Why there are no missing links

[n2doc]

Category: Evolution
Posted on: December 31, 2010 3:54 PM, by PZ Myers

his topic came up earlier this week: creationists are always yammering about the "missing link" and how it's missing and therefore evolution is unsupported by the evidence. It's total nonsense, since evolution doesn't predict a "missing link", but it seemed worthwhile to explain why, since there was a recent publication of some exciting data that demonstrates the real complexity of the situation.

Jim Foley and John Hawks and Carl Zimmer have written up the story of the Denisovans. To summarize, another group of Pleistocene humans have been sequenced, called the Denisovans — their identity is murky, as they've only been recognized by a few bones, but the results show that they were genetically distinct from both modern humans and Neandertals, another Pleistocene group that has been sequenced. Like the Neandertal story, in which some Neandertal genes (less than 5%) were introduced into some modern human (European and Asian) populations, what we know about the Denisovans is that some of their genes, about 5%, also spread into a subset of modern human populations, in this case the Melanesians.

That's awesome stuff. There are all these splintered bits of ancestry that come together in complex ways to produce the human species, and that's why there is no missing link. Many people have this false notion that our evolution was a matter of a panmictic gemisch of people rolling fatefully down the smooth channel of history, everyone mingling, all of them tracing a common lineage back and back to a discrete ancestor. It wasn't. Our river of time looked more like this, a braided stream:


This is what we mean when we talk about populations having structure. Branches emerge, whether we call them Neandertals or Denisovans or modern humans, and they are distinct but there can still be genes flowing between them to some degree. Even within modern humans we have structure, where groups maintain a kind of genetic integrity over space and time; I can look at my own recent lineage and see how my mother's Scandinavian connections were maintained through several generations in America, or I can look at my father's pedigree that goes back about 400 years in the New World and see that even though they were constantly scudding along at the very edge of the American frontier, mingling with Native Americans and black slaves and freedmen and Chinese railroad workers and Japanese farmers, somehow in their marriages, nothing but Scots/Irish/Anglo-Saxon names turn up.

more
http://scienceblogs.com/pharyngula/2010/12/why_there_are_no_missing_links.php

[niyad]

1. I thought the missing link had been found--the repukian and tea parties.

[gtar100]

2. We only wish they *were* missing.

But they live and breed among us to the earth's detriment.

[txlibdem]

4. They say they can't wait for The Rapture. I'll bet they're secretly terrified of it.

Those that actually believe in that sort of thing, that is.

[Sancho]

3. I can't wait to use "panmictic gemisch" at Bible study!

That will send all my repub friends searching for the urban dictionary.

[Nihil]

5. I love the analogy to a braided stream ...

> There are all these splintered bits of ancestry that come together in complex ways
> to produce the human species, and that's why there is no missing link. Many people
> have this false notion that our evolution was a matter of a panmictic gemisch of
> people rolling fatefully down the smooth channel of history, everyone mingling, all
> of them tracing a common lineage back and back to a discrete ancestor. It wasn't.
> Our river of time looked more like this, a braided stream

:applause:

The Creationists are looking for a specific lock in a canal and ignoring the
beautiful river flowing alongside ...

[kickysnana]

6. Everything is now in the DNA and RNA we just haven't decoded all of it yet. n/t

[amyrose2712]

7. There is a funny Futurama clip that touches on this..

I was looking for it earlier today, but couldn't find it.