Michael Bell8th June 2016
A series of recent experiments has shown that various types of fish and birds are able to distinguish between different individual humans. Classically, this has been supposed to be possible only between the members of more advanced species, and specifically for those that have developed socialization to the point of needing to be able to recognize and characterize particular individuals. A husband recognizes his wife, at least if he does not mistake her for a hat; a dog recognizes its mistress; and even a snake knows its owner. Of course, vision is not the only sensory modality involved: smell is no doubt equally important; and if animals are telepathic, they may also be using techniques to which my wife and I have no access.
As described in the journal Scientific Reports, a team of scientists from Oxford and Queensland Universities found that archerfish were able to learn and recognize faces with a high degree of accuracy, discriminating one face from up to 44 others. This species of tropical fish, known for its ability to spit jets of water to knock down aerial prey, were presented with two images of human faces and trained to choose one of them using their jets. The fish were then presented with the learned face and a series of new faces and were able to correctly choose the face they had initially learned to recognize. They were able to do this task even when more obvious features, such as head shape and colour, were removed from the images.
First author Dr Cait Newport, Marie Curie Research Fellow in the Department of Zoology at Oxford University, said: "The fact that archerfish can learn this task suggests that complicated brains are not necessarily needed to recognize human faces. Humans may have special facial recognition brain structures so that they can process a large number of faces very quickly or under a wide range of viewing conditions."
Separately, as reported in PLOS ONE by Masanori Kohda from the Osaka City University, Japan and colleagues, daffodil cochlid fish attended to digital models with unfamiliar faces longer and from a further distance than to models with familiar faces. This is a group-living species and the results suggest that fish may be able to distinguish individuals accurately using facial color patterns.
In two further experiments, animal behaviour experts from the University of Lincoln in the UK and the University of Vienna worked with pigeons and crows. Their results, published in Avian Biology Research shows that pigeons can reliably discriminate between familiar and unfamiliar humans, and that they use facial features to tell people apart. The experimental group birds were able to recognise and classify the familiar people using only their faces, whereas the birds without prior training failed. In a separate study, published in the journal Animal Cognition, the team investigated the ability of carrion crows to differentiate between the voices and calls of familiar and unfamiliar humans and jackdaws. The crows responded significantly more often to unfamiliar than familiar human voices and, conversely, responded more to familiar than unfamiliar jackdaw calls.
Humans have long been inclined to credit themselves with mental abilities denied to 'lesser' species, although little by little, the differences have been whittled away by successive researchers. There always will be differences, of course, albeit in some cases to the disadvantage of humans, but by now research has demonstrated a remarkable degree of homology between the brains of multiple species, including ourselves. Evolution is very parsimonious.
Many scientists are now somewhat grudgingly coming to accept that we are not quite as exceptional as we like to imagine we are, but one respect in which they lag far behind the truth is in respect of sociality. By all means, it is true that the achievements of our society, some glittering and some noticeably debased, have been erected on the foundations of group living, but there is a disconnect between the admitted role of sociality in human existence and its comparable importance for earlier species, which is highlighted by these results, exemplified by the description, above, of cochlid fish as being 'group living', as if other types of fish behave otherwise. Did you ever see a type of fish that did not school? or a type of bird that did not flock? Why then would they not be able to recognize each other, not just as conspecifics, but as individuals? It must be admitted that individuality has reached a peak of elaboration in human groups, but this has been built on a principle that already existed.
In searching for the origins of individuality, we may not go as far as to propose that ragworms distinguish themselves one from another, although even a ragworm may 'notice' or respond to the fact that a fellow ragworm is bigger or smaller or smellier or faster, and behave accordingly. The question is: at what stage of evolutionary development did awareness of difference between oneself and one's fellows come to have a significant adaptive advantage; because that is the moment at which individuality arose as a fundamental principle of life, alongside the ability to notice it.
Michael BellOctober 22, 2014
Recently published research in Proceedings of the National Academy of Sciences
suggests that early human use of fire had major social implications as well
as the more commonly described dietary and physiological aspects.
