Monkey Business


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By Elsa Youngsteadt

Podcast available: Monkey Business

The rhesus macaque has played a central role in research on HIV, depression and immunity, and is the organism in which Rh (rhesus) factor was discovered; that's the protein some humans have and some don't, designated by the + or - in our blood types. Now the Rhesus Macaque Genome Sequencing and Analysis Consortium has sequenced 98% of this monkey's DNA, and the entire April 13, 2007 issue of Science magazine is dedicated to biomedical and evolutionary insights from all those A's, T's, G's and C's.

The monkey's genome is about 93% similar to that of humans and knowing exactly where it's similar and where it's different will be an important aid to biomedical research, where the monkey is used as a model for human physiology.

But now the rhesus macaque is one of three fully sequenced primate genomes, together with the human and chimpanzee. Put three together, and you can make a family tree, something you can't do with only two. Humans and chimpanzees are so similar 99% of their DNA sequence matches and just by comparing the two, it's impossible to tell which of those differences represent evolutionary changes in the human lineage, and which represent changes in the chimpanzee lineage, much less which of the many similarities are or are not shared with other primates. Now the rhesus monkey comes to the rescue, putting all that in perspective.

The macaque is our more distant relative, it shared a common ancestor with humans and chimpanzees about 25 million years ago, whereas humans and chimpanzees diverged from one another only 6 million years ago. Sequences in common among all three organisms also probably represent the sequence of their common ancestor. But comparing the three species also tells us more about the differences between humans and chimpanzees. In some of the places where they differ, the chimpanzee sequence will resemble the monkey sequence, while the human sequence does not. This will pinpoint places where the human genome stands apart from those of all other primates, helping us understand what happened during primate evolution that defines our species.

Special issue of Science magazine, including teaching resources, lesson plans, and interactive poster about the macaque genome

CNN news release

National Institutes of Health news release

Baylor college genome project page

University of Michigan's Diversity Web

NESCent Podcast

Questions for review and discussion

1. How is the Rhesus macaque used in human medical research, and how will the genome sequence make it a more effective model organism?

2. What is a primate? How are the Rhesus macaque, humans and chimpanzees related to one another? (You could draw a family tree).

3. How will the macaque sequence help to interpret the similarities and differences between the human and chimpanzee sequences?

4. What else could comparison of the three genomes tell us about the process of primate evolution, besides showing us where the human and chimpanzee have retained ancestral sequences and where they have evolved? For ideas, check out the Science magazine poster at


Molecular Sequences & Primate Evolution: Amino Acid Differences in Beta Hemoglobins in Primates from ENSI (Evolution and the Nature of Science Insitute)

Multiple Alignment from BioQUEST

DNA: Genome from DNA Interactive, Dolan DNA Learning Center

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