The warm-up act for this program was a dinosaur program called “Jurassic Fight Club”, which was loaded with CGI and lots of gratuitous razzle-dazzle — but I thought it was a hoot. It also had enthusiasatic scientists talking about how they figured out what had happened (although it does bug me that they treated some speculative stuff in the narrative as if it were factual). Most of the show was taken up with glitzy animations, but it was balanced with at least some discussion of the process of science, so I’ll give it a thumbs up.
Now to settle in for the story of the evolution of eyes…
Oooh: “the sparks of evolution are tiny, random changes called mutations”. I’m pleased that it jumps right in without compromise. It also promptly pushes the timeline back to 600 million years, and describes work done on jellyfish eyes. They show some very cool behavioral studies of how jellies respond to different wavelengths of light, illustrating why even simple animals would find light-sensing organs beneficial.
Teaser before the first commercial: trilobites. It looks they’re trying for a chronological approach.
The commercials are really annoying: Kinoki foot pad quackery and bigfoot. Bleh.
Now we get a quick summary of the Cambrian explosion — I saw an anomalocaris swim by. The first fossil eyes are from the Cambrian; compound eyes on arthropods. Modern insects are shown, explained as not descendants of trilobites, but probably share the same genes Good acknowledgment of the successful utility of dragonfly eyes.
Dang. Too little time spent on invertebrates — they’re already switching gears to focus on vertebrates.
Pikaia! Cool. Kinda nice that they’re setting up the vertebrate eye as an icon of evolution, and a kind of machine — good dig at ID. There’s also a nice simple animation of how an eye patch could form an eye cup, then an eye with a lens.
Yeah, they already leap into those sexy, glitzy dinosaurs. A little more time should be spent on those unsexy hagfish and lampreys, more interesting as transitional forms, but OK, most people wouldn’t find them as interesting as I would. They show Kent Stevens (UO! Yay!) work on identifying visual fields from dinosaur fossils, and discuss binocularity.
T. rex makes for good visuals, but is it really the best animal for discussing the evolution of vertebrate eyes? The innovations were all in place before the dinosaurs came on the scene!
Next lead-in: we’re about to learn about mammals and night vision.
Primitive mammals were largely nocturnal. So what are the special adaptations in the mammalian eye for night vision? Lots of isolated eyes in jars; the answer from comparative anatomy is that the size of the cornea is important. Cool: tarsiers have eyes that are bigger than their brains.
Another strategy: the tapetum, a reflective layer at the back of the eye. Nifty dissection of a big cat’s eye to show the structure.
Looks like the last 15 minutes of the program will be about human vision…
We lucky humans have color vision. Mammals radiated into numerous niches after the great extinction at the K/T boundary, and primates moved into the trees. Why did natural selection favor improved color vision in primates? Monkeys are shown to favor the youngest, tenderest leaves…which have color differences from old leaves.
Primates also have binocularity for better depth perception, an adaptation for living in trees. This gives them a narrower field of view, unfortunately. Birds of prey targeted these animals with limited vision, which made group living more advantageous for primates. They suggest that this would promote more social behavior and intelligence.
Summary: Not bad. The title is a bit of a misnomer, though, since only a little bit of it was about the evolution of eyes. A program more true to its title would have spent much more time on invertebrates, would have said more about the molecular underpinnings of vision, and would have concentrated on hagfish, lampreys, and teleosts among the vertebrates.
I know…dinosaurs and people are much more popular creatures, so the show compromised on the science for the sake of visual appeal. That’s an unfortunate reality of the conventions of TV programming, but it would have been nice to see them break out of that straitjacket, especially since the early part of the show on jellyfish was arresting and cool, showing that it can be done.
It was unabashedly pro-evolution, too, not giving a second to the silly stories we get from creationists. That’s a real plus, too.