Why Are Squirrel Monkeys Color Blind?
Researchers have discovered the key to red-light vision in a species of squirrel monkeys – a gene. This gene instructs the body to make different proteins in order to detect red light. The team discovered that male squirrel monkeys lacking the gene were color blind. The team added the gene to the monkeys’ DNA. This discovery has important implications for gene therapy and the evolution of primates. This article will examine the genetics of red-light perception, the possible pathways of dichromatic color blindness in squirrel monkeys, and the possibility of gene therapy for dichromatic vision in these species.
Evolution of primate color vision
The evolution of trichromatic color vision in primates is a fascinating subject for paleontologists. There are many reasons why this particular trait evolved, and the study of other species’ color vision is important in gaining a deeper understanding of how primates perceive and use color. Specifically, this study explains how the ability to see colors in trichromatic forms evolved in primates. In addition, it explains how the ability to detect different wavelengths of light helped primates evolve their ability to distinguish between them.
The evolution of primates’ color vision is complicated, and it is possible that primates evolved trichromacy independently from each other. Old-world primates, which include humans and gibbons, evolved this trait independently of the New World lineages. Although there is no conclusive evidence to suggest that the two lineages diverged before they split, scientists believe that they were both dichromats and monochromats at some point.
Loss of S-cone function in platyrrhine monkeys
The S-cone, which is responsible for color vision, is lost in platyrrhine monkeys. The opsin gene produces multiple M/L cone pigments, but the arrangement is not universal. Several species of platyrrhine monkeys have unknown color vision arrangements, although there are two striking variants on this theme. These findings have important implications for the adaptive value of cone-based vision.
The S-cone gene is highly homologous to the S-cone gene of human. The mutations in this gene cause a stop codon that prevents the production of viable S-cone pigments. As a result, the monkeys’ lack of colour vision is probably due to loss of S-cone function. But how can we know for sure?
The two main pigments of mammals belong to the LWS and SWS gene classes. Interestingly, the long-wave pigment is derived from rod RH1 pigment. In addition, some marsupials have a conserved and expressed RH2 opsin gene. The loss of S-cone function in platyrrhine monkeys may be a consequence of the evolution of two different color-opponent systems.
Possible pathways to dichromatic color blindness in squirrel monkeys
In previous studies, scientists have observed that humans suffer from a condition called dichromatic color blindness, a condition in which one or more colours are distorted. The research team has now used gene therapy to restore full color vision in two squirrel monkeys. While male squirrel monkeys have no receptors for red or green colours, females have these receptors and can see the entire spectrum. The researchers at the University of Washington have now used this technique to reprogram the retinal cells and restore color vision in these male and female squirrel monkeys.
The gene responsible for dichromatic color vision in humans is encoded on the X chromosome. However, female squirrel monkeys carry only one X chromosome, and the two opsin alleles are homozygous. Therefore, females are trichromatic. Despite this, females are often homozygous for one opsin gene, while males carry both alleles.
Gene therapy for dichromatic color blindness in squirrel monkeys
Researchers have successfully used gene therapy to cure red-green color blindness in squirrel monkeys. Human segments of DNA were implanted in the retinas of the monkeys’ eyes and were shown to correct color vision. This treatment may help cure a range of vision conditions in humans and other animals. The researchers plan to test gene therapy in other species. In the meantime, they are hopeful that one day, it will be available for humans.
Researchers have been working on injecting genes into the eye of a monkey for 10 years. The goal of their research is to find a simple way to treat this disease. Since the disease affects 3.5 million humans, and as many as 16 million in China and India, gene therapy could help people with colorblindness. It affects mainly Caucasian men; 8 percent of these individuals are unable to distinguish between green and red hues.
What percentage of squirrel monkey males are colorblind?
Males are born colorblind at a rate of 8 percent.
What are the consequences of squirrel monkey colorblindness?
While not severe colorblindness can make it difficult for squirrel monkeys to distinguish between ripe and unripe fruits which can impact their foraging and feeding habits.
Additionally colorblindness may also make it difficult for males to distinguish between potential mates.
How does squirrel monkey colorblindness compare to human colorblindness?
Squirrel monkey colorblindness is more severe than human colorblindness as humans are able to see some colors while squirrel monkeys cannot.
What causes squirrel monkey colorblindness?
Squirrel monkey colorblindness is caused by a lack of cones in the eye.
Cones are responsible for color vision and without them an animal can only see in black and white.
What is the difference between rods and cones?
Rods and cones are two different types of cells in the eye responsible for vision.
Rods are responsible for black and white vision and are more sensitive to light while cones are responsible for color vision and work best in bright light.
How many cones does a squirrel monkey have in its eyes?
A squirrel monkey has three cones in its eyes while a human has three million.
How does the number of cones in a squirrel monkey’s eye compare to other animals?
Squirrel monkeys have fewer cones in their eyes than other animals which is why they are colorblind.
Do all animals have cones in their eyes?
No not all animals have cones in their eyes.
Some animals like dogs only have rods and are not able to see colors.
How do animals without cones see the world?
Animals without cones in their eyes see the world in black and white.
What other animals are colorblind?
Penguins lions and some bats are also colorblind.
What does it mean to be colorblind?
Being colorblind means that an individual cannot see colors or can only see some colors.
What are the most common colors that people with colorblindness cannot see?
The most common colors that people with colorblindness cannot see are green and red.
What are the consequences of human colorblindness?
While human colorblindness is not severe it can make it difficult for individuals to distinguish between colors.
This can make it difficult to do things like choose clothes that match or read traffic lights.
How many types of colorblindness are there?
There are four types of colorblindness: deuteranomaly (red-green colorblindness) protanomaly (red-green colorblindness) tritanomaly (blue-yellow colorblindness) and monochromacy (complete colorblindness).
Is there a cure for colorblindness?
No there is no cure for colorblindness.
However there are treatments that can help people with colorblindness to see colors more clearly.
Jessica Watson is a PHD holder from the University of Washington. She studied behavior and interaction between squirrels and has presented her research in several wildlife conferences including TWS Annual Conference in Winnipeg.