Papers on planning and yawn contagion in great apes recently published. Both are open access.
Two new open access papers in cognitive reasearch on primates have recently been published involving researchers from the department.
Press release for the paper on yawn contagion (scroll for Swedish):As chimpanzees grow, so does yawn contagion
Chimpanzees catch yawns from humans - and, like humans, develop this sensitivity gradually
Do you get tired when others yawn? Would a chimpanzee get tired if you yawned? New research from Lund University in Sweden establishes for the first time that chimpanzees catch yawns from humans, i.e. the yawn is contagious. But not if the chimpanzee is too young. The study found that, like humans, chimpanzees develop a susceptibility to contagious yawning gradually. While juvenile chimpanzees (5-8 years of age) catch human yawns, infant chimpanzees seem immune to yawn contagion. Aside from humans, cross-species yawn contagion and a gradual development thereof, has previously been demonstrated in only dogs.
Yawning together is not just a sign of being tired at the same time. Previous research, on adult humans, chimpanzees, bonobos, baboons and dogs, has suggested that contagious yawning may be used as a measure of empathy, that is the ability to feel or imagine others’ emotional experiences. One of the reasons is that we tend to be more susceptible to catch yawns from those we are close to.
The yawning research was carried out at Tacugama Chimpanzee Sanctuary in Sierra Leone, where 33 orphaned chimpanzees, aged between 13 months and 8 years, engaged in bouts of playful interaction with a researcher, who repeatedly either yawned, gaped (simply opening of mouth without yawning) or wiped her hand over her nose. Yawning, but not nose-wiping, was contagious. While younger chimpanzees did not respond to yawning, chimpanzees above 5 years of age yawned contagiously - that is, they yawned more in the yawning context than in any of the other ones.
As a way of examining the role that empathy with the yawner played for contagion, the study also compared the chimpanzees’ reactions towards yawns from their human surrogate mother and a stranger. Contrary to prediction, there was no difference in the likelihood of yawning when engaging with an unfamiliar person from someone with whom the chimpanzees had a close relationship.
The developmental pattern found in the study is consistent with what previous research has found for humans. Humans also show a developmental increase in susceptibility to yawn contagion, with children seemingly beginning to yawn contagiously around the age of four. This is the time when also empathy-related behaviours and the ability to accurately identify others’ emotions begin to manifest clearly.
One interpretation, that the researchers propose, is that “the results of the study reflect a general developmental pattern, shared by humans and other animals. Given that contagious yawning may be an empathetic response, the results can also be taken to mean that empathy develops slowly over the first years of a chimpanzee’s life”.
But what does the lack of a difference between the surrogate mother and the unfamiliar human yawning model mean?
“We do not have the full explanation yet, as it is a complex phenomenon that is being explored” Madsen and colleagues say. There are however at least two possible explanations.
One factor is that familiarity - which has been used to stand for empathy - seems to play out differently in immature and adult individuals. The present study suggests that juvenile chimpanzees generalise their yawn responses to humans, irrespective of familiarity and attachment history. In contrast, previous research on adult chimpanzees has shown that contagious yawning is targeted mostly towards familiar individuals. This research on adult individuals has, however, been conducted on chimpanzees that have seen other chimpanzees yawn, and furthermore only on video. The researchers are therefore cautious.
“Future research will have to examine whether there might be multiple reasons for yawning in response to others’ yawns, and whether these differences apply differently within and between these two species. That is, whether chimpanzees may apply ‘targeted empathy’ to interactions with members of their own species – and selectively catch yawns from familiar chimpanzees -, while they apply a more generalised form of empathy to interactions with humans.” A reason for this may be that chimpanzees typically engage in competitive, even hostile, relationships with unfamiliar members of their own species, but rarely do so with humans, who they mostly experience as cooperative.
