... Cataclysmic events happen every now and then and causes extinctions and hardship on surviving organisms
Indeed, it appears that periodic cataclysmic events are required in order to keep evolution going.
We've seen several eras in Earth's history where life appears to "stagnate" at some level, proceeding with little-or-no change for long periods. The last of which was the "age of dinosaurs", which lasted 170 million years or so, depending on how you define the starting point. It ended with the Chicxulub impact.
We also see numerous examples of species which are largely unevolved; for example, ants have been around for 120 million years and one species [americanscientist.org] of prehistoric ant is apparently still living in the Amazon. Coelacanths [wikipedia.org] have been around in their present form for about 400 million years.
The overall impression is that life tends to "stagnate": once life evolves into an efficient survival mechanism, there's no pressure to evolve further. Evolution aims at being a better "fit" for the unchanging environment, but more complexity is simply not needed.
This is why I believe the Drake equation [wikipedia.org] is overly optimistic. I think it omits the factor "fraction of star systems that experience occasional planetary meteor strikes". If we ever travel to another star, we're likely to find it teeming with life, but stagnated at some level.
This may be one factor (of possibly several) that explains the Fermi paradox.
The "doubling rate" identified in the article may be an artifact of Earth, and that's only if Genome complexity [fourmilab.ch] is even a reasonable measure to make. Lilies have 30x the genome size of humans - another explanation might be that genome complexity is related to genome size, which does not have much selection pressure. It's not a peer-reviewed paper.
Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/RZAvsjtDBE4/story01.htm
UT Austin Lizzie Velasquez NFL Network att libya engadget twin towers
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.