According to a new study by University of Otago researchers, pigeons (Columbidae) can learn to distinguish real words from non-words by visually processing their letter combinations.
The researchers, led by Dr. Damian Scarf of the University of Otago’s Department of Psychology, trained rock pigeons (Columba livia, not to be confused with Streptopelia decaocto from the photo) to peck four-letter English words as they came up on a screen, or to instead peck a symbol when a four-letter non-word, such as "URSP" was displayed.
The researchers found that the pigeons' performance was on a par with that previously reported in baboons for this type of complex task.
Dr. Damian Scarf and his colleagues added words one by one with the four pigeons in the study eventually building vocabularies ranging from 26 to 58 words and over 8'000 non-words. To check whether the pigeons were learning to distinguish words from non-words rather than merely memorizing them, they introduced words the birds had never seen before.
The pigeons correctly identified the new words as words at a rate significantly above chance.
Co-author Prof. Onur Güntürkün, from the Department of Biopsychology at the Ruhr-University Bochum, Germany, said "that pigeons — separated by 300 million years of evolution from humans and having vastly different brain architectures — show such a skill as orthographic processing is astonishing."
"We may have to seriously re-think the use of the term ‘bird brain’ as a put down," added study senior author Prof. Michael Colombo, from the University of Otago’s Department of Psychology.
According to a new study led by Dr. Ole Andreassen of the University of Oslo (Norway), schizophrenia emerged after Homo sapiens diverged from Homo neanderthalensis.
Schizophrenia has existed throughout recorded human history and persists despite its severe effects on thought and behavior, and its reduced rates of producing offspring. Dr. Andreassen and colleagues looked at the genome of Neanderthals to pinpoint specific regions of the genome that could provide insight on the origin of the mental disorder in evolutionary history. They analyzed genetic data from recent genome-wide association studies of people with schizophrenia for overlap with Neanderthal genomic information.
"Some scientists think that schizophrenia could be a ‘side effect’ of advantageous gene variants related to the acquisition of human traits, like language and complex cognitive skills, that might have increased our propensity to developing psychoses," Dr. Andreassen said.
"We analyzed recent large genome-wide association studies of schizophrenia and a range of other human phenotypes (anthropometric measures, cardiovascular disease risk factors, immune-mediated diseases) using a statistical framework that draws on polygenic architecture and ancillary information on genetic variants," they explained.
"We used information from the evolutionary proxy measure called the Neanderthal selective sweep score."
Parts of the human genome associated with schizophrenia, so called "risk loci", were more likely to be found in regions that diverge from the Neanderthal genome. An additional analysis to pinpoint loci associated with evolutionary markers suggests that several gene variants that have undergone positive selection are related to cognitive processes. Other such gene loci are known to be associated with schizophrenia and have previously been considered for a causal role in the disorder.
"Our findings suggest that schizophrenia vulnerability rose after the divergence of modern humans from Neanderthals and thus support the hypothesis that schizophrenia is a by-product of the complex evolution of the human brain," Dr. Andreassen said.
"This study suggests that schizophrenia is a modern development, one that emerged after humans diverged from Neanderthals. It suggests that early hominids did not have this disorder," said Dr. John H. Krystal, Editor of Biological Psychiatry.
According to a new study led by Kyoto University researcher Saho Takagi, domestic cats (Felis catus) really have a certain understanding for elements of physics and the cause-and-effect principle.
The researchers tested if cats use a causal rule to infer if a container holds an object, based on whether it is shaken along with a sound or not. They also checked if cats expect an object to fall out or not, once the container is turned over.
"We presented cats with either an object dropping out of an opaque container or no
object dropping out (turning-over phase) after producing either a rattling sound by
shaking the container with the object inside, or no sound (shaking phase),"
Dr. Takagi and co-authors explained.
"The relation between the sound and the object matched with physical laws in half of
the trials (congruent condition) and mismatched in the other half (incongruent condition)."
The scientists found that the cats looked longer at containers shaken together with a noise, which suggests that cats use a physical law to infer the existence of objects based on whether they heard a rattle. Further, the cats also stared longer at containers in incongruent conditions, meaning an object dropped despite its having been shaken noiselessly or the other way around. The cats realize that such conditions don't fit into their grasp of causal logic.
"Cats use a causal-logical understanding of noise or sounds to predict the appearance
of invisible objects," said Dr. Takagi, who is lead author of a paper published this week
in the journal Animal Cognition.
"Hunting cats often need to infer the location or the distance of their prey from sounds
alone because they stake out places of poor visibility," Dr. Takagi said.
"Further research is needed to find out exactly what cats see in their mind’s eye when
they pick up noises, and if they can extract information such as quantity and size from
what they hear."
