Human Beings and Chimpanzees: Further Apart than Expected

It was discovered that chimpanzees are not as closely related to human beings as expected.

The world’s second largest science journal, the U.S.’ Science magazine, and the U.K.’s Nature magazine simultaneously published in their September 1 online edition of their recent findings of chimpanzee genes.

The number of genome sequences for human beings and chimpanzees are almost the same, about 3 billion, as DNA is composed of four kinds of sequential bases: A, G, C, and T.

So far it is known that the genome sequences for the two species differ only by 1.2 percent.

However, the “Chimpanzee Genome Sequencing Consortium,” comprising teams from the U.S., Italy, Germany, Israel, and Spain, reported in Nature magazine that the difference was 3.9 percent.

The research team explained, “The difference is 1.2 percent when genome sequences of the two are compared individually, but given DNA insertions or losses throughout the evolutionary process, the difference gets bigger.”

The research this time found that more than 50 human genes are totally or partially absent in the chimpanzee counterparts.

For example, three immunity-related genes causing infection were not found in chimpanzees. While the animals produce enzymes to fight Alzheimer’s disease, it was revealed humans have lost the function.

Meanwhile, Science magazine made a comparative analysis on genes from major organs of the two species.

Dr. Svante Paabo and his research team of Germany’s Max Planck Institute for Evolutionary Anthropology examined the genome sequences and functions from the cells of five organs – namely brain, heart, liver, kidney, and testicles – from five people and six chimpanzees.

The findings showed the biggest difference of the two species in the testicles’ genome sequences reaching 32 percent, and it was about eight percent for other organs.

By contrast, even the genes with identical genome sequences in the brain showed a big difference in protein-generating (manifestation) activities.

Thousands of genes are in operation in the brains of human beings and chimpanzees, but 15 percent of the genes are much better manifested in the former than in the latter.

Nature magazine also mentioned that the research team of Dr. Sally McBrearty of the University of Connecticut succeeded in excavating chimpanzee fossils for the first time in the world. They found three fossils of chimpanzee teeth in the deposit layers, estimated to be 500,000 years old in Kenya.

This is where the fossils of current human beings were found. Thus, these findings refute the previous hypothesis that the two species lived in separate places since they separated themselves from the same ancestors five to eight million years ago.

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