Just wondering....

[spaceditto]

I couldn't help it I had to see what you all thought about this:

go to the site to check out;
http://www.space.com/scienceastronom...ex_010710.html

:wink:

[Argos]

I canīt refrain from saying that a sperm cell does really look like a comet.

[astronomymanjoe]

I have one thing to say about that and here it is

that is just plain freaky

[spaceditto]

Touche!!!! xaine i agree with you this is freaky

[nebularain]

From the article:

Comet or asteroid impacts could have stressed asexual organisms enough to send them down the path of sexual reproduction after forcing a flurry of genetic mutations, the study shows. Heavy doses of radiation might also have done the trick.

OK, so in ancient times people thought comets foreshadowed (or caused) doom. In modern times, scientists have speculated that comets brought the origins of life to this planet. Now we have a claim that comets are responsible for starting sexual reproduction. Man! These comets really must be all-powerful beings!

[beskeptical]

I ain't totally buying it.

All major stressors can lead to jumps in evolution, whether it's a disease, ice age, or asteroid impact. But to attribute a single event to the onset of regular sexual exchange of DNA lacks background understanding of how single celled micro-organisms exchange DNA today. There are at least four ways I can think of off hand. Two organisms can fuse & share DNA, it can be transferred by viruses and phages, consumed & incorporated rather than digested, and, exchanged between single celled organisms despite the fact they reproduce asexually. It makes more sense that sexual reproduction emerged step by step. Then, due to the fact that it increased the speed diversity to exchange genes on a regular basis, the family tree expanded exponentially.

That doesn't mean the story doesn't have some plausibility. It might have been a final straw or something. I think we are always trying to understand evolution in too simplistic terms. It's analogous to thinking of electrons orbiting protons like planets but that's not really exactly what occurs.