Cosmic accidents - one giant leap for a cell

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Cosmic accidents - one giant leap for a cell
OP - October 02, 2010, 06:20 AM

A freak event created the ancestor of all multicellular life on Earth. Without this unconventional genesis, we might never have become more than bacteria

Life is what you make of it. For the first organisms on the newly watery Earth, that was little. For a billion years or more, single-celled entities simply morphed, multiplied and colonised the oceans. Photosynthesis was one innovation: from about 2.5 billion years ago, blooms of sea bacteria supplied Earth's atmosphere with its first whiff of oxygen. But when the next turning point came, it was in a rather unexpected direction.

....

The countless simple cells living in many different environments on Earth have had over 3 billion years to evolve complexity. It could have happened repeatedly - and yet it appears to have happened just once, perhaps 2 billion years ago. All complex life is descended from a single common ancestor.

Why is that so? Because, says Nick Lane of University College London, natural selection normally favours fast replication, keeping simple cells simple. Then a freak event occurred: an archaeon engulfed a bacterium and the two cells formed a symbiotic relationship. That transformed the dynamics of evolution, leading to a period of rapid change that produced innovations such as sex. The incorporated bacterium eventually evolved into mitochondria, the energy generators of complex cells.

http://www.newscientist.com/article/mg20727795.900-cosmic-accidents-one-giant-leap-for-a-single-cell.html

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- TheRationalizer
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Re: Cosmic accidents - one giant leap for a cell
Reply #1 - October 02, 2010, 11:33 AM

You need 2 things. First you need the occurrence that life starts, and then you need it to be successful. It may have happened a few times but died out, 99.9% of specifies we know of are already extinct after all.

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- Saif Rahman
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Re: Cosmic accidents - one giant leap for a cell
Reply #2 - October 02, 2010, 07:54 PM

One thing I dont get, is why bother with sexual reproduction. Its does not seem effective to me for the benefits it has to offer. Mating takes energy, is at risk from predation during fertlisation, more often than not requires both partners to be at the same place at the same time, only half the species can procreate, and requires complex evolved tools to do the job.

Why no just produce assexually with occasional random mutations & pop them out like no-ones business instead.

Sounds like a much better plan, no?

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Re: Cosmic accidents - one giant leap for a cell
Reply #3 - October 02, 2010, 08:05 PM

Sexual reproduction results in greater variation in later generation(s), therefore more chances of the species surviving if there are changes in the environment. Or something. Shit I need to brush up on my biology.
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Re: Cosmic accidents - one giant leap for a cell
Reply #4 - October 02, 2010, 08:09 PM

http://www.pbs.org/wgbh/evolution/sex/advantage/index.html
- Saif Rahman
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Re: Cosmic accidents - one giant leap for a cell
Reply #5 - October 02, 2010, 08:13 PM

My point is about the trade-off being too high. The disadvantages with sexual reproduction to me appear to outweigh the benefits with the type of assexual reproduction I listed below. For starters you need 2 people to feed with resources, as opposed to one. As well as the other disadvantages listed below.
Quote from: Prince Spinoza on October 02, 2010, 08:05 PM
Sexual reproduction results in greater variation in later generation(s), therefore more chances of the species surviving if there are changes in the environment. Or something. Shit I need to brush up on my biology.

You can get great variation with random mutation in an assexual environment

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