How can birds - those animals with such tiny brains - perform complicated cognitive behaviors comparable to primates? A new study led by Dr. Suzana Herculano-Houzel from Vanderbilt University finally found an answer on that question: birds have significantly more neurons packed into their brains than are stuffed into mammalian and even primate brains of the same mass.
The scientists systematically measured the number of neurons in the brains of 28 avian species ranging in size from the tiny zebra finch to the emu.
"We found that birds, especially songbirds and parrots, have surprisingly large numbers
of neurons in their pallium: the part of the brain that corresponds to the cerebral cortex,
which supports higher cognition functions such as planning for the future or finding
patterns," Dr. Herculano-Houzel said.
"That explains why they exhibit levels of cognition at least as complex as primates."
The neurons in avian brains are much smaller and more densely packed than those in mammalian brains. According to the study, parrot and songbird brains contain about twice as many neurons as primate brains of the same mass and 2 to 4 times as many neurons as equivalent rodent brains.
Further, the proportion of neurons in the forebrain of birds is also significantly higher.
"One of the important implications of the study is that it demonstrates that there is
more than one way to build larger brains," Dr. Herculano-Houzel said.
"Previously, scientists thought that as brains grew larger neurons had to grow bigger
as well because they had to connect over longer distances."
"But bird brains show that there are other ways to add neurons: keep most neurons
small and locally connected and only allow a small percentage to grow large enough to
make the longer connections. This keeps the average size of the neurons down."
Long-tailed macaques (Macaca fascicularis aurea) on Piak Nam Yai, one of Thailand's islands, are using stone tools to process and eat shellfish and nuts, a new study led by Dr. Michael Haslam from the University of Oxford shows. The study actually provides the first archaeological evidence of tool use by Old World monkeys, and finds that the macaques have been using the technique for decades, if not thousands of years.
"We find that primates with much smaller brains than humans have innovative ways of
exploiting the food sources available to them," Dr. Haslam said.
"Macaques in the forests on the island come down to the shore when the tide is out
to forage, and use stones as tools in order to break open shells and hard nut casings to
access the food inside."
The macaques break open oysters attached to large boulders. They dislodge the top half of the shell using their crushing tool and then scoop out the meat with their fingers. Once a macaque has a good stone for the job, they keep it to crack open other shells or nuts.
The macaques often discard their tools around where they had enjoyed their meal. So, when the animals had left the shore, Dr. Haslam's team went on land to closely examine the tools for marks. They found features such as pitting on the flat side, or crushing and fracture marks on the narrow ends of the stones.
The scientists also excavated the area beneath a prominent boulder for evidence of discarded stone tools used by previous generations of macaques. Having identified the tell-tale marks of food processing, the team spotted ten tools in the oldest archaeological layer, at 65 cm below the surface.
The excavated tools have been dated between 10 and 50 years old by obtaining radiocarbon dates for oyster shell debris found in the same undisturbed archaeological layer.
"What we don’t have at the moment is a body of archaeological evidence to compare
the evolutionary behavior of other primates with our own," Dr. Haslam said.
"Uncovering the history of the macaques’ foraging behavior is a first step."
"As we build up a fuller picture of their evolutionary history, we will start to identify
the similarities and differences in human behavior and that of other primates."
According to a new study published in the journal Scientific Reports, fish can discriminate between human faces.
"Being able to distinguish between a large number of human faces is a surprisingly
difficult task, mainly due to the fact that all human faces share the same basic
features," said study lead author Dr. Cait Newport, a researcher at the
University of Oxford.
"All faces have two eyes above a nose and mouth, therefore to tell people apart
we must be able to identify subtle differences in their features. If you consider the
similarities in appearance between some family members, this task can be very
"It has been hypothesized that this task is so difficult that it can only be
accomplished by primates, which have a large and complex brain. The fact that the
human brain has a specialized region used for recognizing human faces suggests that
there may be something special about faces themselves."
"To test this idea, we wanted to determine if another animal with a smaller and
simpler brain, and with no evolutionary need to recognize human faces, was still able
to do so."
The study authors found that archerfish (Toxotes chatareus) are capable of discriminating one face from up to 44 new faces. The archerfish (which are known for their ability to spit jets of water to shoot down aerial prey) were presented with two images of human faces and trained to choose one of them using their jets. Later, when presented with the learned face and a series of new faces, the fish were able to select the face they had initially learned to recognize.
"Using a two-alternative forced-choice procedure, we show that archerfish
(Toxotes chatareus) can learn to discriminate a large number of human face images, even
after controlling for color, head-shape and brightness," the scientists said.
"This study not only demonstrates that archerfish have impressive pattern discrimination
abilities, but also provides evidence that a vertebrate lacking a neocortex and without an
evolutionary prerogative to discriminate human faces, can nonetheless do so to a high
degree of accuracy."