Genome Information (CGI)
at UC. More progress in areas such as characterization of genetic
structure of world populations, origin and pre-historical migrations of
human populations in East Asia and Southeast Asia is expected.