Human evolution hasn't slowed down, it has sped up

[Flannel Boy]

Hu­man ev­o­lu­tion has been speed­ing up tre­mend­ous­ly, a new study con­tends—so much, that the lat­est ev­o­lu­tion­ary changes seem to large­ly ec­lipse ear­l­ier ones that ac­com­pa­nied mod­ern man’s “ori­gin.”

Hawks and Cochran al­so ana­lyzed past ge­net­ic stud­ies to es­ti­mate the rate of prod­uction of genes that un­der­go pos­i­tive se­lec­tion—that is, genes that spread be­cause they are ben­e­fi­cial. “The rate of gene­ration of pos­i­tively se­lected genes has in­creased as much as a hun­dred­fold dur­ing the past 40,000 years,” they wrote.

A “thing that should prob­a­bly wor­ry peo­ple is that brains have been get­ting smaller for 20,000 to 30,000 years,” said Coch­ran. But brain size and in­tel­li­gence aren’t tightly linked, he added. Also, growth in more ad­vanced brain ar­eas might have made up for the shrinkage, Coch­ran said; he spec­u­lated that an al­most break­neck ev­o­lu­tion of high­er fore­heads in some peo­ples may re­flect this. A study in the Jan. 14 Brit­ish Den­tal Jour­nal found such a trend vis­i­ble in Eng­land in just the past mil­len­ni­um, he noted, a mere eye­blink in ev­o­lu­tionary time.

Research pub­lished in the Sept. 9, 2005 is­sue of the re­search jour­nal Sci­ence by Lahn and col­leagues found that two genes linked to brain size are rap­idly evolv­ing in hu­mans.

An­thro­po­l­o­gist Jef­frey Mc­Kee of Ohio State Uni­ver­si­ty said the new find­ings of ac­ce­l­er­ated evolution bear out pre­dic­tions he made in a 2000 book The Rid­dled Chain. Based on com­put­er mod­els, he ar­gued that ev­o­lu­tion should speed up as a pop­u­la­tion grows. This is be­cause pop­u­la­tion growth cre­ates more op­por­tu­ni­ties for new mu­ta­tions; al­so, the ex­pand­ed pop­u­la­tion oc­cu­pies new en­vi­ron­men­tal niches, which would drive ev­o­lu­tion in new di­rec­tions.

Lahn said he’s not con­vinced that the ac­cel­er­at­ed phys­i­cal ev­o­lu­tion is tied to pop­u­la­tion growth. “It may be a long way be­fore” an­yone can test the truth of this, he wrote.

But oth­er fac­tors could al­so ex­plain an accele­ration, ac­cord­ing to an­thro­po­l­o­gist John Kings­ton of Em­o­ry Uni­ver­si­ty in At­lan­ta, Ga. Ev­o­lu­tion might speed up be­cause we have changed our own en­vi­ronment, which in turn changes the ev­o­lu­tion­ary pres­sures. “We now con­trol our own en­vi­ronment and ecol­o­gy to some ex­tent,” he said.

For instance, if you in­vent spears, you per­haps can af­ford to be slight­er-framed be­cause you can stand fur­ther away from wild an­i­mals, Coch­ran said. He ar­gued that a pow­er­ful syn­er­gy be­tween these sorts of changes and expand­ing pop­u­la­tion ex­plains the “fant­as­tic­ally ra­pid” re­cent evo­lu­tion.

“A very big change”

Ove­rall, the find­ings could amount to “a very big change” in tra­di­tion­al think­ing for two rea­sons, ac­cord­ing to Mc­Kee. First, he said, many re­search­ers had mis­tak­en­ly as­sumed pop­u­la­tion growth would slow down ev­o­lu­tion, be­cause new mu­ta­tions would take too long to spread through a large pop­u­la­tion.

Sec­ond, the find­ings deal a fi­nal blow to a lin­ger­ing view among an­thro­po­l­o­gists of ev­o­lu­tion as a lad­der “with us as the be-all-end-all,” he said. That idea went out of fash­ion in the 1950s but still per­sists “in the backs of our minds,” he added.

Many of the changes found in the ge­nome or fos­sil rec­ord re­flect me­tab­o­lic alt­er­a­tions to ad­just to ag­ri­cul­tur­al life, Cochran said. Oth­er changes simp­ly make us weaker.

In the June 2003 is­sue of the re­search jour­nal Cur­rent An­thro­po­l­ogy, Hel­en Leach of the Uni­ver­si­ty of Ota­go, New Zea­land wrote that skele­tons from some pop­u­la­tions in the hu­man line­age have un­der­gone a pro­gres­sive shrink­age and weak­en­ing, and re­duc­tion in tooth size, si­m­i­lar to changes seen in do­mes­ti­cat­ed an­i­mals. Hu­mans seem to have do­mes­ti­cat­ed them­selves, she ar­gued, caus­ing phys­i­cal as well as men­tal changes.

De­spite all the alte­rations, Mc­Kee said he be­lieves the no­tion of an “o­rig­in” of mod­ern hu­mans around 200,000 years ago re­mains use­ful. “It’s just a thresh­old point” at which hu­mans take on most of the phys­i­cal fea­tures we rec­og­nize, he re­marked, and as such, need­n’t be dis­carded. Coch­ran said it can still be ar­gued that the key change was lang­uage; but when this ori­gi­nated re­mains far from clear.

What­ever the imp­li­ca­tions of the recent findings, McKee added, they high­light a ubiq­ui­tous point about ev­o­lu­tion: “every spe­cies is a tran­si­tion­al spe­cies.”

http://www.world-science.net/exclusives/070326_evolution.htm

bobobobo

[MrAngryFace]

Thank transfats!

[Flannel Boy]

Like you'll ever pass on your autistic genes.

[Cheebs]

There's a good chance my kids won't get what I have? Ok I guess that's positive.

he means you'll be too busy spinning plates to look at a lady.

[Flannel Boy]

DONT CHANGE THIS THREAD IN ANOTHER RUZBEH HAS AUTISM THREADS YOU FUCKING TURDS

[Takuan]

DONT CHANGE THIS THREAD IN ANOTHER RUZBEH HAS AUTISM THREADS YOU FUCKING TURDS

(Image removed from quote.)

:LOL

[Candyflip]

*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?

[brawndolicious]

*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?

I too would like to know this.

[bagofeyes]

I just wanna be able to fly

[Valcrist]

*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?

Richard Dawkins' books are pretty well written.  Selfish Gene especially.

[Van Cruncheon]

i don't see any reference to the almighty in those explanations

why do you hate the troops, malek

[brawndolicious]

^it's an old ass thread man.  I was searching for something else.

[Candyflip]

*sigh*
Whatever I learned about evolution in 9th grade Biology has since escaped me. Any good books on the topic, or is the only real way to acquire a decent understanding through class?

Richard Dawkins' books are pretty well written.  Selfish Gene especially.

Damn this thread is old. It's funny you said this, I just finished that and The Blind Watchmaker last month.

[Flannel Boy]

This graph is from the Economist. Pay no attention to the recent drop off. But overall you can see that human evolution has accelerated over the past 80,000.