Mike Elphick

Crying in adulthood is a phenomenon that could be added to Oolon's list. Why revert to baby antics for relief from emotional pain? Why blubber like a baby to get sympathy and attention?

The closed eyes; the srewed up face; the red discolouration; the open mouth; the gasping and irregular breathing; the tears ready to be mopped up by a caring mother -- all very similar to a baby's body language. It is perfectly understandable why a baby does this, but why should adults revert to such a pathetic state? It's a potty design to use Oolon's expression (excuse the pun)!

That got me thinking about paedomorphosis. This is a phylogenetic change in which the adults of a species retain traits previously seen only in juveniles. This can eventually lead to neotony, or the development of reproductive ability in the larval stage of some animals. (A trend seen in modern humans -- lock your kids up folks!) From the design point of view this is pretty stupid, although one can see benefits if the climate became less favourable for the adult form. However, it is believed that some animals (e.g. certain species of salamander) have almost lost the ability to develop into adult forms.

The neotenous form of a species may become its normal mature form. This is totally in accord with evolution, but why would a Grand Designer go to the bother of creating an adult form only to see the animal discarding the whole idea?

Stephen Jay Gould thought we were a neotenous species of chimpanzee and Desmond Morris of 'Naked Ape' fame thought neoteny was an important factor in human sociobiology.

Not so much the reinvention of a wheel, but the forgetting of a wheel altogether.

espritch

Saber teeth. At least three different cats have independently evolved this. There was also a mammal like reptile in the Permian that had saber teeth.

Berthold

Eusociality:

With hymenopterans it is an obvious choice because of haploid males. As far as I know, eusocial hymenopterans evolved this trait independently several times (i. e. social bees evolved from solitary bees, social wasps from solitary wasps etc.).

But termites did it, too, with all individuals diploid. Their sterile workers are genetically of both sexes, and, other than with hymenopterans, there is a long-lived king of the hive, too.

I don't know specifics about the naked mole rat, but I've seen it counted among eusocial animals, too.

Dlx2

Naked mole rats are diploid and caste is maintained through force.

There's also at least one species of eusocial haplodiploid thrip.

BioBeing

Beetles! Lots and lots of beetles.

Berthold

Body armor:
The general shape of the tortoise and its function was also evolved by ancylosaurs and glyptodonts; since they are phylogenetically quite distant, I suppose the anatomy of the armor differs, too.

Filter feeding:
A lifestyle not usually associated with big, active swimmers; yet it has been adopted, twice among cartilagineous fish (manta rays and giant sharks), once among mammals (which had to evolve baleen for lack of gills).

Palm tree shape:
Tree ferns, cycadeas, Bennettitales (extinct), palm trees proper, several other families of monocots.

Berthold

<could not find my previous post at first, but by now it is shown>

Malintent

well, here is an interesting example you bring up. The windsheild wipers on planes and cars are very different. Cars are meant to run their wipers all the time (during operation). Planes that have wipers (most do not) are designed to only run while the plane is on the ground, taxiing. If it is raining enough that the airflow accross the planes windscreen does not clear the water in flight... then you are prolly in the clouds and there is nothing to see out the window anyway. You are operating in IFR (on instruments - not visually).

As a result, the mechanisms for both car wipers and plane wipers are very different. They do not even move accross the windshield the same way at all - generally speaking.

Martin B

Cripes! Nobody's said the tetrapod ear yet.

This has been re-invented a number of times, with the most superior design by far being that of mammals.

For modern tetrapods, we're looking at at least three re-inventions of the impedance-matching middle ear in amphibians, "reptiles", and mammals. This, of course, depends on how you prefer to optimize vertebrate phylogeny, where one could have it happening as many as four or five times, when fossils are included.

lpetrich

Lens-camera eyes are an obvious and celebrated example of convergent evolution. They evolved twice, once in vertebrates, and once in squid and octopuses (coleoids). The remaining cephalopod, the chambered nautilus, has a pinhole-camera eye; I'm not sure what sort of ancestral eye their common ancestor had had, and I wonder if it's been possible to find fossilized cephalopod soft parts.

Another multi-invention is internal fertilization - it's been invented several times by various land animals, and even by some aquatic animals. It has also been invented by seed plants, interestingly enough.

Grasping organs have been invented numerous times, and in a variety of ways:

• Primates: hands' power grip (fingers against palm)
• Hominids: hands' precision grip (thumb against forefinger)
• New World monkeys: prehensile tail
• Elephants: trunks (elongated noses)
• Perching birds: feet that can grab small branches
• Scorpions, and many crustaceans: last and second-to-last limb segments are grasping claws or pincers that fit against each other
• The tentacles of squid and octopuses

And many sorts of mouths can easily be used for grasping.

Rhinoceros-like animals have evolved several times, nose horns and all.

• Rhinoceroses proper have equines and tapirs as their closest living relatives (Perissodactyla).
• Arsinoitherium (Embrithopoda; Oligocene) had a pair of blade-shaped horns on its nose; its closest relatives were likely elephants, sirenians, and hyraxes (paenungulates).
• Uintatherium (Dinocerata; Eocene) had several bony knobs on its head and enlarged upper canines.
• The largest titanotheres, like Brontotherium (Oligocene), had knobby horns on their noses; they also were perissodactyls.
• The ceratopsians (Cretaceous), the familiar horn-faced dinosaurs.