Superb #sciencesunday collaboration by not one, but two scientists! Don’t miss out on the Eye Candy. Notice the enormous eye sockets (orbits) in the skulls of the nocturnal primates. Can you figure out which ones are more closely related to us?
Originally shared by Chad Haney
Evolutionary forces – Working Together
By examining the skulls of primates and connecting the structure and function of bones Dr. Ross et al hopes to better understand the evolutionary forces that drive variations in the skulls of primates. Dr. Ross brought primate skulls on loan from the Field Museum of Natural History to the lab and I imaged them with our microCT (x-ray computed tomography) which I’ve discussed in previous #ScienceSunday posts. The theme for today’s ScienceSunday is collaborative research. So I collaborated with Erin Kane to present my collaboration with Dr. Ross. Just as in real life, working together, we can get more done and complement each other. Thanks to Erin for the beautiful write up below.
One of the defining features of all primates is our binocular vision. As primates’ ancestors took to the trees, being able to accurately judge distances gave individuals a selective advantage – you survived jumps and were able to have more offspring than individuals without depth perception who broke bones or fell out of trees. The development of binocular vision may also have helped early primates hunt insects better.
The evolution of binocular vision involved moving eyes from the side of the head (like a horse) to the front of our face, where they are today. When primates’ eyes moved to the front of their faces, this changed the distribution of forces exerted on the skull, especially when chewing. Over time, primate ancestors developed a bony ridge, called a post-orbital bar, behind their eye that kept the forces of chewing from deforming the skull and squishing the eyeball.
Tupaia is a tree shrew, one of primates’ closest relatives. Their eyes are on the sides of their faces, so their post-orbital bar isn’t complete. Cheirogaleus, the fat-tailed dwarf lemur, is a prosimian, a relatively primitive modern primate (http://goo.gl/ti65p). It’s skull is very similarly shaped to Tupaia, but it has a complete post-orbital bar, and it’s eyes are closer to the front of its face. Tuapaia is a lot like the proto-primates, organisms called plesiadapids who are likely primates’ ancestors. Cheirogaleus is a pretty good analogy for some of the early primates – nocturnal, probably eating insects, and living solitarily.
About the same time monkeys evolved, primates’ eyes shifted to the front of their faces. In response to the shift in forces from the eyes moving further to the front of their faces, monkeys and apes developed a solid plate of bone at the back of their eyes. Saguinus and Aotus are both South American monkeys with that solid plate of bone at the back of their eyes. Sagiunus is a diurnal monkey, active during the day. Its eyes are much smaller than Aotus, the only nocturnal monkey. Nocturnal primates have really large eyes (compare Aotus and Cheirogaleus) in order to get as much light as possible into their eyes.
Enjoy your collaborations, Memorial Day in the US, and The Monkees.
Instead of Monkee (primate) eyes, maybe you’ll enjoy Hall and Oates – Private Eyes
Check out the Visage Imaging page for more projects that use Amira.
#ScienceSunday curated by Allison Sekuler and Robby Bowles with Wonder Woman Rajini Rao