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The humanity switch: How one gene made us
brainier
09 May 2012 by Sara Reardon
Magazine issue 2864. e
For similar stories, isit t!e "eneti#s and $uman %olution
&ne gene made brains more #om'le( )*mage+ atural $istory
Museum-S#ien#e !oto
/ibrary
%ditorial+ e are t!e im'robable a'e
3$% stage as set. 5round 2. million years ago, t!e erroneous
du'li#ation o7 a
single gene #!anged t!e #ourse o7 our brains eolution 7oreer.
Suddenly, our
an#estors neurons deelo'ed #om'le( s!a'es t!at made t!em #a'able
o7 e(#!anging
in7ormation it! a larger number o7 neig!bouring #ells. 5t t!e
same time, in7ant
sulls be#ame more 7le(ible, alloing t!em to a##ommodate larger
brains.
3!ree ne studies reeal t!is remarable se:uen#e o7 eents.
;ru#ially, t!ey also
s!o t!at t!e #!anges !a''ened 're#isely at t!e same time as our
on $omo
genuss'lit 7rom t!e australo'it!e#ines )see eolutionary
tree.
"ene du'li#ations are rare in !uman !istory. &nly about
olla, ;ali7ornia, 7o#used on
SR"52. 3!is gene !el's drie deelo'ment o7 t!e neo#orte(, !i#! in
!umans
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#ontrols !ig!er?order brain 7un#tions su#! as language and
#ons#ious t!oug!t.
$umans it! mutations in SR"52 are 'rone to e'ile'ti# seizures,
as are mi#e t!at
!ae been engineered to la# it.
%i#!ler noted t!at t!e o77i#ial se:uen#e o7 t!e !uman genome
7eatured una##ounted?7or geneti# material ne(t to SR"52. $is team
7ound t!at t!is as be#ause t!e gene
!ad du'li#ated itsel7 ti#e and t!e #o'ies ere so similar to t!e
original t!at no one
!ad distinguis!ed beteen t!em.
Furt!er analysis reealed t!at t!e 7irst du'li#ation !a''ened
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3!e timing o7 t!e du'li#ations is signi7i#ant. 3!e 7irst
!a''ened
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sediment as able to 'us! into t!e ga' beteen t!e bones
)ro#eedings o7 t!e
ational 5#ademy o7 S#ien#es, @&*+ 10.10Eong .>., ilson
R.I., %an %. %i#!ler, 2012. %olution o7
$uman?S'e#i7i# eural SR"52 "enes by *n#om'lete Segmental
@u'li#ation. Jolume 149, *ssue 4, 11 May 2012, ages 912K922
;!arrier ;., >os!i I., ;outin!o?Budd >., Iim >?%,
/ambert ., de Mar#!ena >., >in ?
/, Jander!aeg!en ., "!os! 5., Sassa 3., olleu( F., 2012.
*n!ibition o7
SR"52 Fun#tion by *ts $uman?S'e#i7i# aralogs *ndu#es eoteny
during
S'ine Maturation &riginal Resear#! 5rti#le. ;ell, Jolume
149, *ssue 4, 11
May 2012, ages 92
