Sunday, February 25, 2007

The evolution of language acquisition

The animal kingdom is full of noisy beasts. Screeching monkeys, barking dogs, squawking chickens…animals use sounds to communicate with each other, both friends and foes. These sounds are instinctual, and although the animals may learn, through observation, when a particular sound is appropriate, the quality of the sounds is not learned; the vocalizations are acoustically innate. What about human vocalizations? Excepting expressions of intense emotions (crying, screaming, laughing), most forms of human vocalizations, particularly speech, are acquired through a learning process. Babies learn to speak by perceiving sounds, imitating them, and then modifying their own vocal output in a process called “vocal learning.”

Vocal learning, or acquiring vocalizations through imitation rather than instinct, is not unique to humans, but is extremely rare in the animal kingdom. In fact, only three other distantly related groups of mammals (elephants, bats, and cetaceans (whales and dolphins)) and three distantly related groups of birds (hummingbirds, parrots, and songbirds) are capable of vocal learning.

The group that has received the most attention from neuroscientists, with respect to vocal learning, includes the songbirds. A growing body of research focuses on the brain structures that allow birds to perceive, learn, and generate songs, and the hope is that this research may contribute to understanding the neural mechanisms underlying human language acquisition. These structures, which include seven “vocal brain nuclei,” are involved in networks that mediate both the perception and production of sounds, allowing birds to hear themselves, hear others, and control the acoustic structure of their vocal output.

By looking at genes that are up- or down-regulated in response to singing behavior, researchers (notably Dr. Erich Jarvis at Duke University) found that these seven nuclei are strikingly similar in location, connectivity, and behaviorally-driven gene expression across all three bird groups, and speculates that similar brain structures are at play in other vocal learners.

This image shows comparable vocal and auditory brain areas among vocal learning birds and humans. Left hemispheres are shown, as that is the dominant side for human language. From Jarvis, Ann. N.Y. Acad. Sci 1026: 749-777 (2004).


Because human brain lesions and brain imaging studies do not allow for a high resolution analysis, the neuroanatomy of comparable vocal nuclei in humans has not been demonstrated. It is interesting to note however, that like birds, humans have brain regions in the cerebrum that control the acoustic structure of their vocal behavior. For example, Broca’s area plays a selective role in speech production; humans with damage to this region have difficulty speaking, but have little or no deficits in comprehension. Somewhat surprisingly, the neuroanatomy of similar structures in other vocal learning mammals (elephants, bats, cetaceans) has not been examined.

Given that parrots and hummingbirds diverged from one another about 65 million years ago, and that birds evolved 50-100 million years after mammals, the evolution of vocal learning is perplexing. Not only did this complex behavior evolve in phylogenically disparate groups, but also, in every species that has been examined, it is governed by similar neural structures. How did these striking similarities evolve?

Dr. Jarvis suggests three hypotheses. The first is convergent evolution; that is, similar structures evolved independently in all vocal learners. This implies significant constraints on how these structures can evolve to mediate this complex behavior. (For comparison, the “eye” is believed to have evolved independently eleven times, but each time has produced dramatically different structures…compare a human eye to those of a spider).

The second hypothesis is that all vocal learners came from a common ancestor, and that vocal learning was thus lost in all non-learners. Given that these animals diverged hundreds of millions of years ago, this would imply that the capacity for vocal learning was lost independently by every other animal; non-human primates would have lost this capacity multiple times before humans evolved with the trait intact. The third hypothesis modifies the first, positing that all animals have rudimentary neural structures for vocal learning, but that these structures have been independently amplified in vocal learners.

All three of these hypotheses are possible alternatives, and all are constrained by the rarity of vocal learning in the animal kingdom. Vocal learning has clear benefits: by permitting the modification of sounds, it allows for innovative and flexible communication. This system may be the foundation upon which spoken language in humans was established, and certainly contributes to reproductive success in songbirds. Further, these attributes may allow animals to maximize sound propagation in novel environments (e.g. if an animal must adjust from living in an open savannah to living on a heavily forested mountain). If such a useful behavior could evolve seven independent times, why didn’t it evolve more often? Alternatively, if vocal learning was present early on, why would most animals have lost the capacity?

Jarvis’s answer: predation. The ability to make novel, varied sounds, and to maximize their propagation, is an excellent way to advertise one’s presence to potential predators. Thus, for the majority of animals, the benefits of vocal learning are far outweighed by the hazards it brings.

