Box 6.3 Evolutionary Psychology

5. Box 6.3 Evolutionary Psychology The brightly colored peacock attracts the attention of the peahen

6. Fig 6.17 Bowerbird Nests To attract mates, male bowerbirds build elaborate bowers of twigs, such as this structure, and decorate them with colorful objects.

7. Evolution of Vertebrate Color Vision • Unlike mammals most vertebrates have tetrachromatic color vision • Fishes, reptiles, birds and amphibians have a tetrachromatic vision relying on 4 cone pigments. • So, the ancestor species such as dinosaurs probably had tetrachromatic vision. • Early mammals such as rodents lost two types of cones, and their vision thus became dichromatic. • Primates evolved trichromatic color vision, although some women are tetrachromats.

8. Mammals exhibit different degrees of color vision. • Four categories of color vision capabilities among mammals: • Minimal color vision with only a single kind of cone pigment and must rely on interactions between rods and cones to discriminate wavelength • found in raccoons • Feeble dichromatic color vision with two kinds of cone pigments but very few cones • found in cats • Robust dichromatic color vision with two kinds of cones and lots of cones • found in dogs • Excellent trichromatic color vision • Certain primates such as humans other great apes and old world monkeys have trichromatic color vision based on three classes of cone photopigments

9. Testing color vision perception in dogs Color Vision Almost Reason Enough for Having Eyes Jay Neitz, Joseph Carroll and Maureen Neitz Optics & Photonics News , January 2001 , page 28

10. Primate Cone Variation • New World primates have variable cone phenotypes • Owl monkeys are monochromats • Spider, Cebus and squirrel monkeys, the males and some females are dichromats, while other females are trichromats • Howler monkeys are the only trichromats • New World primates have only one cone pigment gene per X-chromosome • trichromatic variation in females is based on the presence of allelic diversity at the X-chromosome opsin gene locus • heterozygous females have two genes that encode two different middle-to-long wavelength photopigments • Old World primates including Humans are trichromats • Two photopigment genes, M and L, on the X chromosome • short (S) with maxima near 415–430 nm (human 430) • middle (M) with maxima at 530–537 nm (human 530) • long (L) with maxima at 555–565 nm (human 560)

11. Old World primates: baboons, monkeys such as macaques, colobus, vervet, langur and mandrill, great apes such as chimpanzee and humans. New World primates: monkeys (Platyrrhini) such as marmosets, tamarins, capuchins, spider woolly and squirrel monkeys. chromosome 7 Except Howler Variation of genetics for L cone The Evolution of Primate Color Vision by Gerald H. Jacobs and Jeremy Nathans Scientific American April 2009 page 60

12. Color Vision Deficiency “Color Blindness” • Most color deficiency in humans is due to the absence of cones sensitive to medium-wavelength light (M cones). • Deuteranopia:missing M-cone, 1.5% males • Protanopia:missing L-cone, 1% males • Tritanopia: missing S-cone, rare • Because women have two X chromosomes, a defective gene encoding for the medium-wavelength pigment on the X chromosome is almost always compensated for by a normal copy of the gene on the other X. • Insertion of photopigment genes into animals such as mice with dichromatic vision suggests we may be able to correct color deficiency in humans.

13. The Evolution of Primate Color Vision by Gerald H. Jacobs and Jeremy Nathans Scientific American April 2009 page 63

14. Simulating color deficiencyDeuteranopia:missing M-cone, 1.5% males

15. Charts used to test for color-deficiency • There is a number in the center of the circle.If you can see the number, chances are you are not color-blind. • Plate 1Those with normal color vision should read the number 74. • Plate 2 • Ishihara’s Test for Colour Deficiency: 38 Plates Edition