Differences in Perception Between Monkeys and Humans, According to Specialists
In the heart of the University of Stirling in Scotland, primatologist Andrew Smith has been delving into the intriguing world of New World monkeys, known as tamarins, for nearly a decade. His research has shed light on the effects of different types of sight on these fascinating creatures.
Tamarins have a diverse diet, feasting on the fruit of over 833 plants from 167 different species. One of their favourites is the Abuta fluminum plant, a plant whose ripe fruit is orange. However, orange can be hard to detect without red-green perception, making it interesting to study the role of colour vision in tamarins.
Smith's research has particularly focused on dichromats, primates that have two types of colour receptors in their eyes, as opposed to trichromats, who have three. Dichromats may not be as distracted by colours, allowing them to better see shapes and forms, which could provide an advantage in predator-prey interactions.
Indeed, Smith suggests that dichromats may be better at "breaking the camouflage of predators and prey". This could be a crucial advantage in the dense forests where tamarins live.
On the other hand, Nathaniel Dominy, a primatologist at the University of Chicago, found that trichromatic color vision was essential for Old World apes and monkeys in choosing tender young red leaves. This suggests that the advantages of trichromacy may lie in finding and identifying ripe fruit.
Smith's work has shown that trichromacy indeed provides an advantage in this regard. Trichromat tamarins were 50% more adept at choosing ripe fruit than their dichromat counterparts.
To test this theory, Smith devised an experiment, setting up a wire scaffold in the Belfast Zoological Garden in Ireland, complete with large green paper leaves to simulate the forest canopy.
The experiment revealed that every howler monkey is trichromatic, while the owl monkey is monochromatic, seeing only in black and white. Among tamarins and spider monkeys, all males are dichromats, while females split 60-40 between three- and two-color vision.
However, a mystery remains. Why hasn't trichromacy replaced dichromacy altogether in the evolution of primates? Gerald Jacobs, an expert on mammalian color vision, states that dichromats have a visual deficit and don't do as well in the world.
This research not only deepens our understanding of the visual world of New World monkeys but also offers insights into the evolution of colour vision in primates. It's a fascinating journey that continues to unfold.
In addition to their fruit-eating habits, New World monkeys also consume large quantities of prey such as katydids, frogs, and lizards. Understanding the role of colour vision in their predator-prey interactions could provide further insights into their complex ecology.
