In all three reports the findings were groundbreaking with phrases like "first known" and "most ever."
The range and sensitivity of senses and the different information being sensed -- in all of the animal kingdom -- is mind boggling and goes far beyond the traditional five human senses of taste, touch, smell, hearing and sight. National Geographic, for example, wrote, "Greater mouse-eared bats set their internal magnetic compass using the pattern of light polarization -- light that vibrates in one direction."
Human ears (left) with stereo capability can hear a broad range of sound but other animals have more complex and sensitive ears and can hear a wider or different range of frequencies. This young antelope (middle) has large ears which it can move to focus sounds. Bats (right) depend on their antennae-like ears to determine distances using echolocation, i.e. bouncing changing sounds off of objects.
But understanding animal senses does not stop with the raw data that is sensed. Often this data is processed by the animal's brain, making it much more sensitive. So while a dog has 300 million smell sensors vs. 6 million for humans (a factor of 50), it also has proportionally 40 times more of its brain devoted to analyzing smell than human beings. This means that a dog is 10,000 times more sensitive to smell than humans according to the latest research reported by NOVA on PBS.
Human smell (left) is one of our weakest senses, far surpassed by dogs (middle) who are 10,000 times more sensitive and bears (right) whose ability to smell is 7 times more sensitive than dogs.
Senses are also used in combination with other abilities of an animal, such as the duck-billed platypus who can sense tiny electric impulses in its prey -- and then can zero in on the location by moving its bill in a sweeping manner.
"The platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors. This would explain the characteristic side-to-side motion of the animal's head while hunting." (commons.wikimedia.org)But defining and describing animal senses is only part of how senses operate in a living organism, which brings us to the classic subjective/objective debate. While the stimuli that a sense perceives is clearly outside the organism, the way that the stimuli is interpreted and acted on is determined by the animal, i.e. it is subjective.
With human eyes for example:
"Almost all higher order features of vision are influenced by expectations based on past experience. This characteristic extends to color and form perception...to face and object recognition...and to motion and spatial awareness..." http://www.brainhq.com/brain-resources/brain-facts-myths/how-vision-works
Eyesight is probably the strongest human sense (left) with full color stereoscopic vision and a remarkable ability for edge detection. But other animals such as eagles (middle) have 3.6 times the human visual acuity. Some insects (right) have a compound eye with a fisheye view (180 degrees) of the world that can see objects in focus both near and far at the same time.
In addition, many parts of the brain are often involved in processing the data that is sensed. With face recognition, for example.
"Until now, scientists believed that only a couple of brain areas mediate facial recognition. However scientists have discovered that an entire network of cortical areas work together to identify faces.'This research will change the types of questions asked going forward because we are not just looking at one area of the brain," said Nestor...lead author of the study. "Now, scientists will have to account for the system as a whole...:" http://www.sciencedaily.com/releases/2011/05/110531121319.htmThis means a sound that is objectively 261.6 Hz and 70 decibels will have a different meaning for a human than for a mouse, for example. This sound is middle C or a musical note played at the normal volume on a radio. To a human being it would carry a musical meaning, perhaps reminding him or her of a sweet song but to a mouse it might be a warning that a human was nearby.
And what is my point in this blog about the human experience of time?
I believe that humans have a unique sense, a sense of time that only we possess. And given the wide range of animal senses, it should not be surprising that we might have a sense that other animals do not have. In addition we have the largest brain relative to our body size, a brain which we now know is quite flexible (neuroplasticity). It is capable of storing memories, imagining future events and learning and working with concepts such as long term time both past and future. I believe that this unique sense of time is the principle reason we have become the dominant species on the planet.
Scientific findings have confirmed that there are unique parts of the human brain that deal with time.
"This ability to hold on to a piece of information temporarily in order to complete a task is specifically human. [ED: my emphasis] It causes certain regions of the brain to become very active, in particular the pre-frontal lobe. This region, at the very front of the brain, is highly developed in humans. It is the reason that we have such high, upright foreheads, compared with the receding foreheads of our cousins the apes. Hence it is no surprise that the part of the brain that seems most active during one of the most human of activities [ED: short term memory] is located precisely in this prefrontal region that is well developed only in human beings."Perhaps the most extreme example of short-term memory is a chess master who can explore several possible solutions mentally before choosing the one that will lead to checkmate." SHORT-TERM MEMORY': McGill University, Montreal, Canada
QUOTE FROM WIKIPEDIA ABOUT HUMAN SENSES
Perception not based on a specific sensory organ
Chronoception refers to how the passage of time is perceived and experienced. Although the sense of time is not associated with a specific sensory system, the work of psychologists and neuroscientists indicates that human brains do have a system governing the perception of time, composed of a highly distributed system involving the cerebral cortex, cerebellum and basal ganglia.
