Life on Earth came from one ancestor

[n2doc]

By Tina Hesman Saey, Science News May 12, 2010 | 3:56 pm | Categories: Biology


One isn’t such a lonely number. All life on Earth shares a single common ancestor, a new statistical analysis confirms.

The idea that life forms share a common ancestor is “a central pillar of evolutionary theory,” says Douglas Theobald, a biochemist at Brandeis University in Waltham, Massachusetts. “But recently there has been some mumbling, especially from microbiologists, that it may not be so cut-and-dried.”

Because microorganisms of different species often swap genes, some scientists have proposed that multiple primordial life forms could have tossed their genetic material into life’s mix, creating a web, rather than a tree of life.

To determine which hypothesis is more likely correct, Theobald put various evolutionary ancestry models through rigorous statistical tests. The results, published in the May 13 Nature, come down overwhelmingly on the side of a single ancestor.

A universal common ancestor is at least 102,860 times more probable than having multiple ancestors, Theobald calculates.


No one has previously put this aspect of evolution through such a stringent test, says David Penny, a theoretical biologist and Allan Wilson Centre researcher at Massey University in Palmerston North, New Zealand. “In one sense, we are not surprised at the answer, but we are very pleased that the unity of life passed a formal test,” he says. He and Mike Steel of the University of Canterbury in Christchurch, New Zealand, wrote a commentary on the study that appears in the same issue of Nature.

http://www.wired.com/wiredscience/2010/05/origins-of-life-on-earth/

Theobald’s study does not address how many times life may have arisen on Earth. Life could have originated many times, but the study suggests that only one of those primordial events yielded the array of organisms living today. “It doesn’t tell you where the deep ancestor was,” Penny says. “But what it does say is that there was one common ancestor among all those little beasties.”

[WCGreen]

1. So there was Adam and god did dig that rib out of him....

I can hear it now...

[n2doc]

3. That would mean apes are OUR ancestors! n/t

[Ian David]

5. No, they're still cousins. But humans and apes are all ancestors of the same, single cell. n/t

[n2doc]

8. I was having fun with the previous post

Of course evolution works the other way. But if the fundies (not that poster) really do want to use this as an example of creationism, well, that's the "logical" conclusion!

[Ian David]

9. I didn't see what "ignored" had said. n/t

[Thor_MN]

15. Uh,,,, Descendants?? The single cell would be the ancestor.

[Duer 157099]

14. Except... the discussion isn't limited to human life

Or did God use Adam's rib to then create all the other life on the planet?

Ask 'em that one.

[ChairmanAgnostic]

2. but what if he was male, like the good book sez? 6000 yrs ago?

Great issue. But, Seriously, the microbial life that lives deep underwater, near or on underwater vents, thrives on acids, extreme temps, bizarre chemical soups, and toxic clouds. No matter when or where life started, those critters bear little resemblance to other life, be it air, water or ground based.

Most water bourn critters still require oxygen to live. But some of these bizarre things find sustenance from things like cyanide.

Given the conditions under which life thrives in the deep black sea (thanks, BP), it is ever more likely that life exists elsewhere, under conditions that we can hardly imagine.

[Rosa Luxemburg]

4. abiogenesis? Our ancestor is a couple of molecules?

http://en.wikipedia.org/wiki/Abiogenesis

[Ian David]

6. Whatever it was, it's probably older than John McCain. n/t

[WCGreen]

7. If such a thing is possible...

[ChairmanAgnostic]

12. it puts lie to Intelligent Design, for one thing

[WCGreen]

13. Amen....

[deutsey]

10. Like anyone can even know that.

[sakabatou]

11. I doubt that means we came from a single individual