Dr Polly Wiessner, Professor of Anthropology at the University of Utah, analysed
the content of 174 recorded or documented day and nighttime conversations among
Kalahari Bushmen, and says that sitting around a campfire at night enables conversations,
storytelling, and social bonding more effectively than daytime interactions.
"I found this really fascinating difference between conversations by firelight
and conversations in the day," says Wiessner. "The day is harsh, you
see the realities, you see the facial expressions, there's work to be done,
and there's social regulation, and at night people kind of mellow out. The day
is productive time for hunting and gathering and the firelight changed our circadian
rhythm, so we stayed awake much longer and it gave a whole new time and space,
and it was a time when no work could be done," she says. "I think
it had an impact on our cognitive evolution; the stories are told in wonderful
language, perhaps increasing linguistic skills and the imagination . . . when
you're out in the dark by a fire, so many of the stimuli are shut out and your
imagination then takes off."
Weissner notes that fireside conversations often focus on wider social contexts
and relationships among a far-flung network of acquaintances, some of whom may
even be dead.
Humans didn't invent fire, of course; they learned to control it, and to use
it for cooking, heating, manufacture, deterrence of predators. And now it seems
that it may have played a considerable role in the development of language and
social structures. Based on archeological evidence, early human use of fire
is dated to between 400,000 and one million years ago, and is commonly associated
with Homo erectus, although many commentators think that fire came into regular
use only towards the end of that time period, perhaps driven at least partly
by the need to cook food to support the metabolic demands of the enlarging human
300-400,000 years ago is (very approximately) the period during which homo
erectus began its gradual transition into homo sapiens, and a time at which
spoken language was beginning itss rapid development alongside the elaboration
of the human social group. Wiessner's 'wonderful language' wouldn't yet exist,
but it's not hard to imagine that firelight would have played a considerable
role in the crucible of linguistic and societal development.Michael BellAugust 27, 2014
There have been many academic studies linking increased brain size in mammals to social complexity: it doesn't seem very contentious to suggest that dealing with the complex behaviours of up to 150 group members would require more brain cells than solitary life. Or at least it seems likely to have been true until the state began to take over management of social relationships: someone should study whether couch potatoes have smaller brains than professional carers. But there have been relatively few rigorous attempt to correlate brain size with particular social behaviours.
Now a team in the University of Colombia's Department of Zoology has carried out research, published in the Journal of Ecology and Evolution, which demonstrates a clear correlation between brain size and the need to care for offspring. OK, it's in stickleback fish, and they're not even mammals, but what seems particularly convincing is that it's the males that have larger brains than the females, and it's the males who do the caring in that particular species. Of course this will be unsurprising to human females, who have long known that looking after their children requires more mental capacity than going down to the pub and watching football, but it does offer an escape route from female domination for those males who are prepared to search for their inner carers.
Well, enough frivolity. In the study, 'Reversed brain size sexual dimorphism accompanies loss of parental care in white sticklebacks', researchers compared regular male sticklebacks to male white sticklebacks, which do not tend to their offspring, and found a clear difference in brain size. They found evidence that this change in male behaviour – giving up caring for the young – occurred at the same time the white stickleback evolved a smaller brain. The white stickleback is a newly-emerged species that only diverged from other sticklebacks 10,000 years ago.
Said lead author Kieran Samuk, a PhD student in UBC's Dept. of Zoology: "This suggests that regular sticklebacks have bigger brains to handle the brain power needed to care for and protect their young. This is one of the first studies to link parental care with brain size."
The association between greater brain size and social complexity is of course demonstrated across many species, not just mammalian. How far back could we go, then in terms of demonstrating a linkage between social (groupish) behaviour and brain size?
Before fish, in general terms, from an evolutionary perspective, came sharks (chondrichthians). They certainly have social behaviours, and there is a wide variety of brain designs and sizes among contemporary sharks. Interesting then, to know if any correlation could be established between shark socializing and their brain size. Then come the invertebrate sea creatures, and another level of difficulty in terms of research. We need submersible robot PhDs, and that is a stretch, currently.
M G BellJanuary 6, 2014
It's well known that cuckoos parasitize the nests of other birds, and the benefit
to the cuckoos of this "brood parasitism" is obvious; what is not
clear is why young members from other nests of the species that is being parasitized
sometimes help to feed an intruder cuckoo chick.