Only seven known groups of distantly related animals are capable of vocal learning--this in itself is fascinating. The fact that seven similar brain structures have evolved in three of these learners only adds to the excitement. Have the brains of mammalian vocal learners evolved similar mechanisms for perceiving and producing sounds? More importantly, have humans? Did this ability to imitate and improvise sounds lead to the evolution of human language?

33 comments:

AnimalEnthusiast said...

This is a great article. I didn't know anything about vocal learning, but I thought it was very interesting. Thanks for sharing the information!

Anonymous said...

Recently I began attempting to learn a new language online, just to have something else to put on my CV, and I was amazed how many different types of language software there are available. In the end I decided to purchase some gear that would help me learn French and it has been amazing, I can’t believe how quickly I am picking it all up! Going to give Russian a go next!

宇韩 said...

wow gold
wow gold
eve isk
wow power leveling
wow power leveling
wow power leveling
wow power leveling
warhammer gold
warhammer power leveling
bestchina traveland
uggsor
ghd straighteners

Cardi Ugg Boots
Classic Short Ugg Boots

Classic Tall Ugg Boots
Metallic Ugg Boots

Mini Ugg Boots
Sundance Ugg Boots

tiffany Jewelry

宇韩 said...

wow gold
wow gold
eve isk
wow power leveling
wow power leveling
wow power leveling
wow power leveling
warhammer gold
warhammer power leveling
bestchina traveland
uggsor
ghd straighteners

Cardi Ugg Boots
Classic Short Ugg Boots

Classic Tall Ugg Boots
Metallic Ugg Boots

Mini Ugg Boots
Sundance Ugg Boots

tiffany Jewelry

Anonymous said...

酒店喝酒,禮服店,酒店小姐,酒店領檯,便服店,鋼琴酒吧,酒店兼職,酒店兼差,酒店打工,伴唱小姐,暑假打工,酒店上班,酒店兼職,ktv酒店,酒店,酒店公關,酒店兼差,酒店上班,酒店打工,禮服酒店,禮服店,酒店小姐,酒店兼差,暑假打工,酒店經紀,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,寒假打工,酒店小姐,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,暑假打工,酒店小姐,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,寒假打工,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,暑假打工,酒店小姐,台北酒店,禮服店 ,酒店小姐,酒店兼差,暑假打工,酒店小姐,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,寒假打工,酒店小姐,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,暑假打工,酒店小姐,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,寒假打工,酒店小姐,台北酒店,禮服店 ,酒店小姐,酒店經紀,酒店兼差,暑假打工,酒店小姐,禮服店 ,酒店小姐,酒店經紀,酒店兼差,寒假打工,酒店小姐,禮服店 ,酒店小姐,酒店經紀,酒店兼差,暑假打工,酒店小姐,禮服店 ,酒店小姐,酒店經紀,酒店兼差,寒假打工,酒店小姐,禮服店 ,酒店小姐,酒店經紀,酒店兼差,暑假打工,酒店小姐,酒店傳播,酒店經紀人,酒店,酒店,酒店,酒店 ,禮服店 , 酒店小姐,酒店經紀,酒店兼差,暑假打工,招待所,酒店小姐,酒店兼差,寒假打工,酒店上班,暑假打工,酒店公關,酒店兼職,禮服店 , 酒店小姐 ,酒店經紀 ,酒店兼差,暑假打工,酒店,酒店,酒店經紀,酒店領檯 ,禮服店 ,酒店小姐 ,酒店經紀 ,酒店兼差,暑假打工, 酒店上班,禮服店 ,酒店小姐 ,酒店經紀 ,酒店兼差,暑假打工, 酒店上班,禮服店 ,酒店小姐 ,酒店經紀 ,酒店兼差,暑假打工, 酒店上班,酒店經紀

Anonymous said...

Hello !.
You may , perhaps curious to know how one can collect a huge starting capital .
There is no initial capital needed You may start earning with as small sum of money as 20-100 dollars.

AimTrust is what you haven`t ever dreamt of such a chance to become rich
The company represents an offshore structure with advanced asset management technologies in production and delivery of pipes for oil and gas.

It is based in Panama with affiliates around the world.
Do you want to become a happy investor?
That`s your chance That`s what you desire!

I`m happy and lucky, I started to take up real money with the help of this company,
and I invite you to do the same. If it gets down to choose a proper partner who uses your funds in a right way - that`s the AimTrust!.
I make 2G daily, and my first investment was 500 dollars only!
It`s easy to join , just click this link http://rocifaqydy.easyfreehosting.com/wycakyl.html
and lucky you`re! Let`s take this option together to get rid of nastiness of the life

Anonymous said...

