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| | Eyes and vision (from primate) -- Britannica Concise Encyclopedia - The online encyclopedia you can trust! (Site not responding. Last check: 2007-10-26) |
 | | In lemurs this angle is considerably less, 60°70°, and in the apes and monkeys and in the slender loris (genus Loris), the divergence has been reduced to 20°. |
 | | In most other investigated platyrrhines (New World monkeys), red and green are determined by alleles at a single locus, again on the X chromosome; thus, males are always dichromatic, whereas females may be either dichromatic (if homozygous) or trichromatic (if heterozygous). |
 | | It is suggested that, during the evolution of catarrhines, the red-green locus duplicated, one of the daughter loci fixing the red gene and the other the green. |
| www.britannica.com /ebc/article-51446 (1072 words) |
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