Did primates develop three-colour vision because they began to live in the day or did they begin to live in the day due to the appearance of this trait? A small animal with bulging eyes – the tarsier – may hold the answer to this question.

 

American scientists analyzed the genes that encode photopigments in the eye of the tarsier, a small primate that branched off early on from monkeys, apes, and humans. They showed that the last common ancestor of living tarsiers had three-colour vision similar to that of monkeys and apes. However, they had enlarged eyes, suggesting they were active at night.

 

According to the researchers, this shows that tarsiers first adapted to dim light levels, such as twilight or the full moon. These light conditions were dark enough to favour large eyes but still bright enough to support trichromatic colour vision. This compromise would have helped the primates switch to daytime living, which allowed them to better see their prey, their predators, and other primates and to expand their territory.

 

Source: http://www.sciencedaily.com/releases/2013/03/130327132537.htm

 

A British study shows that compared to the modern human brain, the brain structure of Neanderthals focussed much larger areas on vision and movement. This difference could have contributed to their extinction.

 

Neanderthals’ brains were similar in size to those of modern humans, but their eyes were larger. Having larger brain areas related to vision and movement meant that there was less room left over to deal with the social interactions required for life in large groups.

 

“Smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments because they would have had fewer friends to help them out in times of need,” explains lead author Eiluned Pearce from the University of Oxford. “Overall, differences in brain organisation and social cognition may go a long way towards explaining why Neanderthals went extinct whereas modern humans survived.”

 

The same researchers had previously shown that humans living in higher latitudes had more areas of the brain dedicated to vision in order to cope with low light levels. They offer the hypothesis that Neanderthals would have developed larger eyes because they evolved in Europe, while their contemporary humans originated from Africa.

 

Source:  http://www.sciencedaily.com/releases/2013/03/130319093639.htm