Research carried out by a team led by evolutionary biologist Dr Naomi
Langmore of the Australian National University has studied this phenomenon,
known as "cooperative breeding", concluding that it is because
the continued presence of a group of the host species acts to deter the cuckoos
from placing their eggs in the hosts' nests in the first place.
"It's a very puzzling type of behaviour," says Langmore. While at
first it was thought that the reason for the young birds to hang around was
simply that they helped to raise more chicks, the research has suggested that
the group mechanism is more credible.
The researchers studied colonies of speckled warblers and fairy wrens, finding that
a team of four or five group helpers made it much more likely the hosts could
defend their nests against cuckoos than a smaller team of only two or three
birds, not being enough individuals to "mob" cuckoos and drive them
"Maybe the main benefit cooperative breeding provides is in safety in
numbers," says Langmore.
"Brood parasites lay their eggs in the nests of other birds and then they
abandon their young to the care of the host," says Langmore. "So the
host loses that brood then they invest weeks or months rearing the cuckoo chick
and very often have no time left to breed again after that. This is a massively
costly thing for the host."
The research showed a clear correlation between the size of groups of fairy
wrens and their ability to resist parasitism.
"If there are four or more individuals in the group they almost never
get parasitized by a cuckoo whereas the small groups of two or three individuals
are much more likely to get parasitized."
"We can't say that brood parasitism actually caused the evolution of cooperative
breeding because we can't say which one came first," says Langmore. "But
we can say that it provides a very strong selective force for the maintenance
of cooperative breeding."M G BellNovember 23, 2013
Research at UCLA on the coloration and complexity of primate faces (monkeys and apes) has shown that there is a correlation between those attributes and the size of social groups, although the effect was less marked among apes as opposed to monkeys, which is thought to be because apes have a more highly developed set of facial expressions which they can use to aid recognition. Past a certain point, muscular expressivity might be a more flexible way of demonstrating individuality than coloration and physiognomical variation.
"Humans are crazy for Facebook, but our research suggests that primates have been relying on the face to tell friends from competitors for the last 50 million years and that social pressures have guided the evolution of the enormous diversity of faces we see across the group today," said Michael Alfaro, an associate professor of ecology and evolutionary biology in the UCLA College of Letters and Science and senior author of the study.
"Faces are really important to how monkeys and apes can tell one another apart," he said. "We think the color patterns have to do both with the importance of telling individuals of your own species apart from closely related species and for social communication among members of the same species."
"Our research suggests increasing group size puts more pressure on the evolution of coloration across different sub-regions of the face," Michael Alfaro said.
Other variables affected coloration such as distance from the equator and the degree of forest cover (true also of humans), but the degree of facial complexity was linked only to group size.
"We found that for African primates, faces tend to be light or dark depending on how open or closed the habitat is and on how much light the habitat receives," Alfaro said. "We also found that no matter where you live, if your species has a large social group, then your face tends to be more complex. It will tend to be darker and more complex if you're in a closed habitat in a large social group, and it will tend to be lighter and more complex if you're in an open habitat with a large social group. Darkness or lightness is explained by geography and habitat type. Facial complexity is better explained by the size of your social group."
Evidently, one must distinguish between group behaviour linked to mutual protection (such as among shoals of fish or herds of bison) and intra-group 'social' behaviour in which characteristics are attributed to individuals, requiring a mechanism to distinguish one individual from another. But it would be unjustified to make a hard and fast distinction between such types of groups. No doubt there is a continuum of intermediate situations between, at the most basic, a group whose members are simply recognizable as conspecifics because of their size, shape, color, or smell, and a complex social group in which individuals' behaviour towards each other depends on memory of previous interactions with a particular individual, emotional drives and external situations (to pick just a few out of many factors determining inter-personal behaviour).
It is an interesting question, as to how far back up the evolutionary tree animals first became able to distinguish indivuals from conspecifics in general. Do dogs recognize each other? – obviously yes; do lizards recognize each other? – hmmm; do sharks recognize each other? There is a lot we don't know!
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