“Alternatively, it is possible that younger chimpanzees switch from a ‘generalised empathy’ to all individuals - irrespective of species - to a more ‘targeted empathy’ as they mature into adults and possibly have stronger reasons to differentiate friends from foes”, the researchers conclude.
The research is published in the journal PLOS ONE, October 16, 2013.
Contact: Elainie Madsen
Tel. +46 727 3210 77
E-mail:
elainie.madsengmailcomIn SwedishSchimpanser smittas av människors gäspningar - och, liksom människor, utvecklar egenskapen gradvis
Blir du trött när andra gäspar? Skulle en schimpans bli trött när du gäspar? Ny forskning vid Lunds universitet visar för första gången att schimpanser smittas av våra gäspningar.
Men inte om schimpansen är för ung. Studien fann att schimpanser, liksom människor, utvecklar känsligheten för gäspsmitta gradvis. Förutom för människor har denna utveckling påvisats enbart för hundar. I den nya studien fann man att schimpanser under 5 år var närmast immuna mot gäspsmitta.
Att gäspa tillsammans är inte bara ett tecken på att man är trött samtidigt. Tidigare forskning på vuxna människor, schimpanser, bonoboer, babianer och hundar gör gällande att graden av gäspsmitta kan användas som ett mått på empati. Vi gäspar helt enkelt mer med de som vi står nära.
Gäspforskningen vid Lunds universitet genomfördes med 33 stycken 13 månader till 8 år gamla föräldralösa schimpanser vid Tacugama Chimpanzee Sanctuary i Sierra Leone. Schimpanserna fick leka stillsamt med en forskare medan denna gäspade upprepade gånger. För att säkerställa att det var gäspningar som utlöste gäspresponser hos schimpanserna så utsattes de också för andra typer av handlingar som involverade ansiktet. Schimpanser över 5 år gäspade mer i samband med forskarens gäspningar än under de andra omständigheterna.
För att undersöka rollen som empati kan spela för gäspsmittning så jämförde studien också schimpansernas reaktioner på när deras mänskliga surrogatmamma gäspade och när den främmande forskaren gäspade. Överraskande nog kunde ingen skillnad hittas i benägenhet att gäspa i närvaro av de olika människorna.
Utvecklingsmönstret är i linje med vad man funnit i tidigare forskning på människor. Människor uppvisar också en ökning av mottaglighet för gäspsmitta, där barn tycks smittas av gäspningar först vid omkring fyra års ålder. Det är också vid denna ålder som beteenden som relaterar till empati och förmågan att tolka andras känslor tydligt visar sig.
Forskarna föreslår att en tolkning av deras studie kan vara att resultatet visar på en typ av utveckling som delas av människor med andra djur. Givet att gäspsmitta kan vara en empatisk respons, föreslår de vidare att empati utvecklas långsamt under en schimpans första år i livet.
Men vad betyder det att skillnaden mellan surrogatmamman och forskaren var obefintlig?
“Vi har inte hela förklaringen ännu”, säger forskarna. “Det är ett komplicerat fenomen som undersöks.”
En anledning är att nivån av familjäritet – det man hittills använt som mått på nivå av empati - verkar ha olika effekter hos unga individer och vuxna. Medan man i den nya studien fann att schimpanser över 5 år generaliserar sina gäspresponser till människor oavsett grad av familjäritet, så har man i tidigare forskning på vuxna schimpanser funnit att gäspsmitta inriktas på välkända individer. Den senare forskningen har dock bara skett på schimpanser som sett andra schimpanser gäspa, och därtill enbart på video. Forskarna är därför försiktiga i sina slutsatser.
Forskningen publicerades i tidskriften PLOS ONE, 16 oktober, 2013.
Kontakt: Elainie Madsen
Tel. 0727 3210 77
E-post:
elainie.madsengmailcom
Great apes can defer exchange: a replication with different results suggesting future oriented behavior is published in Frontiers in Psychology and can be accessed by following the link.
Authors: M. Osvath & T. Persson