This innovative masterpiece brought about a perpetual calendar with moon phase display.
http://www.watchestoo.com
IWC
IWC Da Vinci Automatic Chronograph IW376402
IWC Da Vinci Automatic Chronograph IW376403
IWC Da Vinci Automatic IW452302
IWC Da Vinci Perpetual Calendar Chronograph IW375803
IWC Da Vinci Perpetual Calendar Edition Kurt Klaus IW376203
IWC Da Vinci Perpetual Calendar Edition Kurt Klaus IW376203
IWC Da Vinci Perpetual Calendar Edition Kurt Klaus IW376204
IWC Da Vinci Perpetual Chronograph IW375034
IWC Da Vinci Vintage IW546101

raoliming2 said...

louis vuitton
replica handbags
Handbags
balenciaga replica handbags
chanel replica handbags
chloe replica handbags
fendi replica handbags
gucci replica handbags
hermes replica handbags
louis vuitton replica handbags
miumiu replica handbags
prada replica handbags
ysl replica handbags
chanel replica handbags
gucci replica handbags
louis vuitton replica handbags
balenciaga replica handbags
chanel replica handbags
chloe replica handbags
fendi replica handbags
gucci replica handbags
hermes replica handbags
louis vuitton replica handbags
miumiu replica handbags
prada replica handbags
ysl replica handbags
replica handbags
replica handbags
fake designer handbags
discount replica handbags
replica handbags
replica handbags
replica handbags
designer replica handbags
replica handbags
replica handbags
replica handbags
fake replica handbags
fake replica handbags
replica handbags
replica handbags

kiara said...

Costa Rica Manuel Antonio Tours
Costa Rica Carara Biological
Arenal Volcano Costa Rica
Costa Rica Crocodile Aventure
Costa Rica Poas Volcano
Costa Rica Monteverde Tours
Costa Rica Sea Kayaking
Costa Rica Rafting
Costa Rica Atv Adventure
Costa Rica Tours Canopy
Costa Rica Rainforest Tour
Costa Rica Vacation Rentals
Costa Rica Groups Travel
Los Suenos Costa Rica Tours
Costa Rica Zip Line
Costa Rica Vacation Rentals
Costa Rica los Suenos Vacation Rentals
Costa Rica Wedding
Costa Rica los Suenos Fishing
Costa Rica los Suenos Condos
Costa Rica los Suenos Sportfishing
Los Suenos Resort
Costa Rica Whale Watching Tours
Costa Rica Dolphin Watching Tours
Costa Rica Dominical
Costa Rica Dominical Tours
Dominical Tours
Dominical Costa Rica Tours
Costa Rica DMC Incentive Travel

Anonymous said...

To be a noble benign being is to from a kind of openness to the world, an cleverness to group uncertain things beyond your own control, that can take you to be shattered in hugely exceptional circumstances for which you were not to blame. That says something very impressive relating to the condition of the ethical life: that it is based on a corporation in the uncertain and on a willingness to be exposed; it's based on being more like a shop than like a sparkler, something kind of dainty, but whose mere precise handsomeness is inseparable from that fragility.

Anonymous said...

Advice in old age is foolish; for what can be more absurd than to increase our provisions for the road the nearer we approach to our journey's end.
[url=http://chopardhappy.livejournal.com/]Watches[/url]
Watches

office said...

Realizing he might have dug himself in there,Microsoft Office 2010the general emphasized that Office 2010he had spent some time as a junior Office 2007officer working "very closely Microsoft Officewith the Israeli air force" and that heMicrosoft Office 2007had found that "more cosmopolitan,Office 2007 key liberal version of the Israeli population" Office 2007 downloadto be just chock full Office 2007 Professionalof that sort of "goodwill" necessary Windows 7to give a bunch of land back Microsoft outlook 2010to the Palestinians.

xiaoxia said...

Here is Ugg boots e-shop. We ugg outlet store has beautiful and best ugg
classic cardy with cheap price, fast shipping and good service for sale.mbt shoes sale

Anonymous said...

It’s really a great and helpful piece of information.
I’m glad that you

shared this helpful information with us. Please keep us up
to date like this. Thanks for

sharing.
My web site :: www.centerforneighborhoods.org

Anonymous said...

I’m impressed, I need to say. Really not
often do I encounter a blog that’s both educative and entertaining, and let me let you know, you
will have hit the nail on the head. Your

concept is excellent; the problem is one thing that not

sufficient persons are talking intelligently about. I'm very

comfortable that I stumbled throughout

this in my seek for one thing regarding this.
Also visit my site - repeats

Anonymous said...

