Hi!

Is there any evidence, that evolution proceeded faster than it should have, I mean compared to the rate of mutations and estimates for selection pressures?
Or, put differently, does it seem surprising that evolution produced humans in no more than 3.8 years or so? Does it look like nature must have been in a hurry?
No, I'm not asking cause I believe in creation, I'm just curious.

Thanks a lot!

Michael,

This one is really tricky to work on. Pretty much by definition evolution takes a long time, however, just how long something may take to eveolve (a certain behaviour, an organ, a new species etc.) is more or less unknown. Some things might evolve and become fixed in a population in tens of generations, while other species may look nearly identical after tens of millions of years.

Dramatic changes to an environment seem to be catalysts for rapid evolution. After all, if all your food goes extinct, the climate changes and you are stranded on an island you will have to evolve fast or die. Species may be unchanged for generations beofre 'suddenly' evolving new traits, though probably nothing quite as dramatic as Stephen J. Gould's 'punctuated equilibrium' model.

Some mutations can be pretty dramatic and operate over very short periods of time (though nothing like the single generations of the X-Men unfortunately). In one recent study of lizards on an island, scientists introduced a new predatory lizard. The prey lizards had always lived on the ground without much threat and so had a variety of leg lengths, reflecting a lack of selection. Now they rapidly evolved much longer legs in order to become faster and escape the predators. (Here the word 'evolved' is a little akward, actually the short legged lizards were eaten - but certainly there was selection from the lizard population). Afterwards, the remaining lizards actually reversed the trend fot long legs and instead evolved short legs which they combined with a new behaviour - they started climbing trees.

Believe it or not, these two turn arounds happened in just a year. First the lizards became longer legged, and then shorter legged (shorter than the originals) while adapting to a new behaviour. Two complete changes in shape, plus a new behaviour as a result of a single new factor in their environment (a new predator). This just goes to show how fast evolution can be. Scale that up a few times and you can see how profound changes can happen very, very fast.

To be picky I would be very surprised if humans evolved in 3.8 years - I imagine you mean 3.8 million. :-)

Still, humans did evolve relatively fast, but they were probably helped by their brains. A large brain allows for more complex social interactions and more complex behaviour (and in our case more tool use). With better survivorship and an increase in ability to hunt with new tools, this may have allowed us to spend more energy growing larger and evolving better brains in a snowball effect.

Some calculations by Richard Dawkins suggested that the eye could evolve in as little as 500 000 years. These were deliberately on the short side, and I doubt anyone would seriously expect that to have happened, but it is certainly possible. If something as complex as an eye can for in half a million years, then humans appearing from advanced apes in nearly 4 million years does not seem so extreme.