Friday, November 21, 2008

The Female Macaque Brain

Or: male macaques are from Mars, female macaques are from Venus...


Monkey gossip hints at social origins of language
WOMEN may be fed up with being stereotyped as the chattier sex, but the cliche turns out to be true - in female-centric monkey groups at least. The gossipy nature of female macaques also adds weight to the theory that human language evolved to forge social bonds.


The NewScientist article starts out on the wrong foot, implicitly trotting out the old Brizendine canard,1
• A woman uses about 20,000 words per day while a man uses about 7,000
In a thoroughly researched series of posts from 2006, Mark Liberman explained there's no evidence at all for that claim:
I looked through the book to try to find the research behind the 20,000-vs.-7,000-words-per-day claim, and I looked on the web as well, but I haven't been able to find it yet. Brizendine also claims that women speak twice as fast as men (250 words per minute vs. 125 words per minute). These are striking assertions from an eminent scientist, with big quantitative differences confirming the standard stereotype about those gabby women and us laconic guys. The only trouble is, I'm pretty sure that both claims are false.
But back to the gossiping monkeys.

Many researchers think that language replaced grooming as a less time-consuming way of preserving close bonds in ever-growing societies.

Nathalie Greeno and Stuart Semple from Roehampton University in London hypothesised that if this was true then in species of animals with large social networks, such as macaques, vocal exchanges should be just as important as grooming.

The duo listened to a group of 16 female and eight2 male macaques living on Cayo Santiago island off Puerto Rico for three months. They counted the grunts, coos and girneys - friendly chit-chat between two individuals - while ignoring calls specific to the presence of food or a predator.

The team found that females made 13 times as many friendly noises as males. "The results suggest that females rely on vocal communication more than males due to their need to maintain the larger social networks," Greeno says.

This is not at all surprising, because the social structure of rhesus monkey troops is female-centric. As the authors (Greeno & Semple, 2008) explain in their paper:

In female-bonded primate species, adult females spend significantly more time involved in grooming than adult males and also devote a much higher proportion of their time to same-sex rather than mixed-sex grooming interactions.

And why are these monkey vocalizations considered "gossip"? The NewScientist article continues:

Females were also much more likely to chat to other females than to males. Greeno suggests this is because female macaques form solid, long-lasting bonds as they stay in the same group for life and rely on their female friends to help them look after their offspring. In contrast, males, who rove between groups throughout their life, chatted to both sexes equally (Evolution and Human Behavior, DOI: 10.1016/j.evolhumbehav.2008.09.002).

So here we have the nonverbal vocalizations of female monkeys as a precursor to the "chattier" nature of female humans...


MTV's Artist of the Week 04.21.08: Gossip

Footnote

1 This quote was from the original version of Louann Brizendine's book, The Female Brain.

2 The original paper said there were only 7 male monkeys, or to be precise: 16 adult females and 7 adult males. One set of analyses did correct for this unequal number. There were also an unknown number of juvenile monkeys, although the article did not say how many. Data were collected only from the adults, with separate analyses examining vocalizations directed towards all monkeys vs. vocalizations directed towards adults only.

Reference

N GREENO, S SEMPLE (2008). Sex differences in vocal communication among adult rhesus macaques. Evolution and Human Behavior DOI: 10.1016/j.evolhumbehav.2008.09.002

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5 Comments:

At November 21, 2008 5:04 AM, Anonymous Anonymous said...

Hmmmm.... i've just read the New Scientist article, and you seem to ignore some important sentences that suggest NS did actually get the point of the research. For instance, in the first paragraph:

"The gossipy nature of female macaques also adds weight to the theory that human language evolved to forge social bonds," which suggests the real news i is the implication of the work for the evolution of language - not sex differences in humans....

and later on:

"Many researchers think that language replaced grooming as a less time-consuming way of preserving close bonds in ever-growing societies.

Nathalie Greeno and Stuart Semple from Roehampton University in London hypothesised that if this was true then in species of animals with large social networks, such as macaques, vocal exchanges should be just as important as grooming."

and....

"It is not known whether early human societies were female-centric, as macaques are, but the team believe that their findings support the theory that human language evolved to strengthen ties between individuals," which also gives the same message.

In fact, the article makes no suggestion that this explains sex differences in human communication, because there are none. Instead, it is pointing out that sociability leads to greater language use - which could explain why we developed language in the first place.

 
At November 21, 2008 6:05 AM, Blogger The Neurocritic said...

I did get the point of the article, Anonymous, but I thought it started out on the wrong foot in the title and first paragraph by (1) bringing up the old stereotype, which it made no effort to rebut; and (2) comparing social vocalizations (grunts, coos, girneys) to gossip.

 
At November 21, 2008 6:11 AM, Blogger The Neurocritic said...

Oh, I should add that in their Discussion, Greeno and Semple went out of their way to distinguish their monkey results from results in humans, but the NewScientist article did not.

The sex differences in adult rhesus macaques' rate of vocalisation documented here contrast markedly with the lack of evidence for such differences in our own species. Mehl et al. (2007) recently debunked the idea that in Western cultures, women talk more than men; their data revealed no significant variation between the sexes with respect to the number of words spoken per day. This lack of difference may reflect the fact that modern humans are not female-bonded in the sense that this term is used to describe nonhuman primate social structure. Data on daily word use among traditional societies where female kin networks are strong, and matrilocality is the norm, are needed to assess whether the link between sociality and reliance on vocal communication seen in the present study is relevant also to humans.

 
At November 23, 2008 7:14 PM, Blogger Sandra said...

Were the juvenile monkeys texting each other a lot?

 
At November 23, 2008 7:23 PM, Blogger The Neurocritic said...

Yes, and Twittering too.

 

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