Hello my family member! I want to say that
this post is amazing,

nice written and include approximately all vital infos.
I would

like to peer extra posts like this .
Feel free to visit my website :: newunionism.blogspot.ru

Anonymous said...

I’ll right away take hold of your rss feed as I

can't to find your e-mail subscription link or e-newsletter service. Do

you've any? Kindly let me recognise so that I may subscribe.
Thanks.
Feel free to surf my blog ; http://www.jobsinspain.org/

Anonymous said...

Its such as you learn my mind! You seem to grasp a

lot approximately this, like you wrote the ebook in it or
something. I feel that you simply can do with some p.c.

to

drive the message home a bit, but instead of that,

this is wonderful blog. An excellent read. I'll definitely be back.
Also visit my page : embassy of spain in the philippines website

Anonymous said...

Super-Duper website! I am loving it!! Will come back again.

I am bookmarking your feeds also.
Feel free to surf my web blog ... www.diysolarheatingspain.com

Anonymous said...

I want to express some thanks to

this writer just for rescuing me from such a

instance. As a result of

looking out throughout the the net and finding

methods that were not

pleasant, I figured my life was

done. Existing minus the

answers to the problems you've sorted out all through your main short article is a crucial case, and ones that could have badly

damaged my career if I hadn't come across your site.

Your own personal natural talent and kindness in handling every aspect was precious.
I don't know what I

would have done if I hadn't discovered such a
thing like this. It's possible to at this moment look forward to my future. Thanks for your time very much for your specialized and

effective help. I will not hesitate to suggest the website to anyone who would like tips

on this situation.
Also visit my web site :: car classifieds San Augustin

Anonymous said...

Hello there, simply was alert to your blog thru Google, and found
that it is truly informative. I am going to

watch out for brussels. I will appreciate when you proceed this in future.
Lots of folks will probably be benefited from your
writing. Cheers!
Take a look at my blog post Www.Catralproperty.net/catralforum.html

Anonymous said...

This is very interesting, You're a very skilled blogger. I have joined your feed and look forward to seeking more of your wonderful post. Also, I have shared your site in my social networks!

my blog; michael kors mens watches

Anonymous said...

After research a few of the blog posts in your web
site now, and I truly like your manner of blogging. I bookmarked
it to my bookmark website listing and will be checking back soon.
Pls check out my site as properly and let me know what you
think.

My weblog クロエ バッグ

Anonymous said...

1 year anniversary to FB suspension... hope everyone of you doing nicely over there.


my web-site: how to attract women

Anonymous said...

Can girls make use of the nitric oxide supplements?

my blog mike chang's six pack shortcuts complete download

Anonymous said...

Your style is so unique in comparison to other
folks I have read stuff from. I appreciate you for posting when
you have the opportunity, Guess I will just bookmark this web site.


My webpage: acoustic guitar chords for beginners

Anonymous said...

no it does not it just depends in case you eat to much meals.


my web site calorie Calculator build muscle lose fat

Anonymous said...

Any quiries or any issues or need to join this you should contact 9327522635.
Supervisor in herbalife !

Also visit my weblog :: vegan weight loss foods to avoid

Anonymous said...

Merry Christmas to you and yours from Annie, Bean and all the #Moo's right here at Authentic Haven Brand Natural Brew I'm so looking
forward to growing wonderful gardens this coming 2012

my website ... order arrow sheds

Anonymous said...

Thanks for some other informative website. Where else could I
am getting that type of information written in such an ideal way?

I have a project that I'm just now operating on, and I have been on the look out for such info.

Here is my homepage; vigrx plus really work yahoo

Anonymous said...

I absolutely agree together with your post. I've lived right here for almost three years now and also you are so appropriate about the misleading numbers. Enjoyable spot to complete issues and celebration, but boyfriend and partner are few and far among. My solitary close friends have told me stories which have made me believe twice about remaining right here. Once my deal is up in seventeen months, I'm outta here.


my site; female mind mastery kirsten price

Anonymous said...

I can't stand touching raw meat so I purchased a box of sterile latex gloves and keep them inside the kitchen.

Feel free to surf to my blog healthy cooking for one or two

Anonymous said...

Just a guess but I bet he pegged it there through self experimentation.
I mean I've to imagine he knows what worked for him...and his clients.

Here is my web-site: eat healthy cheap and easy