NOTE: It is quite significant that the most used noun in the English language is *time* according to the Concise Oxford English Dictionary, with the words year, day and life not far behind. While I can document this for English, I don't have the resources to document this in other languages -- but I assume that time is the most used noun in other languages as well.While we cannot go back tens of thousands of years to reconstruct how a long term sense of time came about, there is perhaps another way to understand how it developed. When our children are young, they only live in the moment, but over years, especially as a result of education, they learn a long term sense of time. This process occurs starting with childhood, continues until adulthood and can be observed and studied.
Measures of performance on tests of working memory increase continuously between early childhood and adolescence; theorists have argued that the growth of working-memory capacity is a major driving force of cognitive development.
School Teaches Cultural Assumptions About Time
During the twenty year 'long childhood' of humans, young people learn their culture's expectations about time. While I will write a full blog about this, suffice it to say students in school learn about time more than any other subject. They learn to arrive on time, to not be late to each of their classes and to manage time such as doing their homework or studying for a final exam. These time demands become more stringent as a student gets older.
"People can time-travel cognitively because they can remember events having occurred at particular times in the past (episodic memory) [ED: e.g. the sense of when] and because they can anticipate new events occurring at particular times in the future. The ability to assign points in time to events arises from human development of a sense of time and its accompanying time-keeping technology." William Roberts, Are Animals Stuck in Time?
Take, for example, this very simple sentence that anyone of us might say -- yet which is extremely sophisticated:"When I finish this job in about an hour, I will be done for the day."This sentence which includes past, present, future and future perfect (a past that is in the future at the present time but will be past at a future point), is something we humans understand, but cannot be understood by any other animal.
While we have all learned to live with clocks and show up on time, our personal sense of 'when' is not tied to man-made artificial timekeeping.
"Sharks smell through a pair of nostril-like holes, called nares...When its olfactory sensors detect the odor of a potential catch, the shark will turn into the current that is carrying the chemical. In addition, a shark's olfactory talents are so refined that it can often tell which of its nares is getting the stronger scent signal, guiding it even more precisely toward its prey." http://www.pbs.org/kqed/oceanadventures/episodes/sharks/indepth-senses.html
Understanding other types of animal senses has led to major scientific breakthroughs in the past, such as the development of radar which came about in part due to the study of how bats navigated in the dark and which also led to the development of sonar and ultrasound technology. (commons.wikimedia.org)
Because humans have hands that are free along with good vision,eye-hand skills have been critical to the creation of civilization. (commons.wikimedia.org)
The incredibly intuitive ancient Greeks said most of what I have written about the human sense of time through their mythology.
Detail: "The creation of man by Prometheus. Marble relief, Italy, 3rd century CE." Louvre Museum, Paris, France. (commons.wikimedia.org)
THE CREATION OF HUMANS AND THE ANIMALS
"Epimetheus began by giving the best traits to the animals — swiftness, courage, cunning, stealth, and the like — and he wound up with nothing to give to man. So Prometheus took the matter in hand and gave man an upright posture like the gods."
Yet since the natural qualities of fur, flight and strength etc. and had been taken, Prometheus went a step further to help mankind. He famously stole fire from the gods.
"Fire was bestowed upon mankind by Prometheus and with it came the beginning of civilization. Prometheus taught man how to craft tools from iron ore. He showed them how to plant crops and live through agriculture. Man learnt to craft weapons to defend themselves from wild animals. With fire they learnt to survive cold winters and defy the seasons. With fire man began to thrive and became superior to the animals of the wild."
In stealing fire from the gods, Prometheus also taught humans how to think ahead because starting a fire, keeping a fire going, cutting wood for the winter -- all took forethought, the skill needed to master time.
By stealing fire from the gods, teaching men crafts and agriculture, Prometheus, the god of forethought, gave man the gift of long term time, a quality more powerful than claws and sharp teeth. He taught humans about planning, about steps in a process, about the concept of 'when'. So only humans were given the ability to understand this dimension of time -- something the creatures impulsively made by his brother, Epimetheus, did not have.